Biological effects of co-transfection of transforming growth factor beta 1 and vascular endothelial growth factor mediated by adeno-associated virus on promoting the dermal ulcer healing in diabetes mellitus

Jiaming SAI; Huiqin ZHANG

ABSTRACT

BACKGROUND:

The ulcer wound is hard to heal in diabetic patients,and it is believed to be caused by the microcirculatory disorder of wound and decreased contents of endogenous growth factors in patients with diabetes mellitus.

OBJECTIVE:

To observe the biological effects of adeno-associated virus (AAV) mediated transforming growth factor beta1 (AAV-TGFβ1) and vascular endothelial growth factor (AAV-VEGF) in promoting the dermal ulcer healing of diabetic rabbits.

DESIGN:

A randomized controlled animal experiment.SETTINGS Medical College, Qingdao University; Affiliated Hospital of Medical College, Qingdao University.MATERIALS The experiments were carried out in the gynecological laboratory, Affiliated Hospital of Medical College, Qingdao University from July 2004 to January 2006. Twenty-four healthy adult New Zealand rabbits were randomly divided into co-transfection group (n=12) and control group (n=12).

METHODS:

① The dermal ulcer models of diabetic rabbits was established by injecting alloxan (130 mg/kg) via ear vein, and the ulcer wound was made by operation. ② In the co-transfection group, the wound was locally infiltrated, and injected with AAV-TGFβ1 virus and AAV-VEGF virus (the concentration was 9×106 virus granules/mL respectively). The rabbits in the control group were treated with injection of saline.MAIN OUTCOME

MEASURES:

① The levels of TGFβ1 and VEGF gene transcription in the healing tissue were detected with polymerase chain reaction (PCR) at 1 month postoperatively. ② The capillary density in the wound margin was counted with microcirculation microscope at 3 weeks postoperatively. ③ The collagen Ⅰ and Ⅲ were isolated and detected with Western blotting by protein gel electrophoresis and semi-dry electrophoretic transfer. ④ The content of collagen in the ulcer healing issue was detected at 1 day, 1, 2 and 3 weeks, 1, 2, 3, 4, 5 and 6 months postoperatively. ⑤ The thickness, color and quality of the wound healing were observed postoperatively.

RESULTS:

All the 24 rabbits were involved in the analysis of results. ① The expressions of TGFβ1 and VEGF gene transcription in the co-transfection group were increased as compared with those in the control group. ② The capillary density at the wound margin in the co-translection group was higher than that in the control group [(19.18±3.56), (6.43±1.52)/mm2,t=3.21, P ＜ 0.05]. ③ The content of collagen Ⅰ in the ulcer healing tissue in the co-transfection group was obviously increased, and the proportion of collagen Ⅰ in the constituent ratio of collagen Ⅱ and Ⅲ was increased.④ The contents of collagen in the ulcer healing tissue at 1 day after transfection were close without significant difference between the two groups (t=1.55, P ＞ 0.05). After that, the contents of collagen in the cotransfection group were all significantly higher than those in the control group (P ＜ 0.05). ⑤ The ulcer healing in the control group was obviously lagged with bad quality.

CONCLUSION:

The combination of AAV-TGFβ1 and AAV-VEGF can efficiently transfect the dermal ulcer wound in diabetic rabbits, obviously increase the capillary density in ulcer tissue, markedly improve the proportion of collagen I in the constituent ratio of collagen Ⅰ and Ⅲ in healing tissue, and obviously ameliorate the condition of ulcer healing.