Naomi Berrie Diabetes Center, Columbia University, New York, New York, USA.
Department of Pediatrics, Department of Obstetrics and Gynecology, Columbia Stem Cell Initiative, Columbia Irving Medical Center, Columbia University, New York, New York, USA.
JCI Insight. 2021 Mar 8;6(5):141553. doi: 10.1172/jci.insight.141553.
Limitations in cell proliferation are important for normal function of differentiated tissues and essential for the safety of cell replacement products made from pluripotent stem cells, which have unlimited proliferative potential. To evaluate whether these limitations can be established pharmacologically, we exposed pancreatic progenitors differentiating from human pluripotent stem cells to small molecules that interfere with cell cycle progression either by inducing G1 arrest or by impairing S phase entry or S phase completion and determined growth potential, differentiation, and function of insulin-producing endocrine cells. We found that the combination of G1 arrest with a compromised ability to complete DNA replication promoted the differentiation of pancreatic progenitor cells toward insulin-producing cells and could substitute for endocrine differentiation factors. Reduced replication fork speed during differentiation improved the stability of insulin expression, and the resulting cells protected mice from diabetes without the formation of cystic growths. The proliferative potential of grafts was proportional to the reduction of replication fork speed during pancreatic differentiation. Therefore, a compromised ability to enter and complete S phase is a functionally important property of pancreatic endocrine differentiation, can be achieved by reducing replication fork speed, and is an important determinant of cell-intrinsic limitations of growth.
细胞增殖的限制对于分化组织的正常功能非常重要，对于由具有无限增殖潜力的多能干细胞制成的细胞替代产品的安全性也是必不可少的。为了评估这些限制是否可以通过药理学方法建立，我们使从人多能干细胞分化而来的胰腺祖细胞暴露于小分子中，这些小分子通过诱导 G1 期阻滞或损害 S 期进入或 S 期完成来干扰细胞周期进程，并确定产生胰岛素的内分泌细胞的生长潜能、分化和功能。我们发现，G1 期阻滞与完成 DNA 复制的能力受损相结合，可促进胰腺祖细胞向产生胰岛素的细胞分化，并可替代内分泌分化因子。在分化过程中降低复制叉速度可提高胰岛素表达的稳定性，并且所得细胞可在不形成囊性生长的情况下保护小鼠免受糖尿病的侵害。移植物的增殖潜力与胰腺分化过程中复制叉速度的降低成正比。因此，进入和完成 S 期的能力受损是胰腺内分泌分化的一个功能上重要的特性，可通过降低复制叉速度来实现，并且是细胞内在生长限制的重要决定因素。
