Round spermatid injection into human oocytes: a systematic review and meta-analysis

Haploid like spermatid generation by transplantation of neonatal mouse testicular tissue into the epididymal fat of castrated adult mouse

OBJECTIVE

Many cancer survivors may experience irreversible infertility due to chemotherapy treatment for childhood cancer. In this study, spermatogenesis development was evaluated following the grafting of fresh and frozen-thawed testicular tissue from neonatal mice to the epididymal fat of adult mice.

METHODS

After bilateral castration of recipient mice, fresh or frozen-thawed neonatal testis tissues were grafted into the epididymal fat of the mice. Grafted testicular tissue was evaluated eight weeks after implantation using H&E staining, real-time PCR, immunofluorescence staining, and TUNEL assay. Blood was drawn from recipient mice to determine testosterone, FSH, and LH levels.

RESULTS

A gradient of different types of germ cells, from spermatogonia to elongated spermatids was observed. The upregulation of meiotic and post-meiotic genes and proteins in fresh and frozen grafted groups confirmed the progression of meiosis and post-meiosis in grafted tissues. There were no significant differences in the expression of apoptosis and necrosis genes between the grafted and non-grafted control groups. Additionally, no significant differences were observed between the control and experimental groups in hormonal assessments.

CONCLUSIONS

The optimal hormonal and temperature conditions of the epididymal fat could support spermatogenesis in grafted immature testicular tissue. This grafting technique could pave the way for fertility preservation.

Clinical outcomes of round spermatid injection vs intracytoplasmic sperm injection: The role of hormonal pretreatment for nonobstructive azoospermia

BACKGROUND

Round spermatid injection (ROSI) into oocytes offers men with nonobstructive azoospermia (NOA) the opportunity to have biological offspring in cases where mature spermatozoa are not detected. However, the clinical outcomes of ROSI remain poor. This study compared the outcomes of ROSI with intracytoplasmic sperm injection (ICSI) and investigated the effect of hormonal pretreatment.

METHODS

This retrospective cohort study enrolled infertile couples undergoing either ROSI or ICSI at the reproductive center in Taipei Veterans General Hospital. The administration of selective estrogen receptor modulators, gonadotropins, and aromatase inhibitors in male patients were recorded. Relevant hormonal markers and biochemical parameters were determined. The outcomes of ROSI and ICSI were assessed based on fertilization rate, implantation rate, and live birth rate.

RESULTS

A total of 36 couples were recruited in the ROSI group, whereas 39 couples were recruited in the ICSI group for the analysis. Patients in each group demonstrated similar characteristics, except for a higher proportion of male patients in the ROSI group who were pretreated with anastrozole. The fertilization rate and implantation rate were similar between ROSI and ICSI groups after adjusting for confounding variables. The live birth rate was significantly lower in the ROSI group (8.3%) than in the ICSI group (30.8%) before and after adjusting for confounding variables.

CONCLUSION

ROSI demonstrated fertilization and implantation rates comparable to those of ICSI for male patient with NOA undergoing testicular sperm extraction surgery. Anastrozole may improve the outcomes of ROSI into oocytes. Further studies evaluating the effect of anastrozole administration on ROSI outcomes are warranted.

A brief history of technical developments in intracytoplasmic sperm injection (ICSI). Dedicated to the memory of J.M. Cummins

Intracytoplasmic sperm injection (ICSI) is an assisted reproductive technology for treatment of severe male infertility introduced into clinical practice in 1992. This review provides a brief history of the development of ICSI by acknowledging major developments in the field. The review addresses key developments in pre-clinical and early studies, how ICSI compares with in vitro fertilisation, long-term consequences, how the mechanistic approach to ICSI has changed in both manual and semi-automated approaches, and how sperm selection procedures are integrated into ICSI. From the beginnings using animal models in the 1960-1970s, the development of ICSI is a remarkable and transformative success story. Indeed, its broad use (70% of cycles globally) exceeds the need required for treating infertile males, and this remains a controversial issue. There remain questions around the long-term health impacts of ICSI. Furthermore, advances in automation of the ICSI procedure are occurring. An estimated 6million children have been born from the ICSI procedure. With further automation of sperm selection technologies, coupled with automation of the injection procedure, it is likely that the proportion of children born from ICSI will further increase.

Clinical management of nonobstructive azoospermia: An update

Approximately 1% of the general male population has azoospermia, and nonobstructive azoospermia accounts for the majority of cases. The causes vary widely, including chromosomal and genetic abnormalities, varicocele, drug-induced causes, and gonadotropin deficiency; however, the cause is often unknown. In azoospermia caused by hypogonadotropic hypogonadism, gonadotropin replacement therapy can be expected to produce sperm in the ejaculate. In some cases, upfront varicocelectomy for nonobstructive azoospermia with varicocele may result in the appearance of ejaculated spermatozoa; however, the appropriate indication should be selected. Each guideline recommends microdissection testicular sperm extraction for nonobstructive azoospermia in terms of successful sperm retrieval and avoidance of complications. Sperm retrieval rates generally ranged from 20% to 70% but vary depending on the causative disease. Various attempts have been made to predict sperm retrieval and improve sperm retrieval rates; however, the evidence is insufficient. Further evidence accumulation is needed for salvage treatment in cases of failed sperm retrieval. In Japan, there is inadequate provision on the right to know the origin of children born from artificial insemination of donated sperm and the rights of sperm donors, as well as information on unrelated family members, and the development of these systems is challenging. In the future, it is hoped that the pathogenesis of nonobstructive azoospermia with an unknown cause will be elucidated and that technology for omics technologies, human spermatogenesis using pluripotent cells, and organ culture methods will be developed.

Bridging the Gap: Animal Models in Next-Generation Reproductive Technologies for Male Fertility Preservation

This review aims to explore advanced reproductive technologies for male fertility preservation, underscoring the essential role that animal models have played in shaping these techniques through historical contexts and into modern applications. Rising infertility concerns have become more prevalent in human populations recently. The surge in male fertility issues has prompted advanced reproductive technologies, with animal models playing a pivotal role in their evolution. Historically, animal models have aided our understanding in the field, from early reproductive basic research to developing techniques like artificial insemination, multiple ovulation, and in vitro fertilization. The contemporary landscape of male fertility preservation encompasses techniques such as sperm cryopreservation, testicular sperm extraction, and intracytoplasmic sperm injection, among others. The relevance of animal models will undoubtedly bridge the gap between traditional methods and revolutionary next-generation reproductive techniques, fortifying our collective efforts in enhancing male fertility preservation strategies. While we possess extensive knowledge about spermatogenesis and its regulation, largely thanks to insights from animal models that paved the way for human infertility treatments, a pressing need remains to further understand specific infertility issues unique to humans. The primary aim of this review is to provide a comprehensive analysis of how animal models have influenced the development and refinement of advanced reproductive technologies for male fertility preservation, and to assess their future potential in bridging the gap between current practices and cutting-edge fertility techniques, particularly in addressing unique human male factor infertility.

What Does Intracytoplasmic Sperm Injection Change in Embryonic Development? The Spermatozoon Contribution

The intracytoplasmic sperm injection (ICSI) technique was invented to solve severe male infertility due to altered sperm parameters. Nowadays, it is applied worldwide for the treatment of couple infertility. ICSI is performed with any available spermatozoon from surgery or ejaculated samples, whatever are the sperm motility, morphology or quantity. The aim of the present review was to study if embryo development and kinetics would be modified by (1) ICSI under the technical aspects, (2) the micro-injected spermatozoa in connection with male infertility. From published data, it can be seen that ICSI anticipates the zygote kinetics Furthermore, because fertilization rate is higher in ICSI compared to conventional in vitro fertilization (IVF), more blastocysts are obtained for clinical use in ICSI. Sperm and spermatozoa characteristics, such as sperm parameters, morphology and vitality, DNA content (levels of sperm DNA fragmentation, microdeletions, and chromosomal abnormalities), RNA content, epigenetics, and sperm recovery site (testicular, epididymis, and ejaculated), have an impact on fertilization and blastocyst rates and embryo kinetics in different ways. Even though ICSI is the most common solution to solve couples' infertility, the causes of male infertility are crucial in building a competent spermatozoa that will contribute to normal embryonic development and healthy offspring.

How to improve the clinical outcome of round spermatid injection (ROSI) into the oocyte: Correction of epigenetic abnormalities

Background

First successful human round spermatid injection (ROSI) was conducted by Tesarik et al. in 1996 for the sole treatment of nonobstructive azoospermic men whose most advanced spermatogenic cells were elongating round spermatids. Nine offsprings from ROSI were reported between 1996 and 2000. No successful deliveries were reported for 15 years after that. Tanaka et al. reported 90 babies born after ROSI and their follow-up studies in 2015 and 2018 showed no significant differences in comparison with those born after natural conception in terms of physical and cognitive abilities. However, clinical outcomes remain low.

Method

Clinical and laboratory data of successful cases in the precursor ROSI groups and those of Tanaka et al. were reviewed.

Results

Differences were found between the two groups in terms of identification of characteristics of round spermatid and oocyte activation. Additionally, epigenetic abnormalities were identified as underlying causes for poor ROSI results, besides correct identification of round spermatid and adequate oocyte activation. Correction of epigenetic errors could lead to optimal embryonic development.

Conclusion

Correction of epigenetic abnormalities has a probability to improve the clinical outcome of ROSI.

Spermatogonial Stem Cell-Based Therapies: Taking Preclinical Research to the Next Level

Fertility preservation via biobanking of testicular tissue retrieved from testicular biopsies is now generally recommended for boys who need to undergo gonadotoxic treatment prior to the onset of puberty, as a source of spermatogonial stem cells (SSCs). SSCs have the potential of forming spermatids and may be used for therapeutic fertility approaches later in life. Although in the past 30 years many milestones have been reached to work towards SSC-based fertility restoration therapies, including transplantation of SSCs, grafting of testicular tissue and various in vitro and ex vivo spermatogenesis approaches, unfortunately, all these fertility therapies are still in a preclinical phase and not yet available for patients who have become infertile because of their treatment during childhood. Therefore, it is now time to take the preclinical research towards SSC-based therapy to the next level to resolve major issues that impede clinical implementation. This review gives an outline of the state of the art of the effectiveness and safety of fertility preservation and SSC-based therapies and addresses the hurdles that need to be taken for optimal progression towards actual clinical implementation of safe and effective SSC-based fertility treatments in the near future.