In the human pancreas, groups of so-called “endocrine cells” secrete the hormones insulin and glucagon, which are critical for regulating blood glucose levels; dysregulation of hormone secretion can lead to diabetes. In a recent edition of the journal Diabetes, Klaus Kaestner and colleagues published a study looking at the pattern of active or “expressed” genes of individual endocrine cells from the pancreases of juveniles, adults, and Type I and Type II diabetics. Interestingly, the genes expressed in both juvenile and Type II diabetic endocrine cells were not typical of either adult insulin or glucagon cells, but instead had a mixed expression of both insulin and glucagon cell genes. This observation supports the ideas that (1) juvenile endocrine cells have to mature to acquire distinct cellular characteristics and functionality, and (2) that during the onset of Type II diabetes, endocrine cells may acquire more juvenile characteristics and lose their ability to secrete insulin, thus leading to Type II diabetes. There were also a significant number of cells that expressed genes typical of both an endocrine cell and a completely different type of pancreatic cell, called a ductal cell—suggesting a possible transition between ductal and endocrine fates. These intriguing endocrine-ductal cells might serve as a source of cellular replacement, since human endocrine cells rarely replicate.

Earlier this year, a team at the Karolinska Institute published a paper that profiled gene activity in single cells from human embryos created in the context of in vitro fertilization. Now this group has announced their plans to edit the DNA of normal human embryos to study how changing the activity of these genes affects early embryonic development. This type of work is highly controversial. While many people believe that it could eventually lead to creating “designer babies” that have been edited and screened to have certain favorable traits, others believe that this type of work has the potential to eventually cure inherited diseases prior to an embryo’s implantation in the uterus. At this time, doing this type of research in the US is not illegal, but the same regulations that prohibit federal funds from being used to create new stem cell lines also prohibit the use of federal funds to do this type of research. I have a long-standing interest in the intersection of genetic engineering, equality of opportunity, and the distribution of talents and skills; the questions and concerns that this type of research engenders are moving from science fiction towards reality.