Antlers could hold clues to stem cell research

Research carried out by veterinary scientists at the Royal Veterinary College reveals that deer antler regeneration may use stem cells and involves similar mechanisms to those used in limb development. The research could take us towards a ‘holy grail’ in human medicine: the ability to restore organs damaged through trauma, disease, cancer or excision.

Many lower animals such as newts can renew damaged parts of their bodies but antler growth is the only example of mammals being able to regrow large complex organs.

Deer antlers are large structures made of bone that annually grow, die, are shed and then regenerate. Although dead tissue when used for fighting, during growth they consist of living bone, cartilage blood vessels and fibrous tissue covered in skin.

The research suggests that unlike the regenerative process in the newt, antler growth does not involve reversal of the differentiated state but is stem cell based. Antler growth appears to involve specific stimulation of the necessary stem cells present in the locality. If we can understand how deer have adapted the normal means of development, cell renewal and repair to redevelop a complete organ, it may be possible to achieve the same outcome in damaged human tissues.

The research also shows that developmental signaling pathways are important. ’Antler-specific’ molecules may not exist and growth may be a particular use of molecules that all mammals share. There is similarity in the signals used to stimulate antler growth and those used for other processes.

Antler shedding is triggered by a fall in the hormone testosterone, a hormonal change that is linked to an increase in day length. Although the antler growth cycle, from the shedding of the velvet skin and casting of the dead antler to regrowth, is closely linked to testosterone, oestrogen may be a key cellular regulator, as it is in the skeleton of other male mammals. Identifying how hormonal and environmental cues interact with local signalling pathways to control antler stem cell behaviour could have an important impact on human health, if this knowledge is applied to the engineering of new human tissues and organs.

Professor Joanna Price, who heads research on antler regeneration at the Royal Veterinary College, said “The regeneration of antlers remains one of the mysteries of biology but we are moving some way to understanding the mechanisms involved. Antlers provide us with a unique natural model that can help us understand the basic process of regeneration although we are still a long way from being able to apply this work to humans”.

Stem cells have the remarkable potential to develop into many different cell types in the body. Serving as a sort of repair system for the body, they can theoretically divide without limit to replenish other cells as long as the person or animal is alive. Stem cell research can help develop therapies for diseases that do not have any treatment at the present time, and develop new approaches towards prevention and treatment of debilitating diseases affecting the nervous system and key organs, such as Parkinson’s.