By Emma Yasinski
Xerostomia, or dry mouth, impacts about 20% of elderly adults and many patients who are undergoing radiation therapy or who wrestle with the immune system disorder known as Sjogren's Syndrome.
Xerostomia can be both uncomfortable and detrimental to the health of sufferers.
As the American Dental Association notes, xerostomia can bring about difficulties in tasting, chewing, swallowing, and speaking. Dry mouth also increases the odds of developing dental decay, demineralization of teeth, tooth sensitivity, and/or oral infections. In addition, healthy saliva contains enzymes helpful for digestion and minerals to repair enamel.
There are currently limited options for providing relief or preventing adverse aftereffects: some medications may help stimulate saliva production while other patients may need to resort to artificial saliva. Lifestyle adjustments, including chewing sugar-free gum, also help some patients, according to the ADA.
But better treatments may be in the offing.
Recently, at the 47th Annual Meeting of the American Association for Dental Research (AADR), Kelsea Hubka, a graduate student in Bioengineering at Rice University, presented a method she is working on to rebuild salivary glands using a patient’s own stem cells. Hubka is completing scientific research as a visiting student at the University of Texas Health Science Center School of Dentistry.
Hubka told Incisor her research is focused on developing a technique using adult stem cells, in the hope that she can culture a patient’s own stem cells while that patient is undergoing and recovering from surgery and have them ready to be implanted back into the donor after the procedure.
Acinar and Ductal Cells
Stem cells can differentiate into any number of cell types found in the body depending on the signals they receive from their environment. Hubka is working to develop an environment outside of the body that will coax these cells to differentiate into the cell types that make up the salivary gland.
She encapsulated the stem cells in a clear, biocompatible hydrogel which contained sites for the cells to attach and grow. The molecule she used to build these hydrogels was able to bind fibroblast growth factors (FGF)-7 and -10, molecules that signal the cells how they should differentiate.
In one experiment she used no growth factors at all. In another, the growth factors were available at a constant concentration. In the last condition, Hubka created concentration gradients - higher concentrations of the growth factors in one area - gradually decreasing to lower concentrations in another area. She cultured these cells for 2.5 weeks and then observed the types of cells that developed.
She found that the concentration gradients were the most promising condition. They allowed the cells to differentiate into both acinar cells, which make saliva, and ductal cells, which deliver that saliva to the mouth.
Hubka says she still has a long way to go before the technique can be used clinically. While using the growth factors to make the cells differentiate into acinar and ductal cells is a big step forward, the team now needs to see if they can prompt these cells to grow along with nerve cells and blood vessels, which will be necessary to form functional salivary glands.
“In the long run we would hope to help all patients with dry mouth, including Sjogren's Syndrome and cancer survivors with radiation-induced xerostomia, using this tissue replacement technology,” she said.
Author: Contributing writer Emma Yasinski received her Master of Science (MS) in science and medical journalism from Boston University. Her articles have also appeared at TheAtlantic.com, Kaiser Health News, NPR Shots, and Genetic Engineering and Biotechnology News.
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