Pancreatic Differentiation of Oral Minor Salivary Gland Stem Cells.

Introduction: Stem cells from various sources including major salivary glands have been used to establish pancreatic differentiation in an attempt to provide new treatment options for patients with diabetes mellitus. In contrast, the potential of using the more easily accessible intraoral minor salivary glands has not been evaluated so far.

Materials and methods: Salivary stem cells were isolated from normal labial minor salivary glands that were removed during the excision of a mucocele and were attempted to differentiate into pancreatic cell lines using a culture medium enriched with activin A, retinoic acid and GLP-1.Real time RT-PCR was used to evaluate the expression of the genes of pancreatic transcription factors MafA, Ptf1a, Hb9 and Arx. Complementary, 22 labial minor salivary gland paraffin-embedded specimens were examined using immunohistochemistry for the presence of the relevant gene products of the pancreatic transcription factors Arx, MafA, Ptf1a and Pdx1.

Results: The differentiated salivary stem cells(cells of passage 3) expressed the genes of the pancreatic transcription factors MafA, Ptf1a, Hb9 and Arx even on the first day of the experiment while immunohistochemistry also confirmed the presence of the protein products of Arx, MafA, Ptf1a as well as Pdx1[> 50% of the specimens for Arx(5/8) and MafA(7/8), < 50% for Ptf1a(5/11) and Pdx1(5/11)] in ducts, mesenchymal connective tissue and acinar cells.

Conclusions: Labial minor salivary glands may share gene and protein characteristics with pancreas suggesting a possible usefulness for pancreatic regeneration or substitution in cases of deficiency.