Size matters: effects of PLGA-microsphere size in injectable CPC/PLGA on bone formation

摘要

The aim of this study was to evaluate the effect of PLGA microsphere dimensions on bone formation after injection of calcium phosphate cement (CPC)/PLGA in a guinea pig tibial intramedullarly model. To this end, injectable CPC/PLGA formulations were prepared using PLGA microspheres with either a small (similar to 25 mu m) or large (similar to 100 mu m) diameter, which were incorporated at a 20:80 ratio (wt%) within apatite CPC. Both CPC/PLGA formulations were injected into a marrow-ablated tibial intramedullary cavity and, after an implantation period of 12 weeks, histology and histomorphometry were used to address bone formation. The results demonstrated bone ingrowth throughout the entire scaffold material for both CPC/PLGA formulations upon PLGA microsphere degradation. More importantly, bone formation within the CPC matrix was>two-fold higher for CPC-PLGA with 25 mu m PLGA microspheres. Additionally, the pattern of bone and marrow formation showed distinct differences related to PLGA microsphere dimension. In general, this study demonstrates that PLGA microsphere dimensions of similar to 25 mu m, leading to pores of similar to 25 mu m within CPC, are sufficient for bone ingrowth and allow substantial bone formation. Further, the results demonstrate that PLGA microsphere dimensions provide a tool to control bone formation for injectable CPC/PLGA bone substitutes. Copyright (c) 2013 John Wiley & Sons, Ltd.