Soft Tissue Reaction to Microgrooved Poly-L-lactic Acid Implants Loaded with Transforming Growth Factor β 3

Abstract

In both normal and disturbed wound healing, the generation of large, contracting scars can raise serious functional and cosmetic problems. A possible strategy to minimize or avoid the generation of scar tissue surrounding an implant is to apply transforming growth factor-β₃ (TGF-β₃) to the implant. TGF-β₃ (0, 1, or 2.5 μg) was freeze-dried onto poly-L-lactic acid (PLA) microgrooved substrates (width, 10 μm; depth, 1 μm) and implanted subcutaneously on the backs of rats for 2 and 8 weeks. After sacrifice, implants and surrounding tissue were histologically processed. Light microscopic and histomorphometric evaluation of capsule thickness, capsule quality, and implant-tissue interface was performed. In addition, we stained for α-smooth muscle actin (SMA), collagen, and ED-1 (a monocyte-macrophage marker). All implants were surrounded by a fibrous capsule. Capsules of the implants loaded with 1 or 2.5 μg of TGF-β₃ showed significantly higher capsule quality. This meant that capsules were more mature compared with implants without TGF-β₃. However, no significant differences were found in terms of thickness of the capsules or quality of the interface. Finally, apparently significant differences were also found in the expression of α-SMA, when comparing the various growth factor concentrations at both implantation points. In conclusion, the use of microgrooved PLA substrates with TGF-β₃ did not lead to an overall improvement of periimplant tissue healing.