The range of allograft products for spinal fusion has been extended with the development of cellular bone matrices (CBMs). Most of these combine demineralized bone with viable cancellous bone prepared in a manner that retains cells with differentiation potential. The purpose of this study was to compare commercially-available human CBMs in the athymic rat model of posterolateral spinal fusion. The products compared were Trinity ELITE® (TEL, OrthoFix), ViviGen (VIV, DePuy Synthes), Cellentra (CEL, Zimmer Biomet), Osteocel® Pro (OCP, NuVasive), Bio4 (BIO, Stryker) and map3 (MAP, RTI Surgical). Bone from the ilia of syngeneic rats was used as a control to approximate the human gold standard. All implants were stored, thawed, and prepared per manufacturer's instructions and all implantations occurred within the manufacturer's time allowance for use after preparation. In total, fifteen 9–10 week old male rats were implanted per implant type, with three different lots of each implant used per five rats to account for lot-to-lot variability. Under anesthesia, a posterior midline longitudinal skin and subcutaneous incision was made, followed by bilateral longitudinal paraspinal myofascial incisions to expose the transverse processes at the L4–5 level. Implants (0.3 cc of allograft or freshly harvested syngeneic iliac bone graft) were placed bilaterally. Surgeons were blinded as to CBM implant type. Incisions were closed with sutures and in
Autogenous bone grafting limitations have motivated the development of Tissue-Engineered (TE) biomaterials that offer an alternative as bone void fillers. However, the lack of a blood supply within implanted constructs may result in avascular necrosis and construct failure. 1. The aim of this project was to investigate the potential of novel TE constructs to promote vascularisation and bone defect repair using two distinct approaches. In Study 1, we investigated the potential of a mesenchymal stem cell (MSC) and endothelial cell (EC) co-culture to stimulate pre-vascularisation of biomaterials prior to in vivo implantation. 2. In Study 2, we investigated the potential of TE hypertrophic cartilage to promote the release of angiogenic factors such as VEGF, vascular invasion and subsequent endochondral bone formation in an in vivo model. Collagen-only (Coll), collagen-glycosaminoglycan (CG) and collagen-hydroxyapatite (CHA) scaffolds were fabricated by freeze-drying. 3. , seeded with cells and implanted into critical-sized calvarial and femoral defects in immunocompetent rats. In Study 1, Coll and CG scaffolds were initially seeded with ECs, allowed to form capillary-like networks before the delayed addition of MSCs and continued culture prior to calvarial implantation. In Study 2, CG and CHA scaffolds were seeded with MSCs and cultured under chondrogenic and subsequent hypertrophic conditions to form a cartilage pre-cursor prior to calvarial and femoral implantation in