The effect of PLGA sphere diameter on rabbit mesenchymal stem cells in adipose tissue engineering.

To investigate the effect of injectable PLGA sphere's diameter on adipose tissue engineering, rabbit mesenchymal stem cells were attached to various diameters of injectable PLGA spheres (<75; 75-100; 100-150; 150-200; and 200-250 microm). These five groups were cultured in adipogenic media for 2 weeks in vitro and injected into necks of nude mice. Prior to in vivo study, cell proliferation and adipogenic differentiation were determined by hexosaminidase assay and Oil red O staining after 2 weeks. Group C (100-150 microm) showed the highest adipogenic differentiation and the proliferation capacity of Group B (75-100 microm) was significantly higher than that of any other group. We harvested newly formed tissues from necks of nude mice after 1 and 4 weeks. Although PLGA spheres have not been degraded and there was no significant histological difference among various sizes of spheres after 1 week, well-organized fat pads (PLGA spheres were completely degraded) could be observed, and the histology of the 100-150 microm groups resembled that of native tissue after 4 weeks. Based on these experiments, we could conclude that the optimal size of PLGA spheres for adipogenesis was 100-150 microm.