Male Contraceptive Development Research Articles

Development of new hormonal male contraception for the couple.

Current options for male contraception are limited to condoms, the withdrawal method, or a vasectomy. Studies indicate that men have expressed growing interest in bearing responsibility for family planning. To review prior studies investigating the role of an androgen-only or androgen with progestin regimen for hormonal male contraception and to provide an update of a promising new hormonal agent, a transdermal gel. Thus far, there have been six studies conducted in couples evaluating the contraceptive efficacy of an androgen-only or androgen co-administered with a progestin regimen for hormonal male contraception. The only ongoing study is by the National Institute of Child Health and Human Development, in collaboration with the Population Council. They have developed a novel transdermal gel containing testosterone and segesterone acetate (Nestorone), a progestin. An ongoing phase II study enrolling more than 460 couples has shown great potential with respect to the product's efficacy, safety, reversibility, and acceptability. As this agent advances in development, a rapid at-home test for sperm concentration will provide couples with immediate feedback regarding their potential for pregnancy. There is promise for the first-of-its-kind hormonal male contraceptive, a transdermal gel, to achieve market approval for distribution in the United States and elsewhere. Its safety, efficacy, reversibility, and user-control are all appealing qualities that make it readily adoptable for clinical practice.

Individual disruption of 12 testis-enriched genes via the CRISPR/Cas9 system does not affect the fertility of male mice

More than 1200 genes have been shown in the database to be expressed predominantly in the mouse testes. Advances in genome editing technologies such as the CRISPR/Cas9 system have made it possible to create genetically engineered mice more rapidly and efficiently than with conventional methods, which can be utilized to screen genes essential for male fertility by knocking out testis-enriched genes. Finding such genes related to male fertility would not only help us understand the etiology of human infertility but also lead to the development of male contraceptives. In this study, we generated knockout mice for 12 genes (Acrv1, Adgrf3, Atp8b5, Cfap90, Cfap276, Fbxw5, Gm17266, Lrrd1, Mroh7, Nemp1, Spata45, and Trim36) that are expressed predominantly in the testis and examined the appearance and histological morphology of testes, sperm motility, and male fertility. Mating tests revealed that none of these genes is essential for male fertility at least individually. Notably, knockout mice for Gm17266 showed smaller testis size than the wild-type but did not exhibit reduced male fertility. Since 12 genes were not individually essential for male fertilization, it is unlikely that these genes could be the cause of infertility or contraceptive targets. It is better to focus on other essential genes because complementary genes to these 12 genes may exist.

Current global status of male reproductive health.

Current global status of male reproductive health.

Spem2, a novel testis-enriched gene, is required for spermiogenesis and fertilization in mice

Spermiogenesis is considered to be crucial for the production of haploid spermatozoa with normal morphology, structure and function, but the mechanisms underlying this process remain largely unclear. Here, we demonstrate that SPEM family member 2 (Spem2), as a novel testis-enriched gene, is essential for spermiogenesis and male fertility. Spem2 is predominantly expressed in the haploid male germ cells and is highly conserved across mammals. Mice deficient for Spem2 develop male infertility associated with spermiogenesis impairment. Specifically, the insufficient sperm individualization, failure of excess cytoplasm shedding, and defects in acrosome formation are evident in Spem2-null sperm. Sperm counts and motility are also significantly reduced compared to controls. In vivo fertilization assays have shown that Spem2-null sperm are unable to fertilize oocytes, possibly due to their impaired ability to migrate from the uterus into the oviduct. However, the infertility of Spem2−/− males cannot be rescued by in vitro fertilization, suggesting that defective sperm–egg interaction may also be a contributing factor. Furthermore, SPEM2 is detected to interact with ZPBP, PRSS21, PRSS54, PRSS55, ADAM2 and ADAM3 and is also required for their processing and maturation in epididymal sperm. Our findings establish SPEM2 as an essential regulator of spermiogenesis and fertilization in mice, possibly in mammals including humans. Understanding the molecular role of SPEM2 could provide new insights into future therapeutic treatment of human male infertility and development of non-hormonal male contraceptives.

Nonhormonal Male Contraceptive Development-Strategies for Progress.

Despite the widely demonstrated public health benefits of contraception, limited contraceptive options are available for men, placing both the contraceptive burden and opportunity solely on women. This review outlines the need for an increased focus on male contraceptive development and highlights several related topics, including the perspectives of women and men on male contraceptives, historical challenges, and reasons behind the persistent delays in male contraceptive development. It also discusses the importance of serendipitous observations in drug discovery and the limitations of depleting sperm or spermatogenic cells as a contraceptive approach. It further provides an overview of ongoing research and development on novel methods, with a goal to offer insights into the multifaceted aspects of nonhormonal male contraceptive development, addressing its implications for the health of men and women. SIGNIFICANCE STATEMENT: Despite well over half a century of effort in developing male contraceptives, there are no approved male contraceptive drugs on the market. This review aims to present strategies for progress in nonhormonal male contraception based on lessons learned from history, with the hope of expediting development and bringing a male contraceptive drug closer to reality.

Innovation and Challenges in Male Contraception

The unwanted cases of pregnancy have increased resulting in improper family planning and cases of depression or stillbirth. The decision regarding reproduction is shared equivalently by men and women. Although the contraception methods result in effectiveness, they have more complications than effective results. Hormonal disbalance and endometriosis are a few such examples. Contraception for males is limited, yet has more effective results and fewer complications. The development of male contraception is vastly researched over the past few decades. Various hormonal and non-hormonal methods are being developed to provide better contraception with minimum or no disadvantage. The basic advantage of developing a male contraceptive includes its availability, low cost, no side effects, and ease of use.

Practice and development of male contraception: European Academy of Andrology and American Society of Andrology guidelines.

Despite a wide spectrum of contraceptive methods for women, the unintended pregnancy rate remains high (45% in the US), with 50% resulting in abortion. Currently, 20% of global contraceptive use is male-directed, with a wide variation among countries due to limited availability and lack of efficacy. Worldwide studies indicate that >50% of men would opt to use a reversible method, and 90% of women would rely on their partner to use a contraceptive. Additional reasons for novel male contraceptive methods to be available include the increased life expectancy, sharing the reproductive risks among partners, social issues, the lack of pharma industry involvement and the lack of opinion makers advocating for male contraception. The present guidelines aim to review the status regarding male contraception, the current state of the art to support the clinical practice, recommend minimal requirements for new male contraceptive development and provide and grade updated, evidence-based recommendations from the European Society of Andrology (EAA) and the American Society of Andrology (ASA). An expert panel of academicians appointed by the EAA and the ASA generated a consensus guideline according to the GRADE (Grading of Recommendations, Assessment, Development and Evaluation) system. Sixty evidence-based and graded recommendations were produced on couple-centered communication, behaviors, barrier methods, semen analysis and contraceptive efficacy, physical agents, surgical methods, actions before initiating male contraception, hormonal methods, non-hormonal methods, vaccines, and social and ethical considerations. As gender roles transform and gender equity is established in relationships, the male contribution to family planning must be facilitated. Efficient and safe male-directed methods must be evaluated and introduced into clinical practice, preferably reversible, either hormonal or non-hormonal. From a future perspective, identifying new hormonal combinations, suitable testicular targets, and emerging vas occlusion methods will produce novel molecules and products for male contraception.

Novel progestogenic androgens for male contraception: design, synthesis, and activity of C7 α-substituted testosterone†.

Male contraceptive development has included use of testosterone (T) with or without a progestin or the use of a single molecule such as progestogenic androgens (PA) for suppression of testicular T production. Expanding upon the vast amount of data accumulated from nortestosterone (NT), NT analogs, and their prodrugs, a new series of PA, the C7 methyl, and ethyl α-substituted T analogs 7α-Methyltestosterone (7α-MT) and 7α-Ethyltestosterone (7α-ET), respectively, were hypothesized and designed to have superior androgenic and progestogenic activities when compared with parent T. Results from androgen receptor and progesterone receptor competitive binding and transcriptional activation assays showed favorable activities for these T analogs. Additionally, 7α-MT and 7α-ET were shown to be active substrates for aromatase in vitro, mitigating a potential negative impact on bone mineral density with long-term use. In conjunction with this observation, the diminished metabolism of these T analogs by 5α-reductase may reduce potential concerns for prostatic growth. In the Hershberger in vivo rat bioassay, 7α-MT and 7α-ET showed superior androgenic and anabolic activities as compared with T. These C7 α-substituted T analogs also showed clear progestogenic activity in the McPhail bioassay which evaluated endometrial glandular arborization in a rabbit model. The discovery of aromatizable molecules with reduced metabolism by 5α-reductase that have androgenic, anabolic, and progestogenic properties indicates that the core and/or prodrugs of 7α-MT and 7α-ET are promising molecules for further development as male contraceptive PAs.

In Vitro Study on Spermicidal Action of Hydro-methanol Extract of Tinospora cordifolia (Willd.) Stem in Rat and Human Sperm: a Comparative Analysis.

Human fertility regulation is a major way to control overpopulation. In this perspective, this study emphasized the in vitro effect of hydro-methanol extract of Tinospora cordifolia (TCHME) stem for spermicidal and reproductive hypo-functions using human and rat samples. Control, 0.5-, 1-, and 2-mg TCHME-charged groups were considered to assess the relevant parameters. Levels of spermiological parameters like sperm motility, viability, the integrity of plasma and acrosomal membrane, and nuclear chromatin decondensation were significantly reduced (p < 0.05) in the dose- and duration-dependent TCHME-charged groups compared to the control. The inhibitory concentration 50 (IC50) of TCHME on motile human and rat sperms were 0.8 and 0.4 mg/ml, respectively. Testicular androgenic key enzymes and antioxidant enzymes (human sperm pellet, testes, and epididymis of rat)' activities were significantly diminished (p < 0.05), while antioxidant enzymes' activities were significantly elevated (p < 0.05) in renal and insignificantly (p > 0.05) elevated in hepatic tissues of rat in TCHME-charged groups compared to the control. Significant elevation (p < 0.05) of thiobarbituric acid reactive substances (TBARS)' level in human sperm pellet, testes, and epididymis of rats and significant diminution (p < 0.05) in TBARS levels of liver and kidney were observed in TCHME-charged groups. It focused that TCHME is more potent for stress imposition on reproductive tissues and sperm compared to the other tested tissues. Non-significant alterations (p > 0.05) in glutamic oxaloacetic transaminase (GOT) and glutamic pyruvic transaminase (GPT) activities in the said organs of rat indicated its non-toxic effect. It highlighted that TCHME possesses spermicidal and reproductive tissue-specific effects which strengthen the possibilities of male contraceptive development from it.

Various gene modification techniques to discover molecular targets for nonhormonal male contraceptives: A review.

The identification and characterization of relevant targets are necessary for developing nonhormonal male contraceptives. The molecules must demonstrate that they are necessary for reproduction. As a result, a sophisticated technique is required to identify the molecular targets for nonhormonal male contraceptives. Genetic modification (GM) techniques are one method that can be applied. This technique has been widely used to study gene function that effected male fertility and has resulted in the discovery of numerous nonhormonal male contraceptive target molecules. We examined GM techniques and approaches used to investigate genes involved in male fertility as potential targets for nonhormonal contraceptives. The discovery of nonhormonal contraceptive candidate molecules was increased by using GM techniques, especially the Clustered Regularly Interspaced Short Palindromic Repeats/Cas9 method. The discovery of candidate nonhormonal contraceptive molecules can be a wide-open research for the development of nonhormonal male contraceptives. Therefore, we are believing that one day nonhormonal male contraceptives will be released.

The world needs better male contraceptives: What is taking so long?

Forty percent of US pregnancies are unintended despite currently available contraceptives. A substantial number of men use the currently available methods of male contraception, condoms and vasectomy, and a large majority would be interested in novel forms of male contraception if available. Research into male contraception has been ongoing for more than 50 years, with hormonal contraceptives nearing clinical utility and non-hormonal methods hopefully becoming available, albeit with a longer time frame. However, uncertainly regarding benchmarks for the efficacy and safety of male contraception continue to be an issue with development and regulatory approval. In addition, pharmaceutical industry support is minimal with the NIH and Foundations being the main research funders. Given the continuing high rates of unintended pregnancy, many of which are now occurring in areas with extremely restricted access to legal abortion, additional focus and investment in male contraceptive development is imperative.

A global grounded theory exploration of investigators’ perspectives on male hormonal contraceptive development and acceptability

ABSTRACT While best practices have been proposed on how to engage men in family planning (FP), the limited options of male hormonal contraceptives (MHC) are a barrier to reaching men as clients of FP programs. The lack of alternative MHC is preventing the global health community from providing holistic reproductive healthcare. A qualitative grounded theory study was conducted in 2020 to explore MHC experts’ perceptions around the development and theoretical acceptability of MHCs. Individual in-depth interviews were conducted with 15 key informants. The informants cited evidence that there is a demand for MHC. The inability to access this data by the pharmaceutical industry was acknowledged. Many informants expressed concern of the possibility for MHC to increase male power in a predominantly patriarchal world. To most informants, at least for the initial introduction of MHC, fertility sharing is something that will largely happen among couples alone rather than individually. There is proven demand among women and men for MHC, however industries may still be reluctant to invest. Effort is needed by the sexual and reproductive health and rights community to include male engagement in FP and to advocate for the development and use of MHC as a tool for women’s empowerment.

Bivalent BET Bromodomain Inhibitors Confer Increased Potency and Selectivity for BRDT via Protein Conformational Plasticity.

Bromodomain and extraterminal domain (BET) proteins are important regulators of gene transcription and chromatin remodeling. BET family members BRD4 and BRDT are validated targets for cancer and male contraceptive drug development, respectively. Due to the high structural similarity of the acetyl-lysine binding sites, most reported inhibitors lack intra-BET selectivity. We surmised that protein-protein interactions induced by bivalent inhibitors may differ between BRD4 and BRDT, conferring an altered selectivity profile. Starting from nonselective monovalent inhibitors, we developed cell-active bivalent BET inhibitors with increased activity and selectivity for BRDT. X-ray crystallographic and solution studies revealed unique structural states of BRDT and BRD4 upon interaction with bivalent inhibitors. Varying spacer lengths and symmetric vs unsymmetric connections resulted in the same dimeric states, whereas different chemotypes induced different dimers. The findings indicate that the increased intra-BET selectivity of bivalent inhibitors is due to the differential plasticity of BET bromodomains upon inhibitor-induced dimerization.

Hormonal Male Contraception: Formative Research to Develop and Test Communication Messaging.

Male-controlled contraception is limited, yet a promising hormonal male contraceptive (HMC) development in may increase options for men to share in the work of pregnancy prevention. This study examined college-aged (18–26 years) men’s and women’s perceptions of influential marketing strategy for an experimental novel HMC method, a transdermal gel. Six focus groups (n = 29) were conducted to glean insights for ad prototype creation. Ad prototypes were designed and then tested in semi-structured interviews (n = 20) to understand whether the messages were adequately representing the attributes intended while also allowing participants to contribute insights on improving appeal. A constant comparative approach was used for data contextualization and theme identification. Results provided a foundation for the creation of HMC message prototypes, aimed at increasing knowledge and uptake of a novel family planning method for men. Representation of a relatable character, or drawing on authentic experiences, aligned best with participant values. Focus groups illuminated salient concepts for HMC marketing, including humor, destigmatization, information, and credibility. Interview message testing yielded an understanding of elements participants responded most strongly to, including (1) ad sentiment and (2) trustworthiness. Findings provide a basis for understanding the placement of a potential marketing campaign to effectively frame HMC uptake as easy to use, safe, and popular while building on peer norms and group acceptability among a college-aged demographic. Healthcare providers and other practitioners can utilize these findings while engaging in family planning conversations, interventions, and message development.

C2CD6 regulates targeting and organization of the CatSper calcium channel complex in sperm flagella.

The CatSper cation channel is essential for sperm capacitation and male fertility. The multi-subunit CatSper complexes form highly organized calcium signaling nanodomains on flagellar membranes. Here, we report identification of an uncharacterized protein, C2CD6, as a subunit of the mouse CatSper complex. C2CD6 contains a calcium-dependent, membrane-targeting C2 domain. C2CD6 associates with the CatSper calcium-selective, core-forming subunits. Deficiency of C2CD6 depletes the CatSper nanodomains from the flagellum and results in male sterility. C2CD6-deficient sperm are defective in hyperactivation and fail to fertilize oocytes both in vitro and in vivo. CatSper currents are present but at a significantly lower level in C2CD6-deficient sperm. Transient treatments with either Ca2+ ionophore, starvation, or a combination of both restore the fertilization capacity of C2CD6-deficient sperm. C2CD6 interacts with EFCAB9, a pH-dependent calcium sensor in the CatSper complex. We postulate that C2CD6 facilitates incorporation of the CatSper complex into the flagellar plasma membrane and may function as a calcium sensor. The identification of C2CD6 may enable the long-sought reconstitution of the CatSper ion channel complex in a heterologous system for male contraceptive development.

High-throughput phenotypic screening of the human spermatozoon.

Despite recent advances in male reproductive health research, there remain many elements of male infertility where our understanding is incomplete. Consequently, diagnostic tools and treatments for men with sperm dysfunction, other than medically assisted reproduction, are limited. On the other hand, the gaps in our knowledge of the mechanisms which underpin sperm function have hampered the development of male non-hormonal contraceptives. The study of mature spermatozoa is inherently difficult. They are a unique and highly specialised cell type which does not actively transcribe or translate proteins and cannot be cultured for long periods of time or matured in vitro. One large-scale approach to both increasing the understanding of sperm function and the discovery and development of compounds that can modulate sperm function is to directly observe responses to compounds with phenotypic screening techniques. These target agnostic approaches can be developed into high-throughput screening platforms with the potential to drastically increase advances in the field. Here, we discuss the rationale and development of high-throughput phenotypic screening platforms for mature human spermatozoa and the multiple potential applications these present, as well as the current limitations and leaps in our understanding and the capabilities needed to overcome them. Further development and use of these technologies could lead to the identification of compounds which positively or negatively affect sperm cell motility or function or novel platforms for toxicology or environmental chemical testing among other applications. Ultimately, each of these potential applications is also likely to increase the understanding within the field of sperm biology.

Knowledge and Perception Regarding the Development and Acceptability of Male Contraceptives Among Pharmacists: A Mixed Sequential Method.

Community pharmacists play a crucial role in providing comprehensive patient education regarding contraception methods. This study aims to investigate Jordanian pharmacists’ knowledge and perceptions toward male oral contraceptive pills (OCPs). A mixed-explanatory sequential method was divided into two phases. The first was a self-administered electronic survey that was distributed to community pharmacists/trainees in Jordan. The second phase was carried out through online semi-structured in-depth interviews targeting the maximum variation purposive sample of community pharmacists. A total of 158 (response rate 98%) questionnaires were included in the analysis. The majority of the participants were female (n = 118, 74.2%). In terms of knowledge, only 25% of participants acknowledged the presence of male OCPs and almost half were uncertain about the mechanism of action and the possible uses. The findings of the interviews confirmed a relatively negative perception toward male OCPs and the identified barriers to male OCPs were cultural norms, side effects, and poor compliance. It is argued that there is a negative perception toward male OCPs due to the majority of pharmacists not believing such products will be successful in Jordan. Once these pills are approved for their effectiveness and safety, men may need further education and encouragement to take an active role in family planning along with their partners.

Dissecting EPPIN protease inhibitor domains in sperm motility and fertilizing ability: repercussions for male contraceptive development.

EPPIN (epididymal protease inhibitor) is a mammalian conserved sperm-binding protein displaying an N-terminal WFDC (whey-acidic protein four-disulfide core) and a C-terminal Kunitz protease inhibitor domains. EPPIN plays a key role in regulating sperm motility after ejaculation via interaction with the seminal plasma protein SEMG1 (semenogelin-1). EPPIN ligands targeting the SEMG1 binding site in the Kunitz domain are under development as male contraceptive drugs. Nevertheless, the relative contributions of EPPIN WFDC and Kunitz domains to sperm function remain obscure. Here, we evaluated the effects of antibodies targeting specific epitopes in EPPIN's WFDC (Q20E antibody, Gln20-Glu39 epitope) and Kunitz (S21C and F21C antibodies, Ser103-Cys123 and Phe90-C110 epitopes, respectively) domains on mouse sperm motility and fertilizing ability. Computer-assisted sperm analysis showed that sperm co-incubation with S21C antibody (but not F21C antibody) lowered progressive and hyperactivated motilities and impaired kinematic parameters describing progressive (straight-line velocity; VSL, average path velocity; VAP and straightness; STR) and vigorous sperm movements (curvilinear velocity; VCL, amplitude of lateral head movement; ALH, and linearity; LIN) compared with control. Conversely, Q20E antibody-induced milder inhibition of progressive motility and kinematic parameters (VAP, VCL and ALH). Sperm co-incubation with S21C or Q20E antibodies affected in vitro fertilization as revealed by reduced cleavage rates, albeit without changes in capacitation-induced tyrosine phosphorylation. In conclusion, we show that targeting specific epitopes in EPPIN Kunitz and WFDC domains inhibits sperm motility and capacitation-associated events, which decrease their fertilizing ability; nevertheless, similar observations in vivo remain to be demonstrated. Simultaneously targeting residues in S21C and Q20E epitopes is a promising approach for the rational design of EPPIN-based ligands with spermostatic activity.

Catalyzing momentum in male contraceptive development†.

Globally, nearly half of all pregnancies are unplanned. Male contraceptives offer the potential to decrease unintended pregnancy and introduce contraceptive equity, but decades of research have yet to bring a novel product to market. New funding avenues from the philanthropic sector seek to stimulate research in male contraceptives through investments, grants, and support for trainees alongside other programs that encourage product development and ultimately commercialization. This Forum outlines the purpose of and funding opportunities provided by Male Contraceptive Initiative, a funding agency and non-profit focused on the advancement of non-hormonal, reversible contraceptive technologies for those who produce sperm.

TSSK3, a novel target for male contraception, is required for spermiogenesis.

We have previously shown that members of the family of testis-specific serine/threonine kinases (TSSKs) are post-meiotically expressed in testicular germ cells and in mature sperm in mammals. The restricted post-meiotic expression of TSSKs as well as the importance of phosphorylation in signaling processes strongly suggest that TSSKs have an important role in germ cell differentiation and/or sperm function. This prediction has been supported by the reported sterile phenotype of the TSSK6 knock-out (KO) mice and of the double TSSK1/TSSK2 KO. The aim of this study was to develop KO mouse models of TSSK3 and to validate this kinase as a target for the development of a male contraceptive. We used CRISPR/Cas9 technology to generate the TSSK3 KO allele on B6D2F1 background mice. Male heterozygous pups were used to establish three independent TSSK3 KO lines. After natural mating of TSSK3 KO males, females that presented a plug (indicative of mating) were monitored for the following 24 days and no pregnancies or pups were found. Sperm numbers were drastically reduced in all three KO lines and, remarkably, round spermatids were detected in the cauda epididymis of KO mice. From the small population of sperm recovered, severe morphology defects were detected. Our results indicate an essential role of TSSK3 in spermiogenesis and support this kinase as a suitable candidate for the development of novel nonhormonal male contraceptives.