Epigenetic Variation between Human Induced Pluripotent Stem Cell Lines Is an Indicator of Differentiation Capacity.

Variation in the differentiation capacity of induced pluripotent stem cells (iPSCs) to specific lineages is a significant concern for their use in clinical applications and disease modeling. To identify factors that affect differentiation capacity, we performed integration analyses between hematopoietic differentiation performance and molecular signatures such as gene expression, DNA methylation, and chromatin status, using 35 human iPSC lines and four ESC lines. Our analyses revealed that hematopoietic commitment of PSCs to hematopoietic precursors correlates with IGF2 expression level, which in turn depends on signaling-dependent chromatin accessibility at mesendodermal genes. Maturation capacity for conversion of PSC-derived hematopoietic precursors to mature blood associates with the amount and pattern of DNA methylation acquired during reprogramming. Our study therefore provides insight into the molecular features that determine the differential capacities seen among human iPSC lines and, through the predictive potential of this information, highlights a way to select optimal iPSCs for clinical applications.

Enhanced engraftment, proliferation, and therapeutic potential in heart using optimized human iPSC-derived cardiomyocytes.

Human pluripotent stem cell-derived cardiomyocytes (CMs) are a promising tool for cardiac cell therapy. Although transplantation of induced pluripotent stem cell (iPSC)-derived CMs have been reported in several animal models, the treatment effect was limited, probably due to poor optimization of the injected cells. To optimize graft cells for cardiac reconstruction, we compared the engraftment efficiency of intramyocardially-injected undifferentiated-iPSCs, day 4 mesodermal cells, and day 8, day 20, and day 30 purified iPSC-CMs after initial differentiation by tracing the engraftment ratio (ER) using in vivo bioluminescence imaging. This analysis revealed the ER of day 20 CMs was significantly higher compared to other cells. Transplantation of day 20 CMs into the infarcted hearts of immunodeficient mice showed good engraftment, and echocardiography showed significant functional improvement by cell therapy. Moreover, the imaging signal and ratio of Ki67-positive CMs at 3 months post injection indicated engrafted CMs proliferated in the host heart. Although this graft growth reached a plateau at 3 months, histological analysis confirmed progressive maturation from 3 to 6 months. These results suggested that day 20 CMs had very high engraftment, proliferation, and therapeutic potential in host mouse hearts. They also demonstrate this model can be used to track the fate of transplanted cells over a long time.

Efficient Detection and Purification of Cell Populations Using Synthetic MicroRNA Switches.

Isolation of specific cell types, including pluripotent stem cell (PSC)-derived populations, is frequently accomplished using cell surface antigens expressed by the cells of interest. However, specific antigens for many cell types have not been identified, making their isolation difficult. Here, we describe an efficient method for purifying cells based on endogenous miRNA activity. We designed synthetic mRNAs encoding a fluorescent protein tagged with sequences targeted by miRNAs expressed by the cells of interest. These miRNA switches control their translation levels by sensing miRNA activities. Several miRNA switches (miR-1-, miR-208a-, and miR-499a-5p-switches) efficiently purified cardiomyocytes differentiated from human PSCs, and switches encoding the apoptosis inducer Bim enriched for cardiomyocytes without cell sorting. This approach is generally applicable, as miR-126-, miR-122-5p-, and miR-375-switches purified endothelial cells, hepatocytes, and insulin-producing cells differentiated from hPSCs, respectively. Thus, miRNA switches can purify cell populations for which other isolation strategies are unavailable.

[Changes in nutritional status and nutritional intake among elderly residents of a community over a 10-year period: the Hisayama Study].

The purpose of this study was to investigate the changes in nutritional status and nutrient intake among 387 elderly residents (> or = 60 y.o.) of Hisayama Town. A dietary survey was carried out at baseline in 1988 and repeated at the end of the follow-up period in 1998. During the 10-year follow-up period, mean values of body height and weight, and body mass index significantly decreased in both sexes. Likewise, blood hemoglobin and serum total cholesterol levels significantly decreased, while serum albumin and HDL-cholesterol levels significantly increased. Among dietary factors, mean energy intake significantly decreased due mainly to a decrease in the amount of carbohydrate intake, but no significant changes in the amount of protein and fat intakes were observed. The percentages of the Recommended Dietary Allowance for all nutrients eaten except for iron changed at the levels above 100%. The percentage of energy derived from carbohydrate significantly decreased, while those from protein and fat significantly increased. In conclusion, among community-dwelling healthy elderly people, mean energy intake significantly decreased due to a decrease in the amount of carbohydrate intake, and the fat intake relatively increased, with advancing age, but the blood lipid profile remained unchanged.