Effects Of Nerve Growth Factor-Insulin Composite Gel On Deep Second Degree Scald Wound Healing In Diabetic Rats

Objective To prepare nerve growth factor (NGF)-insulin composite gel and observe the effects of NGF-insulin composite gel on deep second degree scald wound healing in diabetic rats. Methods Carbomer980, NGF (4000U),and insulin (800U) were used to prepare the insulin gel, NGF gel, and NGF-insulin composite gel. The character of NGF-insulin composite gel was observed, and the in vitro drug release was tested. Seventy-five SPF Wistar male rats, weighing200-250g, were divided into5groups randomly,15rats each group:normal control group (group A), diabetes control group (group B),insulin gel treatment group (group C), NGF gel treatment group (group D), and NGF-insulin composite gel treatment group(group E). The type1diabetes rat model was established by intraperitoneal injection of Streptozotocin (55mg/kg) in groups B,C, D, and E, while the rats in group A were injected with the same dose of citric acid and calcium citrate buffer. After modeling success, deep second degree scald wound on the back was made with constant temperature water bath box. Wounds were treated with carbomer blank gel in groups A and B, with insulin composite gel in group C, with NGF gel in group D, and with NGF-insulin composite gel in group E, once a day. At3,7,11,15, and21days after injury, the scald wound healing was observed and healing rate was calculated; the full-thickness skin specimens were harvested from3rats of each group for histological and immuohistochemical staining observation. Results The NGF gel、insulin gel and NGF-insulin composite gel was clear and transparent, and had good moisture retention capacity and adhesion; it was easy to apply and clean up. The drug release in vitro lasted more than24hours and maintained for30days. No rat died during the experiment. At3days after injury, wound area did not reduce in all groups; at7,11,15, and21days, group E had the highest wound healing rate, and group B had the lowest; significant differences were found between group E and group B and when compared with the other groups (P<0.05). HE staining showed that group E surpassed other groups in the growth of granulation tissue and collagen fiber. Immunohistochemical results showed that the CD34and proliferating cell nuclear antigen (PCNA) expressed at3days, and the number of positive cells increased gradually with time; the microvessel density and PCNA expression were highest in group E and were lowest in group B, showing significant differences when compared with the other groups and between group E and group B (P<0.05).Conclusion NGF-insulin composite gel can improve deep second degree scald wound healing in diabetic rats.