Immunological aspects observed in an experimental model of Abdominal Rectus Fascia Transplant in rats without immunosuppression, initial results.

JEREMIAS MOREIRA; IVANA IVANOFF; PABLO STRINGA; MARIA VIRGINIA GENTILINI; ARRIOLA BENITEZ, P. CONSTANZA; ARACELI CASTRO; MARTIN RUMBO; GONDOLESI GABRIEL

Congreso; LXXI Reunión Anual de la Sociedad Argentina de Inmunología; 2023

Background: At the end of intestinal or multivisceral transplant, it is essential to perform a primary closure of the abdominal wall. Synthetic meshes can increase the risks of infections and predispose to tissue reactions, present high costs and low availability on the market. The non-vascularized Transplantation of the Abdominal Rectus Fascia (TxARF) has been proposed as alternative. However, the absence of an experimental model, prevents a better understanding of the immunological phenomena of TxARF and its possible clinical implications.Aim: Was to develop and characterize an experimental model of TxARF in rats and to study the impact of immune response in an allogenic model.M&M: The TxARF is performed by applying the "Miami technique". 18 TxARF were performed, 9 were isogenic (ISO) and 9 allogeneic (ALLO) transplants, no immunosuppressive treatment was used. Sprague Dawley and Wistar rats were used. Non-implanted ARF were taken as Control (Ct). Pet Scan of the abdominal wall of some recipients was performed at day 30 and 120. Recipient rats were sacrificed at 30 or 120 postoperative days (POD) and graft samples were taken for H&E, Masson´s Trichrome, and immunohistochemistry for CD3+ cells. Relative amounts of CD4+ and CD8+ T cells were determined by flow cytometry. Turnover of hematopoietic cells in the graft was analyzed by flow cytometry using GFP+Wistar rats as recipients. Serum samples were taken for donor specific antibody (DSA) analysis. Statistical tests of Normality, One-way ANOVA tests and Kruskal-Wallis tests were used for the analysis of histopathological results.Results: Survival at day 30 and 120 was 100%. No adhesions were observed between the graft and the abdominal viscera neither in ISO or ALLO transplants. New blood vessels were observed in all samples. At 30 POD, the mean percentage of collagen fibers stained by Masson´s Trichrome was more than 10 times higher in the TxARF ALLO and ISO groups than in the Ct (p