Fostering hopes: Lab-produced sperm could transform fertility treatment

Eoghan Cunnane

Imagine a future where a diagnosis of untreatable male infertility is no longer the end of the road – because science has found a way to produce human sperm from lab-engineered testicular tissue.

This might sound like science fiction, but I’m leading a team of researchers at the University of Limerick (UL) to work on making the production of human sperm from lab-engineered testicular tissue a reality. If successful, this could redefine fertility treatment and bring hope to the millions of people around the world affected by male infertility.

Why now? Because male reproductive health is in decline – and the numbers are too stark to ignore.

Over the past seven decades, sperm counts have decreased dramatically while conditions like testicular cancer, hormone imbalances and genital malformations are on the rise.

The precise causes of declining male reproductive health are still being debated. While genetics may play a role, no single genetic factor has been shown to affect male fertility at a population level. Instead, much of the focus has turned to the environment, particularly endocrine-disrupting chemicals.

These chemicals, which can interfere with hormone function, are found in common items such as plastics, pesticides, cosmetics and even painkillers. There is growing evidence that exposure to these substances in the womb can increase the risk of testicular cancer, reduce sperm quality, and lead to male infertility later in life.

For some men, fertility issues are treatable – lifestyle changes, hormone therapy, or surgery to correct blockages in the reproductive tract can help. But for a large proportion, there is no identifiable cause.

This type of unexplained infertility, known as idiopathic infertility, currently leaves patients with only one option: surgical sperm retrieval (SSR).

SSR involves surgically opening the testicles to search for viable sperm for use in assisted reproductive technologies like IVF. However, success is far from guaranteed. In some cases, the chance of finding even a single usable sperm cell is as low as 40%.

And if SSR fails, the only option left is to use donor sperm – a difficult and emotional decision for many people.

So, given the ethical and biological limits on experimenting directly with humans, researchers have turned to preclinical models to study the human testes. These include ex vivo tissue (human or animal tissue studied outside the body), in vitro cell cultures (human testicular cells grown on lab plates), and animal models (typically rodents or primates).

Our research is attempting to overcome this challenge by combining biology with mechanical engineering and materials science. We started by analysing human testicular tissue samples from a range of donors, building a detailed understanding of how the tissue functions.

This data was fed into the design of model systems that replicate human testicular tissue – not just biologically, but mechanically and structurally. The ultimate goal is to create a model that can not only mimic testicular function but produce viable human sperm.

Lab-produced sperm could revolutionise fertility care. It might one day offer a solution to men who have undergone failed SSR procedures, childhood cancer survivors whose fertility was damaged by chemotherapy or radiation, and male patients with severe, unexplained infertility who currently have no treatment options.

This isn’t just a scientific experiment. It’s about restoring hope to those for whom existing medical approaches have run out of answers.

Cunnane is Associate Professor in Biomedical Materials Engineering, University of Limerick