Scientists have developed an infertility technique that may help some infertile men to father children.

Around half of all human infertility is attributable to male defects, and 70 to 90% of these stem from impaired sperm development.

Researchers from the University of Pennsylvania, whose research is published in the journal Nature Medicine, have developed a way to generate viable sperm cells using a technique called germ cell transplantation.

The technique has been successfully tested in mice.

The researchers transplanted germ, or immature, cells from infertile mice into the testes of mice that produced fully functioning sperm.

This transfer restored fertility and resulted in offspring carrying the genetic makeup of the infertile donor males.



Cancer implication

In an accompanying editorial, Edinburgh-based fertility experts Dr Howard Cooke and Dr Philippa Saunders say the findings of the study could potentially help childhood cancer survivors to become fathers.

It is expected that by the year 2010 childhood cancer survivors will make up 0.25% of the adult population.

However, many cancer treatments can cause damage to the body's genetic material, leading to infertility.

Adult sperm can be frozen and stored for use in IVF and other fertility techniques

But, at present, doctors are not able to preserve children's sperm cells in a way that will make them useful later in life.

However, the new study shows that sperm cells retain the potential to function effectively despite being placed in a defective environment.

Therefore it raises the possibility of successfully preserving immature sperm cells and successfully reintroducing them into the testicles following cancer treatment.



Dr Cooke and Dr Saunders also argue that the research opens up the possibility of a new way to correct genetic faults. However, they warn that such a use would be fraught with ethical difficulties