Short heat stress induces rat submandibular glands' basal cells growth

One of the major causes for salivary impairment is radiation therapy. At present, no satisfactory treatment for this condition is available. Affected patients mainly suffer from rampant dental caries, frequent mucosal infections, and difficulties while swallowing and chewing dry food, all of which considerably decrease their quality of life. Previous reports suggested that submandibular glands' basal epithelial cells are localized in the ductal (striated/intercalated) compartment and in the instance of damage proliferate to replace damaged tissue. Working hypothesis: Salivary gland basal epithelial cells expressing integrin α6β1, can be considered as containing adult salivary gland stem cells. We can induce basal cell proliferation by non invasive heat stress pretreatment, isolate and cultivate them for future regeneration of damaged functional secretory tissue. Objective: To examine the effect of short heat stress condition on the amount and growing potential of salivary gland integrin α6β1 positive cells. Methods: Adult male rats were subjected to short heat stress condition followed by isolation of salivary gland parenchymal cells using the Percoll gradient technique. Thereafter, α6β1 positive cells were secluded by magnetic activating cell sorter (MACS) methodology and analyzed before and after cultivation using collagen I pre-coated flasks or feeder layer. Results: FACS analysis indicated that stress condition increased integrin α6β1 positive isolated cells from 6% to 29% in the parenchymal fraction (corresponding to 0.5% and ~2.5% from the whole glands' tissue respectively). Colony formation efficiency (CFE) and cell proliferation assays indicated that the proliferate potential of heat stressed animals originated cells , were 4 to 5 folds greater then in cells originated from control animals. These cells are currently being characterized for their ability to differentiate to adult salivary gland cells. Conclusion: Short heat acclimation stress condition increases salivary gland integrin α6β1 positive cells amount and proliferate potential.