rhBMP-2 using biphasic calcium phosphate block as a carrier induces new bone formation in a rat subcutaneous tissue

Abstract

Purpose: The carrier for the delivery of bone morphogenetic proteins(BMPs) should also serve as a scaffold for new bone growth. In addition, predictable bone formation in terms of the volume and shape should be guaranteed. This study evaluated the ectopic bone formation of recombinant human BMP-2(rhBMP-2) using a micro macroporous biphasic calcium phosphate (MBCP: mixture of β-TCP and HA) block as a carrier in a rat subcutaneous assay model. Materials and Methods: Subcutaneous pockets were created on the back of 40 male Sprague-Dawley rats. In the pockets, rhBMP-2/MBCP and MBCP alone were implanted. The blocks were evaluated by histological and histometric parameters after a healing interval of 2 weeks (each 10 rats; MBCP and rhBMP-2/MBCP) or 8 weeks (each 10 rats; MBCP and rhBMP-2/MBCP). Results: The shape and volume of the block was maintained stable over the healing period. No histological bone forming activity was observed in the MBCP alone sites after 2 weeks and there was minimal new bone formation at 8 weeks. In the rhBMP-2/MBCP sites, new bone formation was evident in the macropores of the block. The new bone area at 8 weeks was greater than at 2 weeks. There was a further increase in the quantity of new bone with the more advanced stage of remodeling. Conclusions: A MBCP block could serve as a carrier system for predictable bone tissue engineering using rhBMPs. KEY WORDS: rhBMP-2; biphasic calcium phosphate block; carrier; ectopic bone formation.

A review: In vivo studies of bioceramics as bone substitute materials

“…The scaffold from Strontium oxide (SrO) and magnesium oxide (MgO) doped β-TCP [137] fabricated a 3D interconnected femoral defect of a rat model, the same author Solaiman T. [138] with his co-workers, examined the effect of (Sr) and magnesium in TCP scaffolds on healing in the femoral condyle of Rabbits compared with pure TCP, showed an enhanced network of blood vessel formation and increased formation of an osteon as shown in Figure 15. A group of researchers [139][140][141][142][143] has attempted to use biphasic calcium phosphate (β-TCP incorporation with HA) which called biphasic calcium phosphate (BCP) for application in bone tissue engineering. Moreover, Abeer et al [144] evaluated the effectiveness (of BCP) combined with a hyaluronic acid gel to regenerate femoral condylar defects in a rat model.…”