Immunofluorescence and Immunohistochemistry of MSCs and Salivary Glands

For immunofluorescence, cultured MSCs were fixed in 4% paraformaldehyde (PFA) and processed as described previously^{58 (link)}. Cells were stained with primary and secondary antibodies listed in Table S1. For immunohistolocalization assays, freshly collected fetal SGs and adult SMGs were fixed and embedded as described previously^{59 (link)}. 10 µm cryostat sections were subsequently stained with primary and secondary antibodies (Table S1) and were counterstained with ProLong® Gold antifade reagent with 6-diamidino-2-phenylindole (DAPI) (Life Technologies, Grand Island, NY). Images were captured on Leica CTR6500 (Leica Microsystems, Buffalo Grove, IL) and EVOS epifluorescence microscopes (Thermo Fisher Scientific, Waltham, MA). Images were further analyzed using NIH-ImageJ software (NIH, Bethedsa, Maryland). Quantification of the images was done using NIH-ImageJ software to analyze 10 to 15 random images at 20x magnification from ≥3 fetal and adult SMG sections.