110-OR: Generation of a Novel Mouse Model to Study ß-Cell Proliferation
Authors: TOKUMOTO SHINSUKE , YABE DAISUKE , TATSUOKA HISATO , USUI RYOTA , FAUZI MUHAMMAD , GOTO HISANORI , OGURA MASAHITO , INAGAKI NOBUYA 
Published: June 2019

Background and Aims: The induction of β-cell proliferation could relieve the progression of diabetes. Many factors have been claimed to be potential β-cell mitogens, but their impacts on β-cell replication have been poorly reproduced and validated due to unstandardized β-cell proliferation assay and lack of alternative methods. In this study, we aimed to generate a novel mouse model that enables more accurate quantification of β-cell proliferation by using a cell cycle monitoring biosensor (Fucci2a).
imaging of the pancreas from this mouse model. Next, 3D images of optically cleared pancreas samples were obtained for the analysis of replicating β-cell number and morphometric data per islet following the mitogenic intervention of insulin receptor antagonist (S961). Moreover, in order to examine whether glucose mediates S961-induced β-cell proliferation, we compared the β-cell proliferation rate between the hyperglycemic S961 monotherapy group and the normoglycemic S961 group with coadministration of SGLT2i (S961 + SGLT2i group). vivo Materials and Methods: We established a novel mouse line in which the Fucci2a reporter is specifically expressed in β-cells (RIP-Cre; Fucci2aR). We performed real-time 3D in
Results: We succeeded in real-time visualization of cell cycle progression of β-cells. A strong correlation between replicating β-cell number per islet and islet size was found in both S961 (r = 0.87, p &lt;0.01) and vehicle groups (r = 0.77, p &lt;0.01). While hyperglycemia induced by S961 treatment was normalized in the S961 + SGLT2i group, there was no significant difference in β-cell proliferation rate between the S961 monotherapy and S961 + SGLT2i groups.
Conclusion: Here we present the first in vivo 4D images of cell cycle phase transition of β-cells. The strong correlation between islet size and its proliferative capacity suggests stochastic replication of β-cells. S961-induced β-cell replication was not mediated by glucose. Thus, this novel mouse could be a powerful tool for β-cell proliferation assessment.

Disclosure
S. Tokumoto: None. D. Yabe: Advisory Panel; Self; Abbott. Research Support; Self; Astellas Pharma Inc. Speaker's Bureau; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Daiichi Sankyo Company, Limited, Eli Lilly and Company, Merck Sharp & Dohme Corp., Novo Nordisk Inc., Ono Pharmaceutical Co., Ltd., Sanofi K.K., Taisho Pharmaceutical Co., Ltd., Takeda Pharmaceutical Company Limited. H. Tatsuoka: None. R. Usui: None. M. Fauzi: None. H. Goto: None. M. Ogura: Research Support; Self; Takeda Pharmaceutical Company Limited. Speaker's Bureau; Self; AstraZeneca, Boehringer Ingelheim International GmbH, Daiichi Sankyo Company, Limited, Eli Lilly and Company, Kyowa Hakko Kirin Co., Ltd., Merck & Co., Inc., Mitsubishi Tanabe Pharma Corporation, Novo Nordisk Inc., Ono Pharmaceutical Co., Ltd., Sanofi, Takeda Pharmaceutical Company Limited. N. Inagaki: Research Support; Self; Astellas Pharma Inc., Boehringer Ingelheim Pharmaceuticals, Inc., Daiichi Sankyo Company, Limited, Japan Tobacco Inc., Kyowa Hakko Kirin Co., Ltd., Merck Sharp & Dohme Corp., Mitsubishi Tanabe Pharma Corporation, Novartis Pharmaceuticals Corporation, Ono Pharmaceutical Co., Ltd., Sanofi, Sumitomo Dainippon Pharma Co., Ltd., Takeda Pharmaceutical Company Limited.