Working with freshly extracted human third molars (wisdom teeth) scientists have been able to isolate stem cells that can turn into the ligament that hold teeth into place.
Scientists at the National Institute of Dental and Craniofacial Research (NIDCR), one of the National Institutes of Health, and their colleagues have isolated human postnatal stem cells for the first time directly from the periodontal ligament, the fibrous, net-like tendon that holds our teeth in their sockets.
The scientists also say these cells have "tremendous potential" to regenerate the periodontal ligament, a common target of advanced gum (periodontal) disease. This enthusiasm is based on follow up experiments, in which the researchers implanted the human adult stem cells into rodents, and most of the cells differentiated into a mixture of periodontal ligament including the specific fiber bundles that attach tooth to bone and the mineralized tissue called cementum that covers the roots of our teeth.
"The stem cells produced beautifully dense, regenerated tissue in the animals," said Dr. Songtao Shi, a senior author on the paper and an NIDCR scientist. "That was when we knew they had great potential one day as a treatment for periodontal disease, and we're continuing to follow up on this promise with additional animal work." The results are published in the current issue of The Lancet.
The isolated cells were able to form periodontal ligament.
After further validation of their findings, Shi said he and his colleagues decided to pursue the next big question: Could these stem cells actually form periodontal ligament and cementum when transplanted into mice?
Of the 13 transplants each of which was derived from a distinct colony of stem cells cultured in the laboratory and loaded into a hydroxyapetite carrier eight produced a dense mixture of cementum and periodontal ligament. Interestingly, the cells even produced fibrous structures similar to the so-called Sharpey's fibers, which insert into both cementum and bone to hold teeth in place. The other five transplants showed no signs of differentiation.
Shi said his group is now following up on this finding in larger animals. If successful, Shi said he would be eager to evaluate their regenerative ability in people with advanced periodontal disease, which can be extremely difficult to control with current treatments.
My guess is they want to extract similar cells from large non-human animals because for ethical and practical reasons it is easier to do most of the work toward developing therapies using animals before attempting trials in humans.
While the press release has just been released to announce the publishing of the results in Lancet it appears this work was done last year, a patent has already been filed on it, and the final confirming step involved putting the human cells into immunicompromised mice to form the specialized ligament cells.
The NIH announces a new technology wherein stem cells from the PDL have been isolated from adult human PDL. These cells are capable of forming cementum and PDL in immunocompromised mice. In cell culture, PDL stem cells differentiate into collagen fiber forming cells (fibroblasts), cementoblasts, and adipocytes. It is anticipated that these PDL stem cells will be useful for periodontal tissue regeneration to treat periodontal disease.
It is hard to guess when this work will translate into wide availability of human treatments. But the consensus of German stem cell researchers is that some stem cell therapies will be available within 10 years.
My guess is that there are many more sources of adult stem cells hiding in various locations of the human body waiting to be found. Expect to read many more reports of discoveries of types of adult stem cells. Each such discovery is helpful not just as a potential starting source of cells for cell thearpies but also to compare to other cell types to develop a better understanding of how cells differentiate. The more cell types scientists have to compare the better they will be able to figure out how cells control their cell types and how to intervene to alter cell types for therapeutic purposes.
|Share |||Randall Parker, 2004 July 11 04:51 PM Biotech Organ Replacement|