Microencapsulation of living cells and tissues.

A new microencapsulation procedure involving an all-aqueous phase system was developed. Viable cells or tissues were suspended in sodium alginate droplets, which then were gelled by calcium chloride solution. A permanent, semipermeable membrane was formed on the surface layer of the temporary gel capsules by treatment with a solution of polylysine. Finally, true living cell-containing microcapsules were produced by "liquefying" the gel within the microcapsules through calcium-ion removal by simple ion exchange. Microencapsulated living cells and tissues continued to grow and flourish. In tissue culture medium, microencapsulated rat pancreatic islets continued to release insulin and remained sensitive to glucose and theophylline stimulation, responding with a typical physiological biphasic insulin-release pattern for over 2 months. Microencapsulation of other viable cells and tissues such as red blood cells, hepatoma cells, sperm cells, and pancreatic endocrine tissues also was successful.