Effects of stem cell on anastomosis in the colon anastomosis done in everolimus-immunsupressed rats: Experimental study

Gastrointestinal system surgery operations have been applied intensively due to the malignant or benign causes. Anastomosis leakages that are seen after the gastrointestinal system operations cause important mortality and morbidity. There have been a lot of studies on the reduction and management of anastomosis leakage for many years. After the solid organ transplantation, to prevet the formation of the immune reaction against to transferred organ and to provide long-term survival of the graft, immunosuppressive treatment protocols are applied to the patients. Gastrointestinal system operations can be performed during or after the organ transplant surgery in these patients receiving immunosuppressive treatment. Commonly applied immunosuppressive treatment protocols are, calcineurin inhibitors, corticosteroids and the single or multiple combinations of the antiproliferative agents. When the calcineurin inhibitors can not be used, treatment protocols with m- TOR inhibitors have been preferred. Although m- TOR inhibitors are less nephrotoxic than the calcineurin inhibitors and they provide stronger immunosuppression, they have adeverse effects like delay in wound healing, infertility, pneumonitis and thrombocytopenia. However, several treatments have been tried to reduce the adverse effects of mTOR inhibitors in wound healing. Mesenchymal stem cell therapy has positive effects on wound healing and it decreases the anastomosis leakages due to the differentiation characteritics to multiple tissues and the increased formation of new blood vessels. In this study, it is aimed to investigate the effect of the stem cells that are derived from adipose tissue on wound healing in rats that are immunosuppressed with m-TOR inhibitors. In this study, 60 Sprague- Dawley male rats were used. Four groups of 14 rats each were formed. Also 4 rats were used to obtain the stem cells. We immunsupressed the third and the fourth groups of four main groups with everolimus everyday from 7 days prior to laparatomy. Anastomosis was performed, after the descending colon of all the rats in all groups was completely cut. In the second and forth groups we performed subserosal stem cell injection into the anastomotic region. All of the groups were randomly divided into two equal subgroups . One of the subgroups of each main groups were sacrified on the 4th day, and the other ones were sacrificed on the 7th day. In each groups, the bursting pressure of the colonic anastomosis, tissue hydroxyproline level measurement and histopathological evaluation were done. Immunohistochemicaly, florescent microscopic examination was done for the following of the DiI marked adipose derived stem cells in the study group. As a result of the analysis, there is no statistically siginificant difference in the weight loss distribution between the experimental groups when considering the animals that are sacrified on the 4th day (p= 0,013). When all the groups are evaluated in terms of adhesion parameters, minimal adhesion was observed in the 85,7 % of the animals that are sacrified on the 7. day and that are in the groups of everolimus+ stem cell while indermediate adhesion was observed in the 14,3 % of them. Adhesion rate on the 4th day is significantly higher than the adhesion rate on the 7th day. The effect of the sacrifice day on the level of the hydroxyproline is statistically siginficant at 95 % confidence level. (p< 0,001). When we look, it is observed that the average hydroxyproline levels of the animals that are sacrified on the 7th day are higher than the average hydroxyproline levels of the animals sacrified on the 4th day. When the animals sacrified on the 4th day are considered, there is a statistically significant difference in terms of the average of the bursting pressures between the Control and Stem Cell groups ( p= 0,002) and between the Stem Cell and Everolimus groups ( p<0,001). When evaluating the results of the analysis of reepithelization, ischemic necrosis, fibrosis and the deterioration of the muscular layer, no significant difference was determined. When evaluating the vascular proliferation results, there was no significant difference between the groups that were sacrified on the 4th day (p= 0,226) , whereas there was a significant difference among the groups that were sacrified on the 7th day ( p= 0,003). Subserosal stem cell injections to colon anastomosis in immunosupressed rats with everolimus and in non- immunosuppressed rats increase the anastomotic resistance, decrease the weight loss and increase the vascular proliferation. In the risky gastrointestinal system anastomosis, adipose tissue derived stem cell application may be an appropriate method.