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Background— The generation of vascular progenitors (VPs) from human induced pluripotent stem cells (hiPSCs) has great potential for treating vascular disorders such as ischemic retinopathies. However, long-term in vivo engraftment of hiPSC-derived VPs into the retina has not yet been reported. This goal may be limited by the low differentiation yield, greater senescence, and poor proliferation of hiPSC-derived vascular cells. To evaluate the potential of hiPSCs for treating ischemic retinopathies, we generated VPs from a repertoire of viral-integrated and nonintegrated fibroblast and cord blood (CB)–derived hiPSC lines and tested their capacity for homing and engrafting into murine retina in an ischemia-reperfusion model. Methods and Results— VPs from human embryonic stem cells and hiPSCs were generated with an optimized vascular differentiation system. Fluorescence-activated cell sorting purification of human embryoid body cells differentially expressing endothelial/pericytic markers identified a CD31 + CD146 + VP population with high vascular potency. Episomal CB-induced pluripotent stem cells (iPSCs) generated these VPs with higher efficiencies than fibroblast-iPSC. Moreover, in contrast to fibroblast-iPSC-VPs, CB-iPSC-VPs maintained expression signatures more comparable to human embryonic stem cell VPs, expressed higher levels of immature vascular markers, demonstrated less culture senescence and sensitivity to DNA damage, and possessed fewer transmitted reprogramming errors. Luciferase transgene-marked VPs from human embryonic stem cells, CB-iPSCs, and fibroblast-iPSCs were injected systemically or directly into the vitreous of retinal ischemia-reperfusion–injured adult nonobese diabetic-severe combined immunodeficient mice. Only human embryonic stem cell– and CB-iPSC–derived VPs reliably homed and engrafted into injured retinal capillaries, with incorporation into damaged vessels for up to 45 days. Conclusions— VPs generated from CB-iPSCs possessed augmented capacity to home, integrate into, and repair damaged retinal vasculature.

INTRODUCTION AND OBJECTIVES: The major therapies for prostate cancer (PCa) such as radio-, chemoor androgen deprivation therapy induce DNA damage. Thus the DNA damage response (DDR) and expression of DDR genes are key factors in determining outcome of PCa therapies. Histone demethylase JMJD1A regulates the gene expression by demethylating H3K9. Our previous work shows that JMJD1A is essential for the long-term proliferation and survival of PCa cells in vitro or in the xenograft prostate tumor model, partly via its effect on the activities of androgen receptor (AR) and c-Myc transcription factors. Here, we find a new role for JMJD1A in the expression of DDR genes and sensitivity of PCa cells to irradiation and androgen deprivation. METHODS: Real-time PCR was used to measure the mRNA levels of some DDR genes in the PCa cells (control or siRNA knockdown (KD) of JMJD1A, AR or c-Myc). Chromatin immunoprecipitation (ChIP) was used to evaluate the binding of JMJD1A to the AR or MYC binding sites on these DDR genes. JMJD1A-KD PCa cells were treated with or without ionizing radiation (IR), and analyzed by the r-H2AX staining (a widely used marker for the DNA double strand breaks (DSBs)), western blot analysis of DNA damage signaling proteins, flow cytometry analysis of cell cycle, and GFP reporter assays for the DSB repair via the homologous recombination (HR) or non-homologous end joining (NHEJ) pathways. The growth of these PCa cells was also measured under the IR and androgen deprivation conditions. RESULTS: JMJD1A was found to promote the expression of some DDR genes by co-activating AR and/or c-Myc. The DDR genes regulated by JMJD1A encode factors mediating the DSB repair by both HR and NHEJ pathways. JMJD1A KD led to increased r-H2AX foci in the non-irradiated cells, and the delayed clearance of r-H2AX foci in the irradiated cells. JMJD1A KD also increased the levels of phospho-DNAPK or phospho-CHEK2 in the western blot analysis and caused G2 cell cycle arrest. Consistently, JMJD1A KD reduced the percentage of GFPpositive cells that reflects the DSB repair by both HR and NHEJ pathways. JMJD1A-KD cells showed a reduced growth under IR and androgen deprivation conditions. CONCLUSIONS: JMJD1A promotes the DSB repair via regulation of DDR gene expression through AR and/or c-Myc. The role of JMJD1A in the DSB repair may contribute to the resistance of PCa cells to the radioand androgen deprivation therapies.