Bone induction by biomimetic PLGA-(PEG-ASP)n copolymer loaded with a novel synthetic BMP-2-related peptide in vitro and in vivo.

BMP-2 is one of the most important growth factors of bone regeneration. Polylactide-co-glycolic acid (PLGA), which is used as a biodegradable scaffold for delivering therapeutic agents, has been intensively investigated. In previous studies, we synthesized a novel BMP-2-related peptide (designated P24) and found that it could enhance the osteoblastic differentiation of bone marrow stromal cells (BMSCs). The objective of this study was to construct a biomimetic composite by incorporating P24 into a modified PLGA-(PEG-ASP)n copolymer to promote bone formation. In vitro, our results demonstrated that PLGA-(PEG-ASP)n scaffolds were shown to be an efficient system for sustained release of P24. Significantly more BMSCs attached to the P24/PLGA-(PEG-ASP)n and PLGA-(PEG-ASP)n membranes than to PLGA, and the cells in the two groups subsequently proliferated more vigorously than those in the PLGA group. The expression of osteogenic markers in P24/PLGA-(PEG-ASP)n group was stronger than that in the PLGA-(PEG-ASP)n and PLGA groups. Radiographic and histological examination, Western blotting and RT-PCR showed that P24/PLGA-(PEG-ASP)n scaffold could induce more effective ectopic bone formation in vivo, as compared with PLGA-(PEG-ASP)n or gelatin sponge alone. It is concluded that the PLGA-(PEG-ASP)n copolymer is a good P24 carrier and can serve as a good scaffold for controlled release of P24. This novel P24/PLGA-(PEG-ASP)n composite promises to be an excellent biomaterial for inducing bone regeneration.

[Adhesion, proliferation and osteodifferentiation of bone mesenchymal stem cells on PLGA-[ASP-PEG] tri-bolck polymer scaffolds].

OBJECTIVE: To explore the adhesion,proliferation and osteodifferentiation of bone mesenchymal stem cells (BMSCs)on the prepared lactic acid/glycolic acid/asparagic acid-co-polyethylene glycol(PLGA-[ASP-PEG])tri-block polymer scaffolds. METHODS: Modified PLGA with polyethylene glycol (PEG) and asparagic acid(ASP)that has many liga nds,and then the synthesis PLGA-[ASP-PEG] tri-block polymer material was prepared. BMSCs were cultured in PLGA-[ASP-PEG] polymer material and poly lactic acid-co-glycolic acid(PLGA)were used as control group. Precipitation method, MUT assay and total cellular protein detection were used to test the adhersion and proliferation of BMSCs. After the third generation of BMSCs was cultured on PLGA-[ASP-PEG] tri-block polymer scaffolds for 14 day and 28 day with osteogenic supplements,the osteodifferentiation of MSCs were observed through alkaline phosphatase(ALP) staining and calcium tubercle staining. RESULTS: BMSCs grew adherent to the surface of PLGA-[ASP-PEG] polymer scaffolds and the number of BMSCs was much higher than that of PLGA. The precipitation method suggested that adhesion and proliferation of BMSCs on the surface of PLGA-[ASP-PEG] was much higher than the control group (P < 0.05). MTU assay showed that after BMSCs were cultured for 20 days,the absorbance A of PLGA-[ASP-PEG] polymer scaffolds and PLGA were 1.336 and 0.780 respectively. Total cellular protein could image the adhersion and proliferation of BMSCs indirectly. After BMSCs were cultured for 12 days,the total cellular protein of PLGA-[ASP-PEG] and PLGA were 66.44 microg/pore and 41.23 microg/pore respectively. PLGA-[ASP-PEG] polymer scaffolds had well biocompatibility and cell adhersion. The positive results with ALP staining and calcium tubercle staining in both groups indicated tri-block polymer scaffold and its degradations had no effect on osteodifferentiation. CONCLUSION: PLGA-[ASP-PEG]could improve the adhesion and proliferation of seed cells on bone-matrixmaterial, maintain the morphous of seed cells and had no obvious effect on cell osteodifferentiation.