In This Issue of Diabetes

摘要

According to Lam et al. (p. 674), a novel population of highly proliferative hormone-negative islet cells may exist in human pancreata, and there is a hint that they might play an essential role in islet function and growth. Using a large collection of nondiabetic and type 1 diabetes human pancreas samples, the authors initially focused on the protein Ki67 as a marker of cell proliferation and reportedly found populations of proliferative islet cells. However, the population showed no signs of expressing insulin or that they were lymphocytes or endothelial cells. The question then was what were they. The authors report that pancreatic polypeptide, somatostatin, and ghrelin cells showed no real sign of proliferation. In contrast, glucagon-expressing α-cells were proliferative but only comprised about one-third of the total population of proliferative islet cells. The majority of the population was reportedly negative for any hormone expression. The focus then moved to the possibility that the proliferative cells might express markers of islet endocrine progenitors. After excluding one key progenitor (Ngn3), they found that most of the hormone-negative proliferative cells uniformly contained immunoreactivity for Sox9 (typically present in islet progenitors) and ARX (an α-cell marker). There were also various markers of islet endocrine cells and of various potential cellular functions. Author Jake A. Kushner told Diabetes. "Given previous work that reveals an age-dependent decline in p-cell proliferation, we were genuinely shocked to find these high-proliferative islet endocrine cells in adult pancreata. But, what does the presence of these cells mean? Honestly, we don't know. The most obvious implication is that islets might retain some degree of plasticity into adulthood. These highly proliferative islet endocrine cells may play an unknown role in islet growth and/or regeneration. We're eager to see where this research leads and hopeful that our findings could someday translate to help patients with diabetes."