Researchers from the Columbia University College of Dental Medicine, USA, found in the jaw bone stem cells capable of restoring damaged cartilage and joints. The findings were published October 10 in Nature Communications.
Stem cells are located in the temporomandibular joint (TMJ), which connects the lower jaw to the skull base. After transplantation in animals with degeneration in the temporomandibular joint, the stem cells restored cartilage in the joint. Just one cell transplanted in a mouse became fundamental to the spontaneous creation of cartilage, bones and even the beginning of the formation of the bone marrow niche.
“This is very exciting for the field because patients who have problems with their jaws and TMJs are very limited in terms of clinical treatments available”, – said Mildred C. Embree, DMD, PhD, assistant professor of dental medicine at Columbia University Medical Center (CUMC) and the lead author of the study.
According to the National Institutes of Health, only in the United States, about 10 million people, mostly women, suffer from TMJ disorders. Currently, treatment involves either surgery or palliative care aimed at the symptoms, but it cannot restore the damaged tissues. Dr. Embree says that stem cells found in the joint, can be used to restore it.
Cartilage plays the role of shock absorber and enables the joint to move smoothly. The temporomandibular joint is the fibrocartilage, which is also found in the knee meniscus and in the discs between the vertebrae. Since the fibrous cartilage is not restore, an injury or illness that lead to its damage can cause permanent disability.
The group of scientists have been working to regenerate cartilage using stem cells – the immature cells that can differentiate into almost all types of tissues. Given the problems associated with transplantation of donor stem cells, such as rejection, researchers interested in using the patient’s own stem cells.
“The implications of these findings are broad, including for clinical therapies. They suggest that molecular signals that govern stem cells may have therapeutic applications for cartilage and bone regeneration. Cartilage and certain bone defects are notoriously difficult to heal”. – said Dr. Jeremy Mao is co-director of the Center for Craniofacial Regeneration at Columbia and), co-author of the work. His own research with stem cells has regenerated teeth and the meniscus, the pad of cartilage within the knee and temporomandibular joint was dedicate in 2003.
In a series of experiments described in the new work, Dr. Embree and Dr. Mao and they colleagues, have identified stem cells of fibrous cartilage (fibrocartilage stem cells, FCSCs) of the joint, and have demonstrated that they are able to form cartilage and bone both in vitro, and in vivo, when implanted in animals.
“I did not have to add any reagents to cells. They have been “programmed” to this “, – says Dr. Embree. Despite the fact that many of the regeneration of damaged tissues, using techniques require specific growth factors or biomaterials for further cell growth Embree’s notes that FCSCs spontaneously grew and matured.
The team of scientists also determined that the Wnt, molecular signal, depleting reserves FCSCs, causes degeneration of cartilage. Injections to animals with degenerative changes of the temporomandibular joint a Wnt-blocking molecule called sclerostin, led to the growth of cartilage and joint healing.
Dr. Embree and her colleagues are now working on the search for other small molecules that could be used to inhibit Wnt and promote FCSC growth. Their goal – the creation of the drug with minimal side effects, which could be entered directly into the joint.
Children with juvenile idiopathic arthritis often have a developmental disorder of the lower jaw, which is not treating by existing drugs. Since the center of the jaw is in the growth of the TMJ, of the study may offer new strategies for the treatment of such children, as well as a better understanding of the growth and development of the jaw.
Currently, orthodontists use outdated technology fixes defects forming the lower jaw, such as special locking devices. Dr. Embree emphasizes that the study results may indicate ways of managing the growth of the jaw at the cellular level.
The researchers argue that in the end the results can be used to restore fibrous cartilage in other joints, including the knees and spinal discs. “These types of cartilage are composed of a variety of cellular components, so we have to study the molecular basis of the regulation of the cell”, – says Dr. Embree.