Light coaxes stem cells to repair teeth

In a first, scientists, including one of Indian-origin, have used light to coax stem cells to regrow parts of teeth.
The study, led by David Mooney, a Core Faculty member at the Wyss Institute for Biologically Inspired Engineering at Harvard, is the first to demonstrate the ability to use low-power light to trigger stem cells inside the body to regenerate tissue.
The researchers used a low-power laser to trigger human dental stem cells to form dentin, the hard tissue that is similar to bone and makes up the bulk of teeth.
They outlined the precise molecular mechanism involved, and demonstrated its prowess using multiple laboratory and animal models.

A number of biologically active molecules, such as regulatory proteins called growth factors, can trigger stem cells to differentiate into different cell types.
Current regeneration efforts require scientists to isolate stem cells from the body, manipulate them in a laboratory, and return them to the body - efforts that face a host of regulatory and technical hurdles to their clinical translation.

"Our treatment modality does not introduce anything new to the body, and lasers are routinely used in medicine and dentistry, so the barriers to clinical translation are low," said Mooney, who is also the Robert P Pinkas Family Professor of Bioengineering at Harvard's School of Engineering and Applied Sciences (SEAS).

"It would be a substantial advance in the field if we can regenerate teeth rather than replace them," Mooney said.
Lead author and dentist Praveen Arany, an Assistant Clinical Investigator at the National Institutes of Health (NIH), took rodents to the laboratory version of a dentist's office to drill holes in their molars.
He treated the tooth pulp that contains adult dental stem cells with low-dose laser treatments, applied temporary caps, and kept the animals comfortable and healthy.
After about 12 weeks, high-resolution x-ray imaging and microscopy confirmed that the laser treatments triggered the enhanced dentin formation.
"It was definitely my first time doing rodent dentistry," said Arany, who at the time of the research was a Harvard graduate student and then postdoctoral fellow affiliated with SEAS and the Wyss Institute.

The dentin was strikingly similar in composition to normal dentin, but did have slightly different morphological organisation.
The typical reparative dentin bridge seen in human teeth was not as readily apparent in the minute rodent teeth, owing to the technical challenges with the procedure, researchers said.
The study is published in the journal Science Translational Medicine.