title: ALK5 inhibition maintains islet endothelial cell survival but does not enhance islet graft revascularisation or function.
abstract: Islet transplantation is a potential treatment for Type 1 diabetes but long term graft function is suboptimal. The rich supply of intraislet endothelial cells diminishes rapidly after islet isolation and culture, which affects the revascularisation rate of islets after transplantation. The ALK5 pathway inhibits endothelial cell proliferation and thus inhibiting ALK5 is a potential target for improving endothelial cell survival. The aim of the study was to establish whether ALK5 inhibition prevents the loss of intraislet endothelial cells during islet culture and thus improves the functional survival of transplanted islets by enhancing their subsequent revascularisation after implantation. Islets were cultured for 48 h in the absence or presence of 2 different ALK inhibitors: SB-431542 or A-83-01. Their vascular density after culture was analysed using immunohistochemistry. Islets pre-cultured with the ALK5 inhibitors were implanted into streptozotocin-diabetic mice for either 3 or 7 days and blood glucose concentrations were monitored and vascular densities of the grafts were analysed. Islets cultured with ALK5 inhibitors had higher vascular densities than control-cultured islets. Three days after implantation, endothelial cell numbers in islet grafts were minimal, irrespective of treatment during culture. Seven days after implantation, endothelial cells were evident within the islet grafts but there was no difference between control-cultured islets and islets pre-treated with an ALK5 inhibitor. Blood glucose concentrations were no different between the treatment groups. In conclusion, inhibition of ALK5 improved intraislet endothelial cell numbers after islet culture, but this effect was lost in the early post-transplantation period.
authors.affiliation: Diabetes Research Group, Division of Diabetes and Nutritional Sciences, King's College, London, UK.
authors.forename: A J F
authors.initials: AJ
authors.lastname: King
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton General Hospital, Southampton, UK.
authors.forename: C E
authors.initials: CE
authors.lastname: Clarkin
authors.affiliation: Diabetes Research Group, Division of Diabetes and Nutritional Sciences, King's College, London, UK.
authors.forename: A L F
authors.initials: AL
authors.lastname: Austin
authors.affiliation: Diabetes Research Group, Division of Diabetes and Nutritional Sciences, King's College, London, UK.
authors.forename: L
authors.initials: L
authors.lastname: Ajram
authors.affiliation: Diabetes Research Group, Division of Diabetes and Nutritional Sciences, King's College, London, UK.
authors.forename: J K
authors.initials: JK
authors.lastname: Dhunna
authors.affiliation: Diabetes Research Group, Division of Diabetes and Nutritional Sciences, King's College, London, UK.
authors.forename: M O
authors.initials: MO
authors.lastname: Jamil
authors.affiliation: Diabetes Research Group, Division of Diabetes and Nutritional Sciences, King's College, London, UK.
authors.forename: S I
authors.initials: SI
authors.lastname: Ditta
authors.affiliation: Diabetes Research Group, Division of Diabetes and Nutritional Sciences, King's College, London, UK.
authors.forename: S
authors.initials: S
authors.lastname: Ibrahim
authors.affiliation: Diabetes Research Group, Division of Diabetes and Nutritional Sciences, King's College, London, UK.
authors.forename: Z
authors.initials: Z
authors.lastname: Raza
authors.affiliation: Diabetes Research Group, Division of Diabetes and Nutritional Sciences, King's College, London, UK.
authors.forename: P M
authors.initials: PM
authors.lastname: Jones
mesh_terms: D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D001786:Blood Glucose / Q000378:metabolism; D002452:Cell Count; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004149:Dioxoles / Q000494:pharmacology; D042783:Endothelial Cells / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000098:blood supply*; D016381:Islets of Langerhans Transplantation; D008297:Male; D008810:Mice, Inbred C57BL; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors* / Q000378:metabolism; D013882:Thiosemicarbazones / Q000494:pharmacology
chemical_list: C459179:4-(5-benzo(1,3)dioxol-5-yl-4-pyridin-2-yl-1H-imidazol-2-yl)benzamide; C507011:A-83-01; D001549:Benzamides; D001786:Blood Glucose; D004149:Dioxoles; D007328:Insulin; D011720:Pyrazoles; D018125:Receptors, Transforming Growth Factor beta; D013882:Thiosemicarbazones; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625842:Tgfbr1 protein, mouse