[Enhancement of proliferation and differentiation of bone mesenchymal stem cells by basic fibrous growth factor controlled release nanoparticles].

This research was carried out to investigate the effect of basic fibrous growth factor (bFGF) controlled release hydrogel nanoparticles on the proliferation and differentiation of mesenchymal stem cells. The dex-GMA-bFGF-NPs were prepared by an improved emulsion polymerization method; their morphology, size and encapsulated ratio were assessed by routine procedure. Dynamic dialysis method was used to determine the release characteristics of dex-GMA-bFGF-NPs in vitro. The secondary culture MSCs were divided into four groups according the different ingredients being added into the DMEM culture medium: free bFGF group (A), blank dex-GMA nanoparticles group (B), dex-GMA-bFGF nanoparticles group (C), nothing group (D). The proliferation of cultured MSCs was measured by using cell counting method, MTT method and flow cytometry. ALP kit was used to evaluate the ALP activity of the MSCs to show the differentiation of the cells by adding the dex-GMA-bFGF-NPs to the DMEM culture medium (C group) or bFGF only (A group). B group and D group were taken as the controls. The results were analyzed by statistical analysis software (SPSS11.0). All results showed that the shape of dex-GMA-bFGF-NPs was spherical. The encapsulated ratio was 88% and more than 85% of the encapsulated bFGF could be released during 14 days. The in vitro cellular study showed the control release of bFGF from nanoparticles could promote the proliferation of MSCs. After 12 days, the cell number in groups A, B and C was (21.97 +/- 0.25) x 10(4) cells/ml, (12.43 +/- 0.13) x 10(4) cells/ml, (27.45 +/- 0.78) x 10(4) cells/ml and (12.03 +/- 0.43) x 10(4) cells/ml, with the difference being statistically significant among them (P < 0.05). The flow cytometry revealed that the G2/M+S percentage in group C was the highest at 4-8 days after plate culture(P < 0.05). During the first 3 days, the proliferation and differentiation of BMSCs between group A and group B were of no significance (P > 0.05), but were much faster than those of group C and D. After 7 days, dex-GMA-bFGF-NPs could enhance BMSCs proliferation and differentiation continually, but bFGF had no enhancement any more, the difference between group A and group B became more significant (P < 0.05). So we made the conclusions the bFGF loading dex-GMA hydrogel nanoparticles can release bFGF more than 21 days and can promote the proliferation and differentiation of the BMSCs through a long period of controlled release of bFGF. Dex-GMA-bFGF-NPs may be an ideal controlled release carrier for bioactive growth factors.