Dried human amniotic membrane as an antiadherent layer for intraperitoneal placing of polypropylene mesh in rats

Intraabdominal peritoneal onlay polypropylene (PP) mesh repair of incisional hernia has the potential risk of adhesions, bowel obstructions, and intestinal fistulae. Fresh or cryopreserved human amniotic membrane (HAM) has been tested as an antiadherent layer in animals, with excellent outcomes. However, it has disadvantages: it is difficult to handle, and it is expensive to store. Another processing method is available: drying in a laminar flow hood and gamma irradiation. Because this method impairs the membrane's cell viability, it may affect its antiadherent properties. However, such properties may also result from the collagen matrix and its basement membrane, which remain after drying. The aim of the present study was to asses dried irradiated HAM in adhesion prophylaxis in rats.

Twenty-four female rats were randomized into two groups. In the first group (control group), PP meshes were placed in the intraabdominal space, and in the second group (treatment group), PP meshes coated with HAM were used. Animals were killed on day 30 after surgery. Adhesions and parietal prosthetic incorporation were assessed macroscopically and expressed as the average percentage of the covered area. The portion of the abdominal wall was then resected for histological testing.

The treatment group had a significantly higher percentage of adhesions and parietal incorporation compared with the control group (p = 0.003). Histological testing showed a higher inflammatory response in the treatment group, with an intense foreign body reaction.

Dried irradiated HAM does not prevent adhesion formation in intraabdominal peritoneal onlay PP mesh repair in rats. Any use of this biomaterial in adhesion prophylaxis must be undertaken respecting graft cell viability as much as possible.