Repeated vas occlusion and non-invasive reversal with styrene maleic anhydride for male contraception in langur monkeys

RISUG® as a male contraceptive: journey from bench to bedside

Even after decades of research men still lack reliable and reversible contraceptive methods comparable to female methods of contraception. Traditional methods of male contraception present a high failure rate and also involve high risk both when used for contraception and for protection against sexually transmitted diseases. Various chemical, hormonal, immunological, vas based and herbal methods of contraception have been examined by scientists world over during the past four decades. Among the possible lead approaches, exogenous hormonal contraception, either alone or in combination with progesterone or antiandrogen, is being viewed at low profile because of their insufficiency in inducing uniform suppression of spermatogenesis and steroid related long term complications. As an alternative to vasectomy, among various intravasal devices being examined, RISUG® (Reversible Inhibition of Sperm Under Guidance), a co-polymer of styrene and maleic anhydride offers long term contraception with safety, efficacy and it can be delivered by no-scalpel injection. Thus it is the only male contraceptive procedure currently under Phase- III Clinical Trial. The non-invasive reversal technique, successfully demonstrated in langur monkeys and functional reversal achieved with dimethyl sulphoxide (DMSO) and sodium bicarbonate (NaHCO3) in rats and rabbits with safety at F1 generation (first filial generation) have projected RISUG® as a better alternative to vasectomy. In this narrative review we revisit the long journey of RISUG® beginning with formulation on a bench towards reaching the market as a safe and effective contraceptive method, discussing various milestones and roadblocks of this expedition awaiting the mandatory regulatory clearance from the Government of India. Successful completion of ongoing phase III clinical trials with demonstration of reversal in human volunteers will give an indigenously developed male contraceptive to the world.

Safety & efficacy of an intravasal, one-time injectable & non-hormonal male contraceptive (RISUG): A clinical experience

Background & objectives:

For improved male contraception, a new polymeric drug molecule – Reversible Inhibition of Sperm under Guidance (RISUG) has been synthesized and has been found to be effective, safe and reversible in various animal species. Phase-I and phase-II clinical trials have confirmed its safety and contraceptive efficacy. The present study was undertaken as a multicentric-limited phase-III clinical trial to test the efficacy and safety of RISUG in human volunteers.

Methods:

One hundred and thirty nine young males each having at least two children and living with wife were given 120 μl of RISUG as bilateral vas intraluminal injection. After the single-dose administration, the individuals were followed in respect of general health and semen parameters. Their wives were also followed particularly to determine onset of pregnancy.

Results:

During the six month follow up, the health of male volunteers and their wives was normal with no significant adverse effects. Temporary scrotal enlargement and mild scrotal and inguinal region pain were manifested in most individuals and resolved within one month without any routine activity impairment. In six individuals, there was injection procedure failure and azoospermia was not achieved. The other 133 individuals had either severe oligozoospermia or azoospermia at the first semen examination one month following RISUG injection; 82.7 per cent individuals had continued azoospermia in the month following first semen examination onwards and the rest 17.3 per cent manifested azoospermia within three to six months.

Interpretation & conclusions:

RISUG intravasal injection appears to be a safe clinical procedure with no significant adverse effects and has high sustained contraceptive efficacy. The localized intervention and continued contraceptive action on single-dose administration were significant features of the RISUG technology.

Contraception with RISUG® and functional reversal through DMSO and NaHCO3 in male rabbits

The study aimed to evaluate reversal of short- and long-term vas occlusion with reversible inhibition of sperm under guidance (RISUG) using dimethyl sulfoxide (DMSO) and sodium bicarbonate (NaHCO3) in male rabbits (Oryctolagus cuniculus). Animals were divided into seven groups containing five animals each. Fortnightly, semen analysis revealed that sperm concentration and output steadily declined after vas occlusion and complete azoospermia was attained at 30-60 days postinjection. Spermatozoa reappeared at 60-75 days of reversal and normozoospermia was noticed between 135 days and 150 days in the reversal groups. All spermatozoa were found nonmotile prior to azoospermia and a gradual recovery in sperm motility was observed between 105 days and 135 days of reversal. A significant decline in viability of sperms was noticed during vas occlusion up to 30-60 days which recovered at 60-75 days postreversal and normalized by 75-105 days in the reversal groups. A significant enhancement in the sperm abnormalities was recorded in all vas occluded animals as well as those in initial periods of reversal. Other parameters, namely, semen volume, ejaculation time, pH, color, and consistency, remained unaltered during all phases of the study. Fertility test, at the intervals of 15 days, demonstrated that animals exhibited complete sterility during the entire period of vas occlusion. A gradual recovery in fertility was observed with the appearance of spermatozoa following vas occlusion reversal and 100% fertility was observed following 135-150 days of reversal. F1 progeny of reversed animals was found normal. The results suggest that reversal with DMSO or NaHCO3 is feasible, with normal progeny, following short- and long-term contraception.

The contraceptive efficacy of intravas injection of Vasalgel™ for adult male rhesus monkeys

Background

Options for male contraception are limited. The purpose of this study was to use a nonhuman primate model to evaluate Vasalgel™, a high molecular weight polymer being developed as a contraceptive device for men.

Methods

Sixteen adult male rhesus monkeys received intravas injections of Vasalgel, consisting of 25% styrene maleic acid in dimethyl sulfoxide. After a one-week recovery, males were returned to outdoor group housing, which included at least 3 and up to 9 intact, breeding females with a successful reproductive history.

Results

Treated males have had no conceptions since Vasalgel injections. All males were housed with intact females for at least one breeding season and seven have been almost continually housed with females for 2 years. Complications were minor and included one incident of incorrect placement of Vasalgel into the vas deferens and the development of a sperm granuloma in one animal. Three unilateral vasectomies were performed, one was necessary for incorrect placement of Vasalgel, the other two were elective.

Conclusions

Intravas injection of Vasalgel in sexually mature adult male rhesus monkeys was effective in preventing conception in a free-living, group environment. Complications were few and similar to those associated with traditional vasectomy.

Relative suitability of DMSO and NaHCO3 for reversal of RISUG® induced long-term contraception

Among the vas-based methods on trial, reversible inhibition of sperm under guidance (RISUG(®) ), a co-polymer of styrene and maleic anhydride is being projected as an effective alternative to No Scalpel Vasectomy. RISUG offers long-term contraception with safety, efficacy in human trials and can be delivered by no-scalpel injection. Currently, the procedure is under phase-III clinical trial. However, reversal of this vas-based drug-induced contraception needs to be established in animal models prior to clinical trials to ensure its claim as an effective alternative for vasectomy. In the present investigation, the relative suitability of dimethyl sulphoxide (DMSO) and NaHCO3 for RISUG induced long-term vas occlusion reversal was carried out in albino rats. Animals were allocated into four groups (n = 10), viz., sham-operated control (group-I), vas occlusion with RISUG for 360 days (group-II), vas occlusion with RISUG for 360 days and reversal with DMSO (group-III) and vas occlusion with RISUG for 360 days and reversal with NaHCO3 (group-IV). A variable response in fertility was observed in different groups. Absolute sterility in group III at all mating intervals, while, zero percent fertility in groups II and IV following 90 days of occlusion was observed. Following reversal restoration of fertility with DMSO at 45 days, whereas, reversal by NaHCO3 at 30 days was noticed. Ejaculated spermatozoa of RISUG injected and initial intervals of reversed animals exhibited various degrees of abnormalities. The testes exhibited focal degeneration in vas occluded animals. The occluded lumen of the vas deferens contained an eosinated polymer with exfoliated epithelium. Following vas occlusion reversal, a complete regeneration in the vas epithelium was seen. All other parameters remained unaltered. The reversal with NaHCO3 resulted into an early resumption of fertility when compared with DMSO and the procedure found to be successful, feasible and safe up to F1 generation. Thus, RISUG provides a hope for reversible male contraceptives.

Male contraception

Contraception is an accepted route for the control of population explosion in the world. Traditionally hormonal contraceptive methods have focused on women. Male contraception by means of hormonal and non hormonal methods is an attractive alternative. Hormonal methods of contraception using testosterone have shown good results. Non hormonal reversible methods of male contraception like reversible inhibition of sperm under guidanceare very promising. In this article we have reviewed the current available options for male contraception.

Family planning: today and in the future

This review covers the state of contraceptive development noting new entries in the clinic (mainly steroidal and different delivery methods) and novel leads for nonsteroidal female- and male-methods in the pipeline. The time taken to market and the absence of partnerships with industry are stressed as major factors for the slow progress in their development.

Sperm characteristics and teratology in rats following vas deferens occlusion with RISUG and its reversal

The functional success of the reversal of vas occlusion by styrene maleic anhydride (RISUG), using the solvent vehicle, Dimethyl Sulphoxide (DMSO), has been investigated. Reversal with DMSO was carried out in Wistar albino rats 90 days after bilateral vas occlusion. The body weight, organ weight, sperm characteristics, fertility test and teratology, including skeletal morphology were evaluated in vas occlusion and reversal animals and in F(1) progenies to assess the functional success of the occlusion and reversal. Body weight, organ weight and the cauda epididymal sperm characteristics of vas occlusion and reversal animals and of F(1) progenies were comparable to control. Ejaculated spermatozoa in the vaginal smear showed detached head/tail, acrosomal damage, bent midpiece, bent tail and morphological aberrations in sperm head after vas occlusion, which returned to normal, 90 days after reversal. Monthly fertility test, post-injection showed 0% fertility, which improved gradually and 100% fertility was achieved 90 days after reversal. The fertility/pregnancy/implantation record and skeletal morphology of the offspring were comparable to control. The results suggest functional success and safety of vas occlusion reversal by DMSO.

Male contraception: Past, present and future

Male contraception research has yielded a number of promising leads over the past 50 years. Yet, little is known by the public due to lack of institutional support and funding. This is unfortunate since, apart from condom and vasectomy, there are many male methods which may be safer, more effective and easier to use. This paper explores male contraception which has been used in the past and the present and discusses some of its potential developments.

Smart RISUG: a potential new contraceptive and its magnetic field-mediated sperm interaction

The rationale and technique underlying a novel concept of noninvasive fertility control by a new Cuproferrogel contraceptive drug, iron oxide–copper–styrene maleic anhydride–dimethyl sulphoxide (Fe₃O₄–Cu–SMA–DMSO) composite named ‘Smart RISUG’ (smart reversible inhibition of sperm under guidance) in presence of pulsed magnetic field (PMF; 1 mT to 800 mT) is explained. It was synthesized by dispersing iron oxide particles and copper particles into SMA-DMSO (male contraceptive RISUG) and characterized for particle distribution, particle size measurement and transmittance peaks, etc. Interaction of the RISUG particles as well as Smart RISUG particles with Albino rat sperm cell was studied in presence as well as absence of PMF. To find an explanation to increased reaching of the Smart RISUG drug into sperm under influence of magnetic field, the transport properties were characterized by high resolution transmission electron microscopy and atomic force microscopy. Smart RISUG could be mobilized into sperm cell membrane at the PMF, 760 mT in about 50 seconds. Adoption of novel drug Smart RISUG involving new technique may open the pathway for non surgical control of drug distribution, detection and restoration of the normal fertility after removal of the contraceptive from the male/female reproductive tube in presence of electromagnetic field.

New perspectives in non-hormonal male contraception

As the world's population continues to soar, contraception has become increasingly important. Recently, men have expressed willingness to share the burden of family planning. Thus, safe, effective and reversible male contraceptives would satisfy an urgent need among couples. Currently, there are several promising non-hormonal contraceptives at various stages of research and development. In addition, major advances in genomic and proteomic research have been instrumental in identifying and characterizing genes and proteins expressed uniquely in the testis or other male reproductive organs, which might become 'druggable' targets for non-hormonal male contraceptive development in the future. Through committed research, advocacy and support, male contraceptives are likely to become a valuable addition to the current choices of family planning.

The use of URYX for reversible vasectomy in a rabbit model

URYX is a biocompatible polymer of ethylene vinyl alcohol dissolved in a dimethyl sulfoxide (DMSO) carrier to allow injection of a very low-viscosity fluid into tissue. Once the material comes into contact with body tissue or fluid, the DMSO rapidly dissipates from the polymer, which results in a precipitate of a coherent solid mass. The purpose of the present study was to determine whether URYX can effectively occlude the vas deferens and whether patency can be restored by redissolving the URYX in vivo using the solvent DMSO. Eight male New Zealand White rabbits (age range, 25-41 weeks; mean age, 33.9 +/- 7.5 weeks; mean weight, 4.0 +/- 0.2 kg) were used in 2 experiments (E1 and E2). In E1, 3 rabbits underwent unilateral vasectomy, and the contralateral vas was injected with either 0.05 or 0.10 mL of URYX, to determine the amount of URYX required to cause obstruction. Two animals underwent bilateral vasectomy, to serve as controls. In E2, 3 animals underwent bilateral URYX injection and were compared with the bilateral vasectomy control rabbits used in E1. After 1 month of initial bilateral URYX treatment, all animals in E2 underwent attempted unilateral reversal with 1.5 mL of DMSO injected into 1 occluded vas deferens. Two end points were evaluated-a clinical end point assessed by semen analyses and a pathological end point assessed by histological analysis of treated tissues, to assess for safety. A 1.5-cm infrapubic incision was made to expose both vasa in anesthetized rabbits. The vasal injection of URYX was performed with a 30-gauge needle. Vasectomy was performed by excision of a 1-cm segment of the vas deferens and subsequent ligation with a 6-0 prolene suture. Semen was collected using an artificial vagina 2-3 times/wk before and 1 month later, after injection treatments and vasectomy. Manual sperm counts were performed. All animals were sacrificed, and tissues (distal vas, injection site, proximal vas, cauda epididymis, caput epididymis, and testis) were harvested and examined for the presence of URYX. The inflammatory response of the wall and adventitia of the vas deferens was given a score (0-15) based on the sum of grades (0 = none, 1 = mild, 2 = moderate, and 3 = severe) for the following categories: foreign body giant cell reaction, granulation tissue, lymphocytes, eosinophils, and scarring, as evaluated by a single pathologist (J.M.). Vasal injection with 0.05 mL of URYX was not sufficient to cause occlusion. Both animals injected with 0.1 mL of URYX were effectively occluded. The injection of occluded vasa with DMSO did not dissolve the URYX plug in the vas lumen. There was no significant difference in vasal inflammatory response scores between vasal units treated with URYX only and vasal units in the vasectomy model. Vasal units subjected to URYX followed by DMSO demonstrated greater inflammatory response scores than vasal units treated with URYX followed by normal saline, URYX alone, or vasectomy. Epididymal and testicular histology remained unaffected in all vasal units in E1. The vasal units in E2 subjected to URYX followed by normal saline showed no histological abnormalities of the epididymis and testis. However, those vasal units subjected to URYX followed by DMSO in E2 showed evidence of adhesions, necrosis, and degenerating cells in the epididymis and a focal foreign body giant cell reaction in the testis. The bilateral vasal injection of URYX can result in azoospermia in the rabbit model. Reversal with subsequent DMSO injection was not achieved. A minimal inflammatory response of the vas deferens was observed with URYX injection alone; however, DMSO following URYX injection resulted in increased vasal inflammation, in addition to epididymal and testicular changes.

Safety evaluation of long-term vas occlusion with styrene maleic anhydride and its non-invasive reversal on accessory reproductive organs in langurs

AIM

To evaluate the safety of the long term vas occlusion with styrene maleic anhydride (SMA) and its non-invasive reversal at the level of accessory reproductive glands ARGs in langurs.

METHODS

The morphology of seminal vesicle and ventral prostate was evaluated by light as well as transmission electron microscopy. Serum clinical chemistry and urine albumin were evaluated in an autoanalyzer using reagent kits. Fructose, acid phosphatase and zinc in the seminal plasma were evaluated spectrophotometrically according to the WHO manual. Serum testosterone, prostate specific antigen and sperm antibodies were evaluated by enzyme-linked immunosorbent assays (ELISA) using reagent kits and hematology was estimated according to standard procedures.

RESULTS

The morphological features and secretory activity of the seminal vesicle and prostate were normal as evidenced by the presence of well-developed mitochondria, rough endoplasmic reticulum, Golgi bodies, secretory granules and normal nuclear characteristics throughout the course of investigation. Serum testosterone and prostate specific antigen remained unaltered and serum antisperm antibodies level presented negative titres. Urine albumin was nil. Total red blood corpuscles (RBC), white blood corpuscles (WBC), hemoglobin (Hb) and red cell indices, serum protein, glucose, cholesterol, creatinine, creatine kinase (CK), serum glutamate oxalate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT), lactate dehydrogenase (LDH), bilirubin, urea, triglycerides and high-density lipoprotein (HDL) did not show appreciable changes following vas occlusion and after its non-invasive reversal. Although fructose, acid phosphatase (ACP) and zinc in the seminal plasma showed a significant reduction following vas occlusion, it could not be related to the morphology of seminal vesicle and prostate.

CONCLUSION

SMA vas occlusion and its non-invasive reversal do not damage the accessory reproductive organs.

Preclinical evaluation for noninvasive reversal following long-term vas occlusion with styrene maleic anhydride in langur monkeys

A preclinical evaluation for reversal through a noninvasive approach following long-term vas occlusion with styrene maleic anhydride (SMA) has been attempted in langur monkeys at the level of semen parameters, sperm functional tests, semen biochemistry, histology and ultrastructure of reproductive organs, hematology and serum clinical biochemistry including antisperm antibodies (ASA), prostate-specific antigen (PSA) and testosterone. Noninvasive reversal through palpation, percutaneous squeezing and electrical stimulation, forced vibratory movements and suprapubic percussion in the inguinal segments and per-rectal digital massage was attempted in seven langur monkeys after 540 days following vas occlusion. The results revealed instant azoospermia reversal on the same day of reversal with impaired sperm quality, which showed gradual improvement and normospermia with normal motility and viability after 60-90 days of reversal. Sperm functional tests, including ultrastructure of spermatozoa, indicative of sterility in the initial ejaculations, reached normalcy after 90-120 days of reversal. The seminal plasma biochemistry indicative of obstructive azoospermia regained a normal pattern after 90-120 days of reversal. The morphology of testes that showed focal degeneration during 540 days of vas occlusion and that of vasa deferentia that showed exfoliation of epithelial cells resumed to normal morphology comparable with control animals after 150 days of reversal. The morphology of the epididymis, seminal vesicle and prostate did not show appreciable changes following vas occlusion and after noninvasive reversal compared with those of control animals. Hematology, serum clinical chemistry, ASA, PSA and testosterone fluctuated within control limits, indicating safety of the procedure at the level of accessory reproductive organs. The results suggest that noninvasive reversal is feasible even after long-term vas occlusion with SMA and is safe without adverse side effects.

Status of immunodiagnosis and immunocontraceptive vaccines in India

The article focuses on the Indian initiative of making kits for diagnosis of various infectious and non-infectious diseases as well as reproductive hormones and hormones in various other endocrine disorders. Indigenous diagnostic kits for the detection of various infections such as filariasis, typhoid, amebiasis, Japanese encephalitis, hepatitis, HIV, dengue, leishmaniasis, malaria, rabies, toxoplasmosis, rotavirus, and group A streptococci have been developed. Agreements to transfer the know-how of some of these leads to industries have been signed. The know-how of enzyme-linked immunosorbent assay (ELISA) for detection of hepatitis C has been successfully transferred to industry and is being commercially produced. For detection of HIV-1 and HIV-2, indigenous diagnostic kits based on three different formats, namely ELISA, Western blot and rapid test have been developed and are being commercially produced by Indian industries. The factors influencing the successful transfer of laboratory-scale diagnostic assays from academia to industry and their commercial exploitation have been discussed. Indian scientists have made seminal contributions in exploring the possibility to develop an effective and safe contraceptive vaccine to control the increasing human population of India. Achieving contraception by means of vaccine is a novel approach, which entails generation of a specific antibody response against antigens critically involved in the process of mammalian reproduction. In India, three major programs on contraceptive vaccines based on the beta-subunit of human chorionic gonadotrophin ((beta)hCG) for women, ovine follicle stimulating hormone (oFSH) for men, and riboflavin carrier protein for both males and females have been initiated. The work at the National Institute of Immunology, New Delhi on contraceptive vaccine for women, based on (beta)hCG, has demonstrated, for the first time, that it is feasible to regulate fertility by such an approach. Basic research being carried out to achieve immunocontraception by interfering at sperm-oocyte interaction level has been briefly discussed. These developments are still at the research stage. In addition to advances in the area of contraceptive vaccines, a non-steroidal contraceptive oral pill has been developed by Central Drug Research Institute, Lucknow, commercially produced by two Indian pharmaceutical companies and has been incorporated in the National Family Welfare Program. Another interesting approach for fertility regulation in male has been developed in India, which involves vas occlusion with styrene maleic anhydride (SMA) and is currently undergoing clinical trials in human subjects.

Family planning needs: new opportunities, emergency contraception and other new technologies

Modern contraception is considered to be one the major advances of the 20th century. Yet, as the next century begins, it is estimated that there is still a largely unmet need for contraception, with millions of couples worldwide who express a wish to limit the number of their children but do not use or are not satisfied with their contraceptive method. While the reasons are numerous, it is clear that there is a need for improved and new methods which are easier to use, under the user's control, with fewer side-effects and responding to the needs of different groups of users, including men. To respond to this need, current contraceptive research and development efforts focus on five main areas: emergency post-coital methods, user-controlled long-acting methods, dual protection methods against both pregnancy and sexually transmitted infections, methods for men, and methods with fewer side-effects including some that are more targeted to specific reproductive biological events. A number of leads are presented which are at various stages of development. Concluding remarks stress the numerous challenges of contraceptive development, not the least of which is the vision required of what the needs of future generations will be, since it takes 10-15 years to bring a new contraceptive to the market. More fundamentally, overall progress towards reducing the unmet need for contraception will depend on the status of women, specifically their decision-making power, and access to education and income.

Trends in male contraception

Methods that are available for male contraception, namely coitus interruptus, condoms, and vasectomy, have been used since the 19th century. With the exceptions of a few improvements of these methods, no major progress has been made with respect to introducing new male contraceptives since then. It is extremely urgent to develop new, safe, effective, and reversible male contraceptive methods. Among all male contraceptive methods that are being investigated, the hormonal approach is the closest to clinical application. Hormonal contraception provides pregnancy protection by means of spermatogenic suppression. Androgen-progestin regimens currently represent the best available hormonal combination for induction of a profound suppression of spermatogenesis. Further development of new steroids is mandatory for increasing the choices of available contraceptive formulations and to optimize long-term safety of these regimens.

Current status of fertility control methods in India

Approximately 48.2% of couples of 15 to 49 years of age practice family planning methods in India. Female sterilization accounts for 34.2%, with male sterilization declining from 3.4% in 1992-93 to 1.9% in 1998-99. Use of the condom increased to 3.1% from 2.4%. There is an urgent need for research to develop new contraceptive modalities especially for men and also for women and to make existing methods more safe, affordable and acceptable. Current efforts in India to develop a male contraceptive are mainly directed towards (i) development of antispermatogenic agents to suppress sperm production, (ii) prevention of sperm maturation, (iii) prevention of sperm transport through vas deferens or rendering these sperm infertile and (iv) prevention of sperm deposition. Research work in the field of prevention of sperm transport through vas deferens has made significant advances. Styrene maleic anhydride (SMA) disturbed the electrical charge of spermatozoa leading to acrosome rupture and consequent loss in fertilizing ability of sperm. A multicentre phase-III clinical trial using SMA is continuing and it is hoped that the SMA approach would be available in the near future as an indigenously developed injectable intra-vasal male contraceptive. The safety and efficacy of available oral contraceptives were evaluated. An indigenously developed oral contraceptive 'Centchorman', which is a nonsteroidal, weakly estrogenic but potently antiestrogenic, was found to be safe and effective and is now being marketed in India since 1991 as a 'once a week' pill. Cyclofem and Mesigyna have been recommended as injectable contraceptives with proper counselling and service delivery by Indian studies. It has been recommended that these injectable contraceptives be added to the existing range of contraceptive methods available in the National Family Planning Programme. Based on the Indian studies CuT 200 was also recommended. Studies have indicated the advantage of intrauterine devices (IUD); they are long acting, relatively easily removed and fertility returns rapidly after their removal. Recent studies have recommended CuT 200 for use up to 5 years. The combination of some plant products i.e. Embelia ribes, Borax and Piper longum has been found to be safe and effective as a female contraceptive and the results of phase-I clinical trials are encouraging. Research work is going on in the country in various areas with special reference to hormonal contraceptive - a three monthly injectable contraceptive, immuno-contraceptives, antiprogestins, etc.