The Effects of Alginate Encapsulation on NIT-1 Insulinoma Cells: Viability, Growth and Insulin Secretion

Transplantation of microencapsulated insulin- secreting cells is proposed as a promising therapy for the treatment of type I diabetes mellitus. In recent years, important advances have been made in the field of immunoisolation and many studies have shown that alginate provides some major advantages for encapsulation over other systems. Since it is known that the extracellular matrix influences the behaviour of encapsulated cells, the aim of the present work has been to study the consequences of encapsulation on some cell functions. For this purpose, cell growth and dynamics of insulin release of NIT-1 cells entrapped in alginate capsules compared with those exhibited by free NIT-1 cells were investigated by means of growth curves, assays, Trypan blue staining and ELISA test. All investigations performed allowed us to conclude that alginate-entrapped NIT-1 cells maintain their growth features and secretory functions although with some important differences. In particular, alginate encapsulation affects the cellular growth profile and causes the lost of time dependence of insulin secretion profile. Transplantation of pancreatic islet cells has been shown to be a potential modality of treating insulin-dependent diabetes mellitus (1). However transplantated cells are rapidly destroyed by immune rejection and immunosuppressive drugs to protect islets grafts are required, resulting in a strong limitation for the clinical application of this therapy (2). Consequently, many efforts have been directed towards