For people without a functional salivary gland, food tastes like it is rolled in sand, says Dr. Simon Tran, Faculty of Dentistry and Canada Research Chair in Craniofacial Stem Cells and Tissue Engineering.

Based on a recent paper by Vijayendra Kumar for the Indian Journal of Stomatology, up to 1.5 litres of saliva is produced in and secreted from the salivary glands every day. Composed mainly of water, saliva contains enzymes and lubricants that help the digestive system break down food, and make speaking, chewing, and swallowing more comfortable.

“Without functioning salivary glands, these actions would prove very difficult,” explained Tran, who has been working on clinical therapies to regenerate lost salivary gland tissue.

Two of the most common reasons for a dysfunctional salivary gland are the result of therapeutic irradiation treatment of patients with head or neck cancer, as well as the autoimmune disease Sjögren’s syndrome.

“Approximately 500,000 new cases of head and neck cancer occur each year worldwide,” Tran said. “Sjögren’s is estimated to affect as many as 4 million people in the United States alone, with nine out 10 patients being women.”

Tran’s lab, based at the Strathcona Anatomy and Dentistry Building, looks to bio-engineer new salivary glands by using bone marrow stem cells. So far, Tran has tested the use of bone marrow cells to bio-engineer salivary glands by means of mice models in the hope of restoring saliva flow. His experiments have been successful, and now Tran is looking ahead to restore salivary flow in humans.

“It’s harder,” Tran said. “The salivary glands, in terms of complexity, are somewhere between skin tissue and the heart.”

Understanding the therapeutic effect of bone marrow stem cells in restoring saliva flow is one of many areas of research on Tran’s list.

Tran and his colleagues have also built a prototype artificial salivary gland using a biodegrable polymer. A small tube-like structure, it is coated with human salivary cells, which would rest in the mouth near the salivary glands. The aim of this prototype is for the cells to form a “basement membrane,” which can lead to the stimulation and regeneration of the salivary tissue cells.

“Meanwhile, there are short term ‘reliefs’ for patients,” Tran said, explaining that artificial saliva or saliva substitutes can be prescribed and are regulated by the FDA as medical devices.

Artificial salivas are used to moisten and lubricate the mouth, but do not stimulate the salivary glands to make saliva, since they have no chemical action. The FDA has also approved several prescription drugs to relieve dry mouth caused by certain medical treatments or conditions, such as Cevimeline for Sjögren’s syndrome and Pilocarpine for radiation of head or neck cancer.