Immunohistochemical localization of CD146 and alpha‐smooth muscle actin during dentin formation and regeneration

Abstract

Cluster of differentiation 146 (CD146) is known to localize in stem cells and precursor cells of various tissues. In this study, to analyze the function of CD146 in odontoblast differentiation, immunohistochemical localization of CD146 was examined during rat molar tooth development and after cavity preparation. At the cap and bell stages, many CD146‐positive cells were visible around the blood vessels in the dental papillae. On Postnatal day 2, osterix‐positive odontoblasts were arranged in the dentin sialoprotein (DSP)‐positive predentin, and many CD146‐positive cells were observed near these odontoblasts with blood vessels. Some perivascular CD146‐positive cells overlapped with Smad4‐positive cells. However, the immunoreactivity for alpha‐smooth muscle actin (α‐SMA), one of the markers for undifferentiated cells, was negligible. Furthermore, the number of these cells decreased in the dental pulp on Postnatal day 28. On Day 4 after cavity preparation, Osterix‐positive odontoblasts appeared lining the reparative dentin. Most of the blood vessels near the reparative dentin showed immunoreactivities for CD146. Reparative odontoblasts actively formed DSP‐positive dentin matrix because these cells were positive for Smad4 and Osterix, but not for α‐SMA. After 7 days, the number of CD146‐positive cells near blood vessels decreased in the dental pulp beneath the cavity. These results suggest that the CD146 is expressed in the perivascular area of the dental pulp and induces vascularization in the vicinity of dentin formation, and some CD146‐positive cells are activated by the bone morphogenetic protein signaling pathway and differentiate into odontoblasts in the early stages of dentin formation and repair.

Electrical stimulation induced pre-vascularization of engineered dental pulp tissue

“…α-SMA is a cytoskeletal protein that is also localized in some stem cells and precursor cells and is considered to be one of the stem cell markers in dental pulp. α-SMA is also expressed in vascular pericytes, myofibroblasts and smooth muscle cells, and plays a key role in wound healing and participates in dental pulp healing [ 22 ]. During dentin formation, the majority of MSCs were identified to be located in the perivascular area, which is considered as a stem cell niche [ 23 ], and in this study, α-SMA positive cells were observed in the perivascular area.…”