What are stem cells?

Stem cells are cells that are able to self-renew (able to replicate many times in the same state) and able to become or ‘differentiate into’ many types of cell. There are broadly two types of mammalian stem cell: embryonic and adult. Embryonic stem cells are ‘totipotent’ and can become any cell in the body and therefore could form a whole organism. Adult stem cells, such as those used by VetCell, are only ‘multipotent’ and are more limited in their differentiation but can become any cells within a closely related family. This limited differentiation actually makes them easier to control in the lab. Using adult stem cells avoids the controversy and restrictions associated with the use of embryonic stem cells.

Mesenchymal Stem Cells

VetCell uses mesenchymal stem cells (MSCs), which are adult stem cells that are able to become tendon cells (tenocytes), bone cells (osteocytes), cartilage (chondrocytes) and fat cells (adipocytes). These can be harvested from the bone marrow or from the Wharton’s Jelly of the umbilical cord. VetCell routinely uses the sternum (breastbone) or tuber coxae (hip) as a source of bone marrow in equine patients. This is done under sedation with little or no discomfort to the horse (at no point is general anaesthetic necessary). In humans this would be taken from the ilium (part of the pelvis).

The mechanism of repair is not yet well characterised but it is thought that when these cells are placed within a core lesion of a tendon, such as that typically seen in horses, the cells read the chemical signals of their environment and bring about an effective tissue repair. Research by Professor Roger Smith at the Royal Veterinary College, founder of the technology, has recently shown that stem cell treated tendons have much more normalised tissue formation showing the characteristic ‘crimp’ pattern associated with stretchy tendon tissue, rather than the amorphous scar tissue of untreated tendons. He has also shown that treated racehorses have half the chance of re-injuring following stem cell therapy, from 57% down to 27% (Godwin & Smith 2011).