In vitro generation of functional gametes is a promising approach for treating infertility, although faithful replication of meiosis has proven to be a substantial obstacle to deriving haploid gamete cells in culture. Here we report complete in vitro meiosis from embryonic stem cell (ESC)-derived primordial germ cells (PGCLCs). Co-culture of PGCLCs with neonatal testicular somatic cells and sequential exposure to morphogens and sex hormones reproduced key hallmarks of meiosis, including erasure of genetic imprinting, chromosomal synapsis and recombination, and correct nuclear DNA and chromosomal content in the resulting haploid cells. Intracytoplasmic injection of the resulting spermatid-like cells into oocytes produced viable and fertile offspring, showing that this robust stepwise approach can functionally recapitulate male gametogenesis in vitro. These findings provide a platform for investigating meiotic mechanisms and the potential generation of human haploid spermatids in vitro.

The purpose of this study was to permit bone marrow mesenchymal stem cells (BMSCs) to reach their full potential in the treatment of chronic wounds. A biocompatible multifunctional crosslinker based temperature sensitive hydrogel was developed to deliver BMSCs, which improve the chronic inflammation microenvironments of wounds. A detailed in vitro investigation found that the hydrogel is suitable for BMSC encapsulation and can promote BMSC secretion of TGF-β1 and bFGF. In vivo, full-thickness skin defects were made on the backs of db/db mice to mimic diabetic ulcers. It was revealed that the hydrogel can inhibit pro-inflammatory M1 macrophage expression. After hydrogel association with BMSCs treated the wound, significantly greater wound contraction was observed in the hydrogel + BMSCs group. Histology and immunohistochemistry results confirmed that this treatment contributed to the rapid healing of diabetic skin wounds by promoting granulation tissue formation, angiogenesis, extracellular matrix secretion, wound contraction, and re-epithelialization. These results show that a hydrogel laden with BMSCs may be a promising therapeutic strategy for the management of diabetic ulcers.

The rat is an important animal model in biomedical research, but practical limitations to genetic manipulation have restricted the application of genetic analysis. Here we report the derivation of rat androgenetic haploid embryonic stem cells (RahESCs) as a tool to facilitate such studies. Our approach is based on removal of the maternal pronucleus from zygotes to generate androgenetic embryos followed by derivation of ESCs. The resulting RahESCs have 21 chromosomes, express pluripotency markers, differentiate into three germ layer cells, and contribute to the germline. Homozygous mutations can be introduced by both large-scale gene trapping and precise gene targeting via homologous recombination or the CRISPR-Cas system. RahESCs can also produce fertile rats after intracytoplasmic injection into oocytes and are therefore able to transmit genetic modifications to offspring. Overall, RahESCs represent a practical tool for functional genetic studies and production of transgenic lines in rat.