Veterinary Stem Cell Therapies Translate into Human Therapies

MIT Technology Review, July 14, 2009

As previously reported on this website a number of times, rapid progress has been made over the past few years in veterinary medicine using autologous adult stem cells. Now, the consistent success of such therapy is finally getting the attention of the human medical community, which is beginning to replicate the veterinary procedures in human clinical trials.

Autologous (in which the donor and recipient are the same individual, whether a person or a dog or a horse) adult stem cell therapy has been routinely used in recent years for the treatment of a variety of conditions in large domesticated animals. Such conditions most commonly include orthopedic injuries in competitive horses, while in dogs the most commonly treated condition is age-related degenerative osteoarthritis. Although such stem cell therapies could also be of benefit to smaller animals such as cats, orthopedic injuries are not usually life-threatening to these smaller animals whereas such an injury could be fatal for a thoroughbred race horse. Consequently, veterinary stem cell therapy has been applied very aggressively to these valuable, expensive, large animals whose lives and competitive careers have literally been saved by such therapies. Even for dogs who do not earn large salaries in high-profile competitions but who are merely beloved pets, autologous adult stem cell therapy has also proven to be life-saving. Meanwhile, in human medicine, however, nothing whatsoever has been allowed to happen in U.S. clinics outside of a small number of government-approved clinical trials, thanks to an outdated, lengthy, lethargic and prohibitively expensive FDA approval process. It is hardly surprising, therefore, that veterinary stem cell medicine has quickly outpaced human stem cell medicine - but now, at last, humans are beginning to learn something from their canine and equine friends.

Companies such as Vet-Stem in the U.S. and VetCell in the U.K. have accumulated numerous documented cases of the benefits of autologous adult stem cell therapy in animals. To name just a few of the advantages, adult stem cell therapy yields faster healing and shorter recovery times than surgical treatments do, and adult stem cell therapy does not pose a risk of any side effects like medications do. Additionally, since the adult stem cells are autologous, there is no risk of immune injection. The U.K. company VetCell derives the autologous adult stem cells from the animal's bone marrow, and to date has treated approximately 1,700 horses with an 80% success rate. By comparison, the U.S. company Vet-Stem derives the autologous adult stem cells from the animal's adipose (fat) tissue, and to date has treated over 2,000 dogs and over 3,000 horses, also with an 80% success rate. With both companies, the procedure is quick, simple, and minimally invasive. Although the treatment is more expensive than conventional veterinary procedures, the adult stem cell treatment actually works, and noticeable improvement is seen almost immediately in all cases, not just in the 80% of cases that exhibit a complete recovery. By sharp contrast, however, conventional surgical and pharmacological therapies, which might initially be less expensive than stem cell therapy, only have a 30% success rate and therefore in the long-term are actually more expensive when repeated treatment is needed, or when improvements are not seen at all. Additionally, reinjury is significantly lower in animals who receive autologous adult stem cell therapy, due to the mechanism of action by which these stem cells activate the healing process. As Dr. David Mountford, a veterinary surgeon and chief operating officer at VetCell, explains, "After 3 years, the reinjury rate was much lower in stem-cell-treated animals: about 23% compared with the published average of 56%" for animals treated with conventional therapies.

According to Dr. Sean Owens, veterinarian and founding director of the Regenerative Medicine Laboratory at UC-Davis, "Soft-tissue injury is the number-one injury competitive horses will suffer, and it can end a thoroughbred horse's career." Additionally, Dr. Owens adds, "Regulatory oversight of veterinary medicine is minimal. For the most part, the USDA (U.S. Department of Agriculture) and the FDA (Food and Drug Administration) have not waded into the regulatory arena for us." Precisely because of such a lack of federal government regulation in the veterinary industry, this newly created research center which Dr. Owens has established is able to dedicate itself to the advancement of animal stem cell medicine, which in turn should translate into the advancement of human stem cell medicine through parallel clinical trials. A number of ongoing clinical trials in horses are conducted at the Laboratory, which include those for tendon tears and those for fractured bone chips in the knee - and now a similar type of autologous adult stem cell therapy for these same conditions will be developed for human clinical trials. Ultimately, such a program will result not only in the development of better treatments for horses, but also in the development of better treatments for humans. Currently Dr. Owens is collaborating with Dr. Jan Nolta, director of the Stem Cell Program at UC-Davis, who has been appointed to oversee the human trials. As Dr. Owens explains, "Part of our mission is to do basic science and clinical trials and also improve ways of processing cells."

Similarly, VetCell of the U.K. initially chose to focus specifically on tendon injuries in horses precisely because these injuries bear such a close resemblance to the same injuries in humans, and therefore the medical procedures should be easily translatable from veterinary to human medicine. In fact, while damage to a rotator cuff or an Achilles tendon would certainly be extremely painful in a human, it probably would not be fatal, whereas such injuries in a horse could prove fatal. The veterinary procedures have therefore had to advance very carefully and meticulously - despite the absence of a controlling government regulatory system - merely because of the severe and extreme nature of such animal injuries. Next year, VetCell plans to begin autologous adult stem cell therapy for human patients with Achilles tendon damage, which will mark VetCell's first human clinical trials in which an equine procedure will be translated to a human procedure. As with the horses, the human autologous adult stem cells will be derived from each human patient's own bone marrow, from which the stem cells will then be isolated, purified, expanded and readministered to the patient therapeutically, usually by injection directly into the area of tissue damage. According to Dr. Mountford, "Our long-term goal is to use it to treat a number of tendon injuries."

Likewise, Vet-Stem of California has already demonstrated success in a double-blind, placebo-controlled clinical trial with autologous adult stem cells in the treatment of arthritic dogs. As Dr. Robert Harman, veterinarian and founding CEO of the company, points out, "About 200,000 hip replacements are done every year in humans. That's a very good target for someone to look at cell therapy." Adipose-derived stem cells have been shown in a number of studies to exhibit highly beneficial immunomodulatory properties - which reduce inflammation, among other benefits - in addition to stimulating the regeneration of cartilage and other tissue. (E.g., "Non-expanded adipose stromal vascular fraction cell therapy for multiple sclerosis", by N.H. Riordan et al., published in the Journal of Translational Medicine in April of 2009, of which Dr. Harman is a coauthor). As Dr. Harman further explains, "In the last couple of years, evidence has come out that the cells we use reduce inflammation and pain, and help lubricate the joint."

Ordinarily, injuries of the bones, joints, tendons and ligaments result in scarring of the tissue, which not only prevents full healing but also often leads to further injuries at a later time. Conventional medical therapies do nothing to address the problem of scar tissue directly, and surgical procedures actually make the problem worse by increasing the severity of tissue scarring which in turn merely exacerbates later complications that will inevitably result from the scar tissue, since such tissue can never be fully rehabilitated. Stem cell therapy, however, allows for the full and complete healing of tissue without scarring, which not only reduces the risk of re-injury of the same tissue at a later date but also restores full physical performance and function, usually very quickly and dramatically. Such is the case in humans as well as in animals. As Dr. Harman succinctly states, "Our success in animals is directly translatable to humans, and we wish to share our evidence that stem cells are safe and effective."

Although Vet-Stem was the first company to commercialize the process in the U.S., and VetCell was the first to do so in the U.K., a number of other companies throughout the world are now also utilizing similar types of technology in which adult stem cells are derived from each animal's own tissue and readministered to the animal as a clinical therapy for the particular medical condition from which the animal suffers. Autologous adult stem cell therapy has proven to be a highly preferable alternative treatment for many animals, especially those whose conditions require surgery or anti-inflammatory drugs, both of which can often be avoided with the stem cell therapy.

Vet-Stem was founded in 2002 as the result of stem cell research conducted at the University of Pittsburgh and UCLA in the late 1990s, when Dr. Bob Harman saw the commercial potential for veterinary applications of such stem cell technology. A veterinarian himself, as well as a statistician and former biotech entrepreneur who had already held the top executive title at 3 biotechnology companies prior to Vet-Stem, Dr. Harman is now the CEO of Vet-Stem as well as one of its founders. Based in San Diego, Vet-Stem patterned its initial clinical model upon the example of other companies that were already involved in human adult stem cell therapies, such as Cytori Therapeutics which had developed a proprietary separation apparatus that harvests human adult stem cells from adipose tissue at the patient's bedside during reconstructive or cosmetic surgery. In a similar procedure, veterinarians extract approximately 2 to 3 tablespoons of adipose tissue from each animal, which are then sent to Vet-Stem's laboratories where the adult stem cells are isolated, purified, expanded and returned within 48 hours to the veterinarian who then administers the stem cells to the animal. The procedure has demonstrated a consistently high success rate and its use is becoming increasingly widespread not only for horses but also for dogs. Among other partnerships, in September of 2007 Vet-Stem licensed their proprietary adult stem cell technology to the Central Veterinary Research Laboratory (CVRL) of Dubai in the United Arab Emirates, thereby allowing the CVRL to offer the same adipose-derived adult stem cell animal therapies throughout the Middle East. Sheik Mohammed bin Rashid al-Maktoum, the ruler of Dubai and the Prime Minister of the UAE, is an avid thoroughbred owner and a sponsor of the Dubai World Cup, the world's most highly-prized horse race. As Dr. Harman described in 2007, "The Central Veterinary Research Laboratory will be an excellent partner in bringing this technology from the U.S. to the Middle East as they are already the most respected reference lab in the region." CVRL now provides stem cell services for the treatment of injuries not only in thoroughbred race horses and Arabian endurance horses, but also in racing camels, among other species, throughout the Middle East. As already mentioned, to date Vet-Stem has treated over 3,000 horses and over 2,000 dogs with joint injuries and degenerative conditions that include tendon and ligament injuries as well as age-related osteoarthritis. Vet-Stem's overall success rate is around 80% in the number of animals who are able to return to normal performance, a rate that is significantly above that of conventional surgical and pharmaceutical therapies.

VetCell Bioscience developed the equine autologous adult stem cell procedure in the U.K., where such therapy is now routine practice at most equine veterinary locations and is even covered by most equine insurance policies. VetCell uses mesenchymal stem cells (MSCs) that are derived from the animal's own bone marrow which is extracted from the horse's sternum, from which the MSCs are then isolated, expanded to more than 10 million cells, re-suspended in bone marrow supernatant which is rich in growth factors and other chemical nutrients, and then the cells are injected directly into the site of the injury where the cells regenerate the tendon tissue and also prevent the formation of scar tissue, which is often a main hindrance to healing and the cause of future reinjury. Physical rehabilitation and a controlled exercise program are also important to the recovery of the horse, and periodic MRI (magnetic resonance imaging) scans are taken to monitor the healing. VetCell Bioscience specializes in the development and commercialization of new biotechnologies for veterinarian musculoskeletal regeneration. VetCell was formed in partnership with the Royal Veterinary College and the Institute for Orthopaedic and Musculoskeletal Science, and is a trading company within MedCell Bioscience, its parent company, which develops musculoskeletal regenerative therapeutics for human clinical treatment. As stated on their website, "VetCell has rapidly commercialised a technique for the multiplication of equine stem cells which can be used in the treatment of tendon and ligament injury. This service is now available to veterinary surgeons in the U.K. and internationally. VetCell has also developed a simple method for separating and storing stem cells from the umbilical cords of foals." Although VetCell specializes in the treatment of horse injuries, they are also expanding their services and products to therapeutic applications for dogs, cats and other domestic species, in addition to their human clinical trials which will commence next year. Headquartered in Cambridge, England with laboratories in Edinburgh, Scotland, MedCell and VetCell also have offices in Germany, Spain, China, Australia, South America, Canada and the United States.

Both Vet-Stem and VetCell use exclusively adult stem cells, derived from each animal's own tissue. Since the cells are autologous (in which the donor and recipient are the same animal), there is no risk of immune rejection. More specifically, the stem cells that are harvested in both procedures are mesenchymal stem cells (MSCs), which are highly potent adult stem cells that are found not only in bone marrow and adipose tissue but also umbilical cord blood. Numerous scientific and clinical studies have been published in the peer-reviewed medical literature detailing the regenerative properties of MSCs.

No embryonic stem cells are ever used in either Vet-Stem's or VetCell's therapies, since embryonic stem cells are highly problematic in the laboratory, whether they are of human or non-human origin. Among other problems, the risk of teratoma (tumor) formation disqualifies embryonic stem cells for use as a clinical therapy, even in animals. Adult stem cells, however, do not pose such risks and are therefore rapidly accumulating a consistent history of successful clinical treatments in veterinary, as well as in human, medicine.