Effect of adenoviral-mediated transfer of transforming growth factor-beta1 on colonic anastomotic healing

Transforming growth factor-beta1 plays a central role in colonic repair. We examined the temporal effect of vector-mediated transfer of transforming growth factor-beta1 on colonic anastomotic healing.

Male Sprague-Dawley rats (n = 24) underwent transection of the distal colon and single-layer anastomosis. Proximal to the anastomosis, the colon was again transected and a colostomy was matured proximally. The distal colon was intubated with a silicone catheter, tunneled along subcutaneous tissues, and connected to a swivel apparatus for postoperative luminal infusion. Rats were randomized into four groups (n = 6 each). Two control groups received 10(10) plaque-forming units of a Type 5 E1-deleted adenovirus carrying the bacterial beta-galactosidase gene either immediately following surgery or on postoperative Day 3. The treatment groups received transforming growth factor-beta1 with the same viral construct at parallel time points. On postoperative Day 6, anastomotic bursting pressure and site were determined in situ with the anastomotic tissue subsequently harvested and analyzed by enzyme-linked immunosorbent assay for beta-galactosidase and transforming growth factor-beta1.

When compared with its corresponding control, the group that received the transforming growth factor-beta1 gene on postoperative day 3 had a significantly higher bursting pressure (mmHg; 119 +/- 16 vs. 160 +/- 12, mean +/- SD; P = 0.001). While the majority of colons (5/6) from the control group burst at the anastomosis, none of the colons in the group that received transforming growth factor-beta1 on day 3 burst at the anastomotic site (P = 0.007). Beta-Galactosidase levels (pg/ml) in anastomotic tissue were significantly increased in both control groups when compared with their respective treatment groups (101 +/- 43 vs. 38 +/- 30, P = 0.01 when infused the day of surgery and 243 +/- 92 vs. 50 +/- 30, P = 0.009 when infused on day 3). Anastomotic levels of transforming growth factor-beta1 were also increased in the group receiving the transforming growth factor-beta1 gene on day 3 (214 +/- 66 vs. 135 +/- 24, P = 0.02).

Gene transfer into the healing colonic anastomosis can be effectively achieved via intraluminal administration of adenoviral vectors. Transfer of transforming growth factor-beta1 increased the strength of colonic anastomoses when given at Day 3 but not at Day 0, demonstrating its diverse effects in the wound healing sequence. Thus, gene transfer of transforming growth factor-beta1 may avoid the need for a diverting stoma in cases of rectal surgery and impaired healing resulting from chemotherapy or radiation.