BACKGROUNDTesticular sperm extraction (TESE) is a surgical procedure to retrieve spermatozoa from the testes of men with azoospermia to help them achieve biological parenthood. Although effective, the surgical procedure is not without complications and haematoma, devascularization, inflammation and a decrease in testosterone levels have been described as such. The prevalence and duration of hypogonadism and associated symptoms after TESE have not been studied systematically.OBJECTIVE AND RATIONALEIn this systematic review we addressed the following research questions: Are serum testosterone levels decreased after TESE and, if so, do these levels recover over time? What is the prevalence of symptoms and signs related to hypogonadism after TESE and are they related to testosterone levels?SEARCH METHODSWe searched the databases Pubmed and Embase from 1 January 1993 to 26 June 2017. We combined subject headings with terms in title and/or abstract for participants, intervention and outcomes. We included all studies that reported on TESE, regardless of the specific technique used, that measured testosterone and/or LH, and/or had information on signs or symptoms related to hypogonadism as defined by hypogonadism guidelines. An additional inclusion criterion was that studies described these measurements both before and after TESE. The quality of the included studies was assessed using the Risk Of Bias In Non-randomized Studies—of Interventions tool.OUTCOMESWe identified 15 studies reporting on total testosterone levels of which five studies also reported on testicular volume and one study on erectile dysfunction. Men with Klinefelter syndrome and men with non-obstructive azoospermia had the strongest decrease in total testosterone levels 6 months after TESE, with a mean decrease of 4.1 and 2.7 nmol/l, respectively, which recovered again to baseline levels 26 and 18 months after TESE, respectively. At 6 months after TESE, some studies reported serum total testosterone concentrations below a cut-off value of 12 nmol/l, where symptoms and signs related to hypogonadism may appear. Furthermore, an increased prevalence of erectile dysfunction related to decreased total testosterone levels 6 months after TESE was reported. Also, in some men a decrease in testicular volume was reported. However, it is not clear if this is related to low testosterone levels.WIDER IMPLICATIONSThe transient, but statistically significant, decrease in total testosterone levels indicates that men are at risk of developing a temporary hypogonadism after TESE, but there is insufficient evidence for whether patients actually experience clinical symptoms in case of decreased serum testosterone levels. To be able to properly counsel TESE patients, more large-scale monitoring on signs and symptoms of hypogonadism, in combination with testosterone measurements, needs to be performed in men undergoing TESE.

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Human and animal studies increasingly point toward a neural pathogenesis of the metabolic syndrome, involving hypothalamic and autonomic nervous system dysfunction. We hypothesized that increased very-low-density lipoprotein-triglyceride (VLDL-TG) secretion by the liver in a rat model for dyslipidemia, that is, the obese Zucker (fa/fa) rat, is due to relative hyperactivity of sympathetic, and/or hypoactivity of parasympathetic hepatic innervation. To test the involvement of the autonomic nervous system, we surgically denervated the sympathetic or parasympathetic hepatic nerve in obese Zucker rats. Our results show that cutting the sympathetic hepatic nerve lowers VLDL-TG secretion in obese rats, finally resulting in lower plasma TG concentrations after 6 weeks. In contrast, a parasympathetic denervation results in increased plasma total cholesterol concentrations. The effect of a sympathetic or parasympathetic denervation of the liver was independent of changes in humoral factors or changes in body weight or food intake. In conclusion, a sympathetic denervation improves the lipid profile in obese Zucker rats, whereas a parasympathetic denervation increases total cholesterol levels. We believe this is a novel treatment target, which should be further investigated.

STUDY QUESTION Is it possible to differentiate primary human testicular platelet-derived growth factor receptor alpha positive (PDGFRα+) cells into functional Leydig cells? SUMMARY ANSWER Although human testicular PDGFRα+ cells are multipotent and are capable of differentiating into steroidogenic cells with Leydig cell characteristics, they are not able to produce testosterone after differentiation. WHAT IS KNOWN ALREADY In rodents, stem Leydig cells (SLCs) that have been identified and isolated using the marker PDGFRα can give rise to adult testosterone-producing Leydig cells after appropriate differentiation in vitro. Although PDGFRα+ cells have also been identified in human testicular tissue, so far there is no evidence that these cells are true human SLCs that can differentiate into functional Leydig cells in vitro or in vivo. STUDY DESIGN, SIZE, DURATION We isolated testicular cells enriched for interstitial cells from frozen–thawed fragments of testicular tissue from four human donors. Depending on the obtained cell number, PDGFRα+-sorted cells of three to four donors were exposed to differentiation conditions in vitro to stimulate development into adipocytes, osteocytes, chondrocytes or into Leydig cells. We compared their cell characteristics with cells directly after sorting and cells in propagation conditions. To investigate their differentiation potential in vivo, PDGFRα+-sorted cells were transplanted in the testis of 12 luteinizing hormone receptor-knockout (LuRKO) mice of which 6 mice received immunosuppression treatment. An additional six mice did not receive cell transplantation and were used as a control. PARTICIPANTS/MATERIALS, SETTING, METHODS Human testicular interstitial cells were cultured to Passage 3 and FACS sorted for HLA-A,B,C+/CD34−/PDGFRα+. We examined their mesenchymal stromal cell (MSC) membrane protein expression by FACS analyses. Furthermore, we investigated lineage-specific staining and gene expression after MSC trilineage differentiation. For the differentiation into Leydig cells, PDGFRα+-sorted cells were cultured in either proliferation or differentiation medium for 28 days, after which they were stimulated either with or without hCG, forskolin or dbcAMP for 24 h to examine the increase in gene expression of steroidogenic enzymes using qPCR. In addition, testosterone, androstenedione and progesterone levels were measured in the culture medium. We also transplanted human PDGFRα+-sorted testicular interstitial cells into the testis of LuRKO mice. Serum was collected at several time points after transplantation, and testosterone was measured. Twenty weeks after transplantation testes were collected for histological examination. MAIN RESULTS AND THE ROLE OF CHANCE From primary cultured human testicular interstitial cells at Passage 3, we could obtain a population of HLA-A,B,C+/CD34−/PDGFRα+ cells by FACS. The sorted cells showed characteristics of MSC and were able to differentiate into adipocytes, chondrocytes and osteocytes. Upon directed differentiation into Leydig cells in vitro, we observed a significant increase in the expression of HSD3B2 and INSL3. After 24 h stimulation with forskolin or dbcAMP, a significantly increased expression of STAR and CYP11A1 was observed. The cells already expressed HSD17B3 and CYP17A1 before differentiation but the expression of these genes were not significantly increased after differentiation and stimulation. Testosterone levels could not be detected in the medium in any of the stimulation conditions, but after stimulation with forskolin or dbcAMP, androstenedione and progesterone were detected in culture medium. After transplantation of the human cells into the testes of LuRKO mice, no significant increase in serum testosterone levels was found compared to the controls. Also, no human cells were identified in the interstitium of mice testes 20 weeks after transplantation. LARGE SCALE DATA N/A LIMITATIONS, REASONS FOR CAUTION This study was performed using tissue from only four donors because of limitations in donor material. Because of the need of sufficient cell numbers, we first propagated cells to passage 3 before FACS of the desired cell population was performed. We cannot rule out this propagation of the cells resulted in loss of stem cell properties. WIDER IMPLICATIONS OF THE FINDINGS A lot of information on Leydig cell development is obtained from rodent studies, while the knowledge on human Leydig cell development is very limited. Our study shows that human testicular interstitial PDGFRα+ cells have different characteristics compared to rodent testicular PDGFRα+ cells in gene expression levels of steroidogenic enzymes and potential to differentiate in adult Leydig cells under comparable culture conditions. This emphasizes the need for confirming results from rodent studies in the human situation to be able to translate this knowledge to the human conditions, to eventually contribute to improvements of testosterone replacement therapies or establishing alternative cell therapies in the future, potentially based on SLCs. STUDY FUNDING/COMPETING INTEREST(S) This study was funded by Amsterdam UMC, location AMC, Amsterdam, the Netherlands. All authors declare no competing interests.

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.

Infertility problems occur in around 10% of all couples worldwide, with male-factor infertility as the sole contributor in 20–30% of these cases. Oxidative stress (OS) is suggested to be associated with the pathophysiology of male infertility. In spermatozoa, OS can lead to damage to the cell membrane, resulting in disruption of DNA integrity and a decrease in motility. Established biomarkers for OS include free thiols and malondialdehyde (MDA), both representing different components of the reactive species interactome (RSI). This exploratory study aimed to investigate seminal plasma-free thiol and MDA levels in relation to semen parameters as defined by the World Health Organization (WHO) to determine if these markers are adequate to define local OS status. Furthermore, this study investigated if there is a relation between systemic and local OS status by comparing seminal concentrations of free thiol (R-SH, sulfhydryl groups, representing the extracellular redox status) and MDA (lipid peroxidation product) levels to those measured in serum. Free thiol and MDA measurements in both serum and semen plasma were performed in 50 males (18–55 y) of couples seeking fertility treatment. A significant positive correlation was found between seminal plasma-free thiol levels and sperm concentration and progressive motility (r = 0.383, p = 0.008 and r = 0.333, p = 0.022, respectively). In addition, a significant positive correlation was found between MDA levels in seminal plasma and sperm concentration (r = 0.314, p = 0.031). This study supports that seminal plasma-free thiols may be promising as local OS biomarkers. No associations were observed between local and systemic OS biomarker concentrations.

Background Origin of human adult Leydig cells (ALCs) is not well understood. This might be partly due to limited data available on the identification and location of human precursor and stem Leydig cells (SLCs) which hampers the study on the development of ALCs. Objectives The aim of the present study was to investigate whether described human (PDGFRα, NGFR) and rodent (NES, PDGFRα, THY1, NR2F2) SLC markers are expressed by a common cell population within human adult testicular interstitial cells in vivo and before and after in vitro propagation. Materials and methods Immunohistochemical analyses were used to identify localization of human adult testicular interstitial cells expressing described SLC markers. Next, interstitial cells were isolated and cultured. The percentage of cells expressing one or more SLC markers was determined before and after culture using flow cytometry. Results NR2F2 and PDGFRα were present in peritubular, perivascular, and Leydig cells, while THY1 was expressed in peritubular and perivascular cells. Although NES and NGFR were expressed in endothelial cells, co‐localization with PDGFRα was found for both in vitro, although for NGFR only after culture. All marker positive cells were able to undergo propagation in vitro. Discussion The partly overlap in localization and overlap in expression in human testicular cells indicate that PDGFRα, NR2F2, and THY1 are expressed within the same ALC developmental lineage from SLCs. Based on the in vitro results, this is also true for NES and after in vitro propagation for NGFR. Conclusion Our results that earlier described SLC markers are expressed in overlapping human interstitial cell population opens up further research strategies aiming for a better insight in the Leydig cell lineage and will be helpful for development of strategies to cure ALC dysfunction.

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