Oocyte activation is a crucial step that comprises the release of the oocyte from meiotic arrest, pronuclear formation and subsequent embryo development. Oocytes are activated by repetitive increases in the intracellular concentration of free Ca²⁺, [Ca²⁺]_i oscillations, which are triggered during fertilization by the introduction of the sperm-specific phospholipase C zeta 1 (PLCZ1). Recent studies have shown that sperm from patients lacking expression of PLCZ1 or expressing mutant forms of PLCZ1 fail to induce [Ca²⁺]_i oscillations or oocyte activation. We first purified recombinant human PLCZ1 (hPLCZ1) protein and evaluated its [Ca²⁺]_i oscillation activity in mouse and human oocytes with the view to investigate its application in the clinic for assisted oocytes activation in lieu of chemical agents. Recombinant hPLCZ1 was synthesized using the Escherichia coli system, and subjected to immunoblot analysis with anti-PLCZ1 and anti-His tag antibodies. [Ca²⁺]_i oscillations by microinjection of recombinant hPLCZ1 into mouse or human oocytes were examined by [Ca²⁺]_i monitoring with Fluo 4. Ploidy of the oocytes with recombinant hPLCZ1 injection was confirmed with fluorescence in situ hybridization. A band of 68 kDa on recombinant protein was detected with both antibodies. Injection of recombinant hPLCZ1 induced [Ca²⁺]_i oscillations in a dose-dependent manner in both mouse and human oocytes. These oscillations, which closely resembled those initiated by the sperm upon fertilization, triggered activation and cleavage in oocytes of both species, although further development of the mice embryos was low. U73122, a PLC inhibitor, blocked the ability of hPLCZ1 to initiate oscillations. Microinjection of recombinant hPLCZ1 into ICSI-failed human oocytes rescued fertilization failure in five of eight attempts. Repeated [Ca²⁺]_i oscillations and oocyte activation were induced in mouse and human oocytes by microinjection of recombinant hPLCZ1 synthesized in E. Coli. Injection of recombinant protein could thus provide a biological solution for inducing artificial activation of oocytes.

BACKGROUND: The purpose of this study was to establish the culture conditions required to isolate, identify and expand male germ stem cell-like cells (GSC-LC) from the testicular tissue of patients with non-obstructive azoospermia (NOA). METHODS AND RESULTS: Testicular tissues obtained from patients (two with maturation arrest (MA, n = 2) and Sertoli cell-only syndrome (SCOS, n = 11) were dissociated and plated into gelatin-coated dishes. After 2–4 weeks, cultures from both MA patients (100%) and four SCOS patients (36.3%) exhibited multicellular colonies, which proliferated successfully until passage 10. GSC-LC in the colonies displayed alkaline phosphatase activity, as well as Oct-4 and integrin b1 expression after every passage. After the fifth passage, GSC-LC were differentiated by encapsulation in calcium alginate and further cultivation. At 2 and 6 weeks, cells expressed c-Kit, Scp3, testis-specific histone protein 2B (TH2B), and transition protein (TP)-1. Fluorescence in situ hybridization additionally disclosed a few tetraploid and haploid cells at 6 weeks. Human oocytes were activated in the absence of artificial activation and cleaved after the injection of presumptive spermatids. CONCLUSIONS: Our novel culture system may be useful for diagnosing the existence of germ cells and facilitating the treatment of NOA patients.

Background: Clinical use of mesenchymal stem cells (MSCs) requires a uniform cell population, and their harvesting is invasive and produces a limited number of cells. Human embryonic stem cell-derived MSCs (hESC-MSCs) can differentiate into three germ layers and possess immunosuppressive effects in vitro. Anticancer treatment is a well-known risk factor for premature ovarian failure (POF). In this study, we investigated the effect of hESC-MSC on recovery of ovarian function in cisplatin-induced POF in mice. Methods: Female mice received intraperitoneal cisplatin for 10 days. On day 12, CHA15-derived hESC-MSCs were transplanted into the mice by tail vein injection. An injection of PBS served as the negative control. Ovaries were removed 28 days after transplantation for assessment of ovarian histology, immunostaining, and fertility testing by superovulation and in vitro fertilization. hESC-MSC transplantation into mice with cisplatin-induced damage restored body weight and ovary size. Results: Mean primary and primordial follicle counts in the hESC-MSC group were significantly improved compared to the PBS group (P < 0.05), and counts of zona pellucida remnants, an apoptotic sign in ovarian follicles, were significantly reduced (P < 0.05). TUNEL assays and cleaved PARP immunostaining indicated apoptosis, which led to loss of ovarian stromal cells in negative control mice, while Ki-67 was higher in the hESC-MSC group and in non-cisplatin-treated controls than in the PBS group. Ovulation was reduced in the PBS group but recovered significantly in the hESC-MSC group. Rates of blastocyst formation from ovulated eggs and live births per mouse also recovered significantly in the hESC-MSC group. Conclusions: hESC-MSC restored structure and function in the cisplatin-damaged ovary. Our study provides new insights into the great clinical potential of human hESC-MSC in treating POF.