There are currently no treatments for dry mouth, where the salivary glands do not produce enough saliva.

Dry mouth is the result of low-producing or non-functioning salivary glands. The often devastating condition – known as xerostomia – has a number of causes, including medication use, radiation treatment for head and neck cancers, autoimmune diseases, diabetes and the process of aging.

There are currently no treatments, and salivary glands have little capacity to renew themselves, highlighting a need for cell-based therapies that can grow new tissue and restore gland function.

In the journal Tissue Engineering Part A, a team from the University of Texas at San Antonio describes how they used silk fibers to provide salivary gland stem cells with a 3D scaffold on which to grow a matrix of salivary gland stem cells.

Senior author Chih-Ko Yeh, a professor in comprehensive dentistry who runs a lab focusing on salivary gland research, says:

“The cells had many of the same characteristics as salivary gland cells that grow in the mouth.”

The achievement is significant because “salivary gland stem cells are some of the most difficult cells to grow in culture and retain their function,” he explains.

Most of us do not give it a second thought – but the saliva we produce in our mouth is critical to good health. As well as initiating digestion, keeping bits of food off our teeth and preventing oral infection, saliva helps us swallow and speak.

Insufficient saliva can lead to bad breath, tooth decay, gum disease and infections in other parts of the body.

Silk is a ‘good choice’ as a scaffolding for stem cells

The findings bring promise to 4 million Americans with an autoimmune disease called Sjögren’s syndrome – a condition where the body attacks its own tear ducts and salivary glands.

They also bring hope to thousands of others who have poor salivary function as a result of radiation treatment for head and neck cancer, and the 50% of older Americans whose medications can cause dry mouth.

For their study, the team made a silk framework from purified silk fibers, populated it with stem cells from rat salivary glands and added a nourishing medium to encourage growth. Prof. Yeh describes what happened:

“After several weeks in culture, the cells produced a 3D matrix covering the silk scaffolds.”

Prof. Yeh explains that silk is a good choice as a scaffolding for the stem cells because it is a natural product, it biodegrades and is flexible and porous.

These properties help oxygen and nutrients reach the growing cells easily, and do not lead to inflammation, which has been a problem with other scaffolding materials, he adds.

‘Great potential’ for research and cell-based therapies

Because of the small number of salivary glands in the human mouth, the team is going to continue using rat salivary glands to fine-tune the method.

Eventually, they hope to use stem cells harvested from human bone marrow or umbilical cord blood to regenerate human salivary glands.

Looking further into the future, Prof. Yeh believes that within the next 10 years, we will be repairing damaged salivary glands in patients by transfusing stem cells, or engineering artificial salivary gland tissue to replace damaged glands. He concludes:

“This unique culture system has great potential for future salivary gland research and for the development of new cell-based therapeutics.”

Earlier this year, Medical News Today learned of another study where an injectable hydrogel boosted stem cell transplantation to help brain recovery after stroke and partially reverse blindness in mice.

The team, which included researchers from the University of Toronto in Canada, said the hydrogel did more than hold the stem cells together – it directly promoted stem cell survival and integration.

Written by Catharine Paddock PhD