Antlers hint at medical leap

The possibility of severed human limbs regenerating has come a step closer following 25 years of research by a Dunedin scientist which has isolated the cells that allow deer to grow new antlers each year.

AgResearch Invermay scientist Chunyi Li has determined that stem cells at the base of antler, or the pedicle, allow deer to grow a fresh set of antlers each year.

They are the only mammal to do so.

Dr Li said it was previously thought the annual antler-growing process was initiated by an embryonic phase, or "dedifferentiation of mature cells", but his discovery confirmed that hitherto unknown stem cells ran the process.

While confident the technology he used had application for human limb regeneration, Dr Li said such an advance was many years away and involved different research skills.

Dr Li said in a remarkable process, the stem cells in deer pedicles were triggered each spring to form cartilage, bone, vessels and other cells, and it was a process of triggering such a reaction in humans that could result in limb regeneration.

"We know, based on antler regeneration, that bone membrane cells are crucial. If we can turn on cells [in humans] that resemble pedicle membrane bone cells, you may be able to deflect scar formations towards a regeneration pathway," he said.

AgResearch applied biotechnologies manager Jimmy Suttie said, despite claims from the Royal Veterinary College in the United Kingdom that it had made the discovery, that honour went to Dr Li.

"Another team from the UK has claimed to be the initial discoverers of the role of antler stem cells. However, Dr Li has published his work at least two years earlier than that group."

AgResearch was in no doubt that Dr Li and his Invermay colleagues discovered the role of stem cells in deer antler regrowth, Dr Suttie said.

Each spring, deer start developing antlers, with growth accelerating through the summer at up to 2cm a day.

Antlers reached their full size in autumn, but by the next spring they were cast and the process started again.

Farmers removed the antlers in their velvet stage in spring, with the velvet used in Asian medicine.

Dr Li said his breakthrough came when he realised an estimated 3.3 million cells in a 2mm thick layer around the pedicle provoked up to 20kg of antler growth in just 60 days.

"It made me ask if it was stem cells that created that growth?"

His discovery has had little publicity so has yet to be picked up by other scientists, but that could change when he addresses an international conference of stem-cell researchers in Australia later this month and another deer research conference in Chile next year.

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Stem cells
- A class of undifferentiated cells able to grow into specialised cell types - for example, skin, muscle, bone.

- Commonly, come from two main sources: embryos (embryonic stem cells) and adult tissue (adult stem cells).

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