Post-Doctoral Research Associate
After a MEng in Materials Science at the University of Oxford, Jenny came to CCMM for a PhD focussed on the production of carbonate substituted hydroxyapatite scaffolds for bone repair. Her early post-doctoral career concentrated on the application of synthetic collagen structures in the repair of load-bearing soft tissues such as tendons and the meniscus. This work included a 12 month EPSRC funded knowledge transfer secondment to Tigenix UK Ltd. Attempting to replicate the structure of these tissues led to a desire to investigate the natural tissues further and Jenny joined QMUL as part of a Wellcome Trust Project considering the mechanics and biology of developing tendinopathy. In 2013 she returned to Cambridge and the biomaterials field working on an ERC project on 3D Engineered Environments for Tissue Engineering.
Freeze-dried structures for megakaryocytes culture and in vitro platelet production
Freeze-drying is perhaps the most common means of producing porous, highly interconnected three-dimensional structures from biomacromolecules such as collagen. During the process, the collagen suspension is frozen, forming an inter-penetrating network of ice crystals, with the collagen pushed out to the crystal boundaries. These ice crystals are then removed at low pressure through sublimation resulting in a porous structure. Freeze-dried structures have been designed to mimic as far as possible the structure and composition of a range of tissues whether for implantation for tissue repair or as an in vitro model of the tissue. The group has recently been awarded an ERC Advanced Grant to continue this research further, with the aim of producing 3D scaffolds with complex orientational and spatial anisotropy relevant to their desired application as well as the capability of providing mechanical or biological cues to the relevant cells.
One field of interest within the grant is the development of three dimensional environments for the culture of megakaryocytes and production of blood platelets. Platelets are essential for blood clotting and in instances where platelet concentration is lower than normal, for example as a result of cancers or blood disorders, transfusions are required. Instead of being entirely reliant upon donors, Dr Cedric Gheveart of the Haematology Department, University of Cambridge has suggested an in vitro system of platelet generation using a suitable three-dimensional structure within a bioreactor cell culture system. This requires a complex structure mirroring to some extent the bone marrow niche and with the presence of biological or chemical cues to initiate platelet formation.
The work therefore considers the design of specific structures for this platelet production application, including the addition of chemical cues (initially fibrinogen) to encourage platelet formation. A multi-layer structure is likely to be required with both compositional and structural variation. Key to the development of three dimensional structures are the characterisation techniques available and to this end the work will concentrate on the development of existing and novel routes of characterising three dimensional structures with an initial focus on micro computed tomography and confocal microscopy.
- D.V. SHEPHERD, J.H. SHEPHERD, S. GHOSE, S.J. KEW, R.E. CAMERON and S.M. BEST
"The process of EDC-NHS cross-linking of reconstituted collagen fibres increases collagen fibrillar order and alignment", APL Materials, 3, 014902, (2015)
- J.H. SHEPHERD, G.P. RILEY and H.R.C. SCREEN
"Early stage fatigue damage occurs in bovine tendon fascicles in the absence of changes in mechanics at either the gross or micro-structural level", Journal of the Mechanical Behaviour of Biomedical Materials, 38, 163-172 (2014)
- J.H. SHEPHERD, K. LEGERLOTZ, T. DEMIRCI, C. KLEMT, G.P. RILEY and H.R.C. SCREEN
"Functionally distinct tendon fascicles exhibit different creep and stress relaxation behaviour. Proceedings of the Institution of Mechanical Engineers", Part H: Journal of Engineering in Medicine, 228; 49-59 (2014)
- J.H. SHEPHERD and H.R.C. SCREEN
"Fatigue Loading of Tendon. International", Journal of Experimental Pathology, 94, 260-270 (2013)
- D. HOWARD, J.H. SHEPHERD, S.J. KEW, S. GHOSE, J.A. WARDALE and N. RUSHTON
"The Release of Growth Factors from a Fibre Reinforced Collagen GAG Matrix Supplemented with Platelet Rich Plasma: Influence on In Vitro Cultured Human Meniscal Cartilage Cells", Journal of Orthopaedic Research, 32, 273-278 (2013)