Human sperm grown in a lab for the first time, claims study

Is this the first lab-grown human sperm? A French team claiming the achievement has moved a stage closer to convincing sceptics by having the work published in a peer-reviewed journal. But some researchers say the evidence offered still falls short of what’s required to make such a large and historic claim. 

Through a 20-year project, the French researchers say they have made human and rat sperm, starting with testicular cells called spermatogonia. Japanese researchers made mouse sperm in 2011, as did Chinese researchers earlier this year, but the French team is the first to claim the step of making human spermatozoa. “It’s the final 20 per cent of the process,” says Philippe Durand of Kallistem, the company in Lyon pursuing the project.

Last year, Kallistem earned a patent for the technique, but this failed to convince sceptics. Now, the work on rat and human sperm has been published in the peer-reviewed scientific journal Biology of Reproduction.

Kallistem says the aim is to help men unable to make sperm because of treatment for childhood cancer, which often destroys spermatogonia. By taking and freezing biopsies containing spermatogonia before boys begin treatment, the technique could make sperm from these cells in the future when they decide to have children.

The key, says Durand, is a bioreactor in which bundles of seminiferous tubules – the structures in the testes that contain spermatogonia – are packaged into tiny cylinders of a watery gel called chitosan. The gel is porous and allows air to diffuse in and out of cells. “It’s the permeability that counts, allowing the passage of oxygen and carbon dioxide in and out of the cells,” says Durand. The gel also keeps bacteria in check, he says.