MIGRATION OF MACROPHAGE-LIKE CELLS WITHIN ENCAPSULATED ISLETS OF LANGERHANS MAINTAINED IN TISSUE-CULTURE

Islets of Langerhans isolated from the pancreas and encapsulated in al ginate-polylysine-alginate microspheres can potentially serve as a sel f-regulating supply of insulin in response to glucose loads. A longitu dinal ultrastructural and immunohistochemical study of encapsulated ra t islets cultured in CMRL-1969 media at a constant glucose concentrati on of 5.5 mmol/L (100 mg%) allowed several observations. First, acinar cells, which remain attached to isolated islets, disappeared within 1 wk in tissue culture, Damaged endocrine cells also disappeared at thi s time. Phagocytic cells having ultrastructural features suggesting th at they are macrophages emerged from the islets within about a week an d ingested portions of the inner layer of capsule polymer. These macro phage-like cells retained these polymers until their death which occur red at around 1-2 mo after isolation; at no time did we observe phagoc ytic cells actually breaching the microsphere capsules, Beta cells rem ained well-granulated over 90 days of culture but accumulated lipofusc in-like residual bodies, Under these conditions, these bodies began to accumulate appreciably after about one week in culture.