Inhibiting DNA methylation as a strategy to enhance adipose-derived stem cells differentiation: Focus on the role of Akt/mTOR and Wnt/β-catenin pathways on adipogenesis

Adipose-derived mesenchymal stem cells (ASCs) represent a valid therapeutic option for clinical application in several diseases, due to their ability to repair damaged tissues and to mitigate the inflammatory/immune response. A better understanding of the underlying mechanisms regulating ASC biology might represent the chance to modulate their in vitro characteristics and differentiation potential for regenerative medicine purposes. Herein, we investigated the effects of the demethylating agent 5-azacytidine (5-aza) on proliferation, clonogenicity, migration, adipogenic differentiation and senescence of ASCs, to identify the molecular pathways involved. Through functional assays, we observed a detrimental effect of 5-aza on ASC self-renewal capacity and migration, accompanied by actin cytoskeleton reorganization, with decreased stress fibers. Conversely, 5-aza treatment enhanced ASC adipogenic differentiation, as assessed by lipid accumulation and expression of lineage-specific markers. We analyzed the involvement of the Akt/mTOR, MAPK and Wnt/β-catenin pathways in these processes. Our results indicated impairment of Akt and ERK phosphorylation, potentially explaining the reduced cell proliferation and migration. We observed a 5-aza-mediated inhibition of the Wnt signaling pathway, this potentially explaining the pro-adipogenic effect of the drug. Finally, 5-aza treatment significantly induced ASC senescence, through upregulation of the p53/p21 axis. Our data may have important translational implications, by helping in clarifying the potential risks and advantages of using epigenetic treatment to improve ASC characteristics for cell-based clinical approaches.

Ultra-narrowband polarization insensitive transmission filter using a coupled dielectric-metal metasurface

A coupled dielectric-metal metasurface (CDMM) filter consisting of amorphous silicon (a-Si) rings and subwavelength holes in Au layer separated by a SiO₂ layer is presented. The design parameters of the CDMM filter is numerically optimized to have a polarization independent peak transmittance of 0.55 at 1540 nm with a Full Width at Half Maximum (FWHM) of 10 nm. The filter also has a 100 nm quiet zone with ∼10^-2 transmittance. A radiating two-oscillator model reveals the fundamental resonances in the filter which interfere to produce the electromagnetically induced transparency (EIT) like effect. Multipole expansion of the currents in the structure validates the fundamental resonances predicted by the two-oscillator model. The presented CDMM filter is robust to artifacts in device fabrication and has performances comparable to a conventional Fabry-Pérot filter. However, it is easier to be integrated in image sensors as the transmittance peak can be tuned by only changing the periodicity resulting in a planar structure with a fixed height.

[Granulocytic "deactivation" in cold urticaria]

Recent advance about pathogenesis of Idiopathic acquired Cold-induced Urticaria underline the role of Neutrophils that, drawn by a specific mast-cell factor (HMW-NCF) might characterise precise stages of disease and presumably specific histologic "subset". This factor together with the chemotactic factor for eosinophils (ECF) can determine the so called neutrophils' "deactivation". In this study we have valued the role of neutrophils in six patients with idiopathic cold-induced urticaria and in a group of control including both patients with other forms of urticaria and healthy controls. The results of our research show the absence of alterations either in cellular neutrophilic chemotaxis or the serum one. Furthermore we have been able to determine that this "deactivation" is specific for idiopathic cold-induced urticaria and that it does not happen in the other forms of physical or non urticaria.

[Preliminary experiences with chemotactic activity of CGRP using the skin window test]

The neuropeptide CGRP (Calcitonin Gene-Related Peptide) develops in sensory fibers of the human skin a series of well proven biological effects and seems particularly correlated with the neurogenic inflammation. In the site of intradermic injection of 50 pmol of CGRP, neutrophilic inflammation was documented. For this reason we have studied using the skin window test the chemotactic actions of this neuropeptide in vivo. The apposition of CGRP (12.5 pmol) on the abraded skin modifies neutrophilic egress, increasing that effect in a significant way in comparison with controls. The action on neutrophils of CGRP helps to explain the importance of this neuropeptide in the genesis of the "Neurogenic inflammation".

Colchicine treatment in a case of pachydermoperiostosis with acroosteolysis

We report a case of pachydermoperiostosis with arthralgia, acroosteolysis, and recurrent staphylococcal folliculitis of the face, treated with colchicine (0.5 mg once daily for the 1st week and 0.5 mg twice daily for the next 3 weeks). The evaluation of arthralgia, hyponchial angle, folliculitis, and pachyderma, performed at basal time and once weekly, showed improvement of symptoms and signs after 7-15 days of treatment. Neutrophilic chemotaxis, evaluated before starting the treatment and after 15 and 30 days of therapy, showed a progressive decrease of the initial very high index. Colchicine provided a beneficial therapeutic response in both inhibiting increased chemotactic activity and in reducing tissular oedema in our patient.