[Vascular endothelial growth factor/polylactide-polyethyleneglycol-polylactic acid copolymer/basic fibroblast growth factor mixed microcapsules in promoting angiogenic differentiation of rat bone marrow mesenchymal stem cells in vitro ].

Objective: To observe the effect of vascular endothelial growth factor/polylactide-polyethyleneglycol-polylactic acid copolymer/basic fibroblast growth factor (VEGF/PELA/bFGF) mixed microcapsules in promoting the angiogenic differentiation of rat bone marrow mesenchymal stem cells (BMSCs) in vitro .

Methods: The BMSCs were isolated by the method of whole bone marrow adherent, and sub-cultured. The passage 3 BMSCs were identified by Wright-Giemsa staining and flow cytometry, and used for subsequent experiments. VEGF/PELA/bFGF (group A), PELA/bFGF (group B), VEGF/PELA (group C), and PELA (group D) microcapsules were prepared. The biodegradable ability and cytotoxicity of PELA microcapsule were determined，and the slow-released ability of VEGF/PELA/bFGF mixed microcapsules was measured. The passage 3 BMSCs were co-cultured with the extracts of groups A, B, C, and D, separately. At 1, 3, 7, 14, and 20 days after being cultured, the morphological changes of induced BMSCs were recorded. At 21 days, the induced BMSCs were tested for DiI-labeled acetylated low density lipoprotein (Dil-ac-LDL) and FITC-labeled ulex europaeus agglutinin I (FITC-UEA-I) uptake ability. The tube-forming ability of the induced cells on Matrigel was also verified. The differences of the vascularize indexes in nodes, master junctions, master segments, and tot.master segments length in 4 groups were summarized and analyzed.

Results: The isolated and cultured cells were identified as BMSCs. The degradation time of PELA was more than 20 days. There was no significant effect on cell viability under co-culture conditions. At 20 days, the cumulative release of VEGF in the mixed microcapsules exceeded 95%, and the quantity of bFGF exceeded 80%. The morphology of cells in groups A, B, and C were changed. The cells in groups A and B showed the typical change of cobble-stone morphology. The numbers of double fluorescent labeled cells observed by fluorescence microscope were the most in group A, and decreases from group B and group C, with the lowest in group D. The cells in groups A and B formed a grid-like structure on Matrigel. Quantitative analysis showed that the differences in the number of nodes, master junctions, master segments, and tot.master segments length between groups A, B and groups C, D were significant ( P <0.05). The number of nodes and the tot.master segments length of group A were more than those of group B ( P <0.05). There was no significant differences in the number of master junctions and master segments between group A and group B ( P >0.05).

Conclusion: VEGF/PELA/bFGF mixed microcapsules have significantly ability to promote the angiogenic differentiation of rat BMSCs in vitro .