Microencapsulation of human parathyroid cells: An "in vitro" study

Background. Patients affected by hypoparathyroidism of variable etiology ar e currently treated with exogenously administered vitamin D and calcium. Hu man parathyroid transplantation has long been investigated as a possible me an of treating these patients to prevent long-term hypocalcemia. However, t he main obstacle for this treatment is represented by tissue rejection. A r eliable method to efficiently protect the transplanted tissue from rejectio n and to allow longterm survival of the graft is the encapsulation of tissu es or cells in alginate-polylysine-alginate membranes, which were successfu lly used for encapsulation of islets of Langerhans. The microencapsulation of parathyroid tissue fragments or of parathyroid cells becomes, therefore, a potential approach for the successful treatment of permanent symptomatic hypoparathyroidism without pharmacological immunosuppression. Materials and methods. We describe microencapsulation of differentiated hum an parathyroid cells derived from adenoma or hyperplastic glands. Longterm viability, cell growth, and parathyroid hormone production of microencapsul ated cells were evaluated together with responsiveness to extracellular Ca2 +. Results. Microencapsulated parathyroid cells maintained proliferative and d ifferentiative properties for a long term in culture with a good response t o extracellular Ca2+ concentration. Conclusions. These findings represent a crucial step toward the constructio n of functional bioartificial parathyroid organoids for the treatment off h ypoparathyroidism in humans, (C) 2001 Academic Press.