Work with stem cell therapy at the UC Davis Veterinary Medical Teaching Hospital has allowed horses to overcome debilitating injuries and may someday contribute to improved health outcomes among humans as well.
Dr. Larry Galuppo, the hospital’s chief of equine surgery, leads a team that uses injected stem cells in place of traditional rehabilitative therapies. Their efforts over the past eight years have restored the ability of horses with severe leg injuries to walk and even run again.
In one instance, Galuppo and his team were able to help a race horse return to competition.
“When we first started, this horse had a really bad knee injury,” Galuppo said. “It had split a lot of the cartilage. We (did) some therapy using fiber and glue and mixed that with stem cells, and I filled all of those cartilage defects and was able to do surgery again to re-evaluate the healing.
“The cartilage looked like it was healing nicely and the horse went back and did very well. It ran in upper-level (competition) and was successful as a race horse.”
In other, less dramatic instances, Galuppo’s team succeeded in enabling horses to engage in light riding once again.
“In the big spectrum: It’s from the professional race horse going back to full performance to the loved horse with a severe injury just being safe for that owner,” Galuppo said.
Stem cells have the unique ability to differentiate into specialized cell types, which can then be used to repair damaged tissues and organs.
Veterinary surgeons at the teaching hospital have injected the cells into horses suffering from tendon, ligament and bone injuries. While the therapy has not worked in every case, it has produced results ranging from pain reduction to substantial regeneration. The best outcomes have occurred in horses whose injuries were detected early.
“An old tendon lesion is basically scar tissue and you can’t bring that back from the dead,” Galuppo said. “The stem cells are doing something, whether it’s to make them feel better, taking away the pain, or whatever, but it’s not making a new tendon.
“That’s why we’ve kind of shifted from trying to resurrect old tendons, which doesn’t happen, to the point where we’re trying to catch them early before there is a major tear and use this therapy to hopefully regenerate a normal tendon.”
The work with stem cell therapy started in 2007, when Galuppo and his team first attempted to derive, culture and store the cells. Galuppo said they subsequently began testing the therapy out on a group of horses with injuries that had not responded to traditional methods.
“We have nothing else to lose, let’s throw some stem cells in there and see what happens,” Galuppo said of his team’s mind-set. “They all didn’t get better, but a number of them did where they really shouldn’t have. “
Galuppo’s team used bone marrow at first before deriving stem cells from additional sources, each of which offers advantages and drawbacks.
In the case of horses younger than 15 years, bone marrow stem cells are relatively easy to collect.
“In the younger horses, we can get it from the hip, and in the older horses, we can get it from the sternum,” Galuppo said.
For horses older than 15, stem cells derived from fat are often a better option because they remain in sufficient quantities throughout the life of the animals.
“We use fat-derived stem cells for older horses because, just like in people, the number of stem cells in the bone marrow declines and it’s really hard to get the stem cells from bone marrow,” Galuppo said.
Stem cells from umbilical cord blood are used to treat severe conditions of the foot, such as laminitis, for which the cells seem to have the highest regenerative potential. Galuppo’s team is still in the early stages of its work with umbilical cord tissue and further research is expected to be conducted at UC Davis.
Stem cells can be introduced to the body of a horse via either injection–often guided by ultrasound–at the site of the injury or injection into an artery.
“We use different routes of therapy depending on the injury,” Galuppo said. “If there’s a big tear, we will actually go with a needle right into the tendon or ligament.
“If it’s a diffuse area, then we will usually go through the arteries. We’ll inject stem cells right in the arteries and we’ve done research where we’ve had the stem cells labeled, so we can actually follow them and how they flow into the vessels and into the tissue. A lot of the injuries are occurring down in the foot of the horse, which you can’t get a needle into, (so) we treat those through the arterial supply.”
The use of stem cell therapy in horses and, particularly, in dogs and other small animals may eventually contribute to human health as well.
“Small-animal naturally occurring disease models are just perfect for what’s going on in people. We can use regenerative medicine for kidney problems, liver problems, all of these (conditions) that you can have in people,” Galuppo said. “And now we have paralleled our research and translational medicine with what they’re studying at the Institute of Regenerative Cures at the UC Davis Med Center.”
Therapies involving stem cells can also be employed more easily in animals than in humans due to different regulations for veterinary and human medicine.
“So far–it may change in the future–… we are not regulated by the FDA,” Galuppo said. “As of now, we are, with the owner’s consent, able to use these therapies early on (whereas) in human medicine, they have to get FDA approval, which takes years.
“It’s not a miracle by any means. It’s one of our tools and I think things are leaning towards using biologics in medicine. I hope to see that in the future and I hope that veterinary medicine is paving the way for both (animals) and humans.”
This article was authored by Will Bellamy, and you can reach him at [email protected].