Syngeneic transplantation of thyroid tissue encapsulated in a cellulose sulphate membrane

A new, simple encapsulation method, the precipitation of a polyelectrolyte complex membrane of cellulose sulphate and poly(dimethyldiallylammoniumchloride) was investigated in syngeneic thyroid transplantation. Half a thyroid gland was placed beneath the kidney capsule either after being encapsulated or as a non-encapsulated control graft. In normo-thyroid as well as hypothyroid recipients, the grafted tissue was viable for up to 12 weeks. Furthermore, the hypothyroid state, which was characterized by a markedly diminished 125iodine incorporation into the thyroid, no body weight gain and undetectable serum thyroxin concentrations, was compensated by the grafted tissue. The encapsulated grafts showed lower iodine incorporation, T4 secretion and body weight gain when compared with non-encapsulated control grafts. This may be due to a partial restriction of TSH by the capsule membrane. It was concluded that the cellulose sulphate membrane is biocompatible and enables the functional survival of syngeneic grafted tissue.