The Development of a Vascularly Implanted Prosthetic Endocrine Pancreas

Abstract

3cm and 1.5 cm implantable prosthetic units were constructed from biocompatible fabrication materials and consisted of a polyethylene shell containing a centrally positioned acrylic copolymer hollow fibre (M.W. cut-off 100K Daltons), with a 10 cm polyethylene cannula attached at either end. Hollow fibre/cannula junctions were potted into the polyethylene shell via a disc of PVC tubing and U/V-cured dental adhesive. The secretory capagity of prototype units was studied in vitro using methylene blue, 125I-insulin and islets from lean and obese mice and optimal physical criteria, i.e. flow rate and perfusion pressure were established. Prototype units provided a constant rate of methylene blue release over a period of 7.5 hours at a flow rate of 0.637 ml/min. and perfusion pressure of approximately 100 mmHg. The rate of 125 I-insulin release from units was proportional to the concentration of labelled insulin originally inserted into the unit but independent of perfusate albumin (BSA V) concentration. Protein coating of hollow fibres by a glutaraldehyde cross-linking technique to reduce thrombogenicity, increased the lag time of prototype wits and the uniformity of the protein coating could not be guaranteed...