OBJECTIVETo evaluate the effect of sustained release of recombinant rat insulin-like growth factor-1(rrIGF-1) from poly (lactide-CO-glycolide) (PLGA) microspheres on bone formation in the peri-implant areas in Goto-Kakizaki rats with type 2 diabetes.

METHODSType 2 diabetes models were successfully established in 20 male Goto-Kakizaki rats, which were then randomly divided into treatment group (sustained release of rrIGF-1 from PLGA microspheres were loaded on the peri-implant areas, n=10) and diabetic group (loaded with isodose placebo from PLGA microspheres, n=10). Another ten male SD rats served as control group (did not sustain any loading). Titanium implants were inserted into the tibias of 30 diabetic and normal animals. Four, 5, and 8 weeks after implantation, local blood samples around the implants were obtained for the determination of serum osteocalcin (OCN), serum bone specific alkaline phosphatase (B-ALP), and serum procollagen I carboxyterminal propeptide (PICP) with enzyme linked immunosorbent assays.

RESULTSFour weeks after implantation, OCN, B-ALP, and PICP were significantly lower in both treatment group and diabetic group than in control group(both P<0.05). Five weeks after implantation, serum OCN and B-ALP levels of the diabetic group were significantly lower than those of the other two groups (all P<0.05). Serum PICP levels of both diabetic group and treatment group were significantly lower than that of control group(both P<0.05). The OCN level in the trealment group was significantly higher in the post-operative 5th week than in the post-operative 4th week, while the PICP levels in the diabetic group were significantly lower than those in the treatment group and control group in the post-operative 8th week (both P<0.05).

CONCLUSIONSustained release of rrIGF-1 from PLGA microspheres loaded on the local peri-implant areas can promote bone formation in the peri-implant areas in Goto-Kakizaki rats with type 2 diabetes.