Translational development of a 3D bioactive nerve conduit for peripheral nerve repair, through application of topographical cues and stem cell support

Using Biotechnology to Improve the Outcome Following Devastating Nerve Injuries

Major nerve injuries can occur during birth, from accidental trauma, or as the result of cancer treatments. Unfortunately they are common (1-2 people in every 1000 each year), mainly affect young patients, and cause permanent disability. Many patients never return to gainful employment and all suffer long and painful recovery times. These injuries rank alongside cerebral palsy and spinal injury in terms of disability, and the effect on the lives of patients and their families. This in turn translates as a significant economic cost to society, both through medical interventions and loss of active members of workforce population. Furthermore, nerve repair limits what can be achieved with face or hand transplantation, and prevents useful transplantation of voiceboxes or legs, as the rate of healing is much slower and less successful than that of other types of tissue (e.g. skin/bone).
Reconstructive microsurgeons can repair damaged nerves, but even under the best circumstances many nerve fibres fail to cross the site of surgical repair or grow back to give function. If the damaged segment of the nerve is more than 1cm long, a sensory nerve must be borrowed from elsewhere in the body to bridge the gap, this causes scarring and permanent numbness at the donor site where this is taken from. Recovery is always very slow (~18 months), painful, and inadequate, since <50% of nerve cells actually regrow through traditional nerve repairs. It is vital that we discover what controls nerve healing and it is well recognised that we need to develop new technologies to improve surgical outcomes for these patients. Promising work is underway at the University of Glasgow and it's collaborating laboratories on this important topic.
Recent scientific advances in laboratory petri-dishes demonstrate that nerves heal better if the contour (topography) of the surface on they're growing on has tiny grooves to guide them - that knowledge has been applied to make tiny patterned tubes to use to direct the growth of repaired nerves. The tubes could also be used to deliver other useful treatments that will help the nerve fibres to grow better - for example a lot of research has been done by our laboratories and others, to show that stem cells taken from patient's fat (removed by liposuction), or safe drug treatments will also improve biological conditions for nerve healing. This project will combine these developments into a 3-D tube (conduit), that will be used to repair damaged nerves. The research will be undertaken at the world class research facilities in the Centre for Cell Engineering, University of Glasgow, and our partner laboratory in Sweden with detailed input from international experts (surgeons and scientists) in the field of nerve repair. By combining guidance cues, stem cells and drug treatments we believe we can enhance nerve healing, and improve quality of life for patients in the future.
Clinical applications of this exciting biotechnology are widespread and include nerve injury following civilian/military trauma, cancer treatments, birth injury, and face, limb, or voicebox transplants.

Background:
Peripheral nerve injury is common, affecting children or young adults, and can be associated with devastating individual, socioeconomic and healthcare costs (e.g.£50,000 cost for median nerve injury). Despite rapid advances in microsurgical reconstruction techniques outcomes following repair remain poor and commercially available nerve conduits fail to surpass the current gold standard of sensory nerve autograft. As we continue to uncover the delicate neurobiology of nerve healing new areas for improving function following injury arise. The rigid 2 and 3-dimensional directional control of axonal growth upon polycaprolactone (clinically licensed, biodegradable) by microscale topographical cues has been demonstrated within our group, University of Glasgow. Evidence of the beneficial impact of differentiated adipose derived stem cells and pharmacological neuroprotection upon neuronal growth has been confirmed by collaborating laboratories. This project will combine these results to form a 3-D bioengineered, micropatterned nerve conduit that addresses the neurobiology of nerve repair, over a three year PhD programme.
Aim
To develop a novel nerve conduit that negates the need for sensory nerve sacrifice and improves the rate and directionality of regenerating nerve fibres across the site of surgical repair.
Method
Optimal conduit specifications will be confirmed in vitro (year 1) before testing in-vivo (year 2-3), as is necessary prior to clinical translation. DRG explant models will be cultured on topographically enhanced 3-D PCL conduits (engineered in house). Optimal stem cell co-culture parameters will be determined and selected to construct the nerve conduit for use in in-vivo studies. Rigorous outcome measures will be used to assess rat sciatic nerve repair using the 3-D nerve conduit to the current gold standard (autologous nerve graft). Furthermore the novel application micro-CT will provide detailed 3-D evaluation of axonal outgrowth.

Beneficiaries of this research are three fold, including the primary investigator and related peripheral nerve researchers, the wider research community and ultimately patients and society.

Patients and Society
This research will focus an important cause of disability in children and adults. Peripheral nerve injury, as a result of trauma, disease infiltration and cancer resection can result in permanent loss of function. Management of a median nerve injury costs society an average of £50,000 and outcomes remain unsatisfactory with lengthy recovery periods. Improving our understanding of nerve repair and how we can improve it will inform future therapies to improve patient outcomes and function and reduce the associated economic to society. In this way the results of this research, along with ongoing work by the University of Glasgow and collaborating laboratories will contribute to improving function and quality of life for future patients.
This PhD project will also allow for increased interaction with the lay public and medical professionals, promote an understanding of the impact of peripheral nerve injury on individuals and the exciting research that is being done to investigate this and other areas of medical technology development. This interaction will take several forms, including school open days, Brachial Plexus Clinic outreach events and medical/surgical conferences. In this way the impact of this research project will extend to promoting an interest in science and applied research to the wider population, which is vital to promote excellence in UK based research of the future.
Significant findings will be relayed to the public through national online and media resources, as appropriate under guidance from the University of Glasgow and MRC communications team.

Wider Research Community
The in vivo and in vitro methodology used in this project can be applied to other research areas e.g. combinational approaches to tissue engineering of other tissues, repair of central nervous system defects and development of 3-D bioreactors. The unique application of micro-CT will provide data/results of interest to other researchers wishing to explore novel means of evaluating growth in 3-D. This will be communicated regularly and efficiently to the wider research community as outlined in the communications plan.
International collaboration will promote knowledge sharing.

Primary Investigator
This research period will equip me with the skills in cell engineering and translational research required to pursue a career in academic plastic and reconstructive surgery. I will register for a PhD and endeavour to develop the skills required to lead future research within this field. This will be of direct benefit to me as an individual, improve my evidence based practice and help me to seek to collaborate with academic, clinical and commercial colleagues to develop novel management strategies for future patients.

Commercial Colleagues
Following refinement of conduit parameters and necessary in vivo testing in larger models commercial partnership will be sought to develop an off the shelf product for clinical translation. This research will help to inform design parameters and suitable sterilisation methods.

Any intellectual property will be protected through the University of Glasgow via its Research Strategy & Innovation Office, which actively supports and encourages all employees to seek to commercially evaluate new ideas and developments arising from their research. This office provides support to staff to protect their ideas and developments, and to execute agreed exploitation strategies. The team at the Centre for Cell Engineering has ample experience with engaging with the Universities Research Strategy & Innovation Office, establishing intellectual property, and its exploitation.
More information on the IP strategy of the University of Glasgow can be found at http://www.gla.ac.uk/media/media_185772_en