Immunoisolation of pancreatic islets interrupts their vascular connections and results in severe cell
hypoxia and dysfunction. This process is believed to be the major obstacle to a successful cure of
diabetes by implantation of bioartificial pancreas. Here we describe a new technology for microalgabased,
photosynthetic oxygen supply to encapsulated islets, in which a thermophylic strain of the
unicellular alga Chlorella was used as a natural photosynthetic oxygen generator. Following determinations
of the optimal number of alga cells required for compensation of islet respiration, an appropriate
number of islets and algae were co-encapsulated in alginate and perifused with oxygenfree
medium at increasing glucose concentrations. No insulin response to glucose was obtained in
islets alone, or upon inactivation of photosynthesis by darkness. However, under illumination, photosynthetic-
dependent oxygen generation induced higher glucose-stimulated insulin response when
compared to normoxic perifusion. Such photosynthetic oxygen generation may have a potential application
in development of various bioartificial tissues, in particular the endocrine pancreas.
