A Comparison On Proliferation Of Stem/Progenitor Cells With Different Methods In Submandibular Gland Of SD Rat

Objective:In order to find an efficient way to induce proliferation of stem/progenitor cell in salivary gland, we compared the proliferation ability of salivary stem/progenitor cells between main duct ligation and heat stress on submandibular gland of SD rat.Methods:Fifteen male Sprague-Dawlye(SD)Rats,10-weeks-old, divide into heat, ligation and normal groups, randomly. Under anesthesia, the duct of glands were ligated and then the glands were harvested after six days. The heat group rat were placed in a heat acclimation box with an ambient temperature of 34.5℃for 48 hours and then the glands were harvested. The normal group rats were fed in normal environment and then removed the submandibular gland. All gland were tested in morphology and detected the percentage of cells that expressed stem/progenitor cell surface marker integrinα6β1, CD90.1, c-Kit with Flow Cytometry, respectively. (FCM)Results:Morphology observation, the glands volume was smallest in the duct ligation group, the gland shape of duct ligation changed to spindle-like and incomplete capsule. The shape of gland in the heat group was similar to normal group, and the color was slightly rosy. The gland weight to body weight ratio in the heat group was 25.3% larger than normal group and was 47.2% larger than duct ligation group. The gland weight to body weight ratio in the normal group was 29.3% larger than duct ligation group. Histological observation, HE and immunohistochemical staining:under the light microscope, the acinar and duct of glands in the heat and normal groups could be observed clearly, but the mitotic figures could be seen in the heat group. After duct ligation, acinar cells disappear and proliferation of duct could be occured. Flow cytometric analysis demonstrated that the percentage of cells positive forα6β1 integrin in the heat group was 26.2±2.4%, the ligation group was 16.9±2.6%, and the normal group was 10.6±0.7%. Statistic demonstrated that the the percentage of cells expressedα6β1integrin in the heat group was highest than duct ligation and normal groups (p<0.05), and the percentage of cells expressedα6β1integrin in the duct ligation group was higher than normal group (p<0.05). The percentage of cells positive for CD90.1 in the heat group, ligation group and normal group were 33.0±25.4%,25.0±4.1%,18.1±3.4% respectively. Statistic demonstrated that the the percentage of cells expressed CD90.1 in the heat group was highest than duct ligation and normal groups (p<0.05), and the percentage of cells expressed CD90.1 in the duct ligation group was higher than normal group (p<0.05). The percentage of cells expressed c-Kit in the heat group was 13.4±3.4%, in the duct ligation group was 13.8±3.0% and in normal group was 8.5±3.1%. Statistic demonstrated that the the percentage of cells expressed c-Kit had no statistic difference between heat group and duct ligation group (p>0.05), but the percentage of cells expressed c-Kit in heat group and duct ligation were higher than normal group(P<0.05).Conclusion:The heat-condition could more useful to induce the proliferation of cells that expressedα6β1integrin and CD90.1. And there was similar effect to induce the proliferation of cells that expressed c-Kit between the heat-condition and duct ligation groups.