The respiratory system, which includes the trachea, airways, and distal alveoli, is a complex multi-cellular organ that intimately links with the cardiovascular system to accomplish gas exchange. In this review and as members of the NIH/NHLBI-supported Progenitor Cell Translational Consortium, we discuss key aspects of lung repair and regeneration. We focus on the cellular compositions within functional niches, cell-cell signaling in homeostatic health, the responses to injury, and new methods to study lung repair and regeneration. We also provide future directions for an improved understanding of the cell biology of the respiratory system, as well as new therapeutic avenues.

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Background: Human induced pluripotent stem cells (hiPSCs) can be harnessed for development of novel therapeutics for metabolic disorders. Results: Karyotypically normal hiPSCs were derived from patients with MODY1, MODY2, MODY3, MODY5, or MODY8. Conclusion: hiPSCs were successfully derived from a variety of MODY patients. Significance: MODY-hiPSCs can be used to explore the role of MODY genes in the development and function of pancreatic islet cells. Maturity onset diabetes of the young (MODY) is an autosomal dominant disease. Despite extensive research, the mechanism by which a mutant MODY gene results in monogenic diabetesis not yet clear due to the inaccessibility of patient samples. Induced pluripotency and directed differentiation toward the pancreatic lineage are now viable and attractive methods to uncover the molecular mechanisms underlying MODY. Here we report, for the first time, the derivation of human induced pluripotent stem cells (hiPSCs) from patients with five types of MODY: MODY1 (HNF4A), MODY2 (GCK), MODY3 (HNF1A), MODY5 (HNF1B), and MODY8 (CEL) with a polycistronic lentiviral vector expressing a Cre-excisable human "stem cell cassette" containing the four reprogramming factors OCT4, KLF4, SOX2, and CMYC. These MODY-hiPSCs morphologically resemble human pluripotent stem cells (hPSCs), express pluripotency markers OCT4, SOX2, NANOG, SSEA-4, and TRA-1-60, give rise to derivatives of the three germ layers in a teratoma assay, and are karyotypically normal. Overall, our MODYhiPSCs serve as invaluable tools to dissect the role of MODY genes in the development of pancreas and islet cells and to evaluate their significance in regulating beta cell function. This knowledge will aid future attempts aimed at deriving functional mature beta cells from hPSCs. Maturity onset diabetes of the young (MODY)2 is an autosomal dominant monogenic diabetic disease typically affecting individuals before the age of 25 years. To date, 11 MODY genes have been identified, comprising both transcription factors and enzymes/hormones: MODY1 (HNF4A), MODY2 (GCK), MODY3 (HNF1A), MODY4 (PDX1), MODY5 (HNF1B), MODY6 (NEUROD1), MODY7 (KLF11), MODY8 (CEL), MODY9 (PAX4), MODY10 (INS), and MODY11 (BLK) (1). Various disease-causing genetic variants have been identified for each of the MODY genes, all of which affect pancreas and beta cell development, ultimately resulting in beta cell dysfunction and diabetes.The advent of induced pluripotency (2) has provided an opportunity to derive human induced pluripotent stem cells (hiPSCs) from MODY patients to model the disease in vitro. Several studies have reported that human somatic cells, commonly skin fibroblasts, can be reprogrammed into hiPSCs. A number of groups have reported the generation of hiPSCs from patients with mitochondrial diabetes, type 1 and type 2 diabetes mellitus (3, 4). However, given the complexity of type 1 and type 2 diabetes mellitus, the use of hiPSCs from these patients requires comparison with multiple controls that are appropriate for the genetic and environmenta...

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Highlights d A FACS-based strategy separates mononucleated and binucleated cardiomyocytes d Mononucleated and binucleated cardiomyocytes are transcriptionally distinct d Binucleation results in the silencing of E2f transcriptional targets d Increased binucleation due to the loss of Ect2 impairs regenerative potential

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The impact of somatic cell proliferation rate on induction of pluripotent stem cells remains controversial. Herein, we report that rapid proliferation of human somatic fibroblasts is detrimental to reprogramming efficiency when reprogrammed using a lentiviral vector expressing OCT4, SOX2, KLF4, and cMYC in insulin-rich defined medium. Human fibroblasts grown in this medium showed higher proliferation, enhanced expression of insulin signaling and cell cycle genes, and a switch from glycolytic to oxidative phosphorylation metabolism, but they displayed poor reprogramming efficiency compared with cells grown in normal medium. Thus, in contrast to previous studies, our work reveals an inverse correlation between the proliferation rate of somatic cells and reprogramming efficiency, and also suggests that upregulation of proteins in the growth factor signaling pathway limits the ability to induce pluripotency in human somatic fibroblasts. STEM CELLS TRANSLATIONAL MEDICINE 2015;4:1101-1108 SIGNIFICANCEThe efficiency with which human cells can be reprogrammed is of interest to stem cell biology. In this study, human fibroblasts cultured in media containing different concentrations of growth factors such as insulin and insulin-like growth factor-1 exhibited variable abilities to proliferate, with consequences on pluripotency. This occurred in part because of changes in the expression of proteins involved in the growth factor signaling pathway, glycolysis, and oxidative phosphorylation. These findings have implications for efficient reprogramming of human cells.