The lacrimal gland provides moisture for the eyes, and like all parts of our physiology is prone to decline and failure in old age. Dry eye conditions, some of which are painful and debilitating, are common in old people. Researchers here demonstrate a cell therapy to spur regeneration of the lacrimal gland in an animal study, a step along the road to achieving the same thing in humans:
The eye's lacrimal gland is small but mighty. This gland produces moisture needed to heal eye injuries and clear out harmful dust, bacteria and other invaders. If the lacrimal gland is injured or damaged by aging, pollution or even certain pharmaceutical drugs, a person can experience a debilitating condition called aqueous deficiency dry eye (ADDE) - sometimes called "painful blindness." If injured, a healthy lacrimal gland naturally regenerates itself in about seven days. When diseased and chronically inflamed, however, regeneration stops - and scientists are not sure why.
Researchers looked at whether they could kick start regeneration by injecting progenitor cells into the lobes that make up the lacrimal gland. Progenitor cells are similar to stem cells in their ability to differentiate into different kinds of tissue. In this study, the researchers used progenitor cells that were poised to become epithelial tissue, a key component of the lacrimal gland. The researchers knew they faced a major challenge: sorting and separating "sticky" epithelial cell progenitors without destroying them. "We had to figure out how to dissociate the tissue into single cells without completely obliterating everything." The researchers solved this problem by developing markers to label the cells of interest and then testing different enzymes and other reagents to draw them out of tissues.
With these cells in hand, the researchers injected them into the lacrimal glands of mouse models of Sjogren's syndrome, an autoimmune disease that results in ADDE, dry mouth and other symptoms. The team used only older, female mice because ADDE most commonly strikes that demographic in humans. The treated mice showed a significant increase in tear production, indicating - for the first time - that epithelial cell progenitors could repair the lacrimal gland. Further tests suggested that epithelial cell progenitors helped by restoring the connection between cells called myoepithelial contractile cells and the lacrimal gland's secretory cells, which produce tears. The next step in this research will be to study how long the improvement in the lacrimal gland lasts after progenitor cell injections.