Polyphenolic compounds are a diverse group of natural compounds that interact with various cellular proteins responsible for cell survival, differentiation, and apoptosis. However, it is yet to be established how these compounds interact in myeloid cells during their differentiation and the molecular and intracellular mechanisms involved. Osteoclasts are multinucleated cells that originate from myeloid cells. They resorb cartilage and bone, maintain bone homeostasis, and can cause pathogenesis. Autophagy is a cellular mechanism that is responsible for the degradation of damaged proteins and organelles within cells and helps maintain intracellular homeostasis. Imbalances in autophagy cause various pathological disorders. The current study investigated the role of several polyphenolic compounds, including tannic acid (TA), gallic acid (GA), and ellagic acid (EA) in the regulation of osteoclast differentiation of myeloid cells. We demonstrated that polyphenolic compounds inhibit osteoclast differentiation in a dose-dependent manner. Quantitative real-time PCR, immunocytochemistry, and western blotting revealed that osteoclast markers, such as NFATc1, Cathepsin K, and TRAP were inhibited after the addition of polyphenolic compounds during osteoclast differentiation. In our investigation into the molecular mechanisms, we found that the addition of polyphenolic compounds reduced the number of autophagic vesicles and the levels of LC3B, BECN1, ATG5, and ATG7 molecules through the inactivation of Akt, thus inhibiting the autophagy process. In addition, we found that by decreasing intracellular calcium and decreasing ROS levels, along with decreasing mitochondrial membrane potential, polyphenolic compounds inhibit osteoclast differentiation. Together, this study provides evidence that polyphenolic compounds inhibit osteoclast differentiation by reducing ROS production, autophagy, intracellular Ca²⁺ level, and mitochondrial membrane potentials.

Despite advances in diabetic wound care, many amputations are still needed each year due to their diabetic wounds, so a more effective therapy is warranted. Herein, we show that the dental pulp-derived stem cell (DPSC) products are effective in wound healing in diabetic NOD/SCID mice. Our results showed that the topical application of DPSC secretory products accelerated wound closure by inducing faster re-epithelialization, angiogenesis, and recellularization. In addition, the number of neutrophils producing myeloperoxidase, which mediates persisting inflammation, was also reduced. NFκB and its downstream effector molecules like IL-6 cause sustained pro-inflammatory activity and were reduced after the application of DPSC products in the experimental wounds. Moreover, the DPSC products also inhibited the activation of NFκB, and its translocation to the nucleus, by which it initiates the inflammation. Furthermore, the levels of TGF-β, and IL-10, potent anti-inflammatory molecules, were also increased after the addition of DPSC products. Mechanistically, we showed that this wound-healing process was mediated by the upregulation and activation of Smad 1 and 2 molecules. In sum, we have defined the cellular and molecular mechanisms by which DPSC products accelerated diabetic wound closure, which can be used to treat diabetic wounds in the near future.