Isolation of tissue progenitor cells from duct-ligated salivary glands of swine.

Tissue stem cells participate in the repopulation of tissue after injury. Tissue injury stimulates the normally quiescent tissue stem cells to differentiate and proliferate, in the process of replacing and/or repairing the damaged cells, and hence effecting tissue regeneration. The salivary glands retain the ability for frequent regeneration.

Arrhythmia induced by spatiotemporal overexpression of calreticulin in the heart.

Calreticulin (CRT) is a Ca(2+)-binding protein of the endoplasmic reticulum essential for cardiac development. For further investigation of the functional mechanism of calreticulin, we generated transgenic mice with spatiotemporal overexpression of calreticulin using a cre-loxP system. To elucidate the role of the protein in cardiogenesis, we adopted Nkx2.

Flow cytometric isolation of endodermal progenitors from mouse salivary gland differentiate into hepatic and pancreatic lineages.

Experimental injury is useful to induce tissue stem cells, which may exist in small numbers under normal conditions. The salivary glands originate from the endoderm and consist of acinar and ductal epithelial cells, which have exocrine function. After salivary gland duct ligation, acinar cells disappear as a result of apoptosis, and duct epithelium subsequently proliferates.

Salivary gland progenitor cells induced by duct ligation differentiate into hepatic and pancreatic lineages.

Tissue damage can be assessed based on regenerative responses, including progenitor cell proliferation. In the salivary gland, tissue damage induced by ligation of main ducts leads to the disappearance of acinar cells and to marked proliferation of ductal cells. Reopening of the ducts leads to repopulation of acinar cells within 1 to 2 weeks, which suggests activation of tissue progenitor cells in a damaged state.