In Vivo CaV3 Channel Inhibition Promotes Maturation of Glucose-Dependent Ca2+ Signaling in Human iPSC-Islets

Biomedicines. 2023 Mar 7;11(3):807. doi: 10.3390/biomedicines11030807.

Abstract

CaV3 channels are ontogenetically downregulated with the maturation of certain electrically excitable cells, including pancreatic β cells. Abnormally exaggerated CaV3 channels drive the dedifferentiation of mature β cells. This led us to question whether excessive CaV3 channels, retained mistakenly in engineered human-induced pluripotent stem cell-derived islet (hiPSC-islet) cells, act as an obstacle to hiPSC-islet maturation. We addressed this question by using the anterior chamber of the eye (ACE) of immunodeficient mice as a site for recapitulation of in vivo hiPSC-islet maturation in combination with intravitreal drug infusion, intravital microimaging, measurements of cytoplasmic-free Ca2+ concentration ([Ca2+]i) and patch clamp analysis. We observed that the ACE is well suited for recapitulation, observation and intervention of hiPSC-islet maturation. Intriguingly, intraocular hiPSC-islet grafts, retrieved intact following intravitreal infusion of the CaV3 channel blocker NNC55-0396, exhibited decreased basal [Ca2+]i levels and increased glucose-stimulated [Ca2+]i responses. Insulin-expressing cells of these islet grafts indeed expressed the NNC55-0396 target CaV3 channels. Intraocular hiPSC-islets underwent satisfactory engraftment, vascularization and light scattering without being influenced by the intravitreally infused NNC55-0396. These data demonstrate that inhibiting CaV3 channels facilitates the maturation of glucose-activated Ca2+ signaling in hiPSC-islets, supporting the notion that excessive CaV3 channels as a developmental error impede the maturation of engineered hiPSC-islet insulin-expressing cells.

Keywords: anterior chamber of the eye (ACE); calcium channel; cytoplasmic-free Ca2+ concentration ([Ca2+]i); in vivo confocal microscopy; islet; stem cell.

Grants and funding

This work was supported by grants from Berth von Kantzow’s Foundation, ERC-2018-AdG 834860 EYELETS, the Family Erling-Persson Foundation, Funds at Karolinska Institutet, the Stichting af Jochnick Foundation, the Strategic Research Program in Diabetes at Karolinska Institutet, the Swedish Alzheimer Association, the Swedish Diabetes Association, the Swedish Foundation for Strategic Research, the Swedish Research Council and the Novo Nordisk Foundation. R.M.S. has been supported by NIH (NIDDK) SBIR grants (2R44DKI 04497-02, 1R43DKl04497-01, 1R43DK108441-01Al, 1R43DK112472-01, 5R44DK104497-03 and 1 R43DK109832-01A1).