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Premature ovarian insufficiency (POI) is defined as the loss of ovarian activity under the age of 40. Theca cells (TCs) play a vital role during folliculogenesis and TCs dysfunction participate in the pathogenesis of POI. Therefore, transplantation of thecal stem cells (TSCs), which are capable of self-renewal and differentiation into mature TCs, may provide a new strategy for treating POI. To investigate the feasibility, safety, and efficacy of TSCs transplantation in clinically relevant non-human primate (NHP) models, we isolate TSCs from cynomolgus monkeys, and these cells are confirmed to expand continuously and show potential to differentiate into mature TCs. In addition, engraftment of autologous TSCs into POI monkeys significantly improves hormone levels, rescues the follicle development, promotes the quality of oocytes and boosts oocyte maturation/fertilization rate. Taken together, these results for the first time suggest that autologous TSCs can ameliorate POI symptoms in primate models and shed new light on developing stem cell therapy for POI., (© 2021. The Author(s).)

Somatic cells can be successfully reprogrammed into pluripotent stem cells by the ectopic expression of defined transcriptional factors. However, improved efficiency and better understanding the molecular mechanism underlying reprogramming are still required. In the present study, a scrape loading/dye transfer assay showed that human induced pluripotent stem cells (hiPSCs) contained functional gap junctions partially contributed by Connexin 45 (CX45). We then found CX45 was expressed in human embryonic stem cells (hESCs) and human dermal fibroblasts (hDFs) derived hiPSCs. Then we showed that CX45 was dramatically upregulated during the reprogramming process. Most importantly, the ectopic expression of CX45 significantly enhanced the reprogramming efficiency together with the Yamanaka factors (OCT4, SOX2, KLF4, cMYC - OSKM), whereas knockdown of endogenous CX45 expression significantly blocked cellular reprogramming and reduced the efficiency. Our further study demonstrated that CX45 overexpression or knockdown modulated the cell proliferation rate which was associated with the reprogramming efficiency. In conclusion, our data highlighted the critical role of CX45 in reprogramming and may increase the cell division rate and result in an accelerated kinetics of iPSCs production.

Gene editing in non-human primates may lead to valuable models for exploring the etiologies and therapeutic strategies of genetically based neurological disorders in humans. However, a monkey model of neurological disorders that closely mimics pathological and behavioral deficits in humans has not yet been successfully generated. Microcephalin 1 (MCPH1) is implicated in the evolution of the human brain, and MCPH1 mutation causes microcephaly accompanied by mental retardation. Here we generated a cynomolgus monkey (Macaca fascicularis) carrying biallelic MCPH1 mutations using transcription activator-like effector nucleases. The monkey recapitulated most of the important clinical features observed in patients, including marked reductions in head circumference, premature chromosome condensation (PCC), hypoplasia of the corpus callosum and upper limb spasticity. Moreover, overexpression of MCPH1 in mutated dermal fibroblasts rescued the PCC syndrome. This monkey model may help us elucidate the role of MCPH1 in the pathogenesis of human microcephaly and better understand the function of this protein in the evolution of primate brain size.

The progressive restriction of cell fate during lineage differentiation is a poorly understood phenomenon despite its ubiquity in multicellular organisms. We recently used a cell fusion assay to define a mode of epigenetic silencing that we termed "occlusion", wherein affected genes are silenced by cis-acting chromatin mechanisms irrespective of whether trans-acting transcriptional activators are present. We hypothesized that occlusion of lineage-inappropriate genes could contribute to cell fate restriction. Here, we test this hypothesis by introducing bacterial artificial chromosomes (BACs), which are devoid of chromatin modifications necessary for occlusion, into mouse fibroblasts. We found that BAC transgenes corresponding to occluded endogenous genes are expressed in most cases, whereas BAC transgenes corresponding to silent but non-occluded endogenous genes are not expressed. This indicates that the cellular milieu in trans supports the expression of most occluded genes in fibroblasts, and that the silent state of these genes is solely the consequence of occlusion in cis. For the BAC corresponding to the occluded myogenic master regulator Myf5, expression of the Myf5 transgene on the BAC triggered fibroblasts to acquire a muscle-like phenotype. These results provide compelling evidence for a critical role of gene occlusion in cell fate restriction.