Stem Cells: The Mysterious, High-Tech Weapon In Laminitis Fight

Every year laminitis claims a startling number of Thoroughbred lives, with the most recent well-known case being Smart Strike, who succumbed to the disease in late March. Over the past few years, veterinarians have developed a new arrow in their quiver of weapons against the crippling condition.

Laminitis occurs when the laminar tissue of the hoof becomes inflamed, posing a risk to the connective tissue between the hoof capsule and the coffin bone. The illness can have a variety of causes and vary in its severity—some horses live with it for years without diagnosis, while others succumb to the disease in a few days. Conventional treatment includes supportive shoeing, anti-inflammatory drugs, and icing of the feet to relieve discomfort and encourage stabilization and eventually, regrowth of healthy hoof wall and tissue.

In recent years, veterinarians and equine scientists have tested the effectiveness of stem cells in the healing process for soft tissue injuries, and the podiatrists at Rood and Riddle Equine Hospital have examined their usefulness in laminitis cases. The results of a three-year survey of cases and results, presented at the 2014 American Association of Equine Practitioners Convention, have been encouraging in some circumstances.

Veterinarians learned that cases which were treated with stem cells quickly were most likely to show improvement. The median time from onset of laminitis to stem cell treatment in the study was 71.5 days. For horses treated before this threshold, there was an 87 percent chance of success after stem cell treatment. Horses treated later had a 53 percent chance of success.  All ten of the cases that received stem cell treatment less than 30 days after onset showed improvement.

Age appeared to play a role, too; median equine age of the 30 cases studied was 11. For younger laminitic horses treated with stem cells, there was an 82 percent chance of success, compared with a 50 percent chance for older horses.

One of the more high-profile cases to benefit from stem cell treatment for laminitis is Bal a Bali, the 2014 Brazilian Triple Crown winner. Fox Hill Farm purchased the horse after an extremely successful South American campaign but was alerted to a health issue while the horse sat in quarantine after disembarking the plane in the U.S. The problem turned out to be laminitis, which Dr. Vern Dryden treated with stem cells, cold therapy, and even maggot therapy.

On Saturday, Bal a Bali won the Grade 3 American Stakes at Santa Anita in his U.S. debut — after nearly a year's rehabilitation and training.

Although these numbers are heartening for cases of young horses receiving treatment quickly, Dryden cautioned the therapy is “not a magic bullet.”

“You have to have proper hoof care management of the laminitic foot” said Dryden, who is a certified journeyman farrier in addition to being a veterinarian in Rood and Riddle's podiatry department. “They've shown promise and they seem to be helping in some situations, but they're not a cure-all.”

Horses receiving stem cell treatment must also receive treatment for pain management, as well as corrective shoeing to lend support to the compromised foot while internal healing can take place—even as things improve internally, the dangers inherent in an unstable hoof are still present.

There is also still a lot we don't know about stem cell treatment for laminitis.

For one thing, there's the cost. Dryden said for a patient at Rood and Riddle, collection and processing of the mesenchymal stem cells derived from the horse's bone marrow is about $2,500 to $2,800. Perfusion, or delivery of the cells into a capillary above the hoof, is an additional fee and may need to be repeated—that's on top of frequent visits from the veterinarian and specialized shoes from the farrier.

Dryden said the cost of the treatment means any decision to proceed should be considered carefully beforehand.

Another challenge to the treatment, Dryden said, is that we're still not sure exactly how the cells work in the healing process—we know that there are fewer stem cells expressing certain genes such as “P63” found in lamellar tissue during a chronic case of laminitis as compared to healthy tissue, which is why it makes sense to boost their numbers. What we don't know is whether the stem cells are traveling to the inflammation site and developing into new, healthy tissues or if they are remaining in the perfusion site and sending growth-stimulating signals to the impacted area.

“There's a lot of unknowns that we're still looking to find out,” said Dryden. “It's incredibly difficult in a clinical setting.  All we have is what we're presented with and retrospectively trying to piece together what helped and what didn't.”

Veterinarians have determined that stem cells tend to stick around the general vicinity where they were injected, though we don't know enough about their movement yet to be sure of how they're working; that is one area Dryden said scientists are using histopathology to gain more information now.

“It's early days still. There's a lot we're going to learn still from this, a whole lot we're going to learn.”