Effects of recombinant adenovirus-mediated double suicide genes on implanted human keloid: experiment with athymic mice

Abstract

To detect the effects of the recombinant adenovirus-mediated double suicide genes constructed by Escherichia coli cytosine deaminase (CD)/5-fluorocytosine (5-Fc) and herpes simplex virus-thymidine kinase (HSV-TK)/ganciclovir (GCV)-CDglyTK on implanted human keloids and mechanisms thereof. Twenty nude mice were implanted with human keloid obtained during operation so as to establish mouse keloid models and then were randomly divided into 4 equal groups: Group A, injected with normal saline (NS) into the keloid once per 3 days for 18 days totally, Group B injected with NS into the keloid and injected intraperitoneally with 5-Fc and GCV; Group C injected with CDglyTK into the keloid, and Group D injected with CDglyTK into the keloid and 5-Fc and GCV injected intraperitoneally. The volume of the implanted keloid tissue was measured 2, 7, 14, 21, 28, 35, and 42 days after operation. On day 42 the keloid tissues were removed to undergo morphological examination, TUNEL method was used to examine the apoptosis of the fibroblasts, and the expression of Bcl-2 and BAX, products of apoptosis-related genes, were detected by immunohistochemistry. Compared to those before treatment the volume of the implanted keloid of Group D began to decrease since 14 days after treatment time-dependently (all P < 0.05), and the volumes of the other 3 groups continued to increase and peaked on days 21, 14, or 7 respectively (all P < 0.05). Microscopy showed infiltration of a larger quantity of histiocyte in the keloid tissue, and more obvious collagen disorganization and apoptosis of fibroblasts in Group D than in the other 3 groups. The protein expression of Bcl-2 was more remarkable and the protein expression of BAX was less remarkable in Group D than in the other 3 groups. The recombinant adenovirus-mediated double suicide gene therapy is effective on the implanted keloid tissue. The main mechanism may be induction of apoptosis in the keloid fibroblasts.