Vas deferens – Temporarily Closed

4. August 2011
Share article

More and more men decide in favour of sterilisation. In contrast to traditional vasectomy, a procedure using a special plastic plug can be easily undone later. Its approval has however been protracted over years.

More and more men go to the urologists’ clinic and have vasectomies done – that is, an abscission of the spermatic duct (vas deferens). Up to one third of those operated complain thereafter of pain from testicular back pressure: newly formed sperm can no longer leave the epididymis, swelling is the result. Other causes of discomfort include inflammation and the increased formation of connective tissue.

It’s true that a vasectomy can in theory be reversed. Surgeons seek in this case to repatch the severed vas deferens under a microscope. The results vary widely, in some publications researchers speak of a 50-percent success rate, in other articles up to 80 percent of all cases fertility can apparently be restored. The longer since the vasectomy was done, the lower the chances are. If there’s a change in life circumstances some years after the surgery by way of a late marriage and there arises a renewed desire for children, “he” has a problem. Alternatives are required.

Plastic in the body

The Indian researcher Sujoy Kumar Guha has, precisely for these men, developed a method: In the RISUG method (Reversible Inhibition of Sperm Under Guidance) urologists inject a special gel under local anesthesia into the vas deferens. RISUG is a synthetic mixture of two components, namely styrene (a base material of polystyrene), and maleic anhydride, an organic acid compound. Dissolved in dimethyl sulfoxide and under bombardment using gamma radiation in the laboratory, a gel-like polymer forms.

After injection into the vas deferens, the plastic hardens quickly. The sticky mass doesn’t close off the involved structures completely, a pressure equalisation of the epididymis remains. And if semen analysis is negative (studies showing that the process takes a maximum of five days) the surgery is said to be successful. Only one in 250 men have remained fertile after the procedure, report Indian urologists. Scientists suspect that, due to moisture in the vas deferens, positive charges form on the polymer. If sperm, with their surface negative charge, pass through these semi-permeable barrier, their cellular membrane gets damaged. What’s more, the flagella stop functioning – and so each journey toward the egg comes to an end.

This is an interesting method especially for couples with a desire to have children later in life: the production of sperm is preserved, but contraception involves neither unwanted hormones nor are annoying condoms necessary. The procedure has no effect on the virility or amount of ejaculate. And if the topic of pregnancy is on the agenda, the plastic can be virtually flushed out with dimethyl sulfoxide. Even after years, men who after using this method were made temporarily sterile, were, according to studies, able to have children again. However, the procedure had to be repeated with some patients three to four times, by which time the plastic was removed entirely.
Sujoy Kumar Guha still aspired nevertheless to do better: he replaced the old well-known polymer with copper and iron oxide grains. In pulsed magnetic field, the particles began to migrate. In the near future, according to Guha, this will make it possible to regain fertility without surgery.

Staying power pays

The path from the laboratory to clinical practice is known to be a long one. The first systematic studies began in 1993 with 17 Indian patients, all of whom were by this method made temporarily infertile. A clinical phase III trial of 193 subjects followed seven years later. In mid-2002, RISUG was just about to launch in Guha’s home country when the setback came: doctors from the World Health Organization (WHO) analysed the work – and were skeptical. Although the procedure in itself was convincing, all of the requirements of manufacture of plastic gel however did not correspond to any pharmaceutical standard, it was said. Also, the studies themselves encountered criticism, they were partly missing – according to appraisers – important data. Nevertheless, the Indian team did not admit defeat.

Then the next bad news: The Indian Council for Medical Research also called for toxicological evidence of safety, since in some patients the scrotum had swollen and proteins were able to be detected in the urine. Fortunately, the plastic mixture proved to be harmless, and development was able to proceed. Regardless, Indian pharmaceutical companies showed little interest in the low cost product that would only be used once. In addition Guha, born 1939, was now in retirement. Was it the end of a dream?

A leap over the pond

It’s here that Elaine Lissner came into the picture. The American, already active in the Male Contraception Information Project, acquired the international rights to the technology for $100,000. With the specially founded Parsemus Foundation she wants to conquer the market by 2015. Before then, some milestones have to be reached: After analysis of RISUG preparations which were produced in India, researchers are now creating plastic product samples with a focus on quality and purity. If the supply of gels matches the expected standard, it will be at the latest in the summer of 2011 that pure Vasalgel – as it has been newly named – will be produced in larger quantities for clinical trials. Parsemus will then dedicate itself to issues of biocompatibility. If everything goes well, the consortium expects toxicological studies, as well as the start of clinical trials in the U.S, in 2012. Meanwhile, the wind has also changed in India – clinical phase III trials are to be conducted anew, this time with the full support of the government.

Who should pay?

The noble goals of Elaine Lissner could however fall short of money – around five million U.S. dollars is needed by Parsemus for all the steps. The American is now hoping for American public support or foundation funds. The global network WomanCare might possibly have an interest that the development of new, affordable technologies in pregnancy prevention accelerates its availability in Africa, Asia and Latin America. Opportunities also exist with the Bill & Melinda Gates Foundation or the Susan Thompson Buffett Foundation.

RISUG would profit from the age-old dream of a “male pill”. Purely pharmacological approaches are still stuck in their infancy. Urologists also expect that the launch of the polymer could have a major impact on the sales of condoms. Whether it’s true that RISUG not only kills sperm but also the Immune Deficiency Virus (HIV) is the subject of further study.

0 rating(s) (0 ø)

Comments are exhausted yet.

Copyright © 2017 DocCheck Medical Services GmbH
Follow DocCheck: