Human-rabbit embryos created

[I, Brian]

Disturbing - a group of Chinese scientists have apparently created Human-rabbit embryos:

http://www.newscientist.com/news/news.jsp?id=ns99994060

Human-rabbit embryos intensify stem cell debate

"Human" embryonic stem cells have been harvested from cloned embryos created by fusing human cells with rabbit eggs, claims a soon-to-be published report by Chinese scientists.

The goal of the experiments by Hui Zhen Sheng of Shanghai Second Medical University was to create a new source of embryonic stem cells (ESCs). These have the ability to transform into any tissue, making them potential sources of replacement cells for the treatment of many diseases.

However, at present, these can only be derived from fertilised human embryos, resulting in widespread controversy. The embryos must be destroyed to harvest ESCs, which some see as ending a potential human life.

In contrast, few experts think the rabbit-human hybrid embryos could be develop beyond the earliest stages. Also, cells from the hybrid contain only a tiny amount of rabbit DNA in mitochondria, structures that supply chemical power to the cell, suggesting the cells might be useful for human therapies.

But the immediate reception of Sheng's paper suggests it is unlikely to calm the fierce debate. It has already been hailed as an important advance, questioned for its scientific rigour and sensationalised as a bizarre mixing of human and animal parts.

Chinese whispers

Rumours of Sheng's work have been circulating for two years in scientific circles and occasional news reports. But she had a hard time finally getting the work accepted by the scientific community. "I was frustrated that it took so long to get the paper published," she told the journal Nature. "And it still may take a while for people to accept the work." One reason for the scepticism is that other researchers have had almost no success in their experiments with interspecies cloning techniques.

Interspecies cloning has attracted researchers because eggs from humans, or endangered animals, are hard to obtain. Instead, scientists use eggs from a readily available source, e.g. cattle, empty out their chromosomes, and insert nuclear DNA from a donor, e.g. a human. The process "reprograms" the genetic material and creates an embryo that is the genetic twin of the donor.

Except for a few animal cloning experiments where the two species were closely related, all these experiments have failed. But in the August issue of Cell Research (vol 13, p 251), a peer reviewed journal of the Chinese Academy of Sciences, Sheng reports remarkable success.

Using donor cells from the foreskins of a five-year old boy and two men, and facial tissue from a woman, her team created hybrid rabbit-human embryos and from them derived ESCs that had the ability to transform into many tissue types.

Human reprogramming

Some see publication of the work as an important step forward. "This is the first paper to convincingly show that you can get human reprogramming," Robin Lovell-Badge of the National Institute for Medical Research in London told Nature.

But others point out shortcomings. ESCs are supposed to be able to reproduce indefinitely, for instance, something the Chinese group did not demonstrate. And that tiny bit of rabbit DNA in the cells could still be a problem for any medical applications. The few rabbit genes present may generate proteins that would be rapidly attacked by the human immune system.

Robert Lanza of Massachusetts-based biotech company Advanced Cell Technology says: "If this is true, it's very important. But their results are very hard to believe."

Lanza's team has tried and failed to derive ESCs from human-cow and human-rabbit embryos. He is now convinced those experiments are doomed for very basic biological reasons. But Lanza says Sheng could easily win over doubters by supplying their hybrid cells to other ESC labs to test.

His own work is now focused on other ways to reprogram cells, partly because of the public reaction to his experiments that mixed human and animal cells. "There is always the yuck factor," he told New Scientist.

[NCrespi]

Does This Mean Human Babies With Big Ears & Small Tails That Will Say: "what's Up, Doc?"

[petertdavis]

I certainly hope that's not where the research is going.