Grant Supports New Theories About Jawbone Formation

Dentistry Today


The Texas A&M College of Dentistry has received a $1.85 million grant from the National Institutes of Health to continue 4 years of previous research challenging current conclusions about how bone forms in the jaw. For example, conventional wisdom says that chondrocytes, or cartilage cells, must form and then experience cell death before bone cells can form in the mandibular condyle.

However, these researchers have found that chondrocytes directly transform into bone and contribute to forming the ramus portion of the lower jaw. The funding will continue through the end of 2021 as the researchers study how cartilage cells directly transform into bone cells during body growth and remodeling. They also will address the underlying molecular mechanism by which the specific genes regulate cell transformation. 

Cell lineage tracing on a transgenic mouse model is essential to their hypothesis. In confocal microscopic images, cells tagged with reporter genes reveal the merging of bone and cartilage proteins seen in representative shades of red and green, one for each type of protein. The cell lineage tracing enables the researchers to follow the cartilage cells and see where they end up during growth.

“You would expect the condylar cartilage cells under the normal theory to end up dying off, but it appears that a number of them are turning into bone cells or potentially forming the walls of blood vessels,” said Robert Hinton, PhD, Regents professor emeritus at the school.

The researchers say their work could impact the knowledge base regarding how the temporomandibular joint grows and develops. In turn, they add, this new information could change approaches to treating malocclusions and even influence new therapies for injuries to cartilage, which, unlike bone, cannot repair itself.

“Finishing this project will provide new knowledge in this understudied area and form a basis for developing novel approaches to prevent, diagnose, and treat temporomandibular joint disorders that affect 5% to 10% of the population in this country,” said Jerry Feng, PhD, assistant dean for research and vice chair of biomedical sciences.

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