Stem cell therapy for tendon injuries is used increasingly in clinical practice, yet a number of important hurdles persist that made one group of researchers look at using embryonic stem cells rather than bone marrow-derived stem cells in horses.
"Obtaining mesenchymal stem cells obtained from a horse’s own bone marrow is invasive, and it then takes two to four weeks to culture the cells before they can be injected into the damaged tendon," said Debbie Guest, BSc, PhD, from the Centre for Preventative Medicine, Animal Health Trust in Newmarket, UK.
This near month-long delay is particularly concerning as it is speculated that stem cells must be injected into a damaged tissue early to achieve a functional improvement.
Embryonic stem cells (ESCs) that have been previously isolated from horses and maintained in cell cultures are an alternative option to bone marrow-derived stem cells.
"We are the first group to look at the use of ESCs in tendon injuries," explained Guest.
As part of their study, Guest and colleagues surgically created three core lesions in the superficial digital flexor tendon in Thoroughbred horses. Bone marrow-derived stem cells and ESCs were then injected separately into different sites.
Key findings were:
- ESCs survived in high numbers after being injected into the tendon lesions;
- High ESC numbers persisted for 90 days;
- Bone marrow-derived stem cells had < 5% survival by 10 days post-injection;
- ESCs were identified throughout the tendon lesion indicating that they migrated from where they were injected to fill the defect; and
- Bone marrow-derived stem cells remained where they were injected.
"These results suggest that ESCs could be a viable option for treating tendon injuries in horses," concluded Guest. "Since these stem cells can be used 'off the shelf,' horses can be treated immediately after being injured and do not need to undergo a bone marrow aspirate."
Guest added, "We are now doing further work to determine if the ESCs have turned into tendon cells and if they are able to regenerate normal tendon tissue. Understanding how the cells function to aid tendon repair is critical to ensure that stem cell technology is optimized to produce the best outcome for every horse that is treated."
The study, "Equine embryonic stem-like cells and mesenchymal stromal cells have different survival rates and migration patterns following their injection into damaged superficial digital flexor tendon" will be published in an upcoming edition of the Equine Veterinary Journal. The abstract is available online.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.