However, he says many challenges must be met before this scenario becomes reality. Although casual observers might wonder why stem cell research hasn't produced a host of clinical applications yet, this field remains in a relatively embryonic state, says Geoffrey J. O'Neill, Ph.D., president of Bio-Matrix Scientific Group, a San Diego-based company focused on developing and marketing healthcare technology including biomedical devices. "Until the late 1990s," he says, "all the stem cell research was basically focusing on bone marrow."Changing focus In the early 1990s, researchers found that stem cells capable of producing red and white blood cells and platelets (pluripotent stem cells) also existed in umbilical cord blood. Therefore, he says researchers began working with cord blood transplantation, "But its applications were still limited to hematological diseases." Dr. O'Neill says this began to change with the discovery of other types of stem cells within the bone marrow. "Instead of stem cells just producing blood cells," he explains, "there are stem cells there — called mesenchymal stem cells — that can give rise to other tissues such as muscle cells, bone or cartilage."z During 30 years of stem cell transplantation, Dr. O'Neill says, "It took a very long time to figure out, first of all, how to identify stem cells." Even today, he says, "It's almost impossible to identify pluripotent stem cells within the bone marrow." By contrast, Dr. O'Neill says it's possible to identify stem cells slightly beyond the pluripotent state — those already committed to differentiate into white or red blood cells, for example — with relative ease. Similarly, he says researchers have learned much about the growth factors that make stem cells turn into other types of cells. An example is erythropoietin, which stimulates red cell production in this way. More recent research By the same token, he notes that recent research has identified fat cells as a fertile source of stem cells. "In other words," Dr. O'Neill explains, "if one extracts fat through liposuction, that fatty tissue is full of mesenchymal stem cells. These cells are now being used, straight from the fat, in clinical trials." They've been shown to have some success at regenerating heart muscle (Miyahara Y et al. Nat Med. 2006 Apr;12(4):459-465. Epub 2006 Apr. 2), he adds. Likewise, he says some veterinarians are using fat cells to repair tendons and ligaments in racehorses. The future "That's where the future is — the fatty tissue is a great source of these cells. And it's basically a waste product" in plentiful supply, Dr. O'Neill says. The above developments notwithstanding, he says, "We still have not been able to identify factors which will make the pluripotent cells divide." It's these cells and associated growth factors that one would want to give to heart attack victims, for instance, to help them repair heart muscle, he says. |
