Endothelial to mesenchymal transition (EndMT) is a leading cause of fibrosis and disease, however its mechanism has yet to be elucidated. The endothelium possesses a profound regenerative capacity to adapt and reorganize that is attributed to a population of vessel-resident endovascular progenitors (EVP) governing an endothelial hierarchy. Here, using fate analysis, we show that two transcription factors SOX9 and RBPJ specifically affect the murine EVP numbers and regulate lineage specification. Conditional knock-out of Sox9 from the vasculature (Sox9fl/fl/Cdh5-CreERRosaYFP) depletes EVP while enhancing Rbpj expression and canonical Notch signalling. Additionally, skin wound analysis from Sox9 conditional knock-out mice demonstrates a significant reduction in pathological EndMT resulting in reduced scar area. The converse is observed with Rbpj conditionally knocked-out from the murine vasculature (Rbpjfl/fl/Cdh5-CreER RosaYFP) or inhibition of Notch signaling in human endothelial colony forming cells, resulting in enhanced Sox9 and EndMT related gene (Snail, Slug, Twist1, Twist2, TGF-β) expression. Similarly, increased endothelial hedgehog signaling (Ptch1fl/fl/Cdh5-CreER RosaYFP), that upregulates the expression of Sox9 in cells undergoing pathological EndMT, also results in excess fibrosis. Endothelial cells transitioning to a mesenchymal fate express increased Sox9, reduced Rbpj and enhanced EndMT. Importantly, using topical administration of siRNA against Sox9 on skin wounds can substantially reduce scar area by blocking pathological EndMT. Overall, here we report distinct fates of EVPs according to the relative expression of Rbpj or Notch signalling and Sox9, highlighting their potential plasticity and opening exciting avenues for more effective therapies in fibrotic diseases.

Dentin hypersensitivity is characterized by short, sharp pain arising from exposed dentin in response to external stimuli. Several modalities have been suggested for treatment of this condition such as low-level laser therapy (LLLT) and application of dentin bonding agents. The aim of this study was to compare the clinical efficacy of diode laser, Nd:YAG laser and dentin bonding agent for treatment of dentin hypersensitivity. Materials and Methods: In this study, 135 teeth of 22 patients diagnosed with dentin hypersensitivity were divided into three groups: In group 1, the teeth were irradiated by diode laser with 810 nm wavelength for 30 seconds and in group 2, the teeth were irradiated by Nd:YAG laser with 1064 nm wavelength for 40 seconds. CLEARFIL SE BOND was applied on teeth in group 3. LLLT was carried out in 3 sessions with 7-day intervals between sessions, during a period of 3 consecutive weeks. Hypersensitivity was assessed by cold test according to the criteria proposed by Uchida at baseline, immediately after treatment and at 1, 3 and 6 months, postoperatively. Results: Reduction of dentin hypersensitivity was observed at 3 and 6 months following the use of Nd:YAG laser (p < 0.001). Reduction in dentin hypersensitivity was observed immediately after treatment in all groups. Statistically significant differences in level of dentin hypersensitivity were found between groups at 3 and at 6 months (p ≤ 0.001). The reduction in dentin hypersensitivity by Nd:YAG laser was significantly superior to that in other groups at this time. Conclusion: The efficacy of Nd:YAG laser in reduction of dentin hypersensitivity was significantly superior to that of other modalities at 3 and 6 months.

The aggressiveness of solid cancers, such as melanoma, relies on their metastatic potential. It has become evident that this key cause of mortality is largely conferred by the tumour-associated stromal cells, especially endothelial cells. In addition to their essential role in the formation of the tumour vasculature, endothelial cells significantly contribute to the establishment of the tumour microenvironment, thus enabling the dissemination of cancer cells. Melanoma tumour vascularization occurs through diverse biological processes. Vasculogenesis is the formation of de novo blood vessels from endothelial progenitor cells (EPCs), and recent research has shown the role of EPCs in melanoma tumour vascularization. A more detailed understanding of the complex role of EPCs and how they contribute to the abnormal vessel structures in tumours is of importance. Moreover, anti-angiogenic drugs have a limited effect on melanoma tumour vascularization, and the role of these drugs on EPCs remains to be clarified. Overall, targeting cancer vasculature remains a challenge, and the role of anti-angiogenic drugs and combination therapies in melanoma, a focus of this review, is an area of extensive exploration.

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The formation of new blood vessels from pre-existing ones, known as angiogenesis, is crucial in development and adulthood. One of the critical players is the zinc-dependent matrixmetalloproteinase MMP14. Complete loss of the protease underscored its importance in vivo as mice died within three weeks after birth due to several severe developmental defects, some due to impaired angiogenesis. To enable the analysis of the specific function of endothelial MMP14 in skin physiology and pathology, we generated mice with constitutive endothelial cell-specific deletion of MMP14 (MMP14 EC-/-). These mice developed and bred with no alterations in tissue vascularization. On the contrary, in pathological conditions, as in melanoma growth, loss of endothelial MMP14 resulted in reduced tumor growth and metastasis. While tumor vessel density and distribution were unaltered, vessel permeability was decreased. Analysis of underlying mechanisms that regulate vessel permeability revealed increased vessel coverage by pericytes. Moreover, VE-cadherin expression was enhanced, while eNOS expression and nitric oxide production in MMP14 EC-/endothelial cells were significantly reduced. Altogether, we show that MMP14 in endothelial cells, although it does not play a significant role during development, orchestrates several events in endothelial cells that control tumor vessel function. These data provide a better understanding of the role of endothelial cell-MMP14 and the potential use of targeting MMP14 as a therapeutic approach in melanoma.

Cutaneous Squamous Cell Carcinoma (cSCC) is the most common and fastest-increasing cancer with metastatic potential. Long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) are novel regulators of gene expression and little is known about their altered expression in cSCC. To elucidate cSCC associated coding and non-coding transcriptomic changes, we performed RNA-seq of 9 cSCCs and 7 healthy skin samples. Differential expression analysis was performed by edgeR. CircRNAs were identified using the find_circ and CIRCexplorer pipelines. Altered expression of 5,352 protein-coding genes, 908 lncRNAs and 55 circular RNAs was identified. Targets of 519 transcription factors were enriched among DEGs, 105 of which displayed altered level in cSCCs, including fundamental regulators of skin development and cSCC malignancy (MYC, RELA, ETS1, TP63). Pathways related to cell cycle, apoptosis, inflammation and epidermal differentiation were enriched. In addition to known oncogenic lncRNAs (PVT1, LUCAT1, CASC9), a set of skin-specific lncRNAs were also dysregulated. A global downregulation of circRNAs was observed in cSCC, and novel circRNAs, including skin-enriched circ_IFFO2 and circ_POF1B, were identified. Results from the RNA-seq were further validated in an expanded cohort using NanoString nCounter assays. In conclusion, through deep sequencing approach we have identified a reference set of coding and non-coding transcripts with altered expression in cSCC, which represent potential therapeutic targets or biomarkers.