Benefiial effects of human serum albumin on stability and functionality of alginate microcapsules fabricated in different ways

摘要

A key engineering challenge in designing microcapules made from biocompatible alginate is maintaining adequate exchange of nutrients and oxygen between the entrapped cells and theenvironment,while simultaneously avoiding swelling and subsequent failure of the microcapsule.Approval for the use of alginate in pharmaceutical and/or biomedical applications also strictly requires that the components of the microcapsule material must meetthe safety criteria of the ASTM and FDA.Incorporation of foetal calf serum (FCS)into the microcapsules for stabilization is not in accordance with the guidelines affirmed by these organizations.FCs should be substituted by microcapsule-stabilizing additives that are medically approved.In this communication,it is shown that 10% FCS can be replaced by 1% human serum albumin (i.e.by an agent for which medical approval is granted)without compromising effects on long-term in vitro stability.Furthermore,it is demonstrated that human serum albumin (HSA)significantly enhances cell survival and,particularly,insulin secretion of encapsulated rat islets over a time period of 3 weeks when incubated in culture medium.Thus,HSA-stabilized microcapsules made from UHV_(Lam)alginate are apparently a romising system for immunoisolation of cells,particularly when alginate is cross-linked by injection of BaCl_2 crystals into the alginate droplets.Slight adjustments of the alginate concentration can tailor the microcapsule permeability to the released therapeutic factor.