Biological Characteristics of Dental Stem Cells for Tissue Engineering

Tissue Engineering with Stem Cell from Human Exfoliated Deciduous Teeth (SHED) and Collagen Matrix, Regulated by Growth Factor in Regenerating the Dental Pulp

Maintaining dental pulp vitality and preventing tooth loss are two challenges in endodontic treatment. A tooth lacking a viable pulp loses its defense mechanism and regenerative ability, making it more vulnerable to severe damage and eventually necessitating extraction. The tissue engineering approach has drawn attention as an alternative therapy as it can regenerate dentin-pulp complex structures and functions. Stem cells or progenitor cells, extracellular matrix, and signaling molecules are triad components of this approach. Stem cells from human exfoliated deciduous teeth (SHED) are a promising, noninvasive source of stem cells for tissue regeneration. Not only can SHEDs regenerate dentin-pulp tissues (comprised of fibroblasts, odontoblasts, endothelial cells, and nerve cells), but SHEDs also possess immunomodulatory and immunosuppressive properties. The collagen matrix is a material of choice to provide structural and microenvironmental support for SHED-to-dentin pulp tissue differentiation. Growth factors regulate cell proliferation, migration, and differentiation into specific phenotypes via signal-transduction pathways. This review provides current concepts and applications of the tissue engineering approach, especially SHEDs, in endodontic treatment.

Vitamin D Effects on Osteoblastic Differentiation of Mesenchymal Stem Cells from Dental Tissues

1α,25-Dihydroxyvitamin D₃ (1,25(OH)₂D₃), the active metabolite of vitamin D (Vit D), increases intestinal absorption of calcium and phosphate, maintaining a correct balance of bone remodeling. Vit D has an anabolic effect on the skeletal system and is key in promoting osteoblastic differentiation of human Mesenchymal Stem Cells (hMSCs) from bone marrow. MSCs can be also isolated from the immature form of the tooth, the dental bud: Dental Bud Stem Cells (DBSCs) are adult stem cells that can effectively undergo osteoblastic differentiation. In this work we investigated the effect of Vit D on DBSCs differentiation into osteoblasts. Our data demonstrate that DBSCs, cultured in an opportune osteogenic medium, differentiate into osteoblast-like cells; Vit D treatment stimulates their osteoblastic features, increasing the expression of typical markers of osteoblastogenesis like RUNX2 and Collagen I (Coll I) and, in a more important way, determining a higher production of mineralized matrix nodules.

Osteogenic differentiation of mesenchymal stem cells from dental bud: Role of integrins and cadherins

Several studies have reported the beneficial effects of mesenchymal stem cells (MSCs) in tissue repair and regeneration. New sources of stem cells in adult organisms are continuously emerging; dental tissues have been identified as a source of postnatal MSCs. Dental bud is the immature precursor of the tooth, is easy to access and we show in this study that it can yield a high number of cells with ≥95% expression of mesenchymal stemness makers and osteogenic capacity. Thus, these cells can be defined as Dental Bud Stem Cells (DBSCs) representing a promising source for bone regeneration of stomatognathic as well as other systems. Cell interactions with the extracellular matrix (ECM) and neighboring cells are critical for tissue morphogenesis and architecture; such interactions are mediated by integrins and cadherins respectively. We characterized DBSCs for the expression of these adhesion receptors and examined their pattern during osteogenic differentiation. Our data indicate that N-cadherin and cadherin-11 were expressed in undifferentiated DBSCs and their expression underwent changes during the osteogenic process (decreasing and increasing respectively), while expression of E-cadherin and P-cadherin was very low in DBSCs and did not change during the differentiation steps. Such expression pattern reflected the mesenchymal origin of DBSCs and confirmed their osteoblast-like features. On the other hand, osteogenic stimulation induced the upregulation of single subunits, αV, β3, α5, and the formation of integrin receptors α5β1 and αVβ3. DBSCs differentiation toward osteoblastic lineage was enhanced when cells were grown on fibronectin (FN), vitronectin (VTN), and osteopontin (OPN), ECM glycoproteins which contain an integrin-binding sequence, the RGD motif. In addition we established that integrin αVβ3 plays a crucial role during the commitment of MSCs to osteoblast lineage, whereas integrin α5β1 seems to be dispensable. These data suggest that functionalization of biomaterials with such ECM proteins would improve bone reconstruction therapies starting from dental stem cells.