TOWARDS THE DEVELOPMENT OF ARTIFICIAL ENDOCRINE TISSUES - P-31 NMR SPECTROSCOPIC STUDIES OF IMMUNOISOLATED, INSULIN-SECRETING ATT-20 CELLS

Transformed, insulin-secreting endocrine cells have been proposed as a n alternative to islets for the development of a bioartificial pancrea s. With appropriate immunoprotection, such cells may be implanted with out the need for patient immunosuppression. Use of continuous cell lin es alleviates the cell availability limitation, but poses questions re garding the stability and biochemical and secretory function of the pr eparation, especially in the longterm. We have developed a bioreactor/ perfusion perfusion system, compatible with a horizontal-bore NMR inst rument, that can maintain immunoprotected endocrine cells for prolonge d periods of time. P-31 NMR spectroscopy was used to study the bioener getics of recombinant, insulin-secreting mouse pituitary AtT-20 cells entrapped as spheroids in calcium alginate/poly-L-lysine/alginate bead s. NMR provided data verifying the macroscopic homogeneity within the bioreactor and allowing the evaluation of changes in cellular bioenerg etics for a period of 70 days under different culture conditions. Leve ls of high-energy phosphates changed slightly during the first 40 days of the experiment, then decreased considerably as cell death occurred . Rates of glucose consumption and insulin-related peptide secretion a lso remained constant for 40 days and decreased rapidly thereafter. Th is study constitutes the beginning of an extensive quantitative analys is of the biochemistry of transformed endocrine cell lines in a seques tered, artificial tissue environment. (C) 1995 John Wiley and Sons, In c.