Repair of oronasal fistulas with human amniotic membrane in minipigs.

We evaluated the use of multilayer human amniotic membrane (HAM) as a grafting material for the repair of mid-palate oronasal fistulas in seven Berlin minipigs. After two weeks, three animals had the fistulas repaired with multilayered HAM grafts, three had them repaired with a collagen-based dermal substitute (INTEGRA((R)), Integra Life Sciences, Plainsboro, NJ, USA), and one fistula was left untreated to serve as a control. Grafts were interposed between the oral and nasal mucosa, traversing the fistulas. After healing for 40 days, the pigs were killed for clinical, histological, and immunohistochemical examination. Two of the three fistulas closed with HAM were successful, the diameter of the third was reduced in size, and there was no change in the diameter of the fistula in the control. This study shows successful closure of oronasal fistulas in minipigs using interposed grafts of cryopreserved HAM, and offers promise as a simple and effective technique for tension-free closure of such fistulas.