Saliva is a watery substance secreted by the salivary glands located in the mouth. Saliva is essential for good health, as it assists in speaking, swallowing, food digestion, preventing oral infections in addition to many other tasks. Without normal salivary function the frequency of dental caries, gum disease (gingivitis), and other oral problems increases significantly.
Hypofunction of salivary glands can be caused by many factors, including diabetes, radiation therapy for head and neck tumors, aging, medication side effects, and Sjögren’s syndrome – an autoimmune disease where the body attacks its own tear ducts and salivary glands. There are currently no treatments for dry mouth, and salivary glands have very little regenerative capacity.
A team of researchers, led by Dr Chih-Ko Yeh, has been searching for cell-based therapies to restore salivary gland function in a study based in San Antonio and published in the journal Tissue Engineering Part A, 2015.
"In our process, we purified the silk fibers by removing a number of contaminants. We put stem cells from rat salivary glands on the silk framework with a media to nourish them. After several weeks in culture, the cells produced a 3-D matrix covering the silk scaffolds. The cells had many of the same characteristics as salivary gland cells that grow in the mouth," Dr. Yeh said.
Silk is a good choice for stem cell scaffolding because it is biodegradable, flexible, natural and porous, allowing oxygen and nutrients reach the growing cells easily. It also does not result in inflammation.
"Until now, retention of salivary gland cell properties has not been possible using other tissue culture techniques. This unique culture system has great potential for future salivary gland research and for the development of new cell-based therapeutics." Dr. Yeh explained.
Because of the small number of salivary glands in the human mouth, the scientists are going to continue using rat salivary glands to refine the method, but eventually hope to use stem cells derived from human bone marrow or umbilical cord blood to regenerate salivary glands for humans.
Ideally, within the next decade, the researchers hope that stem cells can be transfused into damaged human salivary glands to accelerate tissue repair, or replace lost glands.