By: BRADLEY J. FIKES - Staff Writer

POWAY,CA -- Once crippled by a severed tendon, Buzz the border collie is back bounding around the ranch. And his owner gives much of the credit to stem cell treatment provided by a company called Vet-Stem.

Buzz, a show dog who herds cattle and sheep, tore a tendon off the tibia of his right rear leg. A veterinarian removed fat tissue from Buzz and purified it with Vet-Stem's technology. The cells were then implanted at the injury site and regenerated healthy tissue.

Humans have been anxiously awaiting treatments with stem cells for years, while animals such as Buzz are getting there first.

Regulators don't allow stem cell therapies to be tried in humans until they are shown to be safe in animals. And animal treatments are not subject to the extensive regulation required for humans.

"I never thought he would be back to 1,000 percent," John Doyle, the dog's owner, said of the eager collie. But that's what happened with Vet-Stem's help, said Doyle, who lives in Ramona. "It was really a remarkable recovery."

A few months after the treatment, Buzz was back to his full routine without limitation. And that's despite suffering another, rather ignominious injury: One of Buzz's toes was amputated after a cow stepped on it.

Vet-Stem's technology has been used in horses for more than three years. This week, the Poway-based company announced that it has expanded the commercial use of its therapy to dogs. In addition to treating tendinitis, Vet-Stem-trained veterinarians will treat dogs with fractures and diseases such as osteoarthritis and polyarthritis.

Stem cells are the "ancestral" cells that turn into the specialized cells found in animals and humans. But harvesting them has been difficult. One promising source of stem cells, human embryos, raises moral objections from those who consider the embryos human individuals. In recent years, a number of companies such as San Diego's Cytori Therapeutics have chosen to work with fat tissue, which is rich in many kinds of useful stem cells.

Vet-Stem had been treating dogs for some time before its official announcement. One of them was Buzz, who was injured last year. Doyle found out about the therapy through his veterinarian. Buzz, who was 2 when he was injured, could still walk -- but only on three legs.

Doyle's veterinarian reattached the torn tendon to the bone and removed fat cells from Buzz's belly. The cells were sent to Vet-Stem for purification. The purified cells were injected into the site of the injury over a period of a few weeks. Meanwhile, the injured leg was immobilized in a cast.

The bill for all of Buzz's care was about $3,500, Doyle said, estimating that a third of it was the cost of Vet-Stem's treatment.

Some dog owners might blanch at a multithousand-dollar veterinarian bill. But many owners of race or show horses are happy to pay to return their animals to health, said Dr. Julie Ryan Johnson, Vet-Stem's vice president of sales and marketing. The company says that it has treated more than 2,000 horses for tendon and ligament injuries, osteoarthritis and other conditions.

"What we've seen over the last three years is that these horses have had some pretty career-ending injuries, and the stem cells actually return them to performance, which is pretty amazing," said Johnson, a veterinarian.

Stem cells are found throughout the body, Johnson said, and help repair injuries by turning into the required types of replacement cells. If more stem cells of the right kind are placed at the injury site, they make the body's natural repair process more potent.

"The fat's easy to get out, and nobody misses it," Johnson said. "We isolate here in the lab the stem cells, then we concentrate them, then we put them back into the lesion. The stem cells signal other cells to come in and help heal the injury. They increase healing. They decrease scar formation."

Vet-Stem's therapies seem "feasible" for humans, said Dr. Kai Pinkernell, director of research and development at Cytori.

Cytori, however, has decided that for humans, the best initial targets are heart disease and plastic reconstructive surgery, Pinkernell said.

Cytori is now testing "regenerative" cells derived from fat in human trials conducted in Europe. The patients are suffering from an inadequate supply of blood to the heart, or "chronic mycardial ischemia." It is preparing to test the cells in heart attack patients. The technology was first tested in rats, mice and pigs.