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Advanced Biomedical Materials CDT

Student wearing white lab coat and glasses peering towards some equipment

Research projects

CDT research projects are co-created by you, the supervisors and various stakeholders.

Grace McDermott, Advanced Biomedical Materials student

I look forward to the industrial and international collaborations as well as the closer interface of clinically relevant research driven by the programme.

Grace McDermott / Advanced Biomedical Materials student

After a three-month teaching period, you'll start to think about the area that you want to focus on.

Project topics are chosen in February and begin in March in the first year either in Manchester or Sheffield.

Browse through the projects available for 2020 below, and please don't hesitate to contact us with any enquiries.

Available projects

All available projects are listed below. Projects marked * are those which are working with industry.

Projects at The University of Manchester

A smart disposable device for ophthalmic point-of-care*

Supervisor

Philip Morgan

Project outline

The human tear film contains hundreds of proteins and lipids and these biomarkers are potentially important for the diagnosis of local and systemic disease and for predicting the success of contact lens war. Routine collection of the tear film is problematic because of the low volume of sample which is collectable (as low as 1µl per eye), and the impact of factors which are inherently variable such as clinical collection method and variations in patient blinking.

A smart disposable device which is capable of fitting comfortably under the lower eyelid and which is capable to tear film collection and assessment would represent a major diagnostic and analytical advance. This work would constitute part of broader work which addresses the following milestones: tear collection and fluid delivery, a point of care test and senor data processing.

Main questions to be answered

Three important questions are:

  1. What benefits does the smart ophthalmic device offer over current tear film collection methods?
  2. Is the device more reliable that current collection methods?
  3. Can the device be manufactured in form which is comfortable and wearable by potential patients/customers?

Bioengineering of a 3D gut model for drug permeation research

Supervisor

Jian R Lu

Project outline

The intestine represents the interface between the body and food and drink we consume. It mediates the uptake of nutrients and bioactives, including therapeutics, and acts as the line of defence for removing toxins, mutagens and carcinogens ingested. Because of the huge complexity involved, it is essential to undertake as much lab based model research as possible before any animal studies are considered (NC3Rs). However, current gut model research heavily relies on the Transwell culture based on the Caco-2 cell monolayer. This model and other similar ones lack structural and morphological complexity, making them unsuitable for studying efflux transport and metabolic enzymes expressed in the intestinal epithelium.

The aim of this PhD project is to harness recent advances in the design and fabrication of nanoporous conducting composite fibre materials from Dr Jiashen Li’s lab, the recently developed short peptide self-assembled bionanomaterials with antimicrobial release capability from Prof Jian R Lu’s group to construct functional cell sheets as a more physiologically-complex 3D model of the human small intestine. Lu and Penny have developed a Transwell culture based 3D gut model in which the underlying fibroblasts were grown in a collagen scaffold, but there are shortcomings with the scaffold concerning its instability during cell growth implicated by hydrolysis and hydration. In a more recent study using poly(L-lactic acid) (PLLA) and poly (lactic acid)-poly(lactic- glycolic acid) (PLA-PLGA) micro- and nanoporous fibre membrane scaffolds, cell growth was substantially improved, evident from transepithelial electrical resistance (TEER) and permeation behaviour (Carter J, in preparation).

Main questions to be answered

The core part of this project is to extend previous work by demonstrating the consistency and reproducibility in the fabrication of the gut model, focusing on the design and production of the porous fibre membrane scaffolds, evaluation of their structure, stability and functionality for further improvement. The novelty and the central focus of this project is to explore how nanoporous polymeric PLLA and PLA-PLGA membrane scaffolds fabricated from electrospinning and subsequent processing can be further transformed by incorporating conducting polymers such as polypyrrole (PPy) and poly(3,4ethylenedioxythiophene) (PEDOT) with and without infusion of self-assembled short peptide bionanomaterials – the questions to be asked are:

  1. How will the conducting polymers affect the integrity and stability of the new composite fibres and their conducting and permeation?
  2. How can the composite membrane scaffolds be fabricated reproducibly?
  3. How do the new composites affect cell growth?
  4. How does conductivity affect transmembrane permeation of model drugs?
  5. How does incorporation of ECM mimicry peptides affect biocompatibility?
  6. How can antimicrobial peptides (AMPs), once loaded, be manipulated by applying small external current and voltage?
  7. How do AMPs affect cell growth?
  8. Would AMPs selectively target bacteria in a co-culture with the gut model?

Developing CXCR4-targeted drug delivery biomaterials for treatment of chronic lymphocytic leukaemia (CLL)

Supervisor

Simon Webb

Project outline

Present therapies for CLL can induce major disease regression but almost all cases will have a significant residual population of neoplastic cells. Consequently, treatment duration is prolonged, incurring high financial cost, while the variability of residual CLL lymphocytes predisposes patients to the emergence of treatment-resistant clones. Targeted delivery of therapeutic agents within liposomal materials offers an innovative solution to this problem: selective delivery of therapeutic agents to CLL cell populations while protecting the contents from degradation, significantly enhancing drug effectiveness.

The proposal will exploit a new molecular motif (BAT1) that has recently been developed by Burthem and Webb. BAT1 presents a bis(cyclam) that binds to the CXCR4 receptor with high affinity, and it has a hydrophilic tether that permits its linkage to surfaces through a primary amine terminus. The circulating cells of CLL have high expression of CXCR4, and the interaction between CXCR4 and its ligand CXCL12 controls cell migration and enhances the survival of CLL lymphocytes.

BAT1 therefore has several modes of action:

  • (a) it blocks direct survival signals caused by CXCL12 and impairs CLL cell emigration from the bloodstream into tissues;
  • (b) its targeting function allows BAT1-liposomes to deliver their therapeutic contents to the CLL cells.

We have recently shown that attachment of BAT1 to liposomes provides a multivalent display that supports binding to CXCR4-expressing cells from patients, leading to targeted delivery of the exemplar drug doxorubicin with high (relative) specificity and blocked migration of these CXCR4-expressing cells.

Main questions to be answered

  1. In addition to our selective delivery of doxorubicin, we wish to deliver new therapeutic agents known to be effective against CLL (eg. ibrutinib, fludarabine, mitoxantrone); these will be incorporated in the liposomes. The materials properties of the liposomes will be modified to optimise their carriage of different therapeutic cargos, and to promote endosomal escape.
  2. Additional modifications of the liposomal surface to improve circulation and targeting will be explored. Glycolipids and cleavable PEG stealth lipids will be used in addition to BAT1 modification. Lipid-attached glycan molecules, synthesised through a high-throughput chemoenzymatic approach, will be included in the liposome formation; these are selected to increase CLL-targeting specificity, adding functional capability or directing uptake-pathway.
  3. To expand the concepts developed in 2) and further exploit this technology, the modification of other biomaterials with BAT1 and glycan motifs will be assessed. For example, carboxymethylcellulose (CMC) is a key component of wound-healing bandages and is currently studied by joint Webb/Flitsch and Webb/ConvaTec PhD students. The surface modification of CMC with S-Lex glycan could promote local accumulation and activation of cells of the adaptive immune system, which could significantly benefit both immune responses to tumours and wound treatment.

Development of artificial retinas for the treatment of degenerative eye disease and the augmentation of vision

Project title

Development of artificial retinas for the treatment of degenerative eye disease and the augmentation of human vision

Supervisor

Michael Turner

Project outline

In the United Kingdom, almost two million people live with some form of sight loss with the most common causes of vision loss being retinal pigmentosis and age related macular degeneration (AMD). AMD affects over 600,000 people in the UK and is expected to rise to almost 700,000 in 2020. Recent studies in the USA have shown that the likelihood of developing AMD increases from 2.5% of population at age 50 to 14% at 80 years old, as the average age of the population continues to increase then this will be a larger problem for future generations.

The loss of vision, in general, can be associated the absence or loss of photoreceptors, cones and rods, of the retina while the neural cells in the retinal network remain functional. To date artificial prostheses aimed at restoring vision are currently based on photoactive inorganic semiconductor device structures that have been implanted on the surface or embedded within the retina to stimulate a neuronal response.

These devices require complex circuitry, external power and typically suffer from poor biocompatibility and mechanical incompatibility with biological tissue. Improved devices that use the direct photovoltaic response of an implanted array of photodiodes driven by a focussed NIR input that projects the output of an external video camera that samples the visual field.

The NIR input is required as currently in these devices the input ambient light is too dim by a factor of at least 1,000 to produce sufficient photocurrent in the implanted devices to directly stimulate neurons. These devices hence give a single input to the patient and are converted to a black and white image by the retinal network.

Main questions to be answered

This project will examine whether organic semiconductors and organic electronic devices can deliver improved retinal prostheses that are:

  • More sensitive than existing implants to enable direct detection of visual stimuli.
  • Deliver a pixelated spectral response than mimics the output of biological photoreceptors, i.e. red, green and blue cones and rods.
  • Enable neuronal stimulation for colour perception.
  • Examine the possibility of hyperspectral imaging (i.e. UV or NIR neural stimulation) for enhanced human perception.
  • Biocompatible to retinal tissue.
  • Mechanically compatible with biological tissue.

The successful student will develop aqueous inks based on conjugated polymer nanoparticles that are tuned to harvest the maximum photoresponse to visible light over well-defined spectral ranges that are consistent with biological photoreceptors. These inks will be used to print an array of organic electronic devices on soft plastic substrates that can be interfaced directly with retinal neurons to stimulate an optical response. Working with others arrays of devices for multispectral response will be developed and integrated into a system capable of operating as an artificial retina. These will be examined for in vitro performance and promising systems will be taken forward to in vivo studies in visually compromised model systems.

Development of graphene containing 3D printed scaffolds for orthopaedic applications

Supervisor

Olga Tsigkou

Project outline

There is a huge unmet need for millions of people worldwide who suffer bone loss due to injury, infection, disease, or abnormal skeletal development for substitute bone that can seamlessly incorporate itself into the body.

Synthetic materials that can mimic the bone architecture at the micro and macro-scale as alternative bone graft substitutes eliminate risks of donor site morbidity and infection, while being readily available. Substrate intrinsic characteristics such as chemistry, nanotopography and mechanical properties can induce adult stem cell differentiation towards specific lineages. For bone cell growth, vascularization and extracellular matrix deposition stiff 3D porous scaffolds that mimic the bone tissue microenvironment are needed, which traditional methods such as freeze-drying and salt-leaching cannot produce. 3D printing (additive manufacturing), due to a uniform deposition of material according to a computer aided design, can seamlessly control size, density and pore interconnectivity therefore produce patient tailored architectures.

Electrical stimulation has been reported in many animal and clinical studies to enhance bone tissue regeneration through induction of ALPase activity, ECM deposition and mineralisation. The optimal current for bone tissue regeneration is ranging from 5–20μA for bone tissue regeneration. Graphene is as an atom-thick material, which due to its remarkable electrical conductivity, tuneable surface chemistry, maximal surface-to-volume ratio, easy functionalization capacity and mechanical properties has been studied as a biomedical material for bone tissue applications.

Main questions to be answered

This project will focus on the development of an alginate-graphene based ink for 3D printing scaffolds with tuneable pore size, macro-architecture, mechanical properties and electrical conductivity for bone tissue engineering.

The specific questions that this project will answer are:

  • What is the optimal graphene/hydrogel ratio for the development of inks with optimized rheological properties required for 3D printing?
  • Can alginate-graphene inks be developed to successfully print complex 3D structures that mimic trabecular bone architecture? For the mechanical and physical aspect, does graphene increase the strength, elastic modulus, surface roughness and electrical conductivity of the scaffold?
  • What is the effect of scaffolds architectural features, such as surface printed roughness and pore shape/size on bone marrow derived mesenchymal stem cell attachment, viability and differentiation and can they support bone ECM deposition and mineralisation?
  • What are the materials’ electrical and mechanical responses and how they affect materials-cells interactions and bone tissue formation?

Potential of graphene oxide in the repair and regeneration of musculoskeletal tissues

Supervisor

Leela Biant

Project outline

Osteoarthritis is the most prevalent condition worldwide without a disease-modifying drug or cure. It is the cause of significant patient pain and disability, and there is a huge associated personal, healthcare and societal economic burden.

Graphene oxide (GO) and reduced graphene oxide (RGO) have shown regenerative osteogenic potential. There is emerging evidence that GO within hydrogels can act as a growth factor delivery carrier able to enhance chondrogenic differentiation of mesenchymal stem cells. GO therefore represents a promising strategy for musculoskeletal regeneration. The osteochondral unit that fails in articular cartilage injury and osteoarthritis may have enhanced repair potential using GO. However, the osteochondral unit failure happens within the biological milieu of the whole joint (for example, the knee). The other tissues affected in knee osteoarthritis, or indeed with early injury: meniscus, ligament, synovium and synovial fluid are not yet researched with regard to their regenerative potential with GO.

Main questions to be answered

  • How does GO interact with the different tissues of the osteoarthritic knee?
  • Is the regenerative potential for musculoskeletal tissues facilitated by GO?

Real-time, low cost, point-of-care biomimetic sensors for pathogen detection within clinical settings *

Project title

Real-time, low cost, point-of-care biomimetic sensors for pathogen detection within clinical settings, exemplified against candida auris (project working with industry)

Supervisor

Christopher Blanford

Project outline

There is an urgent need to develop rapid, inexpensive, point-of-care detection for the multidrug-resistant fungi found in the environment. Candida auris was first described in Japan in 2009. Since then it has caused hospital outbreaks in every continent. In April 2019, it was reported that eight Britons died from C. auris infections and 587 cases were reported in the US. It is a challenge to identify accurately in the clinical laboratory, is inherently resistant to frontline antifungals, and survives on patients’ skin and in their immediate environment for weeks or months. It is a serious global health threat with a high mortality in invasive and bloodstream infections. Hospital control procedures have yet to be codified and eradication from the skin can be problematic.

This research will exploit the peculiar salt-tolerance traits of C. auris and the specific mechanisms it uses to recognise a host and then evade the host’s defence systems to gain infection. We propose to use scalable manufacturing techniques such as embossing to make single-use, centimetre-scale sensing elements that mimic infection sites’ microstructure and chemistry. C. auris has been reported to secrete several hyphae-inhibiting metabolites. These will be exploited to trigger enzymatic cascade reactions and elicit a colour change.

Colour changes will be continuously imaged and interpreted, through machine-learning (‘AI’) techniques, to detect both the earliest onset of a viable infection as well as quantify the resulting rapidity and virulence. The underlying transduction will be a commodity digital imaging array incorporated within a networked device.

Main questions to be answered

  • Can a network of C. auris sensors provide an early-warning system for infection in clinics, hospitals and other vulnerable communities? What density of sensors is required? Will the alert come early enough in the pathogen’s reproductive cycle that effective prevention and control measurements can be undertaken?
  • How can the system be engineered for “set and forget” point-of-care use? How can the battery life of the transduction system be maximised? How frequently does the environment need to be sampled? Can patterns of detection over a wide area identify sources of infection and predict new sites of infection?
  • How can a stable, inexpensive chemical colorimetric detection be developed to selectively identify C. auris? What modifications will be required to allow these systems to thrive in a high-salt environment? What are likely sources of false positives and can they be eliminated? How do surface chemistry and topography contribute to fungal culture on these sensors?
  • Can this technology be made cost-effective enough for healthcare in emerging economies or for agricultural fungal infections?

Reverse engineering a human blood-brain barrier platform for studying neurovascular diseases

Supervisor

Nigel Hooper

Project outline

Dysregulation of the blood-brain barrier (BBB) is an early and critical event in the pathogenesis of neurovascular diseases, such as Alzheimer’s disease, vascular dementia and stroke. However, there is a lack of knowledge of the molecular and cellular mechanisms underlying the breakdown of the BBB in these diseases due to the difficulty in studying the BBB in vivo.

The multicellular neurovascular unit (NVU) is central to the regulation of BBB function in health and its dysfunction in neurovascular diseases. The NVU comprises endothelial cells, pericytes, astrocytes and neurons. Complex and dynamic interactions between these cells and the surrounding extracellular matrix (ECM) regulate BBB (dys)function.

Appropriate BBB models are essential for understanding the pathological neurovascular functions in Alzheimer’s and vascular dementia and for studying the transport efficacy of drugs that target the brain. Highly robust, predictive and cost-effective in vitro BBB models are needed that accurately recapitulate the complex cell-cell and cell-ECM interactions within the NVU.

This project will focus on incorporating hydrogels that mimic the physical and chemical properties of the brain ECM, 3D bioprinting and microfluidic technology to recapitulate the capillary blood flow, along with the co-culture of human induced pluripotent stem cell (iPSC)-derived endothelial cells, pericytes, neurons and astrocytes, to reverse engineer a 3D BBB model.

This reverse engineered BBB model will exhibit physiologically relevant structures such as tight junctions and its permeability will be comparable to in vivo values, providing a platform to study neurovascular (dys)function and to screen for brain-targeting drugs.

Main questions to be answered

The ECM provides mechanical and biochemical cues to cells and components of the ECM, such as heparan sulphate proteoglycans (HSPGs), promote the formation and aggregation of amyloid which drives the development of Alzheimer’s disease. This project will use induced-pluripotent stem cells (iPCS) differentiated into endothelial cells, astrocytes, pericytes and neurons, in conjunction with novel hydrogels, 3D bioprinting and microfluidic technology to reverse engineer a human BBB model which will be used to answer these questions:

  1. What is the most appropriate natural hydrogel that recapitulates the in vivo mechanical (stiffness, elasticity and viscosity) and biochemical (cell adhesion) properties and supports the growth of the multiple NVU cell types?
  2. What is the contribution of individual ECM components (HSPGs, hyaluronic acid, fibronectin, perlecan etc) to the integrity of the BBB?
  3. What is the effect of alteration of the ECM (e.g. increased stiffness, reduction in proteoglycan content) on BBB function and amyloid deposition?

In addition, the optimised reverse engineered BBB platform will be used to screen for soluble ligands and small molecules that may have the ability to rescue the BBB dysfunction in Alzheimer’s disease.

Self-assembly peptide hydrogels: functional characterisation for peritoneal delivery

Supervisor

Kay Marshall

Project outline

Endometriosis is a debilitating condition that affects an estimated 176 million women worldwide. In endometriosis, cells similar to the lining of the womb grow elsewhere in the body, typically around the reproductive organs, bladder and the bowel. These endometrial-like cells form lesions that thicken, break down and bleed with each menstrual cycle leading to inflammation and the formation of scar tissue. Chronic pelvic pain, infertility and bowel obstruction are the most common symptoms with a significant impact on health-related quality of life estimated at £8.2 billion per annum in the UK alone.

Major symptoms are eased by laparoscopy (keyhole surgery) where deposits of endometriosis are located and destroyed. However, recovery is often short-lived with over 22 percent of women requiring repeat operations due to the regrowth of residual endometriosis cells and/or the formation of new adhesions from surgical trauma. Even after surgery, continuous use of oral contraceptives and progestins are recommended for endometriosis-related pain. Often they cause side effects, including mood changes, acne and headaches, and are unsuitable in women who desire pregnancy. Good medical management may require alternative routes of drug delivery to target sites of endometriosis, such as use of a sophisticated pelvic hydrogel system.

Main questions to be answered

  1. What are the optimal biomechanical and biochemical properties of the novel self-assembling hydrogel to ensure slow, temporal release of anti-oestrogenic drugs at their site of application?
  2. How do the pharmacokinetics, biodistribution and eventual fate of the hydrogel scaffolds change over time?
  3. Is the drug delivery system of clinical relevance? Are the therapeutic effects comparable in mouse and human cells?
  4. Do drug-loaded hydrogels cause endometrial atrophy without affecting the oestrous cycle?
  5. What are the local tissue reactions and foreign body responses to in situ hydrogel implants (changes in hormones, fibrosis, growth factors and inflammatory mediators)?
  6. How does it affect peritoneal regeneration? Is the gross histology of repaired tissues normal (integrity of mesothelium, connective tissue and vasculature)?
  7. Can a device be adapted (e.g. port catheter, spray) for administration of hydrogels within the pelvic cavity?

Smart biomaterial composites with hierarchical architecture for ligament repair and regeneration

Supervisor

Ahu Gumrah Dumanli-Parry

Project outline

Engineering synthetic scaffolds to repair and regenerate ruptured native ligament tissues is a significant engineering challenge due to the need to satisfy both the unique biological and biomechanical properties of these tissues. The graft choice for anterior cruciate ligament (ACL) reconstruction continues to be controversial. While Patellar Tendon (PT) and hamstring tendon (HT) grafts harvested from the patients themselves are still leading the surgical techniques, there is donor site morbidity that can slow rehabilitation and there is limited autologous graft available in for cases of multiligament injury. Linear synthetic fibrous constructs such as LARS (ligament advanced reinforcement system) has suboptimal biological properties which causes synovitis leads to poor success rates and the limitations on the surgery techniques limits their applicability to various cases.

The native human ligament tissue has unique tensile strength and cyclic loading abilities and shows resistance to creep deformation. It demonstrates efficient gliding to reduce abrasion. Such unique combination of mechanical properties is due to the specific hierarchical construction of these tissues; the ligaments primarily consists of longitudinally aligned hierarchical bundles of irregularly undulating, or “crimped,” collagen fibres ranging from 1 to 30 µm in diameter grouped into bundles called subfascicles (15–400 µm in diameter). These subfascicles are further bundled together to form fascicles (150–1000 µm in diameter). In order to mimic such complex mechanical performance, the synthetic grafts should also have similar hierarchical and dynamic structural properties.

Main questions to be answered

  1. The project involves clinical input and a real opportunity to map age related tissue profiling and differentiation via examining ligament tissues from patients that goes under ACL reconstruction surgery.
  2. We will address the influence of the hierarchical multi-scale physical construct of the ligament tissue on the mechanical properties.
  3. Can we use the mimic such complex hierarchical order in of the collagen using simple polysaccharides such as cellulose and chitin in 2D and 3D?
  4. How do multiscale ordered fibrillar structures need to be processed and optimized to give optimum mechanical properties?
  5. Is it possible to bioprint 3D cellular constructs with multiscale (macro-micro-nano) architectures and how does that improve the long-term biomechanical performance of the graft?

Smart nanoparticles as doubly responsive sensors for foreign DNA

Supervisor

Lee Fielding

Project outline

Dr Fielding has ongoing work into the preparation of polymeric hydrogels and colloidal diagnostics for healthcare applications (unpublished work). Dr Jones has developed a colorimetric platform to detect DNA and has expertise in working with viruses and anti-viral materials. The combination of complimentary expertise from the Fielding and Jones provides an ideal platform to develop a nanoparticle-based diagnostic which will act as doubly responsive sensors for foreign DNA. The unmet clinical needs which we seek to address to provide a simple test which can rapidly and easily identify whether a sample (e.g. from a patient) or a device (e.g. an implant or ocular lens) is contaminated with foreign DNA species (e.g. Virus, Bacteria or Fungus).

Main questions to be answered

This project aims to develop a nanoparticle-based diagnostic which will both gel and display a colour change in the presence of amplified DNA. It is well known that cationic nanoparticles can gel in the presence of anionic natural polymers and a colour change can be triggered when DNA binds to dyes prepared in the Jones’ lab. We aim to use both these strategies, in conjunction with isothermal DNA amplification to develop an assay for foreign DNA detection.

This will involve the following stages:

  • Preparing designer nanoparticles containing DNA binding motifs which display a colour change when complexed with DNA.
  • Demonstrating that these nanoparticles form a gel in the presence of amplified DNA.
  • Characterising the gels prepared in relation to relative DNA/particle concentrations and external stimuli.
  • Optimising dye/nanoparticle composition in conjunction with DNA amplification.
  • Initiating trials in clinic with interested clinicians.

Projects at the University of Sheffield

3D printed bespoke biodegradable drug eluting coronary artery stents produced using natural polymers

Supervisor

Ipsita Roy

Project outline

Coronary artery disease (CAD) is caused by narrowing of arteries due to the hardening of cholesterol, fats, and other components of the blood, causing inadequate supply of oxygen rich blood to the heart, leading to myocardial infarction. The most promising treatment of CAD is angioplasty which involves mechanical widening of narrowed blood vessels followed by the deployment of a coronary artery stent. The stent is deployed in its collapsed state and inflated inside the narrowed blood vessel, thus restoring normal blood flow.

There are three types of coronary artery stents, bare metal stents (BMS), drug eluting stents (DES) and the Bioresorbable Vascular Scaffolds (BVS). BMS and DES are metallic stents that result in foreign body reactions including inflammation, in-stent restenosis, thrombosis and stent jailing. BVS are made using bioresorbable polymeric materials which are tailored to resorb once the artery is fully repaired and its function is restored, hence preventing all the above-mentioned problems caused by the BMS and DES. However, the first BVS, ABSORB, produced by Abbott had to be withdrawn due to relatively poor clinical outcomes. The ABSORB stents had limited expansion, suffered from fracture problems, low radial strength, sub optimal strut width and negative recoiling.

The aim of this project will be the development of novel PHA-based 3D printed biodegradable coronary artery stents with tailorable mechanical properties, degradation rates, produced using patient specific CT scans and hence bespoke to specific patient needs, an absolutely unmet clinical need.

Main questions to be answered

  1. Optimal conditions for the production of a range of different PHAs including scl-PHAs, mcl-PHAs and scl-mcl-PHAs (copolymers).
  2. The optimal PHA blend/PHA copolymer with the required mechanical properties for a coronary artery stent (high Young’s modulus and reasonable elongation at break, enabling the stent to inflate and provide the required stiffness and radial strength).
  3. The optimal PHA blend/ copolymer with the required degradation rate. Ideally the stent needs to degrade completely within 2 years.
  4. The in vitro biocompatibility and haemocompatibility of the developed material
  5. The optimal conditions for 3D printing of the stent using the chosen PHA blend/copolymer.
  6. In vitro functionality of the 3D printed stents to be tested using a Biomechanical Reactor System (BMRS) provided by Biocompatible Engineering Solutions where the conditions within a coronary artery will be simulated.

A novel 3D osteochondral scaffold with mechano-identical properties of the native tissue for in situ tissue...

Project title

A novel 3D osteochondral scaffold with mechano-identical properties of the native tissue for in situ tissue regeneration

Supervisor

Aileen Crawford

Project outline

OA is a chronic global disease affecting over 8.5 million people in the UK, causing loss of the articular cartilage surface and changes in the underlying bone. This causes painful, stiff joints and progressive loss of joint mobility leading to functional impairment which can affect daily living and work activities causing a profound loss of quality of life.

Knee and hip joints have the major share of the OA burden loss of joint function. Treatments for OA give valuable pain relief and symptom control but there is no cure.

The progressive disabling nature of OA produces a substantial socio-economic burden of 1-2% GDP. Replacement of the joint with an artificial one may be necessary to restore joint movement, particularly in the knee and hip with 150,000 primary joint replacement operations per annum. While successful, replacement joints have a limited working life and may loosen requiring further corrective surgery. There is an unmet clinical need for an effective and economic regenerative therapy to treat OA and restore function to the joint.

Many patients would benefit if there was a more effective repair of lesions in the joint surface and underlying bone caused by trauma (a risk factor for OA) or early osteoarthritis. We propose an 'off-the shelf', multifunctional, osteochondral scaffold with physical and mechanical properties to match the biomechanical environment of native osteochondral tissue and designed to promote articular cartilage regeneration  by actively recruiting , binding and promoting chondrogenesis of stem cells released surgically during scaffold implantation.

To use appropriate blends of short chain-length poly-3hydroxybutyrate, P(3HB) and medium chain-length Poly-3-hydroxyoctanoate-co-3-hydroxydecanoate-co-3-hydroxydodecanoate), P(3HO-co-HD-co-HDD), polyhydroxyalkanoates (PHAs) to fabricate an osteochondral scaffold. This will have mechanical properties identical to native osteochondral tissue and have a trabecular bone-regenerating-region (BRR), an articular cartilage-regenerating region (ACRR) and a subchondral plate region (SP) to ensure weight bearing. Additionally, the osteochondral scaffold can be further enhanced by bioactivation using our coating technology of cold plasma allylamine deposition and bioactivation with stem cell homing and chondrogenic factors in the ACRR and /or osteogenic factor in the BRR. We have shown this process is achievable, not scaffold dependent and works in vitro and in vivo (patent pending).

The BRR (200-400µm pores) and SP (dense structure with mm pores for MSC migration) will be 3D printed. The ARR will be electrospun (4µm fibres) as a better mimic of the extracellular matrix. The mechanical properties will be determined, and the blends optimised to the required properties. The biocompatibility and suitability for cell growth and appropriate tissue formation of the BRR and ARR will be assessed using MSCs and MG63 (for BRR) chondrocytes and MSCs for the ARR using viability assays and gene expression of major osteogenic and chondrogenic proteins.

Bioactive nerve guides - anti-inflammatory and anti-scarring devices

Supervisor

John Haycock

Project outline

Injury to peripheral nerves through trauma, and sometimes surgery, results in over 300,000 cases each year in the EU. In contrast to the central nervous system, proximal motor and sensory axons have some ability to repair.  Individuals who sustain injury with no loss of tissue can be treated by directly suturing proximal and distal ends together, as end-end anastomosis.

A fundamental understanding of the molecular and cellular responses to injury is essential when designing approaches for repair, especially for implantable nerve guide conduits (NGCs). We have reviewed NGC performance in detail1, with conclusions supporting biomaterials improvements in NGCs a realistic approach (e.g. versus cell therapy). NGCs are typically made from inert biomaterials (eg. polyesters, collagen), and do not stimulate neuronal or Schwann cell adhesion, migration or differentiation for nerve repair.

Consequently, existing devices are poor at supporting regeneration. A major challenge is to increase regeneration distance from a few millimetres to critical gap distances of 10-20 mm. For clinically practical improvement, simple innovations in the biomaterial chemistry, in combination with fabrication methods for making porous and flexible materials to reflect the mechanical properties of nerve are proposed and will be investigated in this project.

In this project we also will address the problems of inflammation and scarring associated with nerve repair.  Devices will therefore delivery key anti-inflammatories (a-MSH, IL-10) and/or an anti-scarring compound (M6P) known to improve functional repair.  Devices will be evaluated in vitro, and in vivo in this PhD project, with a route to following on a clinical study of lingual nerve reconstruction.

Main questions to be answered

  1. Synthesise PGS blends with controlled degradation rates and mechanical properties as candidate materials for NGCs. The main questions are: a) suitability of PGS as a nerve implant biomaterial and b) value in exploiting soft mechanical properties of PGS for this purpose. PGS has been explored for cardiac patches and for retinal transplantation regeneration, but little to date on nerve repair. We recently published on PGS for supporting neuronal and Schwann cell growth in vitro and nerve repair in vivo, using a 1:1 ratio of glycerol:sebacic acid. This created a flexible polymer with favourable mechanical properties for soft nerve repair (3.2 MPa). PGS will be formulated as a low molecular weight prepolymer, which cross-links to produce a fully cross-linked elastomer (using in house methods). A range of blend ratios with varying modulus to support the growth of neuronal and Schwann cells will then be investigated. Primary neuronal and Schwann cells will be cultured on surfaces for 4 days to facilitate neurite sprouting, using methods developed in-house (eg. for selection of optimal blends).
  2. Fabricate PGS blends to form NGCs by microSL. The main question is on identifying an optimal PGS blend suitable for making NGCs by 3D printing. Optimal blends will be investigated in detail for NGC manufacture. Templates will be built by micro-stereolithography (microSL), which enables accurate and rapid construction of 3D scaffolds to make NGCs. We have published on core methods for PGS NGC manufacture4, and will extend these to investigation of porosity. Dimensions will be fabricated suitable for a critical mouse sciatic nerve 6 mm injury gap (8 mm length x 0.9 mm internal diameter x 250 µm wall thickness).
  3. Investigate the problems of inflammation and scarring associated with nerve repair. The main question is whether an increase in inflammation will impede regeneration, and whether local delivery key anti-inflammatories (a-MSH, IL-10) and/or an anti-scarring compound (M6P) will improve functional repair. Acute injury triggers an inflammatory response necessary for early repair, however chronic inflammation is known to be damaging, and can also lead to scar formation. We will therefore combine the scaffold properties of nerve guides, with the therapeutic delivery of a-MSH (a potent anti-inflammatory peptide), IL-10 (an anti-inflammatory cytokine) and/or mannose-6-phosphate (an anti-scarring compound). We have separately published on the roles of a-MSH, IL-10 and M6P as potential therapeutic agents.
  4. Evaluate prototype NGCs using a dorsal root ganglion 3D in vitro chick model. The main question is whether the chick dorsal root ganglion model will allow quantitative evaluation of porous constructs and identify optimal devices according to PGS blend and degree of connected porosity. Analysis will be undertaken for devices using an in vitro 3D chick dorsal root ganglion model established in our group. The model uses chick DRGs isolated at embryonic day development 12 (EDD12), and allows axon and Schwann cell migration distance to be determined. Variables in PGS blend and porosity (using a fixed number of optimally aligned fibres) by light sheet microscopy will be undertaken.
  5. Evaluate selected NGCs using thy-1 YFP mouse and rat in vivo models. The main question is to identify if an optimal PGS blend and porous density from in vitro selection (above) supports axon regeneration in vivo. In vivo evaluation will be conducted on NGCs using genetically modified mice with a subpopulation of axons that express yellow fluorescent protein (YFP). Studies in our lab using this model allow quantification of axon regeneration across injury sites. A critical 6 mm sciatic nerve gap injury will be created using a subset of optimally performing devices will be evaluated at 12 weeks following implantation.

Biomimetic responsive signalling systems

Supervisor

N. H. Williams

Project outline

The transmission and amplification of chemical signals across lipid bilayer membranes is central to many biological processes, from the development of multicellular organisms to information processing in the nervous system. This signal transduction is often associated with an amplified signalling cascade. The ability to reproduce such processes in artificial systems has potential applications in sensing, controlled drug delivery and communication between compartments in tissue-like constructs of membrane compartments. Furthermore, the development of systems that can modulate biomolecule activity, protein immobilisation, and cell adhesion and migration at the liquid–solid interface will be tremendously useful in diverse biological and medical applications. Mimicking the dynamic properties of biological systems requires the creation of responsive artificial systems that can control the presentation of regulatory signals to dynamically regulate biological functions in response to applied stimuli.

For example, the ability to detect local changes in pH is important in the detection of disease; so the development of methods for rapid, non-invasive assessment of changes in pH in complex media is important. As well as detecting changes in the contacting medium or the presence of specific signalling molecules, it is desirable to modulate protein or cellular interactions with synthetic surfaces that can respond to the signal by producing the controlled release of any desired therapeutic – leading to a more effective sensing and responding system.

Main questions to be answered

The main goal of this project will be to create a biomimetic transducer system which can respond to the complex environment of biological media, amplifying any signal and reacting to release novel materials as desired. The system will be generic, so that different targets can be addressed, and any small molecule released in reaction to the surrounding environment. The system will be dynamic, capable of amplifying the chosen signal and of returning to a resting state when the surrounding environment returns to its original condition. In earlier work, we have established a novel and versatile system which functions within vesicles. We aim to integrate this system within suspended membranes near patterned surfaces, so that the solid state can react to "wet" biological conditions.

Bone clip: Developing an angiogenic biomaterial to increase bone healing

Supervisor

Gwen Reilly

Project outline

Medical science has increased life expectancy by ~30% in the last 100 years. This increase in life expectancy is unfortunately not matched by a growth in health expectancy (the number of years in good health) and currently there is, on average, an 8-10 years gap between our life and health expectancy in the UK. During this period, many of us will suffer age-related diseases, which reduce our quality of life and come with a substantial socio-economic cost.

For example, osteoporotic fractures cost €37 billion and result in over a million of years in good health (quality adjusted life years) lost in the EU in 2010.

This project presents a conceptually simple approach to tackling delayed bone healing by using a proangiogenic biomaterial to clip around the damaged bone and stimulate angiogenesis to accelerate bone regeneration. In essence, we aim to develop and evaluate a periosteal bone substitute for clinical applications. This PhD project will build unique expertise to evaluate a tailored solution to this healthcare problem.

In this project we will investigate a synthetic, easy to handle biomaterial can be produced at scale, to release small stable molecules to stimulate angiogenesis when clipped around a non-healing bone defect to initiate bone repair.

Main questions to be answered

This project will study angiogenesis driven bone formation through harnessing innovative fabrication platforms based on polycaprolactone-based polymerised high internal phase emulsions (polyHIPEs). These porous materials can be additive manufactured to include a prototype vasculature. The periosteal substitute material needs to be highly porous to encourage endogenous cell migration and to be easy to load with proangiogenic agents if required.

The programme of work is described under the following objectives:

  1. To optimise the production polyHIPE based porous membranes via additive manufacturing supporting ingrowth of new blood vessels.
  2. To optimise angiogenic factor loading in polyHIPE membranes demonstrating temporal release and evaluating biocompatibility and proangiogenic activity using cultured endothelial cells.
  3. To evaluate loaded and unloaded polyHIPEs with proangiogenic agents for angiogenesis using the CAM assay and the bone defect model.

We will aim to produce a periosteal substrate which can be produced at scale from a well-accepted biodegradable material which can be sterilised and stored as an off-the-shelf sterile material. We hypothesise that by paying attention to the microfabrication of this PCL-based material we can achieve a relatively sophisticated membrane that can be produced at scale and presents a straightforward regulatory route to the clinic.

Development of an in vitro musculoskeletal model of human ageing

Supervisor

Nicola Green

Project outline

Globally, musculoskeletal (MSK) conditions are the leading contributor to disability and are commonly linked with depression and negative impacts on quality of life. MSK conditions have a significant economic impact worldwide and their prevalence is predicted to rise with an increasingly ageing global population.

Currently drug treatments for MSK conditions are screened using monocultures or, at best, co-cultures of cells growing in monolayers in vitro. However, the cell-cell and cell-matrix interactions within the tissues together with the differing mechanical and structural properties of these tissues at the interface between muscle, bone and cartilage mean that monolayer models fail to capture these interactions. MSK ageing also induces extracellular matrix changes but simple 2D monocultures are incapable of recapitulating these changes in any meaningful way. As a consequence, researchers often turn to animal models. However, important differences in size, anatomy and biomechanics limit their relevance and hinder successful outcomes in the MSK drug development.

Attempts to develop 3D models have been described in the literature, but success in this area is limited with many versions incorporating the cells from only one tissue type and therefore omitting the interactions between cell types. There is therefore an unmet need for a reliable, biologically relevant in vitro model of the MSK interface that can reduce and replace animal models, reflect the ageing process and thereby accelerate the development of MSK treatments.

Main questions to be answered

The project will build an in vitro MSK model containing three tissue types: bone, cartilage and muscle. Cells will be grown on 3D microporous polyHIPE (polymerised high internal phase emulsions) scaffolds, with graded mechanical properties to mimic those of the tissues. Electrospun, cell impermeable barriers will be used between regions of polyHIPE to limit cell infiltration while still allowing cell signalling to occur to ensure spatially controlled growth of cells. This will allow us to answer the following:

  1. Can a model be constructed which recapitulates the basic physiology of bone, muscle and cartilage? This will be assessed through (i) cell metabolic activity and proliferation, (ii) expression of relevant chondrogenic, osteogenic and muscle gene expression, appropriate extracellular matrix (ECM) production and mineralisation (for bone model), (iii) histological evaluation, (iv) cell imaging.
  2. Can ageing by induced through exposure to compounds known to promote the process of ageing? Advanced glycation end products (AGEs) and reactive oxygen species (ROS) are produced spontaneously during metabolism. They play important roles in MSK ageing in vivo and in vitro.
  3. Can the healthy and aged models be used to asses cell response to compounds used in MSK treatments e.g. ibuprofen, known to reduce bone healing and cartilage synthesis; and vitamin D, which may affect bone and cartilage regeneration?

Integration of polymeric 3D scaffolds within a perfused organ-on-a-chip system for the development of...*

Project title

Integration of polymeric 3D scaffolds within a perfused organ-on-a-chip system for the development of a soft organ model (project working with industry)

Supervisor

Fred Claeyssens

Project outline

An important research strand in biomaterials is the development of in-lab grown organs, which are increasingly mimicking the structural and biological complexity of human organs. These organs-on-a-chip (OOAC/microphysiological systems) are increasingly developed as an alternative to the use of animals in pharmaceutical testing. The field of OOACs is currently emerging beyond academic research and a number of companies are currently establishing themselves as key players in the field. One of these companies is CN Bio, who have developed a complete microphysiological OOAC system that can investigate multi-organ interactions, and provide a standardised chip/plate based system to investigate drug toxicity and more. In this project we will collaborate with CN Bio to develop polymeric scaffolds enabling 3D cell culture and incorporate these into the CN Bio perfusion system. We will develop soft and flexible polymeric systems to target the development of soft organ models within an organ-on-a-chip systems. These in vitro models will be used to explore healthy and diseased tissue models. For example, we could aim to explore inflamed and cancer tissue models. If successful, this device will fill an important unmet need as a multifaceted organ model/in vitro testing platform.

Main questions to be answered

The main aim of this project is to build an in vitro model of a soft tissue organ, which through the use of perfusion systems and a specialised microenvironment, can be grown in a lab environment and can be assessed as a lab-on-a-chip. We have recently developed the technology to enable this project, in particular we have developed scaffolds with prototype vascular networks based on electrospun membranes. We have also recently combined electrospinning with a 3D micrometer porous materials based on polymerised High Internal Phase Emulsion (polyHIPE).

The potential of these scaffolds/materials can be fully examined with the use of OOAC systems and specialised microenvironments developed by the industrial collaborator.

Additionally, both the academic team and the industrial collaborator have extensive experience in 3D printing of polymeric systems. These materials will form the basic technology to develop the 3D scaffold for the soft tissue model, which will be used to answer the following questions:

  1. Can a 3D tissue model be constructed for medium term cell culture (up to a month) in a perfusion OOAC system that can recapitulate the basic physiology of the native tissue. We will assess the following (i) cell growth and survival and (ii) extracellular matrix formation.
  2. The model will be used to assess drug response to understand if the model can predict any scenarios relevant to the pharmaceutical industry.
  3. The model will further be developed as a disease model, e.g. by incorporating an inflammatory cell component, or similar.

Microfabricating next-generation corneal membranes via the inclusion of partially-enclosed artificial niche...

Project title

Microfabricating next-generation corneal membranes via the inclusion of partially-enclosed artificial niche structures

Supervisor

Ilida Ortega Asencio

Project outline

Corneal disease affects millions of people worldwide with higher prevalence in developing countries. Corneal transplantation and the use of membranes as cell carriers (amniotic membrane, AM) have been relatively successful. Unfortunately, AM is costly and its availability is limited.

Researchers at Sheffield have been working together with LV Prasad Institute (LVPEI, India) with the aim of delivering new alternatives for simplifying corneal treatments and therefore increasing their accessibility. One of our approaches has been the development of a synthetic AM substitute that includes microfeatures to mimic the limbal niches of the cornea. Limbal stem cells are believed to reside in the limbus in well-define microenvironments or niches; these niches provide physical support to the limbal stem cells. Our first prototype niche-containing materials were regarded by our clinical collaborators at LVPEI as potentially very useful to assist them at the time of surgery. These niche structures could be use as guiding points and as points for securing tissue explants to the delivery membranes avoiding the use of fibrin glue (fibrin is expensive and not available in many countries and requires considerable expertise in its use).

Therefore, in this project we aim to design and manufacture a new microfabricated corneal membrane with improved partially enclosed niche designs, able to retain the corneal tissue explants delivered during SLET surgery (Simple Limbal Epithelial Transplantation). The project also will aim to understand the biological contribution of incorporating such niche structures to the membranes using an ex vivo corneal model previously developed and optimised at Sheffield.

Main questions to be answered

  1. Main manufacturing challenges:
    • Can we use electrospinning and 3D-printing approaches to design a new niche structure which is partially enclosed and able to self-hold a tissue explant (~500 µm size)?
    • Can we incorporate these niche designs within a cell delivery membrane and can the degradability and the mechanical stability of this microfabricated membrane be controlled?
  2. Biological questions:
    • How will epithelial and stromal cells residing in the tissue explants respond to different niche morphologies and sizes?
    • Would these niche structures have an impact in differentiation/migration pathways?
    • How these niche structures will impact on the regeneration of a wounded corneal epithelium?

Regenerating the oral mucosa in patients with MRONJ using synthetic poly(glycerol sebacate) scaffolds...

Project title

Regenerating the oral mucosa in patients with MRONJ using synthetic poly(glycerol sebacate)  scaffolds and uncultured adipose cells

Supervisor

Vanessa Hearnden

Project outline

Medicines related osteonecrosis of the jaw (MRONJ) is a severe side effect which occurs in patients receiving antiresorptive treatments for cancer and osteoporosis. MRONJ is defined as "exposed bone in the maxillofacial region that has persisted for eight weeks". Current treatments consist of symptom management but there are no effective cures.

The aim of this project is to develop a novel tissue engineered device which is able to restore the protective soft tissue barrier in patients with MRONJ. To do this we will use our previously developed in vitro model of soft tissue toxicity in MRONJ to design and test a device which incorporates uncultured cells from adipose tissues with a porous, biodegradable polymer scaffold to promote gingival regeneration and closure.

Poly(glycerol sebacate) is an elastomeric, biocompatible polymer which we have previously shown can support cell adhesion, cell proliferation, new matrix deposition and new blood vessel formation without the addition of biochemical stimuli. However, for MRONJ applications, where patients have poor wound healing, additional regenerative stimuli will be required.

Adipose derived stromal cells (ADSCs) have been shown to increase gingival healing in a murine model of MRONJ however regulatory challenges mean cultured cell therapies are still many years from clinical translation. Our research group and others have been studying how uncultured formulations of adipose tissues can provide a source of regenerative cells which can be delivered in a single surgical procedure. This project will test how the addition of cells isolated from adipose tissues can influence gingival regeneration in vitro.

Main questions to be answered

  1. How does the porosity and topography of poly glycerol sebacate (PGS) scaffolds affect gingival cell attachment, migration and re-epithelialisation?
  2. How does the addition of antiresorptive bisphosphonates affect gingival cell attachment and growth in combination with PGS scaffolds?
  3. How can uncultured adipose cells be incorporated into PGS scaffolds and how effective is this as a method of regenerative cell delivery?
  4. Can uncultured adipose cells on PGS scaffolds stimulate wound healing in our in vitro model of MRONJ?

The development of drug-eluting electrospun devices for clinical applications in gynaecology *

Project title

The development of drug-eluting electrospun devices for clinical applications in gynaecology (project working with industry)

Supervisor

Paul Hatton

Project outline

Gynaecological conditions may be painful and frequently impact negatively on a woman’s quality of life with a range of symptoms that include abnormal bleeding or discharges, difficulty in passing urine, and/or reduced fertility.  Current treatments have limitations in many cases, for example systemic drugs require a relatively high dose that risks side effects, while local topical creams may be rapidly washed away. Pessaries have been effective for some forms of drug delivery, but are not applicable for all conditions and have known drawbacks.

The multidisciplinary team supervising this project have a successfully developed an innovative electrospun polymer devices for delivery of therapeutic agents as a platform technology, and this has already been applied to address unmet clinical needs in oral medicine. This platform technology is however applicable to a wider range of situations where local drug delivery is challenging, and we propose here to extend to the field of gynaecology. Gynaecological conditions that would benefit from direct and sustained drug delivery include infections (eg Candida albicans) and lichenoid reactions in the vagina, endometriosis in the uterus, and promotion of healing post-surgery.

The aim of this research is therefore to design, fabricate, characterise and evaluate electrospun patches for unmet needs in gynaecology. On completion, by working with our clinical collaborators and industrial partners (Afyx Therapeutics in Copenhagen), the intention is to translate the most promising technologies for clinical trial and commercialisation.

Main questions to be answered

  1. What are the ideal properties for drug delivery technologies intended for gynaecological applications, and what polymer systems are therefore best suited for fabrication of an electrospun device? The polymer systems need to adhere for longer than the oral equivalents, and the vaginal and uterine tissues may be more easily irritated.
  2. Is it possible to reproducibly fabricate drug-containing electrospun devices using polymers identified for the specific applications prioritised above?
  3. Are drugs and other therapeutic agents released, what are the kinetics and duration of release, and do they retain their biological activity (in solution and in 3D tissue engineered models of the disease). We have previously published on the release of therapeutic agents and their detection in advanced 3D tissue models using mass spectrometry.
  4. Finally, are the new polymer systems capable of releasing other agents that may have a role in future advanced therapies for gynaecological applications, for example cells (for regenerative medicine) or viruses (e.g. for transfection and genetic modification)? The intention is to consider the new platform technology developed here for more advanced therapies including regenerative medicine and local genetic modification of host cells.