Here is recent news of another team working to engineer salivary gland tissue, one of many parts of the body typically given little thought until it stops working. This team doesn't seem to be as close to a functional end result as the Japanese group I pointed out last month, but a diversity of approaches is always a good sign:
Saliva is critical to good health. It helps with speaking, swallowing, washing food off teeth, initial food digestion and preventing oral infections. Insufficient saliva can cause chronic bad breath, cavities, gum disease, as well as systemic infections. There is no treatment for low-producing or nonfunctioning salivary glands, and the glands have little regenerative capability.
A research team is the first to use silk fibers as a framework to grow stem cells into salivary gland cells. Silk is a good choice for stem cell scaffolding because it is natural, biodegradable, flexible and porous, providing the developing cells easy access to oxygen and nutrition. It also does not cause inflammation, as other scaffold materials have. The researchers' new process is the first major step toward helping more than 4 million people in the U.S. with a degenerative autoimmune disease called Sjögren's syndrome, in which the body attacks its own tear ducts and salivary glands. Low saliva production also is a devastating problem for thousands of patients who have had radiation treatment for head and neck cancer, as well as about 50 percent of older Americans whose medications can cause dry mouth, also known as xerostomia.
"Salivary gland stem cells are some of the most difficult cells to grow in culture and retain their function. 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. 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."
Because there are few salivary gland stem cells in the human mouth, the scientists plan to continue using rat salivary glands to refine the process, but eventually hope to use stem cells derived from human bone marrow or umbilical cord blood to regenerate salivary glands for humans.