Computer-Assisted ex vivo, Normothermic Small Bowel Perfusion

Abstract

Background: In the present study, a technique for computer-assisted, normothermic, oxygenated, ex vivo, recirculating small bowel perfusion was established as a tool to investigate organ pretreatment protocols and ischemia/reperfusion phenomena. A prerequisite for the desired setup was an organ chamber for ex vivo perfusion and the use of syngeneic whole blood as perfusate. Methods: The entire small bowel was harvested from Lewis rats and perfused in an organ chamber ex vivo for at least 2 h. The temperature was kept at 37°C in a water bath. Three experimental groups were explored, characterized by different perfusion solutions. The basic perfusate consisted of syngeneic whole blood diluted with either NaCl, Krebs’ solution or Krebs’ solution and norepinephrine to a hematocrit of 30%. In addition, in each group l-glutamine was administered intraluminally. The desired perfusion pressure was 100 mm Hg which was kept constant with a computer-assisted data acquisition software, which measured on-line pressure, oxygenation, flow, temperature and pH and adjusted the pressure by changing the flow via a peristaltic pump. The viability of the preparation was tested by measuring oxygen consumption and maltose absorption, which requires intact enzymes of the mucosal brush border to break down maltose into glucose. Results: Organ perfusion in group 1 (dilution with NaCl) revealed problems such as hypersecretion into the bowel lumen, low vascular resistance and no maltose uptake. In contrast a viable organ could be demonstrated using Krebs’ solution as dilution solution. The addition of norepinephrine led to an improved perfusion over the entire perfusion period. Maltose absorption was comparable to tests conducted with native small bowel. Oxygen consumption was stable during the 2-hour perfusion period. Conclusions: The ex vivo perfusion system established enables small bowel perfusion for at least 2 h. The viability of the graft could be demonstrated. The perfusion time achieved is sufficient to study leukocyte/lymphocyte interaction with the endothelium of the graft vessels. In addition, a viable small bowel, after 2 h of ex vivo perfusion, facilitates testing of pretreatment protocols for the reduction of the immunogenicity of small bowel allografts.

Swine intestinal segment perfusion model for the evaluation of nutrients bioaccessibility

“…It is important to consider that this model is more advanced if compared to a classic ex vivo model which do not provide extracorporeal circulation. This model was obtained following the surgery techniques used for in vivo organ transplantations in order to preserve the organ viability and architecture during the entire experimental period [13].…”

“…It has been demonstrated that the mucosal epithelium is extremely susceptible to ischemia [11] and although ex vivo models can better reproduce the complexity of the in vivo situation when compared to in vitro models, deterioration of the explanted tissue and lack of hemodynamics can cause differences between ex vivo and in vivo data [12]. The perfusion of ex vivo tissue allow to the conservation of organ viability and structure for a longer period compared to classic ex vivo models [13]. Recent studies, showed encouraging results of swine intestinal perfused model suggesting it as a cost-effective, practical and reliable strategy for the study of intestinal physiology, pharmacology and transplantation [14].…”