Dental pulp mesenchymal stem cells plasticity: a promising tool in damaged tissues restoring

Mesenchymal stem cells (MSCs) are multipotent cells obtained from adult tissues, mainly and historically from hematopoietic ones. Extracted MSCs can be opportunely treated to promote both proliferation and differentiation in vitro. This prospect makes potential the MSCs use in autologous transplantation aimed to restoring severely damaged tissues, avoiding the rejection risk. Several scientific publications have recently shown that MSCs can be also obtained from tissues or organs blood-unrelated, such as muscle, fat, brain, skin or gut. An innovative and interesting MSCs supply is represented by dental pulp tissues, easily accessible and nowadays little explored and exploited MSCs source. In our opinion dental pulp derived MSCs could maintain undifferentiated profile probably due to early anatomical site compartmentalization (dental papilla) from the surrounding structure during embryogenesis. Consequently, our study was focused on isolation and characterization of a MSCs line extracted from rat incisors dental pulps (MSCDPs) and its subsequent treatment with adequate differentiating pharmacological stimuli to assess the plasticity skill. Isolated MSCDPs showed fibroblast-like cell morphology and an eccentrical polymorphic nucleus likewise the bone marrow MSCs. Electron microscopy revealed additional morphological aspects: plasma membrane characterized by numerous microvillae and thin extroflections presence; cytosol is very rich in ribosomes, free or endoplasmic reticulum associated while mitochondria are both elongated and round shaped. Nucleus appears irregular formed with various nucleolis and perinuclear-disposed heterochromatin. MSCDPs immunohistologic analysis is positive for CD117 and CD90 antigens (typical of multipotent progenitors), whereas appears negative for markers of lymphocyte (CD45) and haematopoietic (CD34) differentiation. Transcript analysis shows the expression of mRNA encoding for Oct 3/4 (critically involved in undifferentiated embryonic stem cells self-renewal and frequently used as undifferentiated cells marker) and GATA-4 (concerning regulation of gene involved in embryogenesis and myocardial differentiation and function). If treated with appropriate pharmacological stimuli, MSCDPs are able to differentiate towards various cellular histotypes, like adipocytes, chondrocytes, osteocytes, Schwann cells and cardiomyocytes. MSCPDs insulin stimulation resulted in cytoplasmic lipid vesicles appearance, observable by Nile Red stain; chondroblasts TGF-β3 mediated differentiation is evidenced with toluidine blue stain, while inorganic phosphate stimulation to the osteoblastic differentiation MSCDPs has led to massive deposition of calcium salts, as evidenced by alkaline phosphatase activity. Schwann cells forskolin differentiation induction is evidenced by immunohistological S100B (glial-specific calcium binding protein) and GFAP (Glial Fibrillary Acidic Protein) stain. Last cardiomyocytes differentiation is assessed with GATA-4, Connexin-43 and NKX2-5 (whose abundant expression is observed only during cardiac differentiation) immunostainig. With regards to obtained results, we can infer MSCPDs possess an impressive plasticity skill that can be further used in several damaged tissue assay.