In vitro transplantation of spermatogonial stem cells isolated from human frozen-thawed testis tissue can induce spermatogenesis under 3-dimensional tissue culture conditions

The effect of epididymosomes on the development of frozen-thawed mouse spermatogonial stem cells after culture in a decellularized testicular scaffold and transplantation into azoospermic mice

PURPOSE

This study examined SSC proliferation on an epididymosome-enriched decellularized testicular matrix (DTM) hydrogel and spermatogenesis induction in azoospermic mice.

METHODS

Epididymosomes were extracted and characterized using SEM and western blotting. After cryopreservation, thawed SSCs were cultured in a hydrogel-based three-dimensional (3D) culture containing 10 ng/mL GDNF or 20 µg/mL epididymosomes. SSCs were assessed using the MTT assay, flow cytometry, and qRT-PCR after two weeks of culture. The isolated SSCs were microinjected into the efferent ducts of busulfan-treated mice. DiI-labeled SSCs were followed, and cell homing was assessed after two weeks. After 8 weeks, the testes were evaluated using morphometric studies and immunohistochemistry.

RESULTS

The expression of PLZF, TGF-β, and miR-10b did not increase statistically significantly in the 3D + GDNF and 3D + epididymosome groups compared to the 3D group. Among the groups, the GDNF-treated group exhibited the highest expression of miR-21 (*P < 0.05). Caspase-3 expression was lower in the epididymosome-treated group than in the other groups (***P < 0.001). Compared to the 3D and negative control groups, the 3D + epididymosomes and 3D + GDNF groups showed an increase in spermatogenic cells. Immunohistochemical results confirmed the growth and differentiation of spermatogonial cells into spermatids in the treatment groups.

CONCLUSION

The DTM hydrogel containing 20 µg/mL epididymosomes or 10 ng/mL GDNF is a novel and safe culture system that can support SSC proliferation in vitro to obtain adequate SSCs for transplantation success. It could be a novel therapeutic agent that could recover deregulated SSCs in azoospermic patients.

Hyaluronic acid/silicon nanoparticle scaffold induces proliferation and differentiation of mouse spermatogonial stem cells transplanted to epididymal adipose tissue

Spermatogonia stem cells (SSCs) are a unique cell population maintaining male spermatogenesis during life, through their potential for proliferation and differentiation. The application of silicon nanoparticles (SNs) and hyaluronic acid (HA) to induce the differentiation of SSCs seems promising. Herein, we investigate the effect of SN and HA scaffolds on the progression of SSCs spermatogenesis in mice. Initially SSCs were isolated from healthy immature mice and cultured on prepared scaffolds (HA, SN, and HA/SN) in a 3D culture system. Then viability of SSCs cultured on scaffolds was examined using MTT assay and Acridine Orange staining. Then SSCs cultured on scaffolds were transplanted into epididymal adipose tissue (EAT) in mature mice and the result was studied by H&E and IHC staining 8 weeks after transplantation. MTT and Acridine Orange analysis revealed that among three different scaffolds HA/SN based scaffold causes considerable toxicity on SSCs (P < 0.05) while H&E staining showed that culture of SSCs on HA, SN, and HA/SN scaffolds has a positive effect on the progression of SSCs spermatogenesis after transplantation into EAT. IHC staining identified TP1, TEKT1, and PLZF as crucial biomarkers in the spermatogenesis development of SSCs transplanted to EAT. According to the presence of these biomarkers in different experimental groups, we found the most spermatogenesis development in SSCs cultured on HA/SN scaffold (PLZF, P < 0.01) (TEKT1, P < 0.01) (TP1, P < 0.001). Our study showed that, although the cytotoxic effect of the HA/SN scaffold decreases the viability rate of SSCs; however, SSCs that survive on HA/SN scaffold showed more ability to progress in spermatogenesis after transplantation into EAT.

Sertoli Cell-Conditioned Medium Induces Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells to Male Germ-Like Cells in Busulfan-Induced Azoospermic Mouse Model

Non-obstructive azoospermia is a severe form of male infertility, with limited effective treatments. Bone marrow mesenchymal stem cells (BMSCs) can differentiate to different cell lines; therefore, transplantation of these cells is used for treatment of several diseases. Since these cells require induction factors to differentiate into germ cells, we co-transplanted bone marrow stem cells (BMSCs) with Sertoli cell-conditioned medium (SCCM) into the testis of azoospermic mice. This study was carried out in two sections, in vitro and in vivo. For in vitro study, differentiating factors (c-kit and ID4) were examined after 15 days of co-culture of bone marrow cells with Sertoli cell-conditioned medium, while for in vivo study, the azoospermia model was first created by intraperitoneal administration of a single-dose busulfan (40 mg/kg) followed by single-dose CdCl2 (2 mg/kg) after 4 weeks. Mice were divided into 4 groups including control (azoospermia), BMSC, SCCM, and BMSC + SCCM. Eight weeks after transplantation, samples were assessed for proliferation and differentiation via the expression level of MVH, ID4, SCP3, Tp1, Tp2, and Prm1 differentiation markers. The results showed that BMSC co-cultured with SCCM in vitro differentiated BMSC to germ-like cells. Similarly, in vivo studies revealed a higher level of BMSC differentiation into germ-like cells with significant higher expression of differentiation markers in transplanted groups compared to the control. This study confirmed the role of SCCM as an inductive factor for BMSC differentiation to germ cells both in vivo and in vitro conditions.

Ultrastructural study: in vitro and in vivo differentiation of mice spermatogonial stem cells

Mouse testicular tissue is composed of seminiferous tubules and interstitial tissue. Mammalian spermatogenesis is divided into three stages: spermatocytogenesis (mitotic divisions) in which spermatogonial stem cells (SSCs) turn into spermatocytes, followed by two consecutive meiotic divisions in which spermatocytes form spermatids. Spermatids differentiate into spermatozoa during spermiogenesis. Various factors affect the process of spermatogenesis and the organization of cells in the testis. Any disorder in different stages of spermatogenesis will have negative effects on male fertility. The aim of the current study was to compare the in vitro and in vivo spermatogenesis processes before and after transplantation to azoospermic mice using ultrastructural techniques. In this study, mice were irradiated with single doses of 14 Gy 60Co radiation. SSCs isolated from neonatal mice were cultured in vitro for 1 week and were injected into the seminiferous tubule recipient's mice. Testicular cells of neonatal mice were cultured in the four groups on extracellular matrix-based 3D printing scaffolds. The transplanted testes (8 weeks after transplantation) and cultured testicular cells in vitro (after 3 weeks) were then processed for transmission electron microscopy studies. Our study's findings revealed that the morphology and ultrastructure of testicular cells after transplantation and in vitro culture are similar to those of in vivo spermatogenesis, indicating that spermatogenic cell nature is unaltered in vitro.

Recovering Spermatogenesis By Protected Cryopreservation Using Metformin and Transplanting Spermatogonial Stem Cells Into Testis in an Azoospermia Mouse Model

Cryopreservation and transplantation of spermatogonial stem cells (SSCs) may serve as a new method to restore male fertility in patients undergoing chemotherapy or radiotherapy. However, SSCs may be damaged during cryopreservation due to the production of reactive oxygen species (ROS). Therefore, different antioxidants have been used as protective agents. Studies have shown that metformin (MET) has antioxidant activity. The aim of this study was to assess the antioxidant and antiapoptotic effects of MET in frozen-thawed SSCs. In addition, the effect of MET on the proliferation and differentiation of SSCs was evaluated. To this end, SSCs were isolated from mouse pups aged 3-6 days old, cultured, identified by flow cytometry (ID4, INTEGRIN β1+), and finally evaluated for survival and ROS rate. SSCs were transplanted after busulfan and cadmium treatment. Cryopreserved SSCs with and without MET were transplanted after 1 month of cryopreservation. Eight weeks after transplantation, the recipient testes were evaluated for the expression of apoptosis (BAX, BCL2), proliferation (PLZF), and differentiation (SCP3, TP1, TP2, PRM1) markers using immunohistochemistry, Western blot, and quantitative real-time polymerase chain reaction. The findings revealed that the survival rate of SSCs was higher in the 500 μm/mL MET group compared to the other groups (50 and 5000 μm/mL). MET significantly decreased the intracellular ROS production. Transplantation of SSCs increased the expression level of proliferation (PLZF) and differentiation (SCP3, TP1, TP2, PRM1) markers compared to azoospermia group, and their levels were significantly higher in the MET group compared to the cryopreservation group containing basic freezing medium (p < 0.05). MET increased the survival rate of SSCs, proliferation, and differentiation and decreased the ROS production and the apoptosis rate. Cryopreservation by MET seems to be effective in treating infertility.

In vitro spermatogenesis in artificial testis: current knowledge and clinical implications for male infertility

Men's reproductive health exclusively depends on the appropriate maturation of certain germ cells known as sperm. Certain illnesses, such as Klinefelter syndrome, cryptorchidism, and syndrome of androgen insensitivity or absence of testis maturation in men, resulting in the loss of germ cells and the removal of essential genes on the Y chromosome, can cause non-obstructive azoospermia. According to laboratory research, preserving, proliferating, differentiating, and transplanting spermatogonial stem cells or testicular tissue could be future methods for preserving the fertility of children with cancer and men with azoospermia. Therefore, new advances in stem cell research may lead to promising therapies for treating male infertility. The rate of progression and breakthrough in the area of in vitro spermatogenesis is lower than that of SSC transplantation, but newer methods are also being developed. In this regard, tissue and cell culture, supplements, and 3D scaffolds have opened new horizons in the differentiation of stem cells in vitro, which could improve the outcomes of male infertility. Various 3D methods have been developed to produce cellular aggregates and mimic the organization and function of the testis. The production of an artificial reproductive organ that supports SSCs differentiation will certainly be a main step in male infertility treatment.

Fertility preservation in pediatric healthcare: a review

Survival rates for children and adolescents diagnosed with malignancy have been steadily increasing due to advances in oncology treatments. These treatments can have a toxic effect on the gonads. Currently, oocyte and sperm cryopreservation are recognized as well-established and successful strategies for fertility preservation for pubertal patients, while the use of gonadotropin-releasing hormone agonists for ovarian protection is controversial. For prepubertal girls, ovarian tissue cryopreservation is the sole option. However, the endocrinological and reproductive outcomes after ovarian tissue transplantation are highly heterogeneous. On the other hand, immature testicular tissue cryopreservation remains the only alternative for prepubertal boys, yet it is still experimental. Although there are several published guidelines for navigating fertility preservation for pediatric and adolescent patients as well as transgender populations, it is still restricted in clinical practice. This review aims to discuss the indications and clinical outcomes of fertility preservation. We also discuss the probably effective and efficient workflow to facilitate fertility preservation.

Ex-Vivo and In-Vivo Expansion of Spermatogonial Stem Cells Using Cell-Seeded Microfluidic Testis Scaffolds and Animal Model

AIMS

This study was designed to provide both ex-vivo and in-vivo methods for the extraction and expansion of spermatogonial stem cells (SSCs).

METHODS

For in-vivo experiments, azoospermic mouse model was performed with Busulfan. Isolation, culture, and characterization of neonate mouse SSC were also achieved. We performed an in-vivo injection of labeled SSCs to the testes with azoospermia. In ex-vivo experiments, extracted SSCs were seeded on the fabricated scaffold consisting of hyaluronic acid (HA) and decellularized testis tissues (DTT). Immunofluorescence staining with PLZF, TP1, and Tekt 1 was performed for SSCs differentiation and proliferation.

RESULTS

Several studies demonstrated efficient spermatogenic arrest in seminiferous tubules and proved the absence of spermatogenesis. Transplanted SSCs moved and settled in the basement covering the seminiferous tubules. Most of the cells were positive for Dil, after 4 weeks. An epithelium containing spermatogonia-like cells with Sertoli-like, and Leydig cells were evident in the seminiferous tubules of biopsies, and the IHC staining was significantly positive, 4 weeks after injection of SSCs. The results of the ex-vivo experiments showed positive staining for all markers, which was significantly enhanced in scaffolds of ex-vivo experiments compared with in-vitro seeded scaffolds.

CONCLUSION

Ex-vivo SSC differentiation and proliferation using cell-seeded microfluidic testis scaffolds maybe effective for treatment of the azoospermia.

The importance of the urologist in male oncology fertility preservation

OBJECTIVES

To demonstrate that surgical sperm retrieval (SSR) and spermatogonial stem cell retrieval (SSCR) in an oncological context are safe and successful.

PATIENTS AND METHODS

This a retrospective study in a tertiary hospital in the UK. Patients requiring fertility preservation from December 2017 to January 2020 were included. Data were analysed with Microsoft Excel 2016 and the Statistical Package for the Social Sciences (version 20).

RESULTS

Among 1264 patients referred to the Reproductive Medical Unit at the University College of London Hospitals for cryopreservation prior to gonadotoxic treatment, 39 chose to go forward with SSR/SSCR because they presented as azoo-/cryptozoospermic or an inability to masturbate/ejaculate. Interventions were testicular sperm extraction (23 patients) or aspiration (one), electroejaculation (one), and testicular wedge biopsy for SSCR (14). The median (range) age was 15.0 (10-65) years and the median testosterone level was 4.4 nmoL/L. Primary diagnoses were sarcoma in 11 patients, leukaemia in nine, lymphoma in eight, testicular tumour in five, other oncological haematological entities in two, other solid cancers in two, while two patients had non-oncological haematological diseases. SSR/SSCR could be offered within 7.5 days on average. Chemotherapy could follow within 2 days from SSR/SSCR, and bone marrow transplant occurred within 19.5 days (all expressed as medians). The success rate for SSR was 68.0% (at least one vial/straw collected). The mean (SD) Johnsen score of testicular biopsies was 5.23 (2.25) with a trend towards positive correlation with SSR success (P = 0.07). However, age, hormonal profile and type of cancer did not predict SSR outcome.

CONCLUSION

We show that SSR and SSCR in an oncological context are valid treatment options with a high success rate for patients in which sperm cryopreservation from semen is impossible. By providing an effective pathway, fertility preservation is possible with minimal delay to oncological treatment.

Stem Cells and Organs-on-chips: New Promising Technologies for Human Infertility Treatment

Having biological children remains an unattainable dream for most couples with reproductive failure or gonadal dysgenesis. The combination of stem cells with gene editing technology and organ-on-a-chip models provides a unique opportunity for infertile patients with impaired gametogenesis caused by congenital disorders in sex development or cancer survivors. But how will these technologies overcome human infertility? This review discusses the regenerative mechanisms, applications, and advantages of different types of stem cells for restoring gametogenesis in infertile patients, as well as major challenges that must be overcome before clinical application. The importance and limitations of in vitro generation of gametes from patient-specific human-induced pluripotent stem cells (hiPSCs) will be discussed in the context of human reproduction. The potential role of organ-on-a-chip models that can direct differentiation of hiPSC-derived primordial germ cell-like cells to gametes and other reproductive organoids is also explored. These rapidly evolving technologies provide prospects for improving fertility to individuals and couples who experience reproductive failure.

In vitro production of mouse morphological sperm in artificial testis bioengineered by 3D printing of extracellular matrix

Since autologous stem cell transplantation is prone to cancer recurrence, in vitro sperm production is regarded a safer approach to fertility preservation. In this study, the spermatogenesis process on testicular tissue extracellular matrix (T-ECM)-derived printing structure was evaluated. Ram testicular tissue was decellularized using a hypertonic solution containing triton and the extracted ECM was used as a bio-ink to print an artificial testis. Following cell adhesion and viability examination, pre-meiotic and post-meiotic cells in the study groups (as testicular suspension and co-culture with Sertoli cells) were confirmed by real-time PCR, flow-cytometry and immunocytochemistry methods. Morphology of differentiated cells was evaluated using transmission electron microscopy (TEM), toluidine blue, Giemsa, and hematoxylin and eosin (H&E) staining. The functionality of Leydig and Sertoli cells was determined by their ability for hormone secretion. The decellularization of testicular tissue fragments was successful and had efficiently removed the cellular debris and preserved the ECM compounds. High cell viability, colonization, and increased expression of pre-meiotic markers in cultured testicular cells on T-ECM-enriched scaffolds confirmed their proliferation. Furthermore, the inoculation of neonatal mouse testicular cells onto T-ECM-enriched scaffolds resulted in the generation of sperm. Morphology evaluation showed that the structure of these cells was quite similar to mature sperm with a specialized tail structure. The hormonal analysis also confirmed production and secretion of testosterone and inhibin B by Leydig and Sertoli cells. T-ECM printed artificial testis is a future milestone that promises for enhancing germ cell maintenance and differentiation, toxicology studies, and fertility restoration to pave the way for new human infertility treatments in the future.

Mini Bioreactor Can Support In Vitro Spermatogenesis of Mouse Testicular Tissue

Objective

It was in the early 20^th century when the quest for in vitro spermatogenesis started. In vitro spermatogenesis is critical for male cancer patients undergoing gonadotoxic treatment. Dynamic culture system creates in vivo-like conditions. In this study, it was intended to evaluate the progression of spermatogenesis after testicular tissue culture in mini-perfusion bioreactor.

Materials and Methods

In this experimental study, 12 six-day postpartum neonatal mouse testes were removed and fragmented, placed on an agarose gel in parallel to bioreactor culture, and incubated for 8 weeks. Histological, molecular and immunohistochemical evaluations were carried out after 8 weeks.

Results

Histological analysis suggested successful maintenance of spermatogenesis in tissues grown in the bioreactor but not on agarose gel, possibly because the central region did not receive sufficient oxygen and nutrients, which led to necrotic or degenerative changes. Molecular analysis indicated that Plzf, Tekt1 and Tnp1 were expressed and that their expression did not differ significantly between the bioreactor and agarose gel. Immunohistochemical evaluation of testis fragments showed that PLZF, SCP3 and ACRBP proteins were expressed in spermatogonial cells, spermatocytes and spermatozoa. PLZF expression after 8 weeks was significantly lower (P<0.05) in tissues incubated on agarose gel than in the bioreactor, but there was no significant difference between SCP3 and ACRBP expression among the bioreactor and agarose gel culture systems.

Conclusion

This three-dimensional (3D) dynamic culture system can provide somewhat similar conditions to the physiological environment of the testis. Our findings suggest that the perfusion bioreactor supports induction of spermatogenesis for generation of haploid cells. Further studies will be needed to address the fertility of the sperm generated in the bioreactor system..

Cellular Therapy via Spermatogonial Stem Cells for Treating Impaired Spermatogenesis, Non-Obstructive Azoospermia

Male infertility is a major health problem affecting about 8–12% of couples worldwide. Spermatogenesis starts in the early fetus and completes after puberty, passing through different stages. Male infertility can result from primary or congenital, acquired, or idiopathic causes. The absence of sperm in semen, or azoospermia, results from non-obstructive causes (pretesticular and testicular), and post-testicular obstructive causes. Several medications such as antihypertensive drugs, antidepressants, chemotherapy, and radiotherapy could lead to impaired spermatogenesis and lead to a non-obstructive azoospermia. Spermatogonial stem cells (SSCs) are the basis for spermatogenesis and fertility in men. SSCs are characterized by their capacity to maintain the self-renewal process and differentiation into spermatozoa throughout the male reproductive life and transmit genetic information to the next generation. SSCs originate from gonocytes in the postnatal testis, which originate from long-lived primordial germ cells during embryonic development. The treatment of infertility in males has a poor prognosis. However, SSCs are viewed as a promising alternative for the regeneration of the impaired or damaged spermatogenesis. SSC transplantation is a promising technique for male infertility treatment and restoration of spermatogenesis in the case of degenerative diseases such as cancer, radiotherapy, and chemotherapy. The process involves isolation of SSCs and cryopreservation from a testicular biopsy before starting cancer treatment, followed by intra-testicular stem cell transplantation. In general, treatment for male infertility, even with SSC transplantation, still has several obstacles. The efficiency of cryopreservation, exclusion of malignant cells contamination in cancer patients, and socio-cultural attitudes remain major challenges to the wider application of SSCs as alternatives. Furthermore, there are limitations in experience and knowledge regarding cryopreservation of SSCs. However, the level of infrastructure or availability of regulatory approval to process and preserve testicular tissue makes them tangible and accurate therapy options for male infertility caused by non-obstructive azoospermia, though in their infancy, at least to date.

Differentiation and proliferation of spermatogonial stem cells using a three-dimensional decellularized testicular scaffold: a new method to study the testicular microenvironment in vitro

PURPOSE

Successful in vitro transplantation of spermatogonial stem cells (SSCs) demands effective culture systems for SSCs proliferation and differentiation. Natural extracellular matrix (ECM) creates a microenvironment suitable for culture of stem cells. In the present study, we intended to assess the capability of the porous scaffold consisting of hyaluronic acid (HA), chitosan, and decellularized testicular matrix (DTM) as a proper niche for SSCs seeding.

METHODS

The testes of four NMRI mice were extracted for further detergent-based decellularization process. We isolated, cultured, and clarified neonate mouse SSC, and a three-dimensional scaffold was prepared for SSCs culture. The loaded SSCs and hydrogel-based scaffold were investigated by several studies including scanning electron microscopy (SEM), 4',6-diamidino-2-phenylindole (DAPI), 3-[4, 5-dimethyl (thiazol-2yl)-3,5diphenyl] tetrazolium bromide (MTT), Acridine orange, and Immunohistochemistry (IHC) staining.

RESULTS

The efficiency of decellularization process was confirmed by DAPI, hematoxylin and eosin (H&E), and Masson's Trichrome staining. Acridine orange also depicted SSCs proliferation and viability. SEM approved the preservation of ECM components and also showed complex, coiled, and tubular seminiferous tubules, with intact and condensed collagenous form of the tunica albuginea. MTT test also revealed the scaffold's non-toxicity. Expression of PLZF, TP1, and TEKT1 markers also verified the capacity of SSCs proliferation on a cogel scaffold.

CONCLUSION

In conclusion, cogel scaffold consisting of DTM, HA, and chitosan may provide the supporting layer for in vitro SSC differentiation and proliferation.

Strategies for cryopreservation of testicular cells and tissues in cancer and genetic diseases

Cryopreservation of testicular cells and tissues is useful for the preservation and restoration of fertility in pre-pubertal males expecting gonadotoxic treatment for cancer and genetic diseases causing impaired spermatogenesis. A number of freezing and vitrification protocols have thus been tried and variable results have been reported in terms of cell viability spermatogenesis progression and the production of fertile spermatozoa. A few studies have also reported the production of live offspring from cryopreserved testicular stem cells and tissues in rodents but their replication in large animals and human have been lacking. Advancement in in vitro spermatogenesis system has improved the possibility of producing fertile spermatozoa from the cryopreserved testis and has reduced the dependency on transplantation. This review provides an update on various cryopreservation strategies for fertility preservation in males expecting gonadotoxic treatment. It also discusses various methods of assessing and ameliorating cryoinjuries. Newer developments on in vitro spermatogenesis and testicular tissue engineering for in vitro sperm production from cryopreserved SSCs and testicular tissue are also discussed.

Comparison of two culture methods during in vitro spermatogenesis of vitrified-warmed testis tissue: Organ culture vs. hanging drop culture

Solid surface vitrification (SSV) is a cost effective and simple method for testis tissue preservation. Vitrified-warmed testis tissue was successfully cultured using various organ culture methods. In this study, we compared two culture methods viz. hanging drop (HD) and organ culture (OC) methods for in vitro spermatogenesis of goat testis tissue vitrified-warmed by SSV. It was observed that OC method was superior (p < 0.05) to HD method in terms of post-warming metabolic activity of testicular tissue, as measured by MTT assay on Day 7 and Day 14 of culture, respectively. The size of the tissue also played an important role in post-warming metabolic activity and viability (4 mm³: 72.7 ± 1.2% vs. 9 mm³: 62.7 ± 1.3% vs. 16 mm³: 40.5 ± 1.7%) of vitrified tissues with smaller tissue resulting in better result. The vitrification-induced ROS activity significantly decreased during their in vitro culture. Histology and scanning electron microscopy (SEM) showed the rupture of basal membrane, surface morphology and, cell loss due to vitrification. However, histology and immunohistochemistry showed the progression of in vitro spermatogenesis and formation of elongated spermatozoa in both fresh and vitrified-warmed testis tissue cultured by OC method. Taken together, our results suggest that OC method is superior to HD method for culturing goat testis tissue vitrified-warmed by SSV.

Advanced bioengineering of male germ stem cells to preserve fertility

In modern life, several factors such as genetics, exposure to toxins, and aging have resulted in significant levels of male infertility, estimated to be approximately 18% worldwide. In response, substantial progress has been made to improve in vitro fertilization treatments (e.g. microsurgical testicular sperm extraction (m-TESE), intra-cytoplasmic sperm injection (ICSI), and round spermatid injection (ROSI)). Mimicking the structure of testicular natural extracellular matrices (ECM) outside of the body is one clear route toward complete in vitro spermatogenesis and male fertility preservation. Here, a new wave of technological innovations is underway applying regenerative medicine strategies to cell-tissue culture on natural or synthetic scaffolds supplemented with bioactive factors. The emergence of advanced bioengineered systems suggests new hope for male fertility preservation through development of functional male germ cells. To date, few studies aimed at in vitro spermatogenesis have resulted in relevant numbers of mature gametes. However, a substantial body of knowledge on conditions that are required to maintain and mature male germ cells in vitro is now in place. This review focuses on advanced bioengineering methods such as microfluidic systems, bio-fabricated scaffolds, and 3D organ culture applied to the germline for fertility preservation through in vitro spermatogenesis.

Pediatric Research and Health Care for Transgender and Gender Diverse Adolescents and Young Adults: Improving (Biopsychosocial) Health Outcomes

Adolescent and young adult (AYA) transgender health care and research have expanded rapidly in the United States and abroad, but the effects of gender-affirming social, hormonal, or surgical care on overall health remain unclear. Gender diverse identities, also termed nonbinary, have often been neglected in favor of (male/female) binary identities, even in the context of transgender health care and research. No high quality studies have assessed how gender-affirming medical care impact health inequities in transgender and gender diverse (TG/GD) adults, much less in AYAs, despite the fact that that TG/GD adults have higher than average morbidity and mortality across a host of health concerns, from human immunodeficiency virus infection to thromboembolism, and that reported depression with suicidal ideation is >10 times higher in TG/GD adults than in the general population. TG/GD youth have related but different needs from TG/GD adults. TG/GD AYA are embedded in family and schools, where stigma may be difficult to escape; mental health during adolescence has areas of increased risk as well as resilience; and the effects of early hormonal and surgical interventions on long-term health are insufficiently studied. Because of this, an inclusive and proactive approach to addressing the needs of TG/GD AYA by pediatric clinicians, researchers, and educators is particularly crucial. This article focuses on what is known and unknown about clinical practice, research, and education related to TG/GD health. We highlight the role of gender affirmation by clinicians as they care and advocate for TG/GD AYAs; the potential challenges of hormonal treatment for peripubertal youth; and short- and long-term effects on physical and reproductive health of medical or surgical interventions. We also discuss how social context influences knowledge gaps and the health-relevant risks faced by TG/GD AYA. The challenges are formidable, but opportunities await: high priority research questions to explore, educational gaps to be filled, and advocacy that needs the voices of pediatricians to promote policies to facilitate positive health outcomes for TG/GD AYA.

Isolation, identification and differentiation of human spermatogonial cells on three-dimensional decellularized sheep testis

Improvement of in vitro culture methods of Spermatogonial Stem Cells (SSCs) is known to be an effective procedure for further study of the process of spermatogenesis and can offer effective therapeutic modality for male infertility. Tissue decellularization by providing natural 3D and extracellular matrix (ECM) conditions for cell growth can be an alternative procedure to enhance in vitro culture conditions. In the present study, the testicular tissues were taken from brain death donors. After enzymatic digestion, the tissue cells were isolated and cultured for four weeks. Then the identity of the SSCs was confirmed using anti-GFRα1 and anti-PLZF antibodies via immunocytochemistry (ICC). The differentiation capacity of SSCs were evaluated by culture of them on a layer of decellularized testicular matrix (DTM) prepared from sheep testis, as well as under two-dimensional (2D) culture with differentiation medium. After four and six weeks of the initiation of differentiation culture, the pre-meiotic, meiotic and post- meiotic genes at the mRNA and protein levels was examined via qPCR and ICC methods, respectively. The results showed that pre-meiotic, meiotic and post-meiotic genes expressions were significantly higher in the cells cultured in DTM substrate (P ≤ 0.01).The present study indicated that, the natural structure of ECM prepare the suitable conditions for further study of the spermatogenesis process in the in vitro and contributes to the maintenance and treatment of male infertility.

Xeno-Free Propagation of Spermatogonial Stem Cells from Infant Boys

Spermatogonial stem cell (SSC) transplantation therapy is a promising strategy to renew spermatogenesis for prepubertal boys whose fertility is compromised. However, propagation of SSCs is required due to a limited number of SSCs in cryopreserved testicular tissue. This propagation must be done under xeno-free conditions for clinical application. SSCs were propagated from infant testicular tissue (7 mg and 10 mg) from two boys under xeno-free conditions using human platelet lysate and nutrient source. We verified SSC-like cell clusters (SSCLCs) by quantitative real-time polymerase chain reaction (PCR) and immune-reaction assay using the SSC markers undifferentiated embryonic cell transcription factor 1 (UTF1), ubiquitin carboxyl-terminal hydrolase isozyme L1 (UCHL1), GDNF receptor alpha-1 (GFRα-1) Fα and promyelocytic leukaemia zinc finger protein (PLZF). The functionality of the propagated SSCs was investigated by pre-labelling using green fluorescent Cell Linker PKH67 and xeno-transplantation of the SSCLCs into busulfan-treated, therefore sterile, immunodeficient mice. SSC-like cell clusters (SSCLCs) appeared after 2 weeks in primary passage. The SSCLCs were SSC-like as the UTF1, UCHL1, GFRα1 and PLZF were all positive. After 2.5 months’ culture period, a total of 13 million cells from one sample were harvested for xenotransplantation. Labelled human propagated SSCs were identified and verified in mouse seminiferous tubules at 3–6 weeks, confirming that the transplanted cells contain SSCLCs. The present xeno-free clinical culture protocol allows propagation of SSCs from infant boys.