Effect of dentin matrix components on the mineralization of human mesenchymal stromal cells

In teeth with an injured pulp, dentin matrix orchestrates hard tissue repair through the release of dentin extracellular matrix components (dEMCs). dEMCs regulate the differentiation of resident mesenchymal stromal cells (MSCs), thereby affecting mineral deposition. Here, we show that low concentration solubilized dEMCs in osteogenic cultures of human umbilical cord mesenchymal stromal cells (UC-MSCs) and dental pulp stromal cells (DPSCs) enhanced mineral deposition, while adipose stromal cells (ASCs) were barely affected. Interestingly, UC-MSCs displayed significantly greater hydroxyapatite formation compared to DPSCs. UC-MSCs and DPSCs showed a dose-dependent viability and proliferation, whereas proliferation of ASCs remained unaffected. Qualitative analysis of the dEMCs-supplemented osteogenic cultures through scanning electron microscopy demonstrated differences in the architecture of the deposited mineralized structures. Large-sized mineral accretions upon a poorly organized collagen network was the prominent feature of UC-MSCs cultures, while mineral nodules interspersed throughout a collagen mesh were observed in the respective DPSCs cultures. The ability of dEMCs to induce mineralization varies between different human MSCs types in terms of total mineral formation and its architecture. Mineral formation by UC-MSCs exposed to low concentration dEMCs proved to be the most efficient and therefore could be considered as a promising combination for mineralized tissue engineering.