[Intraluminal expansion of a small intestine segment--animal experiment principles and possible clinical application]

In this study we expanded ileal segments of 8 pigs with an intraluminal expander over a period of 6 to 8 weeks till the volume had reached approximately sixfold of the starting volume. The morphological and morphometrical examinations showed flattened villi with elongated crypts and especially an increase in the thickness of the muscularis. The villi appeared flattened through scanning microscopy as well, but the structure of the microvilli was nearly normal. The proliferative activity in the muscularis, estimated immunohistochemically by a monoclonal antibody against PCNA, showed a threefold increase. So it can be assumed, that the increased thickness of the muscle layer was caused not only by muscle cell hypertrophy but also by hyperplasia. The activity of the alpha-glucosidase, a brush border enzyme, was clearly reduced. The minor cause of this effect was the direct damage of the microvilli from the expander, but the major cause was the exclusion of the ileal segment from the small bowel passage and the resulting lack of nutrients. With our technique it seems possible to create an ileum pouch, a stomach substitute or a urinary bladder substitute.