Osteogenesis in human periodontal ligament stem cell sheets is enhanced by the protease-activated receptor 1 (PAR1) in vivo.

Human periodontal ligament stem cells (PDLSCs) have been studied as a promising strategy in regenerative approaches. The protease-activated receptor 1 (PAR1) plays a key role in osteogenesis and has been shown to induce osteogenesis and increase bone formation in PDLSCs. However, little is known about its effects when activated in PDLSCs as a cell sheet construct and how it would impact bone formation as a graft in vivo. Here, PDLSCs were obtained from 3 patients. Groups were divided into control, osteogenic medium and osteogenic medium + PAR1 activation by TFLLR-NH2 peptide. Cell phenotype was determined by flow cytometry and immunofluorescence. Calcium deposition was quantified by Alizarin Red Staining. Cell sheet microstructure was analyzed through light, scanning electron microscopy and histology and transplanted to Balb/c nude mice. Immunohistochemistry for bone sialoprotein (BSP), integrin ß1 and collagen type 1 and histological stains (H&E, Van Giesson, Masson's Trichrome and Von Kossa) were performed on the ex-vivo mineralized tissue after 60 days of implantation in vivo. Ectopic bone formation was evaluated through micro-CT. PAR1 activation increased calcium deposition in vitro as well as BSP, collagen type 1 and integrin ß1 protein expression and higher ectopic bone formation (micro-CT) in vivo.

Pain in Covid Era.

The COVID19 pandemic has impacted the lives and health of persons worldwide and although majority of COVID19 patients present with respiratory symptoms, pain emerges as an important feature of COVID19 infection. About 15-20% of patients progress to a severe condition that requires hospitalization. Although the disease was initially reported as a respiratory syndrome, other systems such as cardiovascular, renal, and nervous systems may be affected in the acute stages, increasing the need for continuous support to treat multiple sequelae caused by the disease. Due to the severity of the disease, damages found after discharge should also be considered. Providing multidisciplinary interventions promoting physical and psychological recovery in the first stages of hospitalization can minimize these damages. Cognitive, physical and psychological dysfunction reported by COVID19 patients after discharge can have profound effects on quality of life. Pain is usually part of this dysfunction, but it is still poorly understood how it affects survivors of COVID19 infections. There is limited information about the clinical characteristics, treatment and outcome of maintenance of pain in COVID19 patients. The purpose of this narrative review is to provide an overview of the implications of COVID19 on acute and chronic pain states.

Involvement of substance P, osteopontin and satellite glial cells on photobiomodulation-induced antinociceptive effect in an experimental model of dentin hypersensitivity.

The aim of this work was to investigate the involvement of substance P (SP), osteopontin (OPN), and satellite glial cells (SGC) on photobiomodulation-induced (PBM) antinociceptive effect in an experimental model of dentin hypersensitivity (DH). Rats ingested isotonic drink (ID, pH 2.87) for 45 consecutive days and after this period received PBM irradiation at λ660 nm or λ808 nm (1 J, 3.5 J/cm2, 100 mW, 10 s, 0.028 cm2, continuous wave, 3 consecutive daily sessions), and were evaluated for nociceptive behavior 24, 48, 72 h, and 14 days after laser treatments. ID ingestion induced an increase on thermal sensitivity of DH characteristics in rats that was completely reversed by PBM treatment at both 660 and 808 nm. Immunohistochemical analysis revealed increased SP expression at both dentin-pulp complex (DPC) and trigeminal ganglia (TG) of DH-rats which did not occur in PBM groups by PBM treatment. Also, the increase of glial fibrillary acidic protein (GFAP) observed in the TG of DH-rats was also reversed by PBM treatment. Finally, PBM at both 660 and 808 nm increased OPN expression in the dentin-pulp complex of DH-rats after 14 days of PBM treatment. All in all, this data demonstrates that PBM reverses nociception in a DH experimental model by inhibiting neurogenic inflammation and inducing a regenerative response.