Boys who contract cancer could in future have their fertility preserved 鈥� with the help of a mouse.
In a proof-of-principle experiment, researchers have shown it is possible to grow immature human testicular tissue in mice. The next step will be to mature the tissue and harvest sperm cells. These would then be frozen for a pre-pubescent cancer patient to use later in his life.
Around 1 in 650 children contract cancer before puberty and about 25% of these die. Most of the survivors are left infertile from the toxic side effects of chemotherapy. 鈥淭here鈥檚 really nothing you can do today to preserve fertility,鈥� says Pasquale Patrizio at Yale University Fertility Center in New Haven, Connecticut.
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The problem is that while adult males can simply freeze some sperm before treatment, young boys are not capable of ejaculating. But Patrizio鈥檚 team have now worked out a technique to derive sperm from immature tissue.
Tissue samples
Tissue from young boys is hard to work with and obtaining it raises ethical questions, so for their experiment the researchers took testicular tissue samples from normal adults and adults with 鈥渋mmature鈥� testes (for example vasectomised men or men undergoing hormone therapy for a sex change). They then implanted this tissue under the skin on the backs of mice.
The normal tissue did not hook up with blood vessels and quickly shriveled. But the tissue from 鈥渋mmature鈥� testes was still viable after 19 weeks, when the mice were killed for examination.
Patrizio believes it should be possible to harvest sperm if the tissue is left in place for another 10 weeks. The next step in the research will be to use tissue from boys.
Moral grounds
Patrizio acknowledges that the work could make some people uncomfortable on moral grounds.
In a recent report on regulations of reproductive technology, the US President鈥檚 Council on Bioethics recommended federal legislation to ban researchers from growing human embryos in another species. Although Patrizio鈥檚 work on sperm would not be covered by such a ban, it is still likely to be controversial.
A more practical concern is whether growing sperm in a mouse might lead to contamination with viruses from the animal. But Patrizio points out that when a patient wanted to father a child, an egg would be fertilised by injecting a single sperm. 鈥淲e are not going to use tissue,鈥� he says.
Patrizio presented his work at the American Society for Reproductive Medicine鈥檚 annual meeting in Philadelphia.