The biological behavior of autologous collagen-based extracellular matrix injected into the rabbit bladder wall

Endoscopic techniques are providing a minimally invasive approach to the tr eatment of vesicoureteral reflux and urinary incontinence. Bovine collagen has been used, but potential degradation over time and sensitivity reaction s have limited its usefulness. We evaluate the use of an autologous collage n-based extracellular matrix preparation injected within the rabbit bladder submucosa and compare it to the stability of bovine collagen-injected simi larly. Of 28 New Zealand white rabbits, 12 underwent injection of autologou s collagen-based extracellular matrix, 12 bovine collagen, and four normal saline sham injections into the anterior bladder submucosa. Twelve collagen specimens were iodinated with iodine 125 (I-125) paraaminobenzoate reagent . The I-125-labeled rabbits were monitored with a gamma camera to assess th e level of decay of radioactivity over 12 weeks. All animals were killed 12 weeks post-injection. Assessment of radioactivity showed minimal differenc e in radioisotope labeling between the autologous and bovine collagen (tota l counts and decay kinetics). Compared to bovine collagen, the autologous c ollagen- based extracellular matrix implants histologically showed increase d fibroblastic and vascular infiltration focally. The most significant hist ologic difference was the marked inflammatory response associated with the bovine collagen implants. These data suggest that in the short term, autolo gous and bovine collagen appear to have similar stability. The response to autologous collagen-based extracelluar matrix may increase longevity of the implant, primarily by reducing immunologic rejection and improving biocomp atibility within the host tissue. Further long-term studies are necessary t o assess the long-term stability of autologous collagen-based extracellular matrix. (C) 1999 Wiley-Liss, Inc.