AIM To investigate the potential of implanting pseudoislets formed from human insulin-releasing β-cell lines as an alternative to islet transplantation. METHODS In this study, the anti-diabetic potential of novel human insulin releasing 1.1B4 β-cells was evaluated by implanting the cells, either as free cell suspensions, or as three-dimensional pseudoislets, into the subscapular region of severe combined immune deficient mice rendered diabetic by single high-dose administration of streptozotocin. Metabolic parameters including food and fluid intake, bodyweight and blood glucose were monitored throughout the study. At the end of the study animals were given an intraperitoneal glucosetolerance test. Animals were then culled and blood and tissues were collected for analysis. Insulin and glucagon contents of plasma and tissues were measured by insulin radioimmunoassay and chemiluminescent enzyme-linked immunosorbance assay respectively. Histological analyses of pancreatic islets were carried out by quantitative fluorescence immunohistochemistry staining. RESULTS Both pseudoislet and cell suspension implants yielded well vascularised β-cell masses of similar insulin content. This was associated with progressive amelioration of hyperphagia(P < 0.05), polydipsia(P < 0.05), body weight loss(P < 0.05), hypoinsulinaemia(P < 0.05), hyperglycaemia(P < 0.05- P < 0.001) and glucose tolerance(P < 0.01). Islet morphology was also significantly improved in both groups of transplanted mice, with increased β-cell(P < 0.05- P < 0.001) and decreased alpha cell(P < 0.05- P < 0.001) areas. Whereas mice receiving 1.1B4 cell suspensions eventually exhibited hypoglycaemic complications, pseudoislet recipients displayed a more gradual amelioration of diabetes, and achieved stable blood glucose control similar to non-diabetic mice at the end of the study. CONCLUSION Although further work is needed to address safety issues, these results provide proof of concept for possible therapeutic applicability of human β-cell line pseudoislets in diabetes. AIM To investigate the potential of implanting pseudoislets formed from human insulin-releasing β-cell lines as an alternative to islet transplantation. METHODS In this study, the anti-diabetic potential of novel human insulin releasing 1.1B4 β-cells was evaluated by implanting the cells, either as free cell suspensions, or as three-dimensional pseudoislets, into the subscapular region of severe combined immune deficient mice rendered diabetic by single high-dose administration of streptozotocin. At the end of the study animals were given an intraperitoneal glucosetolerance test. Animals were then culled and blood and tissues were collected for analysis. Insulin and glucagon contents of plasma and tissues were measured by insulin radioimmunoassay and chemiluminescent enzyme-linked immunosorbance assay respectively. Histological analyzes of pancreatic islets were car ried out by quantitative fluorescence immunohistochemistry staining. RESULTS Both pseudoislet and cell suspension implants yielded well vascularised β-cell masses of similar insulin content. This was associated with progressive amelioration of hyperphagia (P <0.05), polydipsia (P <0.05), body weight loss (P <0.05), hypoinsulinaemia (P <0.05), hyperglycaemia (P <0.05- P <0.001) and glucose tolerance Whereas mice receiving 1.1B4 cell growth attempts showing hypoglycaemic complications, pseudoislet recipients displayed a more gradual amelioration of diabetes, and achieved stable (P <0.05- P <0.001) and decreased alpha cells (P <0.05- P <0.001) blood glucose control similar to non-diabetic mice at the end of the study. CONCLUSION Although further work is needed to address safety issues, these results provide proof of concept for possible therapeutic app licability of human β-cell line pseudoislets in diabetes.