Characterization of Human Salivary gland Stem/Progenitor cells (SGSC)

The primary role of salivary glands is to produce saliva, which provides much of the innate host defense in the oral cavity. Clinically, salivary hypofunction causes significant morbidity and there is no conventional treatment for irreversible gland loss.

Objectives: The purpose of this study was to identify and isolate potential stem/progenitor cells from adult human salivary glands, and to compare them to immortalized human salivary cell lines.

Methods: Human submandibular cells were enzymatically dispersed to produce single cell suspensions and incubated in low calcium (0.1 mM) keratinocyte serum-free nutrient medium. Clonal cells (established from a single cell, SGSC) expanded in low calcium medium were characterized by immunocytochemistry, and subsequently were cultured on top of 5mg/mL Matrigel. The human submandibular and parotid salivary gland cell lines (HSG and HSY) were cultured with DMEM: F12 medium containing 10% FBS. Cells were transplanted subcutaneously or into partially cut salivary glands of immunocompromised mice.

Results: SGSC displayed a mesenchymal rather than epithelial morphology and expressed both epithelial and mesenchymal markers. SGSC, HSG and HSY expressed amylase, chromogranin B (human specific salivary gland protein) and cytokeratin 19 (ductal marker). HSG expressed Aquaporin 5 (acinar marker) in standard culture but SGSC and HSY did not. These cells aggregated in Matrigel. After the aggregation, SGSC and HSY expressed Aquaporin 5. After transplantation, SGSC formed duct- and acinar- like structures, while HSG and HSY formed carcinoma- like masses of cells. Transplants of SGSC, HSG and HSY expressed mRNAs and proteins of both acinar and ductal cell types. But only HSG and HSY expressed mRNA of chromogranin B.

Conclusion: Cells obtained from enzymatically dispersed human submandibular glands appear to include progenitors, a subset of which may be able to form both ductal and acinar phenotypes.

Z01 DE000709