Breakthrough in growing human sperm?

The sperm was grown in a laboratory in Newcastle from embryonic stem cells. Led by Prof Karim Nayernia, researchers developed a method of growing early-stage sperm from human embryonic stem cells by using retinoic acid, a vitamin A derivative.

They found that about 20 per cent of the cells produced early-stage sperm cells or spermatagonia and, after further culture, they could see a number of cells continue to split and divide. The breakthrough came when some cells continued to grow, elongating and growing a tail which caused them to move, and forming recognisable sperm cells.

Nayernia, of Newcastle University and the North East England Stem Cell Institute (Nesci), described the cells as “fully mature, functional” sperm, which he called In Vitro Derived (IVD) sperm. “This is an important development as it will allow researchers to study in detail how sperm forms and lead to a better understanding of infertility in men – why it happens and what is causing it. It will also allow scientists to study how cells involved in reproduction are affected by toxins,” he said.

The scientist, who created mice sperm six years ago using similar techniques, said that he used four criteria to determine whether the cells he produced were sperm. They were: the presence of proteins specific to sperm, one of which is located in the tail and very important for activating egg division; chromosome analysis, which showed that the sperm produced contained 23 chromosomes – this is specific to sperm cells; the shape of the sperm; and finally the movement of the sperm.

But his findings, published in the academic journal Stem Cells and Development, were met by a barrage of criticism by other scientists.

Dr Allan Pacey, from the University of Sheffield, said: “As a sperm biologist of 20 years' experience, I am unconvinced from the data presented in this paper that the cells produced by Prof Nayernia’s group can be accurately called spermatozoa.”

Prof Azim Surani, a specialist in physiology and reproduction at the University of Cambridge, said the cells should be tested to find out how they develop inside an animal egg and added: “These sperm-like cells made in a dish from embryonic stem cells are a long way from being authentic sperm cells.”

Prof Robin Lovell Badge, from the Medical Research Council Institute of Medical Research, also questioned the findings, saying that “they need much better evidence that such in-vitro derived sperm are normal,” but added that any progress “will be very important for research.”

Nayernia responded by saying that his research paper was clearly labelled a ‘proof of principle’ which concludes that it is in its early stages and further research is needed.
Nayernia added that his findings would not lead to human beings being produced ‘in a dish,’ but were rather “a way of investigating why some people are infertile and the reasons behind it.”