P407 hydrogel loaded with nitric oxide microbubbles promotes angiogenesis and functional improvement in testicular transplantation

Prepubertal male patients with cancer have decreased fertility after treatment, but there are currently no suitable means for fertility rescue. Testicular transplantation seems to be a promising treatment. The short-term insufficiency of blood supply after transplantation is the key problem that needs to be solved. In this research, nitric oxide (NO), a gas and small molecule transmitter with the effect of promoting angiogenesis, acted at the site of testicular transplantation. Herein, poloxamer-407 (P407) and lipid microbubble materials served as transport carriers for NO and helped NO to function at the transplant site. P407 hydrogel loaded with NO microbubbles (PNO) slowly released NO in vitro. The three-dimensional space of the hydrogel provided a stable environment for NO microbubbles, which is conducive to the continuous release of NO. In this study, 25% PNO (w/v) was selected, and the gelling temperature was 19.47 °C. The gelling efficiency was relatively high at body temperature. Rheological experiments showed that PNO, at this concentration, had stable mechanical properties. The results from in vivo experiments demonstrated that testicular grafts in the PNO group exhibited a notably accelerated blood flow recovery compared to the other groups. Additionally, the PNO group displayed a significant improvement in reproductive function recovery. In conclusion, PNO exhibited slow release of NO, and a small amount of NO promoted angiogenesis in testicular grafts and restored reproductive function.

Single-cell transcriptome analysis and in vitro differentiation of testicular cells reveal novel insights into male sterility of the interspecific hybrid cattle-yak

BACKGROUND

Interspecific hybridization plays vital roles in enriching animal diversity, while male hybrid sterility (MHS) of the offspring commonly suffered from spermatogenic arrest constitutes the postzygotic reproductive isolation. Cattle-yak, the hybrid offspring of cattle (Bos taurus) and yak (Bos grunniens) can serve as an ideal MHS animal model. Although meiotic arrest was found to contribute to MHS of cattle-yak, yet the cellular characteristics and developmental potentials of male germline cell in pubertal cattle-yak remain to be systematically investigated.

RESULTS

Single-cell RNA-seq analysis of germline and niche cell types in pubertal testis of cattle-yak and yak indicated that dynamic gene expression of developmental germ cells was terminated at late primary spermatocyte (meiotic arrest) and abnormal components of niche cell in pubertal cattle-yak. Further in vitro proliferation and differentially expressed gene (DEG) analysis of specific type of cells revealed that undifferentiated spermatogonia of cattle-yak exhibited defects in viability and proliferation/differentiation potentials.

CONCLUSION

Comparative scRNA-seq and in vitro proliferation analysis of testicular cells indicated that not only meiotic arrest contributed to MHS of cattle-yak. Spermatogenic arrest of cattle-yak may originate from the differentiation stage of undifferentiated spermatogonia and niche cells of cattle-yak may provide an adverse microenvironment for spermatogenesis.

Altered hormonal milieu and dysregulated protein expression can cause spermatogenic arrest in ectopic xenografted immature rat testis

Testis tissue xenografting complemented with cryopreservation is a feasible technique for fertility preservation in children with malignancy receiving gonadotoxic therapy and for endangered species with high neonatal mortality rate. However, xenografted testis of human and most endangered species are known to undergo spermatogenic arrest. In this study, we xenografted immature rat testis onto immunodeficient male mice to investigate the plausible underlying causes of spermatogenic arrest. Histological analysis of xenografted testes collected 8-wk post-grafting showed incomplete spermatogenesis with pachytene-stage spermatocytes as the most advanced germ cells. Although the levels of serum luteinizing hormone and testosterone were normal in recipient mice, those of follicle stimulating hormone (FSH) were significantly high, and specific receptors of FSH were absent in the xenografts. The xenografts demonstrated dysregulated expression of Sertoli cell-transcriptional regulators (WT1 and SOX9) and secretory proteins (SCF and GDNF). In conclusion, results from our study suggested that an altered hormonal milieu in recipients and dysregulated protein expression in xenografts could be a potential cause of spermatogenic arrest in xenografted immature rat testis. Further stereological analysis of xenografts can demonstrate precise cellular composition of xenografts to decipher interactions between germ and somatic cells to better understand spermatogenic arrest in xenografted testis.

The Pluripotent Microvascular Pericytes Are the Adult Stem Cells Even in the Testis

The pericytes of the testis are part of the omnipresent population of pericytes in the vertebrate body and are the only true pluripotent adult stem cells able to produce structures typical for the tree primitive germ layers: ectoderm, mesoderm, and endoderm. They originate very early in the embryogenesis from the pluripotent epiblast. The pericytes become disseminated through the whole vertebrate organism by the growing and differentiating blood vessels where they remain in specialized periendothelial vascular niches as resting pluripotent adult stem cells for tissue generation, maintenance, repair, and regeneration. The pericytes are also the ancestors of the perivascular multipotent stromal cells (MSCs). The variable appearance of the pericytes and their progeny reflects the plasticity under the influence of their own epigenetic and the local environmental factors of the host organ. In the testis the pericytes are the ancestors of the neuroendocrine Leydig cells. After activation the pericytes start to proliferate, migrate, and build transit-amplifying cells that transdifferentiate into multipotent stromal cells. These represent progenitors for a number of different cell types in an organ. Finally, it becomes evident that the pericytes are a brilliant achievement of the biological nature aiming to supply every organ with an omnipresent population of pluripotent adult stem cells. Their fascinating features are prerequisites for future therapy concepts supporting cell systems of organs.

Testosterone Is a Contraceptive and Should Not Be Used in Men Who Desire Fertility

Testosterone has a variety of functions and is commonly used in older men to treat symptoms of hypogonadism, such as decreased libido, decreased mood and erectile dysfunction. Despite its positive effects on sexual function, it has a negative effect on fertility. Exogenous testosterone therapy can negatively affect the hypothalamic-pituitary gonadal axis and inhibit the production of follicle stimulating hormone and luteinizing hormone. The purpose of this review is to discuss the contraceptive properties of testosterone therapy and to discuss strategies to increase testosterone in men with the desire to preserve fertility.

Wistar rats immature testicular tissue vitrification and heterotopic grafting

Objective

To evaluate the efficiency of two vitrification protocols for rat immature testicular tissue and heterotopic transplantation.

Methods

Twenty-four pre-pubertal Wistar rats were divided into three groups (n=8). After orchiectomy, testicular fragments (3mm) from Groups 1 and 2 were vitrified with different cryoprotectant concentration solutions, using sterile inoculation loops as support. After warming up, the fragments were submitted to cell viability assessment by Trypan blue and histological evaluation. Vitrified (Groups 1 and 2) and fresh (Group 3) fragments were grafted to the animals periauricular region. After 8 weeks of grafting, the implant site was histologically analyzed.

Results

The viability recovery rate from Group 1 (72.09%) was higher (p=0.02) than that from Group 2 (59.19%). Histological analysis showed similar tubular integrity between fresh fragments from Groups 1 and 3. Group 2 samples presented lower tubular integrity. We ran histological analyses in the grafts from the Groups. In all groups, it was possible to see the implant site, however, no fragment of testicular tissue or signs of inflammation were histologically found in most samples from Groups 1 and 3. In one sample from Group 2, we found degenerated seminiferous tubules with necrosis and signs of an inflammatory process. In another sample from Group 2, we found seminiferous tubules in the implant site.

Conclusion

The vitrification of pre-pubertal testicular tissue of rats showed little damage to cell viability through histological analysis when we used cryoprotectants in a lower concentration. Heterotopic transplantation could not preserve the structural organization of the testicular tissue.

Characterization of the testicular regeneration potential in premature cockerels

Previous studies have shown that grafted neonatal chicken testicular tissue can develop and produce functional sperm; however, it was unclear whether regenerative processes or proportional growth caused the re-appearance of spermatogenic tissue. We dissociated testicular tissues, performed subcutaneous auto-transplantation of the re-aggregated cells to castrated cockerels, and monitored the post-surgery development of these transplanted aggregates. We found that these transplanted cell aggregates experienced compensatory growth in the form of a 300-fold increase in size, rather than the 30-fold increase observed in normal testis development. Further, these dissociated testicular cell aggregates restored seminiferous tubule structure and were able to produce testosterone and motile sperm. Therefore, we concluded that the dissociated testicular cells from 11-week-old cockerels retained a strong regenerative potential, as they exhibited compensatory growth, restored destroyed structure, and sustained spermatogenesis.

Dysregulation of angiogenesis-specific signalling in adult testis results in xenograft degeneration

Ectopic xenografting of testis is a feasible option for preservation of male fertility and angiogenesis plays a pivotal role in xenograft survival and functionality. When compared to immature testis, the adult testis is unable to establish functional xenografts due to potentially lower efficiency to induce angiogenesis. The precise molecular mechanism, however, remains elusive. In the present study, we compared adult and immature testis xenografts for survival, maturation and germ cell differentiation. Further, we evaluated differential expression of angiogenesis signalling-specific proteins in adult and immature testis and their xenografts. Results showed that adult testis xenografts degenerated whereas immature testis xenografts survived and established spermatogenesis with the production of haploid germ cells. Protein expression analysis demonstrated that immature testis xenografts were able to establish angiogenesis either through eNOS activation via VEGF and PI3K/AKT or through EGFR-mediated STAT3 pathway. The role of ERK/MAPK pathway in xenograft angiogenesis was ruled out. The absence or reduced expression of angiogenesis-specific proteins in adult testis and its xenografts possibly resulted in poor angiogenesis and in their subsequent degeneration. This study provides insight into angiogenesis mechanism that can be utilized to augment testis xenografting efficiency.