Ex vivo intestinal model for the evaluation of nutrient bioaccessibility

Nowadays, the nutrition plays a pivotal role for both human and animal health, and increasingly requires sciencebased evidences to develop effective functional diets. In order to reduce the use of animals for experimental purposes innovative reliable and informative models, simulating the complex intestinal physiology, represent an expanding research field. In this scenario, the aim of this study was to develop and evaluate an intestinal swine ex vivo model for the evaluation of nutrient bioaccessibility and its functionality among time. A pig intestine was harvested, following Maastricht criteria, from a 100 kg pig at the slaughterhouse. The isolated duodenum tract was reperfused in normothermic conditions with heterologous blood after cold ischemic storage. Ex vivo duodenum perfusion model was maintained in controlled pressure conditions (flux pump 1.48 l/min, O2 2 l/min, artery pressure 76/55 mmHg) through extracorporeal circulation for 4 hours. During this period, blood and luminal content samples were collected at regular intervals for the evaluation of the concentrations of glucose by glucometer, minerals (Na, Ca, Mg, K, P) by ICP-AES, lactate-dehydrogenase (LDH) and derivates of reactive oxygen metabolites (D-ROMs) by colorimetric methods. Histological examination was carried on three intestinal segments. The macroscopic observation showed peristaltic activity caused by intrinsic nerves. Measured glucose levels suggested its utilization at cellular level confirming the organ viability in line with histological examination. At the end of the experimental period, intestinal mineral concentrations resulted lower than their level in blood plasma highlighting their bioaccessibility (P<0.001). A progressive increase of D-ROMs and LDH concentration among time, in luminal content, was observed related to a slight oxidative stress (P<0.05). Isolated ex vivo duodenum perfusion developed model fulfils all the prerequisites to study bioaccessibility of nutrients, offering a variety of experimental possibilities in line with 3Rs principles.