Expression and localization of growth factors and their receptors in the mammalian testis. Part I: Fibroblast growth factors and insulin-like growth factors

Testicular niche repair after gonadotoxic treatments: Current knowledge and future directions

The testicular niche, which includes the germ cells, somatic cells, and extracellular matrix, plays a crucial role in maintaining the proper functions of the testis. Gonadotoxic treatments, such as chemotherapy and radiation therapy, have significantly improved the survival rates of cancer patients but have also been shown to have adverse effects on the testicular microenvironment. Therefore, repairing the testicular niche after gonadotoxic treatments is essential to restore its function. In recent years, several approaches, such as stem cell transplantation, gene therapy, growth factor therapy, and pharmacological interventions have been proposed as potential therapeutic strategies to repair the testicular niche. This comprehensive review aims to provide an overview of the current understanding of testis damage and repair mechanisms. We will cover a range of topics, including the mechanism of gonadotoxic action, repair mechanisms, and treatment approaches. Overall, this review highlights the importance of repairing the testicular niche after gonadotoxic treatments and identifies potential avenues for future research to improve the outcomes for cancer survivors.

LOCAL-IGF-1 and GH application IMPROVES germ cell histology, spermatogenesis and fertility after experimental testicular torsion and detorsion

OBJECTIVE

To evaluate the impact of insulin like growth factor-1(IGF-1) and growth hormone (GH) on testis histology, spermatogenesis, and fertility in prepubertal rats exposed to 6 h of testicular torsion (TT) and detorsion.

MATERIAL-METHOD

Forty-eight male Wistar-albino rats weighing 30-70g and at 3-week age were allocated into six groups involving eight rats in each group as follows: Group 1:Sham, Group 2:Control, Group 3:Gelatin, Group 4:Local-IGF-1, 5: Local-GH, Group 6: Systemic-GH. Right testis was only exposed and sutured in the sham group, and right testes were rotated clockwise, 720°, fixed, and 6 h later, detorsion on the testis was done in groups 2-6. Unloaded gelatin, 5 μg local-IGF-1 loaded, and 2IU rhGH loaded gelatin were sutured to the right testis after detorsion in groups 3-5. In Group 6, 0.3IU/100gr/d rhGH was given for seven days via subcuticular route after detorsion. Each of the rats cohabited with two female rats five weeks later. Afterward, both right and left testes were removed. Mean diameter of seminiferous tubules (STD), mean biopsy score count of the testis (TBSC), mean percentage of haploid cells (HCP) were assessed, and fertility parameters were evaluated.

RESULTS

STD and TBSC of the ipsilateral testes were significantly reduced in control and gelatin groups when compared to sham, local-IGF-1, and local-GH groups. STD and TBSC of the ipsilateral testes of the systemic-GH group were decreased compared to the sham group. HCP of the ipsilateral testes of control, gelatin, and systemic-GH groups were significantly lower than the sham, local-IGF-1, and local-GH groups. STD, TBSC, and HCP of the contralateral testes were significantly reduced in control and gelatin groups when compared separately to sham, local-IGF-1, systemic- GH, and local-GH groups. The difference between groups regarding potency, fertility, fecundity indexes, and mean fetus numbers were not significant.

CONCLUSION

Even though there was significant and permanent histologic germ cell damage and reduced HCP in both ipsilateral and contralateral testes, experimental 6 h TT and detorsion in prepubertal rats did not have a negative impact on future fertility. Local-IGF-1and rhGH treatment improved germ cell histology and spermatogenesis in both ipsilateral and contralateral testes of prepubertal rats, subjected to 6 h of TT and detorsion.

The Effects of Local and Systemic Growth Hormone Treatment on Germ Cell Population and Fertility in an Experimental Unilateral Testicular Torsion and Orchiectomy Model

PURPOSE

We evaluated the effects of local and systemic growth hormone on the germ cell population of the contralateral testes of pubertal rats subjected to unilateral testicular torsion and orchiectomy 24 hours later.

MATERIALS AND METHODS

A total of 40 male Wistar-Albino rats at age 3 weeks were divided into 5 groups. In the sham operated group the right testis was sutured and orchiectomy was performed 24 hours later. In groups 2 to 5 orchiectomy was performed 24 hours later following testicular torsion. In groups 3 and 4 unloaded and growth hormone loaded gelatin films, respectively, were sutured on the contralateral testes. In group 5 systemic growth hormone was administered for 7 days. Five weeks later each rat was cohabited with 2 female rats and the left testes were removed for evaluation. Mean seminiferous tubular diameter, mean testicular biopsy score and the mean haploid cell percentage were calculated. Mating studies were performed and fertility parameters were assayed.

RESULTS

Mean seminiferous tubular diameter, mean testicular biopsy score and the mean haploid cell percentage of the contralateral testes were significantly decreased in the control and gelatin groups compared with the other groups. There was no difference between the local and systemic growth hormone groups regarding the haploid cell percentage. There were no differences between the groups in mean fetus numbers, mating or fertility and fecundity indexes except in the gelatin group, in which the mean fetus number was significantly lower.

CONCLUSIONS

Fertility is not affected in rats after 24 hours of testicular torsion and orchiectomy, although there is germ cell injury and a decrease in the percent of haploid cells. Growth hormone administration resulted in the restoration of germ cell histology and an increase in the haploid cell percentage of the contralateral testes. Growth hormone may improve fertility after unilateral testicular torsion and orchiectomy.

Odyssey of the spermatozoon

This Opinion piece is offered as a cursory overview of sperm development, function, and transport through the eyes of an equine veterinarian. My professional background is predominantly clinical in nature, but my fascination with sperm function and preservation has led to a fairly sizeable review of the scientific literature over the years in hopes of extracting laboratory findings that have application to my daily activities in the clinical arena. Spermatozoa are quite unique among cellular types with regard to both form and function, and represent the only endogenously derived cell type that exerts its action in a separate being. This paper takes the reader on a voyage with a mammalian spermatozoon, from its formative stages through its transport in the male and female reproductive tracts, and culminating with its interaction with an ovulated oocyte at the time of fertilization. Specific emphasis is placed on equine spermatozoa when notable research findings have been unveiled.

Adult stem cell transplantation: is gender a factor in stemness?

Cell therapy now constitutes an important area of regenerative medicine. The aging of the population has mandated the discovery and development of new and innovative therapeutic modalities to combat devastating disorders such as stroke. Menstrual blood and Sertoli cells represent two sources of viable transplantable cells that are gender-specific, both of which appear to have potential as donor cells for transplantation in stroke. During the subacute phase of stroke, the use of autologous cells offers effective and practical clinical application and is suggestive of the many benefits of using the aforementioned gender-specific cells. For example, in addition to being exceptionally immunosuppressive, testis-derived Sertoli cells secrete many growth and trophic factors and have been shown to aid in the functional recovery of animals transplanted with fetal dopaminergic cells. Correspondingly, menstrual blood cells are easily obtainable and exhibit angiogenic characteristics, proliferative capability, and pluripotency. Of further interest is the ability of menstrual blood cells, following transplantation in stroke models, to migrate to the infarct site, secrete neurotrophic factors, regulate the inflammatory response, and be steered towards neural differentiation. From cell isolation to transplantation, we emphasize in this review paper the practicality and relevance of the experimental and clinical use of gender-specific stem cells, such as Sertoli cells and menstrual blood cells, in the treatment of stroke.

Tuberoinfundibular Peptide of 39 residues is required for germ cell development

Tuberoinfundibular peptide of 39 residues (TIP39) was identified as a PTH 2 receptor ligand. We report that mice with deletion of Tifp39, the gene encoding TIP39, are sterile. Testes contained Leydig and Sertoli cells and spermatogonia but no spermatids. Labeling chromosome spreads with antibodies to proteins involved in recombination showed that spermatogonia do not complete prophase of meiosis I. Chromosomes were observed at different stages of recombination in single nuclei, a defect not previously described with mutations in genes known to be specifically involved in DNA replication and recombination. TIP39 was previously shown to be expressed in neurons projecting to the hypothalamus and within the testes. LH and FSH were slightly elevated in Tifp39(-/-) mice, suggesting intact hypothalamic function. We found using in situ hybridization that the genes encoding TIP39 and the PTH 2 receptor are expressed in a stage-specific manner within seminiferous tubules. Using immunohistochemistry and quantitative RT-PCR, TIP39 expression is greatest in mature testes, and appears most abundant in postmeiotic spermatids, but TIP39 protein and mRNA can be detected before any cells have completed meiosis. We used mice that express Cre recombinase under control of a spermatid-specific promoter to express selectively a cDNA encoding TIP39 in the testes of Tifp39(-/-) mice. Spermatid production and fertility were rescued, demonstrating that the defect in Tifp39(-/-) mice was due to the loss of TIP39. These results show that TIP39 is essential for germ cell development and suggest that it may act as an autocrine or paracrine agent within the gonads.

Role of Sertoli cell number and function on regulation of spermatogenesis

Testicular function is under the control of expression and repression of several genes and gene products, and many of these works through Sertoli cells. The capability of Sertoli cells to regulate spermatogenesis is dependent on Sertoli cell functions and Sertoli cell number. Sertoli cell number has long been thought to be stable in adults with no proliferation of Sertoli cells once adult numbers have been reached. However, adult horses do not have stable Sertoli cell numbers, and new studies indicate that adult Sertoli cells can be made to re-enter mitotic phase under certain experimental conditions. This review discusses roles of Sertoli cells in regulation of spermatogenesis and methods for estimating the number of Sertoli cells, in a testis, that overcome the problems (assumptions) associated with the indented, pear-shaped of Sertoli cell nuclei which make it difficult to estimate the volume of individual nuclei. Using several approaches to overcome the problems associated with any one method, the horse is identified as a species in which Sertoli cell number is not fixed, but it fluctuates with season. In addition to Sertoli cell numbers, the functions of Sertoli cells that are very important in signaling and controlling spermatogenesis are discussed. Recent studies have shown that "post-mitotic terminally differentiated Sertoli cells" from adult animals could, under certain conditions, re-enter the cell division cycle. Can seasonal influences be a natural set of conditions to induce the Sertoli cells of the horse testis to seasonally re-enter the cell division cycle and explain the seasonal differences in Sertoli cell number as summarized in this review? Alternatively, can seasonal differences in Sertoli cell number reflect, in the horse to a greater extent, but in adults of most species, the presence of some mitotic-capable Sertoli cells in adults? In any case, both Sertoli cell number and function are important in regulation of spermatogenesis.

Localization of the epidermal growth factor (EGF) and epidermal growth factor receptor (EGFR) in the bovine testis

In the last few decades, several growth factors were identified in the testis of various mammalian species. Growth factors are shown to promote cell proliferation, regulate tissue differentiation, and modulate organogenesis. In the present investigation we have studied the localization of EGF and EGFR in the adult bovine testis by means of immunohistochemical method. Our results demonstrated that EGF and EGFR were localized solely to the bovine testicular germ cells (spermatogonia, spermatocytes, and round spermatids). In contrast, the somatic testicular cells (i.e., Sertoli, Leydig, and myofibroblast cells) exhibited no staining affinity. EGF and EGFR were additionally detected in the epithelial lining of straight tubules and rete testis. Interestingly, the distribution of EGF and EGFR in the germ cells was mainly dependent upon the cycle of the seminiferous epithelium since their localization appeared to be preponderant during the spermatogonia proliferation and during the meiotic and spermiogenic processes. In conclusion, such findings may suggest that EGF and EGFR are important paracrine and/or autocrine regulators of spermatogenesis in bovine.

Effects of growth factors on testicular morphogenesis

Since the discovery of the sex-determining gene Sry in 1990, research effort has focused on the events downstream of its expression. A range of different experimental approaches including gene expression, knocking-out and knocking-in genes of interest, and cell and tissue culture techniques have been applied, highlighting the importance of growth factors at all stages of testicular morphogenesis. Migration of primordial germ cells and the mesonephric precursors of peritubular myoid cells and endothelial cells to the gonad is under growth factor control. Proliferation of both germ cells and somatic cells within the gonadal primordium is also controlled by cytokines as is the interaction of Sertoli cells (with each other and with the extracellular matrix) to form testicular cords. Several growth factors/growth factor families (e.g., platelet-derived growth factor, fibroblast growth factor family, TGFbeta family, and neurotrophins) have emerged as key players, exerting an influence at different time points and steps in organogenesis. Although most evidence has emerged in the mouse, comparative studies are important in elucidating the variety, potential, and evolution of control mechanisms.

Localization of Fibroblast Growth Factor I (Acid Fibroblast Growth Factor) and Its mRNA in the Bovine Mammary Gland During Mammogenesis, Lactation and Involution

Growth factors are involved in development and function of the mammary gland. The aim of this study was the localization of fibroblast growth factor 1 (FGF-1) and its mRNA in the bovine mammary gland during different developmental and functional stages. Mammary tissue was obtained from German Brown Swiss cows (n = 23) during defined stages of mammogenesis (before and during pregnancy), lactogenesis, peak lactation and involution. The distribution of FGF-1 mRNA was studied using non-radioactive in situ hybridization, the corresponding FGF-protein was analysed using immunohistochemistry [avidin-biotin peroxidase complex (ABC)-method]. A moderate to distinct staining for FGF-mRNA was found in the epithelium of ducts and developing alveoli during mammogenesis. Post-partum at the same cellular locations, a considerable amount of FGF-1 mRNA, was seen that decreased during lactation. Also during early involution clear staining for FGF-mRNA could still be observed. Immunoreactive FGF-1 was found in considerable concentration in the epithelium of the mammary gland in heifers. The staining intensity generally decreased somewhat during mammogenesis and lactation, but could be always clearly demonstrated in the secretory epithelial cells of alveoli and glandular ducts. Also during the first day after the end of milking, the epithelium displayed a moderate to distinct epithelial immunostaining. Notably, After 4 weeks of involution, in many alveoli a shedding of the FGF-1 positive luminal cell layer was found. In our localization studies, no strict correlation between FGF-1 mRNA and its corresponding protein was found. The various reasons for this finding are discussed.