The BMP-2 content and bone forming potential of 2 leading allograft products (OsteoAMP® and Osteocel® Plus) was tested across 3 commercially available lots. Surprisingly, there was no BMP-2 content associated with the cells contained within Osteocel® Plus. OsteoAMP® contained greater than 1000 times the overall BMP-2 content than Osteocel® Plus. Correspondingly, Osteocel® Plus did not form new bone at any timepoint in the 12 week in vivo study while OsteoAMP® had increasing new bone formation at each sequential timepoint. Interestingly, the highest cellularity of Osteocel® Plus was just prior to implant at t0, decreasing at each timepoint, decreasing further at the terminal endpoint of the study at 12 weeks (82% of cells had died or migrated). Conversely, the cellularity of OsteoAMP® increased at each timepoint. Implants containing living cells are often characterised by the orthobiologics industry as ‘osteogenic’. The positive function and ultimate fate of these cells has been assumed with little to no proof of efficacy. In this study we compare the bone forming ability of the market leading stem cell product claiming osteoinductivity as well as osteogenicity, Osteocel® Plus, against the market leading allograft derived growth factor product, OsteoAMP® which claims osteoinductivity but contains no viable cells. The goal of the study is to determine if a cellular product will form new bone or produce a false positive when evaluated histomorphometrically using an osteoinductive control over time in vivo. Additionally, the osteoinductive potential from each product will be quantified by in vitro by measurement of BMP-2 content via ELISA.Summary
Introduction
Demineralized bone matrix (DBM) is a natural, collagen-based, well-established osteoinductive biomaterial. Nevertheless, there are conflicting reports on the efficacy of this product. The purpose of this study was to evaluate whether DBM collagen structure is affected by particle size and can influence DBM osteoinductivity. Sheep cortical bone was ground and particles were divided in three fractions with different sizes, defined as large (L, 1–2 mm), medium (M, 0.5–1 mm), and small (S, < 0.5 mm). After demineralization, the three DBM samples were characterized by DTA analysis, XRD, ICP-OES, and FTIR. Data clearly showed a particle size-dependent alteration in collagen structure, with DBM-M being altered but not as much as DBM-S. The
The purpose of this study was to understand the effects of terminal sterilisation and residual calcium on human demineralised bone matrix (DBM) in ectopic bone formation in nude rat. The intramuscular implantation of human DBM prepared by the Queensland Bone Bank (QBB) from four donors into eight male athymic rats was used to assess osteoinductivity. The DBM contained different levels of residual calcium and treated with or without gamma-irradiation at 11kGy. At 6 weeks post-implantation, calcium deposition was assessed by manual palpitation and radiological imaging. Tissue morphology and cellular interactions was analysed using various histological staining methods whilst protein expression of anabolic and catabolic biomarkers were examined through immunohistochemistry. All results were then analysed in qualitative, semi-quantitative and quantitative manners and tested for statistical significance. Bone formation was observed in all specimens at the gross level. This was confirmed by histology which revealed bony capsules surrounded by soft tissue in the muscle pockets and differences in tissue components. On a cellular level, variations in osteoclast expression were found between the two groups as well as amongst individual donors through statistical analysis which resulted in an imbalance of the expression of anabolic and catabolic markers. Furthermore, a positive relationship between residual calcium and new bone formation in gamma irradiated DBM samples was found. To date, no studies have compared the effect of calcium in gamma irradiated DBM. Our results suggest that gamma irradiation even at low doses and residual calcium may affect new bone formation. Taken together, this study stresses the importance of selecting ideal conditions for graft processing and the need to identify an optimal level of irradiation and remaining calcium levels that confers a balance between osteoinductivity and sterility.
The concept of “bone graft expanders” has been popularised to increase the volume and biological activity of the implanted Material. Orthoss® granules support exogenously seeded MSCs and attract neighbouring host MSCs.Introduction
HYPOTHESIS
Introduction: Different grafting materials for the filling of large bony defects are used in clinic. Aim of the present study was the comparative analyses of different bony grafting materials concerning their growth factor composition and osteoinductivity in vitro. Materials &
Methods: Different allograft preparations from the tissue bank of the Charité and two commercial demineralized bone matrices (DBM; DBX putty and Allomatrix) were analyzed. Using ELISA-kits following growth factors were quantified: VEGF, IGF-I, FGFa/b, TGF-β1, BMP-2/4, PDGF.
