(By Dr. Joseph D. Lim and Dr. Kenneth Lester Lim, BS-MMG, DDM, MSc-OI)
SCIENCE may be able to fix damaged salivary glands. That’s not to be glossed over.
There are many people whose salivary glands have been damaged by autoimmune illnesses or radiation treatment for cancer. The result: persistent dry mouth.
“Persistent dry mouth causes lots of problems with quality of life, and people forget how important saliva is until they lose it,” says Matthew Hoffman, Ph.D., a Senior Investigator at the Intramural Research Program (IRP), the internal research program of the U.S. National Institutes of Health (NIH).
Dr. Hoffman is working on ways to restore natural saliva production in people whose salivary glands are compromised.
Genetic abnormalities, radiation therapy for cancer, and certain autoimmune diseases can cause the salivary glands to degrade or reduce saliva production. This causes chronic dry mouth, a condition called xerostomia.
It can make tasting, chewing, and swallowing food difficult. Dry mouth also encourages the growth of bacteria inside the mouth and this could lead to infections.
Currently, there is not much that can be done when one suffers from xerostomia, except perhaps constantly drink or sip water.
There is a sticky mouthwash that can substitute for saliva. It coats the mouth and hold moisture. Medication that increases saliva production is uncomfortable as it also increase the production of tears and sweat.
“Radiation oncologists tell us they cure their patients’ cancers, but then their patients come back and say, ‘Hey, you’ve ruined my life,’” Dr. Hoffman says.
By focusing on the damage caused by radiation therapy for head and neck cancers, Dr. Hoffman hopes to understand how immature cells in the mouth interact with nerves. In the process, he hopes to develop treatments and restore functioning salivary glands.
Dr. Hoffman has discovered that immature cells are guided by a particular protein called neurturin, which regulates the synthesis, growth, maturation, and survival of neurons.
Salivary gland function could be restored by adding neurturin to damaged salivary gland cells grown in the lab, as well as by injecting the protein into irradiated salivary glands in mice.
Dr. Hoffman now wants to regenerate the salivary glands using both gene therapy and stem cells.
He wants to align his work with the first-in-human gene therapy trials at the NIH Clinical Center with the aim of repairing salivary glands damaged by radiation.
Dr. Hoffman will use the same gene delivery system to insert an intact copy of the gene that produces neurturin into isolated salivary gland cells. The aim is to test their gene therapy.
Dr. Hoffman has found that not only is it possible to restore salivary gland function using gene therapy, but the therapy can also be used preventively if it is initiated before radiation treatment. “In fact, it worked better to do it that way,” he says.
His research has also attempted to grow new salivary gland cells using stem cells taken from the salivary glands of mice and humans.
He found that clusters of cells could grow and start behaving like salivary gland cells. It promises the possibility of using a person’s own stem cells to regrow damaged salivary glands.
“We’re not there yet, but we can certainly see a potential path forward,” Dr. Hoffman says.
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Dr. Joseph D. Lim is the former Associate Dean of the College of Dentistry, University of the East; former Dean, College of Dentistry, National University; Past President and Honorary Fellow of the Asian Oral Implant Academy; Honorary Fellow of the Japan College of Oral Implantologists; and Honorary Life Member of the Thai Association of Dental Implantology. For questions on dental health, e-mail jdlim2008@gmail.com or text 0917-8591515.
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Dr. Kenneth Lester Lim, BS-MMG, DDM, MSc-OI, graduated Doctor of Dental Medicine, University of the Philippines College of Dentistry, Manila, 2011; Bachelor of Science in Marketing Management, De la Salle University, Manila, 2002; and Master of Science (MSc.) in Oral Implantology, Goethe University, Frankfurt, Germany, 2019. He is an Associate professor; Fellow, International Congress of Oral Implantologists; Member, American Academy of Implant Dentistry and Philippine College of Oral Implantologists. For questions on dental health, e-mail limdentalcenter@gmail.com/PN
