O-9: Generation of Haploid Spermatids with Fertilization and Development Capacity from Human Spermatogonial Stem Cells of Cryptorchid Patients

Background Infertility affects around 15% of couples, and male factors account for 50%. Cryptorchidism is one of the most common causes for azoospermia. Generation of functional spermatids from azoospermia patients is of unusual significance for treating male infertility. It has been recently reported by peers and us that human spermatogonial stem cells (SSCs) can be clearly identified and cultured for a short and long term period. Round spermatids with unknown function can be derived from spermatogonia in vitro in mice (Feng LX, et al., 2002, Science, 297: 392-395). Recently, hapoild spermatids with function to be determined are generated from human pluripotent stem cells (Easley et al., 2012, Cell Reports, 2: 440-446). Nevertheless, the generation of functional haploid spermatids from SSCs in vitro has not yet been achieved in humans. MaterialsAndMethods Immunohistochemistry revealed that human spermatogonia remained whereas meiotic germ cells were rare in cryptorchid patients. RT-PCR and meiotic spread assays showed that expression of numerous markers for meiotic and post-meiotic male germ cells was enhanced in human sermatogonial stem cells (SSCs) of cryptorchidism patients by retinoic acid (RA) and stem cell factor (SCF) treatment. Meiotic spreads and DNA content assays revealed that RA and SCF induced a remarkable increase of SCP3-, MLH1- and CREST- positive cells and haploid cells. Single-cell RNA sequencing analysis reflected distinct global gene profiles in embryos derived from round spermatids and nucleus of somatic cells. Results Spermatogonia remain whereas meiotic male germ cells are rare in cryptorchid patients. - Human SSCs of cryptorchid patients differentiate to phenotypic and haploid spermatids. Distinct gene profiles exist in embryo from haploid spermatid and somatic cell nucleus. - Haploid spermatids from human SSCs have fertilization and development capacity. Conclusion Here we report an efficient approach to obtain human functional spermatids from cryptorchid patients.