Hypothermia Mechanical Perfusion Alleviate Microcirculation Injury In Isolated Pig Small Intestine

Objective: IT is the only effective method to treat end-stage small intestine dysfunction and to get rid of parenteral nutrition.At present,the main difficulties of IT are infection,immune rejection and ischemia reperfusion injury.Effective in vitro intestinal preservation is the key to reduce intestinal injury.Compared with traditional cold storage,mechanical perfusion can significantly reduce the ischemia reperfusion injury of the graft,thus reducing primary dysfunction of graft.The applications of mechanical perfusion in both liver and kidney were well,but few attempts have been made in small intestine transplantation.Intestinal microcirculation is very sensitive to intestinal injury and is an early indicator of IRI and tissue injury.This study will discuss the effect between using HMP and UW solution cold storage in vitro small intestine from the perspective of microcirculation,and explore better methods to protect in vitro small intestine.Methods:1.Establishment of HMP storage device: HMP storage device was established by using heat exchange tank,centrifugal pump,membrane oxygenator,multi-channel physiological recorder,digital display temperature-controlled water box,pressure sensor,ultrasonic blood flow meter,three-way valve,micro-injection pump,blood microthrombin filter,and etc.2.Establishment of an orthotopic IT model for pigs: Ten healthy Bama miniature pigs were selected.The experimental animals were randomLy divided into two groups.Cutting the intestine 200 cm and corresponding blood vessels and then connect to HMP storage device in 4℃ for 6 hours in the group HMP.Cutting the intestine 200 cm and corresponding blood vessels and then preserve in 4℃ UW solution for 6 hours in the group UW.Situ IT was performing when preservation finished.3.Detection of protective effect on IT in pigs: venous blood was collected before 30 minutes at the time of the donor’s laparotomy and after 30 minutes recipient’s intestinal blood flow was opened,the NO and ET-1 were determined.Small intestine tissue was taken for pathological and dry/wet ratio examination.The velocity of blood flow in the small intestinal was measured by laser doppler probe at the time of donor laparotomy and 30 minutes after the blood flow of recipient intestine was opened.Results:ET-1 was increased in both the HMP group and the UW group at the time after 30 minutes intestinal blood flow was opened,and the increase was high in the UW solution group.NO decreased more significantly in UW group,with statistical difference(p<0.05);The results of dry/wet ratio showed that edema of intestine in UW group was higher than that in HMP group(p<0.05).According to the measurement by laser doppler velocimeter,the blood flow velocity both in the HMP group and UW group are decreased,but UW group decreased significantly(p<0.05).Pathology showed: when the blood flow was open for 30 minutes in the HMP group,mild edema of the inherent membrane was seen,scattered lymphocyte infiltration,epithelium on the villus surface was not shed,and capillary congestion was not observed.In the UW group,edema and hyperemia of the inherent membrane,lymphocyte infiltration,partial shedding of villous epithelial cells,focal erosion,and capillary hyperemia were seen.Conclusion: The HMP device is stable and reliable.In vitro preservation of small intestine by HMP and UW solution cold preservation,it was found that whether HMP preservation or UW solution preservation,small intestinal microcirculation was damaged to varying degrees,tissue edema,intestinal mucosal injury.However,the small intestine vasospasm of pigs preserved by HMP was relatively mild,and the blood flow damage is slighter.The protective effect of HMP on the small intestine vasospasm of pigs was stronger than that of the traditional UW solution,the edema and injury caused by ischemia and hypoxia in intestinal tissues were alleviated.