Alginate Microencapsulation of Islet Cells Using Electrostatic Droplet Generator / 대한이식학회지

ABSTRACT

BACKGROUND: Microencapsulation of islet cells has been studied for the treatment of type I diabetes to protect islets from immune attack by recipient cells during islet transplantation. In this study, we established optimal preparation conditions for islet microcapsules with good morphology and cell viability by employing an electrostatic droplet generator. METHODS: To obtain good quality islet microcapsules, various parameters such as the inner diameter of the electrostatic droplet generator nozzle, concentrations and infusion rates of alginate, electrostatic strength, and calcium chloride concentrations were tested. The size and shape of the capsules and cell viability were examined by light microscopy, and insulin secretion from the cells was determined by an ELISA analysis. RESULTS: The optimal preparation conditions for microencapsulation were a 0.35 mm inner nozzle diameter, a 1.75% alginate concentration, a 20 mL/hr alginate infusion rate, a 5 kV electrostatic potential, and a 75 mM calcium chloride. Under these conditions, over 90% of the capsules had a proper size (300~350 micrometer) and shape, and cell viability was 91%. Cell viability was maintained at greater than 80% even after the capsules were cultured for 2 weeks. However, glucose-induced insulin secretion of encapsulated islet cells was reduced by 85% compared to that of nonencapsulated cells. CONCLUSIONS: The results showed that an encapsulation technique using an electrostatic droplet generator is useful for making islet microcapsules with good morphology and cell viability. This technique is necessary to study microencapsulation using primary islets, enhancing glucose-induced insulin secretion, and to perform a functional evaluation of encapsulated islets in vivo in the near future.