Preparation and Bioactivities of PLGA/Nano-hydroxyapatite Scaffold Containing Chitosan Microspheres for Controlled Delivery of Mutifuncational Peptide-adrenomedullin

By tripolyphosphate (TPP) as cross-linker, chitosan microspheres (CMs) loaded with adrenomedullin (ADM) were prepared by an emulsion-ionic cross-linking method. Then, porous poly(lactide-co-glycolide) (PLGA)/nano-hydroxyapatite (nHA)/CMs scaffold was developed by thermally induced phase separation. Scanning electron microscope was used to analyze the characterization of the microspheres and the scaffold and the drug release from them was tested in vitro. Also, the hemolytic effect of the scaffold was tested to evaluate the toxicity of the biomaterial. MG63 cell line and HUVEC cell line were cultured for testing the bioactivity of the scaffold loading ADM. After the cells adhered on the scaffold, the cell proliferation and differentiation were analyzed by methyl thiazolyl tetrazolium(MTT) assay, fluorescent staining and alkaline phosphatase(ALP) assay. The results show that the diameter of the microspheres is well-distributed and the PLGA/nHA/CMs scaffold shows a typical microstructure of polymeric foam. The pores of the scaffold ranged from 30 mu m to 220 mu m and they were interconnected. The hemolytic rate of the biomaterial was less than 5%, which was in line with national standard of medical materials. This study confirmed that PLGA/nHA/CMs/ADM and PLGA/nHA/CMs scaffold could accelerate the proliferation of osteoblast-like cells and vascular endothelial cells and also could stimulate the differentiation of osteoblast-like cells