Sustained release of TGFβ3 from PLGA microspheres and its effect on early osteogenic differentiation of human mesenchymal stem cells

Despite the widespread role of transforming growth factor-beta 3 (TGF beta 3) in wound healing and tissue regeneration, its long-term controlled release has not been demonstrated. Here, we report microencapsulation of TGF beta 3 in poly-d-l-lactic-co-glycolic acid ( PLGA) microspheres and determine its bioactivity. The release profiles of PLGA-encapsulated TGF beta 3 with 50: 50 and 75: 25 PLA: PGA ratios differed throughout the experimental period. To compare sterilization modalities of microspheres, bFGF was encapsulated in 50: 50 PLGA microspheres and subjected to ethylene oxide ( EO) gas, radio-frequency glow discharge (RFGD), or ultraviolet (UV) light. The release of bFGF was significantly attenuated by UV light, but not significantly altered by either EO or RFGD. To verify its bioactivity, TGF beta 3 (1.35 ng/mL) was control-released to the culture of human mesenchymal stem cells (hMSC) under induced osteogenic differentiation. Alkaline phosphatase staining intensity was markedly reduced 1 week after exposing hMSC-derived osteogenic cells to TGF beta 3. This was confirmed by lower alkaline phosphatase activity (2.25 +/- 0.57 mU/mL/ng DNA) than controls (TGF beta 3-free) at 5.8 +/- 0.9 mU/mL/ng DNA ( p < 0.05). Control-released TGF beta 3 bioactivity was further confirmed by lack of significant differences in alkaline phosphatase upon direct addition of 1.35 ng/mL TGF beta 3 to cell culture ( p > 0.05). These findings provide baseline data for potential uses of microencapsulated TGF beta 3 in wound healing and tissue-engineering applications.