Transplantation of encapsulated islets may restore endogenous insulin secre
tion in type 1 diabetics with no need of lifetime immunosuppression of the
recipient. A biomaterial should be developed which combined immunoisolation
with rapid and efficient diffusion of glucose and insulin. Rat islets were
macroencapsulated in capillaries (molecular cut off 50 kD) of differently
modified polysulphone. Macroencapsulated islets were perifused to study the
kinetics of glucose induced insulin secretion into the perifusion medium.
Blending polysulphone (PSU) with poly vinyl pyrrolidone or sodium dodecyl.
sulphate was not suited for islet macroencapsulation since glucose induced
insulin release was absent after encapsulation. Hydroxy methylation (CH2OH)
of PSU improved the secretory behaviour of macroencapsulated islets depend
ing on the degree of substitution (DS). At 0.8 DS glucose induced insulin s
ecretion was delayed and inefficient. At maximal degrees of PSU-substitutio
n (1.8) the kinetics of insulin release and the efficiency of insulin relea
se were very similar to that observed of free floating islets. In conclusio
n, highly substituted hydroxgy methylated polysulphone allows a rapid and e
fficient insulin release after macroencapsulation and is suited for the fur
ther development of a bioartificial pancreas.