Promising use of stem cells for tendon injuries in flat racehorses

Research from Australia suggests that treatment with bone marrow derived mesenchymal stem cells (BM
MSCs) results in improved healing compared with a controlled exercise rehabilitation program alone. 

 Strain of the superficial digital flexor tendon (SDFT) injury is one of the most common and significant injuries in racehorses. The tendon plays a crucial role in the movement and stability of a horse's limb, particularly during high-speed activities like racing. 

 The primary treatment is rest, often for months, to allow the tendon fibres to heal. Full recovery can take over a year, but even then, the tendon may remain weaker and more prone to re-injury, especially if the horse returns to high-intensity activities. Tendons have a limited ability to regenerate, and the damaged fibres are often replaced by scar tissue, which is mechanically inferior and increases the risk of future injury. 

 Research by Rachel O. Salz and colleagues investigated how SDFT (superficial digital flexor tendon) injuries in Thoroughbred racehorses respond to different treatments. They compared the effects of a controlled exercise recovery program alone with those of the same program combined with either autologous bone marrow-derived stem cells (BM-MSCs) or allogenic adipose-derived stem cells (A-MSCs). (Autologous stem cells are taken from the same individual receiving the treatment. Allogenic stem cells come from a donor) 

 The study analysed clinical and race records of 213 Thoroughbreds to see if stem cell treatments improved the chances of horses returning to racing compared to just using the exercise recovery program.  

One group of horses followed a controlled exercise rehabilitation program (CERP) without stem cell treatment, while another group followed the CERP with additional treatment using either BM-MSCs or A-MSCs injected into the damaged tendon. 

The study found that horses treated with intralesional bone marrow-derived mesenchymal stromal cells were three times more likely to return to racing compared to those undergoing only the controlled exercise rehabilitation program. Additionally, these horses were at least twice as likely to participate in five or more races after returning, indicating that the treatment had a lasting impact beyond just recovery. 

 In contrast, the response to adipose-derived mesenchymal stem cells (A-MSCs) was less encouraging. The analysis showed no significant increase in the likelihood of returning to racing or completing five or more races with A-MSC treatment compared to the rehabilitation program alone. However, the researchers noted that the smaller number of horses in this treatment group might have limited the ability to detect a potential effect. 

 For more details, see: 

 Treatment of racehorse superficial digital flexor tendonitis: A comparison of stem cell treatments to controlled exercise rehabilitation in 213 cases 

Rachel O. Salz, Christopher R. B. Elliott, Tomas Zuffa, Euan D. Bennet, Benjamin J. Ahern 

Equine Veterinary Journal (2023) Vol 55, pp 979-987 

https://doi.org/10.1111/evj.13922

EVJ presents growing evidence for regenerative medicine

Processing autologous conditioned serum
for intra-articular injection 
(photo courtesy of Lynn Pezzanite)

Regenerative therapies have become more widely used in equine practice over the past 20 years. They involve treatments that aim to repair or replace damaged tissues and promote healing using the body's natural regenerative capabilities. These therapies are increasingly used to treat injuries, particularly those affecting tendons, ligaments, joints, and cartilage.

 

Despite considerable advances in the field, the true efficacy of veterinary regenerative medicine is still questioned in many instances. To enable easy access to the latest knowledge on the topic, the Equine Veterinary Journal (EVJ) has published a ‘Special Collection’.

Guest edited by Lynn Pezzanite, the Special Collection contains the ‘Top 10’ recent publications from EVJ relating to regenerative therapies over the past five years which may help practitioners select one treatment over another for a specific clinical indication.

 

The term ‘regenerative therapies’ is a broad definition for innovative medical therapies that enable the body to repair, replace, restore, and regenerate damaged or diseased cells, tissues, and organs, while ‘biological products’ are those made from living material (human, animal, plant, microorganisms) used to treat or prevent disease. 

 

Options available to clinicians in equine practice include point-of-care blood or tissue derived products (autologous – derived from the same individual) including platelet rich plasma (PRP), autologous conditioned serum (ACS or interleukin receptor antagonist protein/IRAP), autologous protein solution (APS), bone marrow aspirate concentrate (BMAC or stromal vascular fraction) or cultured stromal cell-based products (autologous or allogeneic – derived from a different individual of the same species). 

 

“Equine practitioners have access to use regenerative medicine to treat joint and soft tissue disorders as well as a variety of other conditions such as wounds, ophthalmic or theriogenology indications,” said Lynn. “However, in some instances due to lack of rigour in clinical study design, lack of demonstrated consistency in product formulation and lack of regulatory oversight that would assure appropriate standards, the true efficacy of some therapies remains controversial. We aim for this special collection to bring some clarity, to aid vets in their treatment choices.”

 

To see the Special Collection, go to::

 

https://beva.onlinelibrary.wiley.com/hub/journal/20423306/homepage/regenerative-therapies-collection