'Stem cells from jaw bone help repair damaged cartilage'

Scientists have identified stem cells in jaw bone that can make new cartilage and repair damaged joints.
The cells reside within the temporomandibular joint (TMJ), which articulates the jaw bone to the skull.
When the stem cells were manipulated in animals with TMJ degeneration, the cells repaired cartilage in the joint, according to the researchers from the Columbia University Medical Centre (CUMC) in the US.
A single cell transplanted in a mouse spontaneously generated cartilage and bone and even began to form a 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 lead author Mildred C Embree, assistant professor at CUMC.

Options for treatment currently include either surgery or palliative care, which addresses symptoms but can not regenerate the damaged tissue.

Embree's findings suggest that stem cells already present in the joint could be manipulated to repair it.
Cartilage helps to cushion the joints and allows them to move smoothly. The type of cartilage within the TMJ is fibrocartilage, which is also found in the knee meniscus and in the discs between the vertebrae.
Since fibrocartilage cannot regrow or heal, injury or disease that damages this tissue can lead to permanent disability.
Medical researchers have been working to use stem cells, immature cells that can develop into various types of tissue, to regenerate cartilage.

Given the challenges of transplanting donor stem cells, such as the possibility of rejection by the recipient, researchers are especially interested in finding ways to use stem cells already living in the body.
Children with juvenile idiopathic arthritis can have stunted jaw growth that can not be treated with existing drugs, Embree said.
Since the TMJ is a growth center for the jaw, the new research may offer strategies for treating these children, and lead to a better understanding of how the jaw grows and develops.
While orthodontists currently rely on clunky technologies like headgear to modify jaw growth, she added, the findings could point towards ways to modulate growth on the cellular level.

The findings could lead to strategies for repairing fibrocartilage in other joints, including the knees and vertebral discs.
"Those types of cartilage have different cellular constituents, so we would have to really investigate the molecular underpinnings regarding how these cells are regulated," researchers said.
The study was published in the journal Nature Communications.