Male hormonal contraception: potential risks and benefits

Impaired Testicular Function without Altering Testosterone Concentration Using an Anti-Follicular-Stimulating Hormone Receptor (Anti-FSHr) Single-Chain Variable Fragment (scFv) in Long-Tailed Macaques (Macaca fascicularis)

FSHr antibodies have been shown to inhibit the differentiation of spermatogonia to primary spermatocytes, resulting in infertility without a pathological effect on reproductive organs. The aim of this study was to develop single-chain variable fragments (scFvs) against the follicular-stimulating hormone receptor (anti-FSHr) using phage-display technology and to evaluate the effects of intratesticular administration of the anti-FSHr scFv on testicular function and testosterone production. A phage clone against the extracellular domain of FSHr selected from a scFv phagemid library was analyzed for binding kinetics by surface plasmon resonance. Using ultrasound guidance, three adult macaques (M. fascicularis) were administered with 1 mL of 0.4 mg/mL anti-FSHr scFv (treatment) and 1 mL sterile phosphate buffer solution (control) into the left and right rete testis, respectively. Testicular appearance and volume, ejaculate quality, and serum testosterone levels were recorded on day 0 (before injection) and on days 7, 28, and 56 (after injection). Testicular tissue biopsies were performed on day 7 and day 56 to quantify the mRNA expressions of androgen binding protein (ABP), inhibin subunit beta B (IHBB), and vascular endothelial growth factor A (VEGFA). The results demonstrated that the anti-FSHr scFv molecule was calculated as 27 kDa with a dissociation constant (K_D) of 1.03 µM. The volume of the anti-FSHr scFv-injected testicle was reduced on days 28 and 56 compared with day 0 (p < 0.05). Total sperm number was reduced from day 0 (36.4 × 10⁶ cells) to day 56 (1.6 × 10⁶ cells) (p < 0.05). The percentage of sperm motility decreased from day 0 (81.7 ± 1.0%) to day 7 (23.3 ± 1.9%), day 28 (41.7 ± 53.4%), and day 56 (8.3 ± 1.9%) (p < 0.05). Sperm viability on day 0 was 86.8 ± 0.5%, which reduced to 64.2 ± 1.5%, 67.1 ± 2.2%, and 9.3 ± 1.1% on days 7, 28, and 56, respectively (p < 0.05). The expression of ABP and VEGFA on days 7 (14.2- and 3.2-fold) and 56 (5.6- and 5.5-fold) was less in the scFv-treated testicle compared with the controls (p < 0.05). On day 56, the expression of IHBB was less (p < 0.05) in the treated testis (1.3-fold) compared with the controls. Serum testosterone levels were unchanged throughout the study period (p > 0.05). This study characterized the anti-FSHr scFv and demonstrated that treatment with anti-FSHr ameliorates testicular function without altering testosterone levels, offering a potential alternative contraceptive for the long-tailed macaques.

Continuing the search for a hormonal male contraceptive

This chapter discusses the mechanisms of action of hormonal male contraception, which suppresses the hypothalamic-pituitary-testis axis. When the intratesticular concentration of testosterone is subsequently suppressed to adequately low concentrations, spermatogenesis is arrested. Androgens are a necessary hormonal male contraceptive component because they not only suppress the hypothalamic-pituitary-testis axis, but also provide the male hormone necessary to maintain peripheral androgen functions. Past studies using testosterone alone and testosterone combined with progestins demonstrated contraceptive efficacy in the female partner at rates similar to combined hormonal female methods. Newer hormonal male contraceptive formulations and the alternative routes of administration are discussed, along with potential barriers, challenges, and opportunities for hormonal male contraceptive development. Novel methods that are safe, effective, reversible, user-friendly, and coitus-independent are intrinsic to equitably meet the various needs and limitations of an increasingly diverse population.

Update on male hormonal contraception

Despite increases in female contraceptive options, 40-45% of pregnancies across the world are still unplanned. While several effective female contraceptive methods have been developed, contraceptive choices for men are still limited to the male condom with its high failure rates and to vasectomies, which are invasive and not reliably reversible. Several studies have demonstrated a great interest among men and women for effective, reversible, and safe male contraceptive methods. Over the years, numerous studies have been performed to develop male hormonal and nonhormonal safe and effective contraceptives. A variety of new molecules are under development as oral or transdermal hormonal contraceptives for men demonstrating few side effects. In our overpopulated world, the development and commercialization of a male contraceptive method that will allow both men and women to take an active role in family planning is mandatory and further research on this topic is required.

Are men ready to use thermal male contraception? Acceptability in two French populations: New fathers and new providers

Background

Since the 1970s, international research has actively pursued hormonal male contraception (HMC) and, to a lesser extent, thermal male contraception (TMC). Although the efficacy of TMC has been confirmed in limited populations, its acceptability has not been studied in either potential users or potential prescribers.

Methods

A cross-sectional descriptive multicentre study of potential male users of TMC (new fathers) and potential prescribers of TMC (new providers) was conducted between November 2016 and February 2017.The participants completed a 3-part survey, and their responses were evaluated to i) determine their socio-demographic profiles; ii) identify personal experiences with contraception; and iii) gauge the participants’ knowledge, interest and preference for male contraception, particularly TMC. For new providers only, the survey included a fourth part to evaluate professional experience with male contraception.

Results

The participation rate was 51% for new fathers (305 NFs) and 34% for new providers (300 NPs, including 97 men (male new providers, MNPs) and 203 women (female new providers, FNPs)). Only 3% of NFs and 15% of NPs knew about TMC (including 26% of the MNPs and 10% of the FNPs, p<0.01). After reading information on TMC, new fathers were significantly less willing to try TMC (29%) than were new providers (40%) (p<0.01). The 3 main advantages of TMC for the new fathers included the following factors: “natural” (52%), “without side effects” (38%) and “non-hormonal” (36%). The main disadvantages were “lengthy wear time” (56%), “daily undergarment wear” (43%) and “concern about possible discomfort” (39%).

Conclusions

Young male and female providers have limited knowledge of male contraception, are interested in further information and would generally prescribe TMC to their patients. Successful expansion of the use of male contraception, including TMC, would require distribution of better information to potential users and providers.

The future of male contraception: a fertile ground

The continued and rapid expansion of the Earth’s population mandates the need for safe and effective measures of contraception. While a plethora of options exist for women, methods of contraception for the male partner are limited to condoms and vasectomy. The sequela of this discrepancy has led to the family planning burden falling disproportionately on the female partner. For the past several decades, extensive research has been undertaken exploring the feasibility of hormonal male contraception. This proposed method of contraception has focused on suppressing spermatogenesis by exploiting the hypothalamic-pituitary-gonadal (HPG) axis. Beginning with proof of concept studies in the early nineties, administration of testosterone in healthy male subjects has been shown to be an efficacious method of inducing sterility. Owing to ethnic differences in spermatogenesis suppression and the comparatively low rate of azoospermia in Caucasian men with androgen-only regimens, investigators have explored the addition of progestins to further enhance the efficacy of hormonal contraception. Though studies have revealed promise with androgen-progestin regimens, the lack of long-term studies has precluded the development of a marketable product. Recently, more research has been directed towards identifying non-hormonal alternatives to male contraception. These non-hormonal options have ranged from the development of devices facilitating reversible occlusion of the vas deferens lumen to medications disrupting various pathways in the process of spermatogenesis. Underlying the development of hormonal and non-hormonal strategies is the shared enthusiasm men and women have towards these male directed methods. The willingness of couples to pursue these alternatives combined with the global need to reduce the psychological and socioeconomic implications of unintended pregnancy ensures that research will continue to bring this goal to fruition.

Male fertility and skin diseases

Male fertility can be affected by a variety of organs diseases, including the skin. Several genodermatoses affect the skin and several other organs including the male reproductive system, commonly in the form of cryptorchidism and hypogonadism. The most relevant syndromes are associated with dyschromias, such as deSanctis-Cacchione, poikiloderma congenital, LEOPARD, and H syndrome; others with ichthyosis, such as Rud, and trichothiodystrophy; or a group of unrelated genodermatoses, such as ablepharon macrostomia, Coffin-Siris, Gorlin-Goltz, and Werner. Acquired skin diseases may also affect male fertility usually in the form of orchitis or epididymal obstruction or androgen antagonists. These include infections (leprosy and HIV), autoimmune (erythema nodosum leprosum), granulomatous (sarcoidosis, Langerhans cell histiocytosis), nutritional deficiency (zinc), and malignancy. Several therapeutics of skin diseases are notorious for their effects on male fertility, most notably are the cytotoxic drugs (methotrexate), irradiation, and antiandrogens (spironolactone, finasteride). Although the prevalence of these skin diseases is low, the associated male infertility represents a challenge due to the difficulty of its management. Clinical management of the skin diseases should include consideration of their effects not only on the diseases but also on the male reproductive system.

Effective Delivery of Male Contraceptives Behind the Blood-Testis Barrier (BTB) - Lesson from Adjudin

The blood-testis barrier (BTB) is one of the tightest blood-tissue barriers in the mammalian body. It divides the seminiferous epithelium of the seminiferous tubule, the functional unit of the testis, where spermatogenesis takes place, into the basal and the adluminal (apical) compartments. Functionally, the BTB provides a unique microenvironment for meiosis I/II and post-meiotic spermatid development which take place exclusively in the apical compartment, away from the host immune system, and it contributes to the immune privilege status of testis. However, the BTB also poses major obstacles in developing male contraceptives (e.g., adjudin) that exert their effects on germ cells in the apical compartment, such as by disrupting spermatid adhesion to the Sertoli cell, causing germ cell exfoliation from the testis. Besides the tight junction (TJ) between adjacent Sertoli cells at the BTB that restricts the entry of contraceptives from the microvessels in the interstitium to the adluminal compartment, drug transporters, such as P-glycoprotein and multidrug resistance-associated protein 1 (MRP1), are also present that actively pump drugs out of the testis, limiting drug bioavailability. Recent advances in drug formulations, such as drug particle micronization (<50 μm) and co-grinding of drug particles with ß-cyclodextrin have improved bioavailability of contraceptives via considerable increase in solubility. Herein, we discuss development in drug formulations using adjudin as an example. We also put emphasis on the possible use of nanotechnology to deliver adjudin to the apical compartment with multidrug magnetic mesoporous silica nanoparticles. These advances in technology will significantly enhance our ability to develop effective non-hormonal male contraceptives for men.

Male hormonal contraception: looking back and moving forward

Despite numerous contraceptive options available to women, approximately half of all pregnancies in the United States and worldwide are unplanned. Women and men support the development of reversible male contraception strategies, but none have been brought to market. Herein we review the physiologic basis for male hormonal contraception, the history of male hormonal contraception development, currents agents in development as well as the potential risks and benefits of male hormonal contraception for men.

The preparation and application of N-terminal 57 amino acid protein of the follicle-stimulating hormone receptor as a candidate male contraceptive vaccine

Follicle-stimulating hormone receptor (FSHR), which is expressed only on Sertoli cells and plays a key role in spermatogenesis, has been paid attention for its potential in male contraception vaccine research and development. This study introduces a method for the preparation and purification of human FSHR 57-amino acid protein (FSHR-57aa) as well as determination of its immunogenicity and antifertility effect. A recombinant pET-28a(+)-FSHR-57aa plasmid was constructed and expressed in Escherichia coli strain BL21 Star TM (DE3) and the FSHR-57aa protein was separated and collected by cutting the gel and recovering activity by efficient refolding dialysis. The protein was identified by Western blot and high-performance liquid chromatography analysis with a band of nearly 7 kDa and a purity of 97.4%. Male monkeys were immunized with rhFSHR-57aa protein and a gradual rising of specific serum IgG antibody was found which reached a plateau on day 112 (16 weeks) after the first immunization. After mating of one male with three female monkeys, the pregnancy rate of those mated with males immunized against FSHR-57aa was significantly decreased while the serum hormone levels of testosterone and estradiol were not disturbed in the control or the FSHR-57aa groups. By evaluating pathological changes in testicular histology, we found that the blood-testis barrier remained intact, in spite of some small damage to Sertoli cells. In conclusion, our study demonstrates that the rhFSHR-57aa protein might be a feasible male contraceptive which could affect sperm production without disturbing hormone levels.

Male contraception: another Holy Grail

The idea that men should participate in family planning by playing an active role in contraception has become more acceptable in recent years. Up to the present the condom and vasectomy have been the main methods of male contraception. There have been and continue to be efforts to develop an acceptable hormonal contraceptive involving testosterone (T) suppression. However the off target affects, delivery of the analogs and the need for T replacement have proven difficult obstacles to this technology. Research into the development of non-hormonal contraception for men is progressing in several laboratories and this will be the subject of the present review. A number of promising targets for the male pill are being investigated. These involve disruption of spermatogenesis by compromising the integrity of the germinal epithelium, interfering with sperm production at the level of meiosis, attacking specific sperm proteins to disrupt fertilizing ability, or interfering with the assembly of seminal fluid components required by ejaculated sperm for acquisition of motility. Blocking contractility of the vas deferens smooth muscle vasculature to prevent ejaculation is a unique approach that prevents sperm from reaching the egg. We shall note the lack of interest by big pharma with most of the support for male contraception provided by the NIH.

Male contraception: history and development

Although the twentieth century has seen great strides in the development of female contraception, not a single new agent has been introduced as an approved method for common use for male contraception. Condoms (considered uncomfortable by some) and vasectomy (a permanent invasive procedure) are the only options provided to men, leaving an undue burden on women to bear contraceptive responsibility. Significant developments have, however, been made with regard to hormonal and nonhormonal contraception, and minor, reversible, procedural contraception. This article reviews the currently available, soon to be available, and theoretically possible methods of male contraception.