Abstract
Introduction: One of the main factors in the success of impaction bone grafting (IBG) in revision hip surgery is its ability to resist shear and to form a stable construct. Bone marrow contains multipotent skeletal stem cells and we propose that in combination with allograft will produce a living composite with biological and mechanical potential. In this study we looked at whether coating of the allograft with type 1 collagen followed by seeding with human bone marrow stromal cells (hBMSC) would enhance the grafts mechanical and biological properties.
Methods: A control group of plain allograft and three experimental groups where used to determine the effects that collagen and hBMSC have on IBG. The samples where impacted in standardised fashion previously validated to replicate femoral IBG, and cultured in vitro for 2 weeks. The samples then underwent mechanical shear testing and biochemical analysis for DNA content and Osteogenic activity.
Results: Collagen coating of the allograft prior to seeding with hBMSC significantly enhanced the mechanical properties of the construct compared to the ‘gold standard’ of plain allograft with a 22% increase in shear strength (p=0.002). The collagen coated group also showed increased osteogenic differentiation of the stromal cells (Alkaline Phospatase specific activity: 124 +/− 18.6 vs 54.6 +/− 9.6 nM pNPP/Hr/ngDNA p= < 0.01).
Discussion: This study has shown a role in the improvement of the biomechanical properties of IBG by coating with collagen and seeding with hBMSC. Collagen coating of IBG is a simple process and translation of the technique into the theatre setting feasible. The improvement in shear strength and cohesion could lead to earlier weight bearing for the patients and allow quicker recovery. The therapeutic implications of such composites auger well for orthopaedic applications. We are currently strengthening the above findings with an in vivo study.
The abstracts were prepared by Mr Matt Costa and Mr Ben Ollivere. Correspondence should be addressed to Mr Costa at Clinical Sciences Research Institute, University of Warwick, Clifford Bridge Road, Coventry CV2 2DX, UK.
