Effectiveness of stem cell therapy for male infertility restoration: A systematic review

Cell therapy has emerged as a prominent leader in regenerative medicine, offering potential solutions for various disorders, including infertility. Half of all infertility cases are related to male factors. The objective of this study is to systematically summarize the existing knowledge regarding studies on stem cell-based therapy for the regeneration of impaired spermatogenesis. Initial searching was performed through main databases (e.g., PubMed, Scopus, Cochrane Library, and Embase) until December 2023. Articles conducted on stem cell transplantation into the testis of infertile models were considered. The titles and abstracts of articles were carefully evaluated and screened by independent authors. Nonrelated articles were deleted. The desired outcomes of infertility treatment after stem cell transplantation were attentively evaluated in the final selected articles. In the primary search, 3237 published studies were identified. Finally, 39 studies were included based on the eligibility criteria. In all studies except for two articles, all the outcomes considered, including germ cells/spermatogonia stem cell differentiation, spermatogenesis restoration, defective testicular tissue regeneration, improved sperm quality parameters, and hormonal levels, as well as increased expression of fertility-related markers and fertility rate, were observed after stem cell transplantation. Transplantation of stem cells, especially MSCs could be a safe and effective method for the treatment of male infertility patients, such as azoospermic cases. Further research to investigate the efficiency of different stem cell sources, providing nutrient conditions for the isolation and differentiation of stem cells, and exploring the paracrine effects of MSCs in male infertility therapy, could be useful.

Current status and reflections on fertility preservation in China

PURPOSE

With the progress of medical technology and renovated conception of fertility, the prospective studies and practice of fertility preservation are drawing more and more attention from medical workers. With the largest population of over 1.4 billion, China makes the experience accumulated in fertility preservation efforts even more relevant. This article summarizes China's experience and shares it with the world to promote the healthy development of fertility preservation.

METHODS

This study was based on multiple Chinese expert consensuses on fertility preservation issued in 2021 and the current national regulations and principles, compared with the latest advice and guidelines issued by global reproductive authorities such as the ASRM and ESHRE. Summarize the experience and reflection of Chinese scholars in the process of fertility preservation.

RESULTS

This study reports on the current situation of fertility preservation in China, sharing the Chinese experience gained in the process of development, and offering Chinese reflections on worrying issues.

CONCLUSION

Fertility preservation is a medical and social issue of reproductive health security, which is conducive to the sound development of the world population and social production.

Methamphetamine Downregulates the Sperm-Specific Calcium Channels Involved in Sperm Motility in Rats

Calcium channels play essential roles in sperm motility. A family of sperm-specific cation channels including CatSper1-4 has been identified as voltage-dependent ion channels that act as sperm motility regulators. Methamphetamine is known to cause apoptosis in seminiferous tubules and affect sperm quality. This research was conducted to investigate the effects of methamphetamine on expression of the CatSper family and Mvh genes. Thirty-six adult Wistar rats were divided into four groups of nine rats each: the control and experimental groups 1, 2, and 3. The control group received no solvents or drugs, but experimental groups 1, 2, and 3 were daily given 0.2 mL of a solution by gavage that contained 0.5, 1, and 2 mg of methamphetamine, respectively, for 45 days. The rats were then anesthetized, and one testis removed from each rat was used in a reverse transcription-polymerase chain reaction (RT-PCR). Analysis of variance (ANOVA) and Tukey's posthoc test were used to analyze the data at the P < 0.05 significance level. Treatment with methamphetamine resulted in decreased testis and epididymis weights compared to the control rats. The results showed that the mRNA fold expression level of the CatSper family and Mvh genes decreased significantly in experimental groups compared to that in the control (P < 0.05). Methamphetamine decreased the expression levels of the CatSper and Mvh genes, and thus, it seemed that it can increase the probability of infertility through sperm motility reduction by lowering the expression levels of these genes.

Overexpression of bmp4, dazl, nanos3 and sycp2 in Hu Sheep Leydig Cells Using CRISPR/dcas9 System Promoted Male Germ Cell Related Gene Expression

Simple Summary

Male germ cell development plays a crucial role in male reproduction, and gene expression also presents an essential regulatory role in its development. Many studies have been devoted to the induction and differentiation of pluripotent stem cells into germ cells in vitro. However, the culture system for pluripotent stem cells from domestic animals is not stable, especially in sheep. Our study attempted to transdifferentiate sheep somatic cells into germ cells in vitro by the overexpression of key germ cell related genes, with the aim of perfecting the construction of germ cell research models in vitro. Therefore, we explored the expression pattern of four crucial genes, bmp4, dazl, nanos3 and sycp2, in Hu sheep testicular development, and investigated the potential efficiency of overexpression of the four candidate genes using the CRISPR/dcas9 system in Leydig cells. We revealed that the overexpression of bmp4, dazl, nanos3 and sycp2 can promote the expression of male germ cell related genes. To the best of our knowledge, this is the first study to construct an overexpression induction system using CRISPR/dcas9 technology, and to induce sheep somatic cells into germ cells in vitro.

Abstract

Male germ cells directly affect the reproduction of males; however, their accurate isolation and culture in vitro is extremely challenging, hindering the study of germ cell development and function. CRISPR/dcas9, as an efficient gene reprogramming system, has been verified to promote the transdifferentiation of pluripotent stem cells into male germ cells by editing target genes. In our research, we explored the expression pattern of the germ cell related genes bmp4, dazl,nanos3 and sycp2 in Hu sheep testicular development and constructed the overexpression model using the CRISPR/dcas9 system. The results indicated that four genes showed more expression in testis tissue than in other tissues, and that bmp4, dazl and sycp2 present higher expression levels in nine-month-old sheep testes than in three-month-olds, while nanos3 expressed the opposite trend (p < 0.05). In addition, the expression of four potential genes in spermatogenic cells was slightly different, but they were all expressed in sheep Leydig cells. To verify the potential roles of the four genes in the process of inducing differentiation of male germ cells, we performed cell transfection in vitro. We found that the expression of the germ cell related genes Prdm1, Prdm14, Mvh and Sox17 were significantly increased after the overexpression of the four genes in Leydig cells, and the co-transfection effect was the most significant (p < 0.05). Our results illustrate the crucial functions of bmp4, dazl, nanos3 and sycp2 in Hu sheep testis development and verified the effectiveness of the overexpression model that was constructed using the CRISPR/dcas9 system, which provided a basis for further male germ cell differentiation in vitro.

Impaired spermatogenesis caused by busulfan is partially ameliorated by treatment with conditioned medium of adipose tissue derived mesenchymal stem cells

Busulfan (BSU) is a chemotherapeutic drug that can cause subfertility or sterility in males. We investigated the effects of adipose tissue-derived mesenchymal stem cells (AT-MSC) conditioned medium (CM) (AT-MSC-CM) on histopathological and molecular characteristics of mouse testes exposed to BSU using stereology. We used adult male mice divided randomly into five groups: control, Dulbecco's modified Eagle's medium (DMEM), dimethyl sulfoxide (DMSO), BSU, and BSU + CM. Thirty-five days following BSU injection, sperm and testis tissues were harvested for stereological and molecular studies. The BSU group exhibited significantly reduced testis volume, interstitium and tubules compared to the other groups, although the volume of the testis remained unchanged for BSU and CM groups. The number of testis cells was reduced in the BSU group compared to the other groups. The CM group exhibited a significantly increased number of testis cells compared to the BSU group. Sperm count and motility, and length density of seminiferous tubules were increased in CM group compared to the BSU group. AT-MSC-CM exhibited ameliorative effects on histopathologic changes of mouse testes exposed to BSU.

Urine-Derived Stem Cells Facilitate Endogenous Spermatogenesis Restoration of Busulfan-Induced Nonobstructive Azoospermic Mice by Paracrine Exosomes

Nonobstructive azoospermia (NOA) is a severe form of male infertility, with limited effective treatments. Urine-derived stem cells (USCs) possess multipotent differentiation capacity and paracrine effects, and participate in tissue repair and regeneration. The aim of this study is to investigate whether the transplantation of USCs or USC exosomes (USC-exos) could promote endogenous spermatogenesis restoration in a busulfan-induced NOA mice model. USCs were cultured and characterized by flow cytometry. High-density USCs were cultured in a hollow fiber bioreactor for exosomes collection. USC-exos were isolated from USCs conditional media and identified by transmission electron microscopy, western blotting, and Flow NanoAnalyzer analysis. USC-exos exhibited sphere- or cup-shaped morphology with a mean diameter of 66.5 ± 16.0 nm, and expressed CD63 and CD9. USCs and USC-exos were transplanted into the interstitial space in the testes of NOA mice per the following groups: normal group; groups treated with no injection, phosphate-buffered saline (PBS), USCs or USC-exos on days 3 and 36 after busulfan administration, respectively. Thirty days after USCs and USC-exos transplantation, spermatogenesis was restored by both USCs and USC-exos in NOA mice 36 days after busulfan treatment as confirmed by immunofluorescence staining and hematoxylin and eosin staining. Moreover, spermatogenic genes (Pou5f1, Prm1, SYCP3, and DAZL) and the spermatogenic protein UCHL1 were significantly increased in both the USCs 36 and USC-exos36 groups compared with the PBS group, as demonstrated using quantitative real-time polymerase chain reaction and western blot analysis. However, the transplantation of USCs or USC-exos at day 3 after busulfan treatment did not improve spermatogenesis in NOA mice. Our study demonstrated that USCs could facilitate endogenous spermatogenesis restoration of busulfan-induced NOA mice through paracrine exosomes but could not protect the mouse testicles at the early stage of destruction caused by busulfan. This study provides a novel insight into the treatment of NOA.