Odontoblasts induced from mesenchymal cells of murine dental papillae in three-dimensional cell culture

Abstract

In an organ culture system under a three-dimensional microenvironment that provides the conditions needed for odontoblast differentiation, a row of odontoblasts can be induced (Kikuchi et al. 1996, 2001). Therefore, in a newly designed three-dimensional cell culture system that fulfils the conditions necessary for odontoblast differentiation (Kikuchi et al. 2002), we examined whether dental papilla cells in rat mandibular incisors could differentiate into tubular dentine-forming cells. In our previously established organ culture system, CM-Dil-labeled cells that were microinjected into isolated dental papillae were replaced by a row of odontoblasts. In a three-dimensional cell culture system, which consists of two kinds of type I collagen in the upper layer over multi-layered cells seeded onto collagen containing Matrigel in the lower layer and which acts as a structural meshwork, dental papilla cells were incubated as multi-layered cells in an artificial extracellular matrix (ECM). The cells aggregated to form a cell mass and invaginated as a cell mass into the ECM. The cells also extended fine fibrillar processes into the ECM. With regard to invagination, the proteolytic activities of matrix metalloproteinase-2 (MMP-2)/membrane type 1-matrix metalloproteinase (MT 1-MMP) were observed on the outer multi-layers of cells within a cell mass adjacent to the ECM. The cell mass progressively shrank to about one-half to one-third of its original diameter and was organized as a tissue surrounded by a newly secreted ECM, like dental pulp-dentine. The cells adjacent to the secreted ECM were constructed as a row of polarized columnar cells. They extended slender processes into the new ECM, which is characteristic of tubular matrix. Dentine sialophosphoprotein (DSPP) and dentine matrix protein 1 (DMP 1) genes, which are specific for odontoblast differentiation, were expressed in an aggregated cell mass where tubular matrix-forming cells were induced. Furthermore, the tubular matrix became mineralized under prolonged culture. These results imply that the putative progenitor cells/stem cells residing in dental papillae can differentiate into odontoblasts under appropriate conditions in vitro.

Differentiation potential of STRO-1+ dental pulp stem cells changes during cell passaging

“…When these stem cells at the 9 th passage are implanted into the renal capsules, most stem cells are in a differentiated state, which conversely leads to the decrease of stem cell number, results in the loss of balance between stem cell proliferation and differentiation, and finally brings about the irregular tissue development [19]. Since the difference between dentin and bone is largely due to the different arrangement of matrix [24], irregular array of dentin and bone matrix secreted by odontoblasts and osteoblasts respectively may bring about the same appearance of bone-like calcification. Finally, the cell number of differentiated chondrocytes may be too limited (weak expression of COL II protein/gene) to perform the sustainable morphogenesis of cartilage in DPSC-P9 group.…”

Mouse Dental Pulp Stem Cells Support Human Umbilical Cord Blood-Derived Hematopoietic Stem/Progenitor Cells in Vitro

“…Previous studies have reported that MSC-like dental pulp stem cells (dental pulp-derived MSCs, DPSCs) exist in the dental pulp (16,25). One of the major roles of DPSCs is thought to be their ability to supply hard tissue components by differentiating into odontoblasts (10). BM-MSCs have also been suggested to supply hard tissue components by differentiation into osteoblasts (28).…”

Hepatocyte Growth Factor Exerts Promoting Functions on Murine Dental Papilla Cells

“…Besides transgenic mouse studies, dental epithelium and mesenchyme derived cells cultured in vitro provide important strategies to study these signaling factors. Dental papilla cells derived from dental papilla and capable of odontoblast differentiation and dentin formation provide a useful model for studying the morphogenesis and differentiation of dental papilla ectomesenchyme during tooth development (31)(32)(33).…”