Contemporary concepts in the evaluation and management of male infertility

Infertility in men is a common condition. At the core of the medical evaluation of the male partner in a couple who are unable to conceive is the history and physical examination. Special attention should be directed to the patient's developmental history and any use of testosterone products. The physical examination focuses on the genitals, and includes assessments of the size and consistency of the testicles, epididymis, vas deferens, and presence of varicoceles. Although many sophisticated tests are available, semen analysis is still the most important diagnostic tool used to assess fertility, and includes parameters such as sperm count, motility and viability. Treatment of male factor infertility can involve targeted agents, in the case of specific conditions such as hypogonadotropic hypogonadism, or it can be empirical-using medical therapy or assisted conception techniques-for patients in whom no underlying cause has been identified. Although an all-encompassing treatment for male factor infertility has not yet been developed, the field offers many promising avenues of research.     

Mitochondria-related male infertility

Approximately 15% of human couples are affected by infertility, and about half of these cases of infertility can be attributed to men, through low sperm motility (asthenozoospermia) or/and numbers (oligospermia). Because mitochondrial genome (mtDNA) mutations are identified in patients with fertility problems, there is a possibility that mitochondrial respiration defects contribute to male infertility. To address this possibility, we used a transmitochondrial mouse model (mito-mice) carrying wild-type mtDNA and mutant mtDNA with a pathogenic 4,696-bp deletion (DeltamtDNA). Here we show that mitochondrial respiration defects caused by the accumulation of DeltamtDNA induced oligospermia and asthenozoospermia in the mito-mice. Most sperm from the infertile mito-mice had abnormalities in the middle piece and nucleus. Testes of the infertile mito-mice showed meiotic arrest at the zygotene stage as well as enhanced apoptosis. Thus, our in vivo study using mito-mice directly demonstrates that normal mitochondrial respiration is required for mammalian spermatogenesis, and its defects resulting from accumulated mutant mtDNAs cause male infertility.     

Management of male infertility by assisted reproductive technologies.

Among the most popular techniques of assisted reproduction for the treatment of male subfertility and infertility are intrauterine insemination, in vitro fertilization and intracytoplasmic sperm injection. The objective of these techniques is to bring more functional spermatozoa closer to the oocyte in order to promote fertilization. These techniques are thus not a cure per se and are only indicated when no specific or effective treatment is available for the male partner, when this treatment has failed or when the improvement of the female fertility status has also failed. While for moderate oligoasthenozoospermia, intrauterine insemination has proved to be a valid treatment, the outcome after conventional in vitro fertilization is limited because of a high incidence of complete fertilization failure. Since the introduction of intracytoplasmic sperm injection, a reliable method has become available in order to achieve fertilization in vitro. Apart from well from ejaculated spermatozoa, epididymal or testicular spermatozoa too can be used successfully for intracytoplasmic sperm injection. The surgical retrieval of spermatozoa for intracytoplasmic sperm injection has therefore become a routine technique in clinical andrology. Although these techniques have been implemented in everyday infertility practice within a few years of their introduction, many concerns about safety continue to exist. Intracytoplasmic sperm injection must be applied with caution, only when no other treatment option is available and when an appropriate prospective follow-up of the offspring is available.     

Cystic fibrosis transmembrane conductance regulator is vital to sperm fertilizing capacity and male fertility

Cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel, mutations of which cause cystic fibrosis, a disease characterized by defective Cl(-) and HCO(3)(-) transport. Although >95% of all CF male patients are infertile because of congenital bilateral absence of the vas deferens (CBAVD), the question whether CFTR mutations are involved in other forms of male infertility is under intense debates. Here we report that CFTR is detected in both human and mouse sperm. CFTR inhibitor or antibody significantly reduces the sperm capacitation, and the associated HCO(3)(-)-dependent events, including increases in intracellular pH, cAMP production and membrane hyperpolarization. The fertilizing capacity of the sperm obtained from heterozygous CFTR mutant mice is also significantly lower compared with that of the wild-type. These results suggest that CFTR in sperm may be involved in the transport of HCO(3)(-) important for sperm capacitation and that CFTR mutations with impaired CFTR function may lead to reduced sperm fertilizing capacity and male infertility other than CBAVD.     

Androgens and spermatogenesis

Male infertility contributes to 50% of all cases of infertility. The main cause is low quality and quantity of sperm. In humans, spermatogenesis starts at the beginning of puberty and lasts lifelong. It is under the control of FSH and testicular androgens, and mainly testosterone (T), and therefore requires a normal gonadotroph axis, intratesticular T production by Leydig cells and functional androgen receptors (ARs) within testicular Sertoli cells. Various clinical cases illustrate the roles of T in human spermatogenesis. Men with complete congenital hypogonadotropic hypogonadism (HH) are usually azoospermic. Treatment by exogenous testosterone injection and FSH is not able to produce sperm. However, combined treatment with FSH and hCG is effective. This example shows that intratesticular T plays a major role in spermatogenesis. Furthermore, testicular histology of men with LH receptor mutations shows Leydig cell hypoplasia/agenesis/dysplasia with conserved Sertoli cell count. The sperm count is reduced, as in males with partial inactivating mutation of the androgen receptor. Some protocols of hormonal male contraception or exogenous androgen abuse induce negative feedback in the hypothalamic pituitary axis, decreasing FSH, LH and T levels and inducing sperm defects and testicular atrophy. The time to recovery after cessation of drug abuse is around 14 months for sperm output and 38 months for sperm motility. In summary, abnormal androgen production and/or AR signaling impairs spermatogenesis in humans. The minimal level of intratesticular T for normal sperm production is a matter of debate. Interestingly, some animal models showed that completely T-independent spermatogenesis is possible, potentially through strong FSH activation. Finally, recent data suggest important roles of prenatal life and minipuberty in adult spermatogenesis.     

Drug insight: Recent advances in male hormonal contraception

As there are limitations to current methods of male contraception, research has been undertaken to develop hormonal contraceptives for men, analogous to the methods for women based on estrogen and progestogens. When testosterone is administered to a man, it functions as a contraceptive by suppressing the secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from the pituitary gland. Since these hormones are the main stimulatory signals for spermatogenesis, low levels of LH and FSH markedly impair sperm production. After 3-4 months of testosterone treatment, 60-70% of men no longer have sperm in their ejaculate, and most other men exhibit markedly diminished sperm counts. Male hormonal contraception is well tolerated, free of serious adverse side effects, and 95% effective in the prevention of pregnancy. Importantly, male hormonal contraception is reversible, with sperm counts usually recovering within 4 months of the discontinuation of hormone treatment. Because exogenous testosterone administration alone does not completely suppress sperm production in all men, researchers have combined testosterone with second agents, such as progestogens or gonadotropin-releasing-hormone antagonists, to further suppress secretion of LH and FSH and improve suppression of spermatogenesis. Recent trials have used combinations of long-acting injectable or implantable forms of testosterone with progestogens, which can be administered orally, by injection or by a long-acting implant. Such combinations suppress spermatogenesis to zero without severe side effects in 80-90% of men, with near-complete suppression in the remainder of individuals. One of these testosterone and progestogen combination regimens might soon bring the promise of male hormonal contraception to fruition.     

Male infertility: pathogenesis and clinical diagnosis

Infertility affects about 7% of all men. The etiology of impaired sperm production and function can be related to factors acting at pre-testicular, post-testicular or directly at the testicular level. Primary testicular failure accounts for about 75% of all male factor infertility. Genetic factors can be identified in about 15% of cases (congenital hypogonadotrophic hypogonadism, congenital absence of vas deferens, primitive testicular failure). Despite progresses, mainly in the field of genetics, the etiology is still unknown in about 50% cases and it is termed "idiopathic infertility". A part from few exceptions, the only available therapy for male factor infertility is assisted reproduction which allows conception also in severe male factor, including azoospermia following testicular sperm extraction. The complete diagnostic workup is important for: i) the identification of treatable/reversible or health-threatening conditions; ii) selection of patients for assisted reproductive techniques; iii) for appropriate genetic counselling including preventive measures (preimplanatation or prenatal diagnosis) to safeguard the health of future offspring.     

Evaluation of the infertile couple

The evaluation of the infertile couple is usually a lengthy investigation in which all possible etiologic factors in both partners have to be considered. Optimal and cost-effective investigation requires adequate recognition of significant historical data and physical findings. Males without stigmata of endocrinopathies or general medical illnesses require an analysis of their semen as the minimum initial step of evaluation. Those suspected of deficient androgen production and/or action and those with abnormal sperm counts, motility, and/or morphology need assessment of their serum concentrations of selected reproductive hormones. When these initial investigations are negative and there are no demonstrable etiologic female factors underlying the state of infertility, specialized sperm function and sperm allergy testing needs to be performed. The initial investigation of the female partner is best served by assessing the frequency of ovulation and adequacy of corpus luteum function. Women without ovulatory defects should be assessed for the presence of the hostile cervical mucus and structural anomalies of the reproductive tract. Investigations of patients with menstrual dysfunctions should be based upon the presence or absence of hirsutism, changes in body weight, and evidence of other endocrinopathies or medical illnesses. Following the identification and normalization of causes of anovulation, further work-up of patients who remain infertile is similar to those with regular menstrual cycles. The diagnosis of idiopathic infertility is essentially by exclusion of all other causes. Algorithms for the diagnostic evaluation of most infertile couples are provided.     

Varicocele: surgical techniques in 2005

Varicocele is the most common diagnosis in men presenting to fertility clinics. Traditional indications for correction of varicocele include scrotal pain, testicular atrophy, and infertility without other apparent causes. Adolescent varicocele correction is indicated if pain or testicular growth retardation is present. Following varicocelectomy most studies report improved semen parameters, increased serum testosterone, improvement in functional sperm defects, and the return of motile sperm in selected azoospermic men. However, conflicting data exists on pregnancy and fertility outcomes. Consistent data supporting the effectiveness of repairing subclinical varicoceles is sparse. Most authors generally agree that the primary effect of varicoceles is on testicular temperature. Varicoceles are diagnosed primarily by physical examination. Radiographic assessments are helpful when physical examination is inconclusive or when further objective documentation of a patient's condition is necessary. Several surgical approaches to varicocelectomy exist, each with its own advantages and drawbacks. We prefer the inguinal approach to varicocelectomy, except when there is a history of previous inguinal surgery. In such cases, the subinguinal technique is employed. Routine use of an operating microscope and a micro Doppler probe affords easier identification of vessels and lymphatics. Varicocele remains the most surgically treatable form of male infertility. Knowing the correct techniques of diagnosis and surgical correction ensures the best chance of successful outcomes in terms of post-operative morbidity, improved semen parameters, and pregnancy rates.     

Recent advances in assisted reproductive technologies

Assisted reproductive technologies (ART) have received considerable attention, both clinically and empirically. Drs. Steptoe and Edwards removed one oocyte surgically from a woman with infertility related to tubal disease. They fertilized this oocyte in vitro and transferred the formed embryo to the woman’s uterus and achieved pregnancy and delivery. The technique of in vitro fertilization (IVF) and embryo transfer (ET) quickly became widely utilized for other causes of infertility as well as for tubal disease. In the last 5 years there has been a number of new developments that are reviewed in this article. The most important and now widely practiced technology has been direct intracytoplasmic injection (ICSI) of the husband’s sperm into the wife’s oocyte. This was developed for treatment of infertility related to low sperm count. Subsequently it was shown that sperm can be aspirated from epididymis or found in testicular biopsy in obstructive azoospermia. Another promising development is in vitro maturation (IVM) of immature oocytes. This has the potential of avoiding ovarian hyperstimulation, which can be uncomfortable and occasionally dangerous. Some oocytes are unable to fertilize and/or develop into normal embryos. It may be possible that the problem is with the machinery of cytoplasm of the oocyte. Therefore cytoplasmic transfer from a normal oocyte to an abnormal oocyte may overcome the problem. Infertile couples may be faced with many psychological problems that become even more complex with various treatments. Whereas donation of oocytes or embryos can be technically quite simple, there are many psychological issues involved. As can be gathered from aforementioned discussions, the treatments developed for infertility appear to be somewhat illogical and in the style of “shot gun therapy.” In the field of infertility, as in other areas of medicine, it is of paramount importance to know the details of disease mechanisms. This in turn will allow specific and logical treatments to be developed.     

Update on cryptorchidism: endocrine,environmental and therapeutic aspects

Cryptorchidism is the most frequent developmental abnormality in boys, present in more than 1% of infants above three months of age. It is associated with an increased risk of infertility and testicular cancer. The etiological quest is often disappointing, except in bilateral cases or associated malformations. Recent focus is on genetic and environmental aspects. Animal models have revealed the role of genes encoding for proteins implicated in testicular migration (InsI3, Hoxa 10), but in humans results are less convincing. While some degree of endogenous hormonal abnormality is suspeeted in some patients, the endocrine disruptor hypothesis is also tested. It is unclear whether the incidence of cryptorchidism has really increased, or whether there is only a better screening for this condition. However, other male reproductive problems, such as subfertility, hypospadias and testicular cancer seem on the rise. This secular trend suggests the possible in utero impact of hormonally active environmental factors, such as pesticides with estrogenic or antiandrogenic effect, and is consistent with the increased risk of cryptorchidism observed in the sons of mothers exposed to diethylstilbestrol during pregnancy. From a therapeutic point of view, there is an agreement that the correction of cryptorchidism is needed, but there is controversy on the best medical and/or surgical approach and on the optimal timing. There is a recent trend in proposing early therapeutic intervention, before 1 yr of age, in the hope of improving fertility; however, there is no proof that such a strategy can reduce the risk of testicular cancer.     

Oxidative stress, sperm survival and fertility control

The human spermatozoon is highly susceptible to oxidative stress. This process induces peroxidative damage in the sperm plasma membrane and DNA fragmentation in both the nuclear and mitochondrial genomes. Such stress may arise from a variety of sources including a lack of antioxidant protection, the presence of redox cycling xenobiotics, infiltrating leukocytes and excess reactive oxygen species production by the spermatozoa. Whenever the levels of oxidative stress in the male germ line are high, the peroxidation of unsaturated fatty acids in the sperm plasma membrane ensures that normal fertilization cannot occur. However, at lower levels of oxidative stress, spermatozoa may retain their capacity for fertilization while carrying significant levels of oxidative damage in their DNA. Epidemiological evidence suggests that subsequent aberrant repair of such damage in the zygote may result in the creation of mutations associated with pre-term pregnancy loss and a variety of pathologies in the offspring, including childhood cancer. Thus, while the induction of oxidative stress in spermatozoa is causally involved in the aetiology of male infertility, the prospects of using such a strategy for male contraception is fraught with potential problems, should the suppression of fertility be incomplete and DNA-damaged spermatozoa gain access to the oocyte.     

Animal models of male infertility: mice bearing single-gene mutations that induce infertility

Genetically defined mouse models of male infertility are described in the present report. The mice were rendered infertile by one of the following gene mutations: Ames dwarf, dwarf, flipper-arm, hightail, hypothyroid, little, pygmy, stubby. The effects of each gene mutation on testicular steroidogenesis and spermatogenesis were elucidated by a comparison of the mutant mice to their normal siblings. Testicular steroidogenesis was assessed directly by determining steroid secretion by testes perfused in vitro. The study provides the first comprehensive assessment of testicular function in the mutant mice. The eight gene mutations can be classified into two groups based on the results. One group of gene mutations (Ames dwarf, dwarf, flipper-arm, pygmy) specifically depress spermatogenesis and testicular steroidogenesis. The infertility of these mutant mice can be linked to the lowered total sperm production. The second group of gene mutations (hightail, hypothyroid, little, stubby) do not specifically depress either spermatogenesis or testosterone secretion. Subsequently, the etiology of the male infertility of the second group of mutant mice is unknown. We propose that these mutant mice provide valuable experimental tools for the study of male infertility and male reproduction.     

Diagnosis and management of renovascular disease and renovascular hypertension

Renovascular disease is a common but complex disorder, the most common causes of which are fibromuscular dysplasia and atherosclerosis. Clinically, it can present as asymptomatic renal artery stenosis, renovascular hypertension, or ischemic nephropathy. Assessing the clinical index of suspicion remains essential in determining an appropriate diagnostic strategy. For diagnosis in patients with suspected fibromuscular disease, it may be reasonable to proceed directly to renal angiography; however, for most patients with suspected atherosclerotic disease, there are a number of noninvasive tests available that can aid in decision making. The choice of the most appropriate initial test should be based on patient characteristics, clinical presentation, and local expertise. Treatment options include medical, surgical, or percutaneous approaches. Generally, in patients with fibromuscular disease, percutaneous intervention provides durable improvement or cure of hypertension. In patients with atherosclerotic disease, the data are less consistent, and there does appear to be a group of patients who will respond well to medical management alone. As technology advances, the diagnostic and treatment paradigms will continue to evolve.     

Fertility preservation options in transgender people: A review

Gender affirming procedures adversely affect the reproductive potential of transgender people. Thus, fertility preservation options should be discussed with all transpeople before medical and surgical transition. In transwomen, semen cryopreservation is typically straightforward and widely available at fertility centers. The optimal number of vials frozen depends on their reproductive goals and treatment options, therefore a consultation with a fertility specialist is optimal. Experimental techniques including spermatogonium stem cells (SSC) and testicular tissue preservation are technologies currently under development in prepubertal individuals but are not yet clinically available. In transmen, embryo and/or oocyte cryopreservation is currently the best option for fertility preservation. Embryo cryopreservation requires fertilization of the transman’s oocytes with a donor or partner’s sperm prior to cryopreservation, but this limits his future options for fertilizing the eggs with another partner or donor. Oocyte cryopreservation offers transmen the opportunity to preserve their fertility without committing to a male partner or sperm donor at the time of cryopreservation. Both techniques however require at least a two-week treatment course, egg retrieval under sedation and considerable cost. Ovarian tissue cryopreservation is a promising experimental method that may be performed at the same time as gender affirming surgery but is offered in only a limited amount of centers worldwide. In select places, this method may be considered for prepubertal children, adolescents, and adults when ovarian stimulation is not possible. Novel methods such as in-vitro activation of primordial follicles, in vitro maturation of immature oocytes and artificial gametes are under development and may hold promise for the future.     

Lack of Spem1 causes aberrant cytoplasm removal, sperm deformation, and male infertility

We identified a previously uncharacterized gene, spermatid maturation 1 (Spem1), encoding a protein exclusively expressed in the cytoplasm of steps 14-16 elongated spermatids in the mouse testis. This protein contains no known functional domains and is highly conserved across mammalian species. Male mice deficient in Spem1 were completely infertile because of deformed sperm characterized by a bent head wrapped around by the neck and the middle piece of the tail. We show that lack of Spem1 causes failure of the cytoplasm to become loose and detach from the head and the neck region of the developing spermatozoa. Retained cytoplasmic components mechanically obstruct the straightening of the sperm head and the stretching of the growing tail, leading to the bending of the head in the neck, followed by the wrapping of the head by the neck or the middle piece of the sperm tail. Our study reveals that proper cytoplasm removal is a genetically regulated process requiring the participation of Spem1 and that lack of Spem1 causes sperm deformation and male infertility.     

Uptake and outcome of assisted reproductive techniques in long-term survivors of SCT

We have audited the invitation for uptake and outcome of artificial reproductive techniques in patients undergoing SCT for haematological malignancy, with the aim of improving our pre-transplant counselling. A postal survey was sent to 434 patients in our centre surviving a minimum of 2 years after allo-SCT, of whom 221 patients responded. Of 112 male patients, 79 were offered sperm storage, 42 banked sperm and 25 subsequently attempted parenthood with stored sperm. A total of 18 were successful, with 29 children born a median of 8 years (range 1-22 years) following SCT. Of 72 females <42 years old, 33 were offered storage of embryos/eggs/ovarian tissue and 12 accepted. Following SCT, four women attempted pregnancy using cryopreserved embryos, with two successes. The majority of patients who were not counselled about infertility or not offered fertility-preservation options provided a likely reason, with completion of family being the most frequent. Nonetheless, 16 patients (11/72 women and 5/112 men) could not provide a reason for the lack of information/invitation. In conclusion, uptake of gamete/embryo storage is high when offered and collected material is used frequently. Pregnancies in partners of male patients were usually successful and our data highlight the value of prolonged cryostorage.