iPSC-Derived Platelets Depleted of HLA Class I Are Inert to Anti-HLA Class I and Natural Killer Cell Immunity

ゲノム編集技術を用いてiPS細胞から「ユニバーサル」な血小板の作製に成功. 京都大学プレスリリース. 2020-01-07.The ex vivo production of platelets depleted of human leukocyte antigen class I (HLA-I) could serve as a universal measure to overcome platelet transfusion refractoriness caused by HLA-I incompatibility. Here, we developed human induced pluripotent cell-derived HLA-I-deficient platelets (HLA-KO iPLATs) in a clinically applicable imMKCL system by genetic manipulation and assessed their immunogenic properties including natural killer (NK) cells, which reject HLA-I downregulated cells. HLA-KO iPLATs were deficient for all HLA-I but did not elicit a cytotoxic response by NK cells in vitro and showed circulation equal to wild-type iPLATs upon transfusion in our newly established Hu-NK-MSTRG mice reconstituted with human NK cells. Additionally, HLA-KO iPLATs successfully circulated in an alloimmune platelet transfusion refractoriness model of Hu-NK-MISTRG mice. Mechanistically, the lack of NK cell-activating ligands on platelets may be responsible for evading the NK cell response. This study revealed the unique non-immunogenic property of platelets and provides a proof of concept for the clinical application of HLA-KO iPLATs

Functional adenosine triphosphate‐sensitive potassium channel is required in high‐carbohydrate diet‐induced increase in β‐cell mass

Abstract Aims/Introduction A high‐carbohydrate diet is known to increase insulin secretion and induce obesity. However, whether or not a high‐carbohydrate diet affects β‐cell mass (BCM) has been little investigated. Materials and Methods Both wild‐type (WT) mice and adenosine triphosphate‐sensitive potassium channel‐deficient (Kir6.2KO) mice were fed normal chow or high‐starch (ST) diets for 22 weeks. BCM and the numbers of islets were analyzed by immunohistochemistry, and gene expression levels in islets were investigated by quantitative real‐time reverse transcription polymerase chain reaction. MIN6‐K8 β‐cells were stimulated in solution containing various concentrations of glucose combined with nifedipine and glimepiride, and gene expression was analyzed. Results Both WT and Kir6.2KO mice fed ST showed hyperinsulinemia and body weight gain. BCM, the number of islets and the expression levels of cyclinD2 messenger ribonucleic acid were increased in WT mice fed ST compared with those in WT mice fed normal chow. In contrast, no significant difference in BCM, the number of islets or the expression levels of cyclinD2 messenger ribonucleic acid were observed between Kir6.2KO mice fed normal chow and those fed ST. Incubation of MIN6‐K8 β‐cells in high‐glucose media or with glimepiride increased cyclinD2 expression, whereas nifedipine attenuated a high‐glucose‐induced increase in cyclinD2 expression. Conclusions These results show that a high‐starch diet increases BCM in an adenosine triphosphate‐sensitive potassium channel‐dependent manner, which is mediated through upregulation of cyclinD2 expression