Ex vivo chick femur culture models to study effects of exogenous cues from bone replacement scaffolds on bone formation

Supervisors: Professor Iain Gibson, Dr Neil Vargesson, Professor Helen Sang

Project Description:

Bone repair and regeneration can be influenced by various guidance cues, including pharmacological cues, hypoxia environment and chemical cues released from scaffolds [1,2]. Translation of these approaches to clinical use can be complex and expensive, largely due to the pre-clinical models that are currently used to study bone repair and regeneration. This PhD project aims to use an ex vivo tissue culture model [3] that may be suitable to test various scaffold materials that present various guidance cues to direct osteogenesis. The PIs lab has developed a number of scaffold systems that can stimulate/induce osteogenesis and can promote blood vessel formation. High throughput models that could be used to test scaffold and growth factor effects on bone remodelling, bone healing in a critical size defect and induction of mineralisation of a cartilage-rich tissue matrix are of interest as they could reduce the need for larger pre-clinical studies. Such ex vivo models will be extremely relevant to research in regenerative medicine, tissue engineering and biomaterials research. Specifically to this project we will test different scaffold materials that have been designed to exhibit controlled release of growth factors that induce osteogenesis. The project will utilise ex vivo cultures of chick femurs [3] and will use direct and indirect interaction with the GF-releasing scaffolds. This model allows us to understand how the early stages of bone repair, specifically endochondral ossification, and later stages, specifically mineralisation of a collagen-rich matrix, can be influenced by various cues. Additionally, the influence of blood vessel formation on bone formation will be studied by implantation of the ex vivo cultured chick femur on to a chick chorioallantoic membrane (CAM), an established model for studying angiogenesis.

Additionally, transgenic chickens developed at the Roslin Institute will provide opportunities to use transgenic lines that express GFP in these studies, either in the femur culture or in the subsequent CAM assay.

The project will involve performing ex vivo cultures and tissue dissection, histological analysis and immunohistochemistry, imaging (light and fluorescence microscopy) and microcomputed tomography (uCT).

The successful candidate would receive multi-disciplinary training in the characterisation of biomaterial scaffolds and substrates, cell culture and cell-material interactions, ex vivo cultures and tissue dissection, histological analysis and immunohistochemistry, imaging (light and fluorescence microscopy) and microcomputed tomography (uCT). Much of the work in our institution is very translational, so the student would also gain exposure to the considerations required to translate aspects of research towards potential clinical use. The approaches used are also consistent with the aims of the 3Rs, with the potential of replacing established large animal pre-clinical models for studying bone replacement scaffolds. 

References:

[1] V.E. Santo et al., Tissue Engineering B, 19 (2013) 308-326; [https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3690094/]

[2] S. Almubarak et al. Biomaterials, 83 (2016) 197-209; [https://www.ncbi.nlm.nih.gov/pubmed/26608518]

[3] E.L. Smith et al., Eur Cell Mater 26 (2013) 91-106 [https://www.ncbi.nlm.nih.gov/pubmed/24027022]

Other: