Researchers in the United Kingdom have succeeded in coaxing human embryonic stem cells into becoming sperm. Though the process is inefficient and there is some debate over whether the sperm are fully developed, this work will hopefully lead to a much-needed experimental system for understanding the biology of sperm development.
The more controversial and longer-term outcome, as suggested by the lead researcher, Dr. Karim Nayernia, is that stem cells might one day be used to generate sperm as a treatment for male infertility.
It's worth pointing out that the same researcher accomplished a similar feat in 2006 using mouse embryonic stem cells to produce mouse sperm. Only in this case, the experiment was taken one step farther - the sperm were injected into mouse eggs. Though the mothers gave birth to live pups, they suffered from many abnormalities. All died within 5 months.
This example illustrates the technical and ethical challenges in moving reproductive technologies from the lab to the clinic. There really isn't an easy path. It also should serve as a reminder that the United States needs to address the relative vacuum in efficacy, safety, and ethical oversight for the rapidly developing field of reproductive technology (a ~$10 billion/yr industry).
In the UK, reproductive technologies are closely regulated at the federal level by a governing body known as the Human Fertilisation and Embrology Authority (HFEA). The UK has carefully crafted rules on the research and clinical use of gametes (sperm/eggs), human cloning, genetic technologies as applied to human embryos or gametes, etc. In this case, any procreative use of sperm created from stem cells is prohibited.
In the United States there are few rules. The practice of medicine, by and large, is regulated at the state level. Our federal government leaders have been unwilling to call for a national discussion on implementing uniform rules for gamete donation, embryo creation, research, storage, etc. (a report from the 2004 Presidential Council on Bioethics notwithstanding). In fact, when Canada passed its Assisted Human Reproduction Act in 2004, it left the United States as one of the few developed nations without a national policy.
The result has been lax medical oversight, introduction of new technologies without sufficient studies on safety, and a piecemeal collection of rules.
The progress coming from the UK reminds us that we need to have a national discussion soon.