Stem cells boom in vet clinics

A horse is given an injection of stem cells in a bid to promote healing in a tendon injury.

Lauren Schnabel/Jessica Cross/Cornell Univ.

Patients seeking unproven stem-cell therapies in the United States often run up against government restrictions. But Vintage Vinty Mark of Lovettsville, Virginia, had no difficulty getting such injections to treat an injured tendon in his leg. The leg improved dramatically, and Vinty went back to training to be a racehorse.

New guidance from the US Food and Drug Administration (FDA) could, however, soon rein in veterinary uses of stem cells, a practice that has exploded in the United States over the past decade, even though most therapies are unproven. Many researchers and veterinarians say that the guidance, a draft of which the agency plans to issue by the end of the year, is overdue. But others worry that FDA interference could hamper research that could benefit animals and their human companions.

In the absence of clear regulations, the industry has burgeoned. Vet-Stem, a company based in Poway, California, has provided stem-cell treatments to more than 5,000 horses, 4,300 dogs and 120 cats since treating its first patient in 2004. Kits provided by MediVet America, based in Nicholasville, Kentucky, have been used to produce stem-cell injections for more than 10,000 horses since 2010. University veterinary departments, independently or through spin-off companies, have offered such services to thousands more animals. Veterinarians send patients tissue samples to the centres to have cells extracted or, increasingly, turn to kits that allow them to extract the cells in-house.

Stem cells are most often used to treat horses, dogs and cats, but clinicians have also sought to use them to repair a lumbar fracture in a Bengal tiger and arthritis in pigs. Researchers have also found stem cells in the fat of bottlenose dolphins, raising hopes for treating the marine-mammal versions of liver disease and type 2 diabetes. Theres not a large vet practice thats not using them, says Wesley Sutter, a veterinarian at Lexington Equine Surgery and Sports Medicine in Kentucky. Some claim [the treatment] cures everything.

Many veterinarians offer unproven stem-cell therapies to satisfy demanding customers, says Dori Borjesson, who specializes in veterinary medicine at the University of California, Davis. Clinicians are sucked into giving treatment even when theres not research to back up uses, she says.

Like the treatments sought by humans, most of those used in animals involve mesenchymal stem cells (MSCs), which can mature into a wide variety of cell types, including bone and cartilage, and have been shown to have anti-inflammatory and other beneficial effects. MSCs are extracted from fat or bone marrow and can be cultured or prepared for injection in concentrated form.

The FDAs position on the use of MSCs in humans is clear. It says that the cells are drugs and therefore must be proved safe and effective before they can be used in treatment, except under certain conditions. No MSC treatments have been approved. But the FDA has different regulations for veterinary medicine, and these do not clearly address MSCs. The agency has not approved any veterinary stem-cell therapies, but neither has it cracked down on any. This is in stark contrast to its high-profile actions against purveyors of unproven human stem-cell treatments, such as Celltex Therapeutics of Sugar Land, Texas,which treated patients with MSCs until the FDA stepped in last September.

That doesnt mean that the agency is not concerned, says Lynne Boxer, a veterinary medical officer in the FDAs Office of New Animal Drug Evaluation in Rockville, Maryland. As with any type of drug product, there are risks and benefits, she says. With stem cells, there is the potential for disease transmission and tumour formation. She declines, however, to say whether current practices are against FDA rules, or to elaborate on what the new draft guidance is likely to contain.

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Stem cells boom in vet clinics