Dental pulp–derived stem cells inhibit osteoclast differentiation by secreting osteoprotegerin and deactivating AKT signalling in myeloid cells

Abstract

Osteoclasts (OCs) differentiate from the monocyte/macrophage lineage, critically regulate bone resorption and remodelling in both homeostasis and pathology. Various immune and non‐immune cells help initiating activation of myeloid cells for differentiation, whereas hyper‐activation leads to pathogenesis, and mechanisms are yet to be completely understood. Herein, we show the efficacy of dental pulp–derived stem cells (DPSCs) in limiting RAW 264.7 cell differentiation and underlying molecular mechanism, which has the potential for future therapeutic application in bone‐related disorders. We found that DPSCs inhibit induced OC differentiation of RAW 264.7 cells when co‐cultured in a contact‐free system. DPSCs reduced expression of key OC markers, such as NFATc1, cathepsin K, TRAP, RANK and MMP‐9 assessed by quantitative RT‐PCR, Western blotting and immunofluorescence detection methods. Furthermore, quantitative RT‐PCR analysis revealed that DPSCs mediated M2 polarization of RAW 264.7 cells. To define molecular mechanisms, we found that osteoprotegerin (OPG), an OC inhibitory factor, was up‐regulated in RAW 264.7 cells in the presence of DPSCs. Moreover, DPSCs also constitutively secrete OPG that contributed in limiting OC differentiation. Finally, the addition of recombinant OPG inhibited OC differentiation in a dose‐dependent manner by reducing the expression of OC differentiation markers, NFATc1, cathepsin K, TRAP, RANK and MMP9 in RAW 264.7 cells. RNAKL and M‐CSF phosphorylate AKT and activate PI3K‐AKT signalling pathway during osteoclast differentiation. We further confirmed that OPG‐mediated inhibition of the downstream activation of PI3K‐AKT signalling pathway was similar to the DPSC co‐culture–mediated inhibition of OC differentiation. This study provides novel evidence of DPSC‐mediated inhibition of osteoclastogenesis mechanisms.

Molecular Biological Comparison of Dental Pulp- and Apical Papilla-Derived Stem Cells

“…According to literature, OPG is supposed to be a pro-osteogenic factor that has the ability to prime undifferentiated mesenchymal stem cells towards mineralization [ 34 ]. Furthermore, it counteracts osteoclastogenesis and is released constitutively to limit the differentiation of osteoclasts and thus controls bone remodeling processes [ 35 ].…”

Zirconia Hybrid Dental Implants Influence the Biological Properties of Neural Crest-Derived Mesenchymal Stromal Cells

“…In addition, recent findings highlighted that zirconia proved to have a good biocompatibility due to the limited inflammatory response and bone loss when compared to titanium implants [ 19 , 20 ]. Human dental pulp stem cells (hDPSCs) represent a suitable cell source among the oral cavity stem cells for conducting in vitro studies on the interactions with dental implant materials due to their peculiar neural crest-origin-related properties, i.e., cell proliferation, differentiation potential and the expression of immunoregulatory molecules, which confer on them the capability to modulate the immune/inflammatory response and to preserve bone mass by modulating osteoclasts [ 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. Based on this premise, the aim of the present study is to investigate the biological properties of hDPSCs when cultured on zirconia-coated titanium surfaces or on traditional titanium surfaces prepared according to different cleansing protocols by assessing cell adhesion, proliferation, osteogenic differentiation and inflammatory response.…”

Secretome of Dental Pulp-Derived Stem Cells Reduces Inflammation and Proliferation of Glioblastoma Cells by Deactivating Mapk-Akt Pathway

“…Invasive procedures raise the risk of complications, such as bleeding, nerve injury, or damage to surrounding tissues, which can further limit the utility of MSC obtained through invasive procedures [ 11 ] . Interestingly, human dental pulp stem cells (DPSC) are acquired by noninvasive procedures from third molar teeth and their therapeutic potential resembles other kinds of MSC which allow them to treat debilitating diseases such as immunodeficiencies, neurological diseases, type 1 diabetes, and bone and cartilage disorders [ 12 – 14 ] . Strong evidence demonstrated that the culture supernatant of MSC (MSC ℗ ) governs various cellular functions such as proliferation, migration, differentiation, and communication due to its cell secretome, which comprises a range of factors, including exosomes, cytokines, and growth factors [ 15 ] .…”

“…As previously illustrated that MSC ℗ decrease breast cancer cell growth and sensitize cancer cells to radiotherapy by downregulating the signal transducer and activator of transcription 3 (STAT3) signaling pathway [ 22 ] . We previously found that DPSC-secreted factors augment wound healing in diabetic mice by upregulating the SMAD signaling [ 13 ] , and suppressing osteoclastogenesis by secreting osteoprotegerin and inhibiting AKT signaling in monocytes [ 12 ] . It was reported that DPSC ℗ inhibit viability and induces apoptosis in human colorectal cancer cells [ 23 ] .…”