Effect Of Localized Delivery Of Insulin-Like Growth Factor-â…  Incorprated With Poly-(D,L-Lactide) On Bone Fracture Healing In Rats

Insulin-like growth factor I (IGF-I) is one of the most important growth factor in bone, which was secreted from the bone matrix, osteoblasts and chondrocytes. IGF-I could promote proliferation and differentiation of osteoprogenitor cells and osteoblasts by mechanism of autocrine and paracrine. In the process of fracture healing, the major function of IGF-I is to promote the formation of callus and remodeling. In this article, we used metal implant incorporated with biodegradable poly-(D,L-lactide) (PDLLA) and IGF-I to perform internal fixation of experimental fracture.I COATING PDLLA ON METALLIC IMPLANTS AS A BIODEGRADABLE LOCALIZED DELIVERY CARRIER OF GROWTH FACTORObjection: To establish a "cold coating technique" for PDLLA on the surface of metallicimplants. To investigate the mechanical stability of the coat layer by intrameduUaryimplantation. Get the in vitro degradation property of PDLLA.Method: PDLLA was resolved in chloroform. Stainless steel K-wires were dipped into theresolution twice and hung dry. The total coating mass was quantified by weighting theK-wire before and after coating. The loss rate of the coating layer was qualified by weightthe K-wire before and after intrameduUary implantation of rat femur. Put the coated K-wirein sterile saline and incubated in 37℃ for 42 days to get the in vitro degradation curve ofcoated PDLLA.Result: The total coating mass of PDLLA is 0.0011±0.0002 g. The loss rate of coatinglayer mass is 21.37 ± 10.36% post-operation The degradation rate of coating layer is 7d—29.1 %, 14d—28.2 %, 42d-34.7 % in vitro respectively.Conclusion: The "cold coating technique" could result in a thin layer of PDLLA in thesurface in metallic implants with better mechanic stability. And the coating layer showed acontinuous degradation in vitro.