Improved surgical outcome by modification of porcine dermal collagen implant in abdominal wall reconstruction in rats

Aim: We earlier showed in rats that fascial repair with Pelvicol, a porcine dermal collagen implant, was associated with a lesser inflammatory response but lower tensile strength in the early postoperative period as compared to Prolene. Herein we wanted to evaluate whether creation of pores in Pelvicol, facilitating ingrowth of fibrous tissue and vessels, would result in a higher tensile strength at d30 without compromising longer term results. Methods: First tensile strength of Pelvicol modified with different pore sizes was evaluated ex vivo. In a second step, Pelvicol implants with pores were used to cover full-thickness abdominal wall defects in 36 rats. Implants were either Pelvicol (non-porous) or with pores of Phi: 0.7,1.2, or 2.0 mm (n = 6 each). Animals were sacrificed on d30 and 90 to evaluate the presence of herniation, infection, adhesions, change in thickness and tensile strength. Histopathology was performed to assess inflammatory response and collagen deposition. Data were compared to available data on Prolene implanted animals at same time points. Results: Pelvicol with pore diameter of 2.5 mm was significantly weaker ex vivo. Animals repaired with non-porous material did develop seroma (2/6) or clinical infection (1/6) whereas none in the other groups did. There was a trend for increasing tensile strength at 30 d with increasing pore diameter, being significant in the 2.0-mm pore size group. This difference disappeared by 90 d, where all materials were equally strong as Prolene. The foreign body reaction was less intense in a pore-size dependent manner, with more abundant neo-vascularization and collagen deposition passing through the pores. Conclusion: Creation of pores in Pelvicol promotes neo-vascularization, collagen deposition, and fibrous tissue ingrowth, and at pore size 2.0 mm tensile strength was increased at d30 whereafter all materials had comparable strength. Neurourol. Urodynam. 24:362-368,2005. (c) 2005 Wiley-Liss, Inc.