OBJECTIVETo study the effect of cotransfection of genes of insulin-like growth factor I (IGF-I) and herpes simplex virus thymidine kinase (HSV-tk) on wound healing.

METHODSThirty male Wistar rats were inflicted with 30% TBSA full-thickness scald. They were then divided into A group (4.6 microg pcDNA3.1/IGF-I+Lipofectamine 2000+saline), B group (3.6 microg pcDNA3.1/HSV-tk+Lipofectamine 2000+saline), C1 group and C2 group (2.3 microg pcDNA3.1/IGF-I+1.8 microg pcDNA3.1/HSV-tk+Lipofectamine 2000+saline), and D group (3.0 microg pcDNA3.1+Lipofectamine 2000+saline) according to the random number table, with 6 rats in each group. The above-mentioned mixtures were subcutaneously injected into left back of each rat the moment after injury and on post scald day (PSD) 7, 14, 21, and 28. Gancyclovir (2.5 mg/100 g) was hypodermically injected into rats in C2 group on PSD 29, 30, 31, 32. Changes in body weight of rats were measured. Wound healing rates were calculated. On PSD 35, the expressions of IGF-I gene in local wound and liver tissue were determined with immunohistochemical staining. The serum expression of IGF-I was determined with radioimmunoassay. Expression of HSV-tk gene in local wound was determined with RT-PCR. Apoptosis of fibroblast in C1 and C2 groups was observed under transmission electron microscope. Data were processed with one-way analysis of variance and Turkey method.

RESULTSBody weight of rats in A, C1, and C2 groups increased from PSD 7 through 35, and the difference between former three groups and B, D groups was statistically significant (with F value respectively 2.764, 4.519, 5.009, 13.449, 5.877, P values all below 0.05). Wound healing rates of rats in A, C1, and C2 groups were higher than those in B, D groups (with F value respectively 5.286, 100.880, 152.380, 127.850, 147.750, P values all below 0.05). IGF-I gene was positively expressed in wound fibroblast in A, C1 and C2 groups, but negatively in liver tissues of all the rats. There was no significant statistical difference among groups in serum content of IGF-I [from (1185+/-170) to (1270+/-130) ng/mL, F=0.355, P=0.838]. HSV-tk gene was positively expressed in rat skin tissue in B, C1 and C2 groups. Fibroblast apoptosis was observed under transmission electron microscope in C2 group, but it was not observed in C1 group.

CONCLUSIONSCotransfection of pcDNA3.1/IGF-I and pcDNA3.1/HSV-tk mediated by liposome can promote wound healing, and inhibit the scar proliferation to some extent.