Novel Observations from Next Generation RNA Sequencing of Highly Purified Human Adult and Fetal Islet Cell Subsets

Understanding distinct gene expression patterns of normal adult and developing fetal human pancreatic a and b cells is crucial for developing stem cell therapies, islet regeneration strategies, and therapies designed to increase b cell function in patients with diabetes (type 1 or 2). Toward that end, we have developed methods to highly purify a, b, and d cells from human fetal and adult pancreata by intracellular staining for the cell-specific hormone content, sorting the sub-populations by flow cytometry and, using next generation RNA sequencing, we report on the detailed transcriptomes of fetal and adult a and b cells. We observed that human islet composition was not influenced by age, gender, or body mass index and transcripts for inflammatory gene products were noted in fetal b cells. In addition, within highly purified adult glucagon-expressing a cells, we observed surprisingly high insulin mRNA expression, but not insulin protein expression. This transcriptome analysis from highly purified islet a and b cell subsets from fetal and adult pancreata offers clear implications for strategies that seek to increase insulin expression in type 1 and type 2 diabetes.