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The article offers information on effects of dynamic shear stress on the biological properties of pericyte-like cells from human dental pulp in an inflammatory micro environment. Topics include information on low immunogenicity and immunomodulatory/anti-inflammatory properties; how they regulate numerous functions including vessel growth; and pericytes localized in the head, dental pulp, thymus and the outflow tract of the aorta.

Introduction & Aim: Mesenchymal stromal/stem cells (MSCs) have been widely characterized for their regenerative and immunomodulatory properties. Recent studies reported that MSCs can contribute to tissue regeneration by modulating inflammatory microenvironment suggesting how these properties are strictly related [1]. MSCs can be isolated from diff erent adult tissues including dental pulp. Human dental pulp stromal/stem cells (hDPSCs) are characterized by multipotency and low immunogenicity, as well as by immunomodulatory properties exerted by diff erent mechanisms (i.e., Fas/FasL pathway) after exposure to an infl ammatory microenvironment [2,3]. Among these immunoregulatory mechanisms, PD-1/PD-L1 pathway seems to be an important effector in the suppression of immune system activation and its role is not fully understood in hDPSCs [4]. Therefore, the present study aimed to 1) investigate the downstream mechanism of a new immune-regulatory pathway, i.e., PD-1/PD-L1, in hDPSCs 2) how the inflammatory microenvironment might affect hDPSCs immunomodulatory potential. Methods: Infl ammatory microenvironment was created in vitro by the activation of peripheral blood mononuclear cells (PBMCs) isolated from healthy donors and rheumatoid arthritis (RA) patients with anti-CD3 and anti-CD28 antibodies. Direct and indirect co-cultures between hDPSCs and PBMCs were carried out to evaluate the activation of immunomodulatory checkpoints in hDPSCs and the inflammatory pattern in PBMCs through Real-Time PCR, Western Blot, Immunofluorescence and Immunohistochemistry analyses. Results: Our data revealed that hDPSCs up-regulate PD-L1 and IL6 via both direct and indirect interaction-dependent mechanisms in response to exposure to CD3/CD28 co-stimulated PBMCs (aPBMCs). This ability is strictly related to hDPSCs stemness status. Moreover, as demonstrated by using a selective PD-L1 inhibitor, hDPSCs were able to activate compensatory pathways (i.e., Fas/FasL). At the same time, hDPSCs are able to control the inflammatory process by modulating pro-inflammatory cytokines expression in aPBMCs. In the second step of our study, we investigate how PD-L1, IL6 and FasL expression might be affected by different inflammatory conditions mimicked by direct and indirect hDPSCsaPBMCs co-cultures at different ratios and timepoints. Our data revealed that PD-L1 and IL6 mRNA levels show the same trend in both direct and indirect co-culture systems, regardless hDPSCs-aPBMCs ratio and timepoints. On the other hand, FasL mRNA levels were significantly up-regulated in hDPSCs only after a direct contact with aPBMCs, with an increasing trend across the different hDPSCs-aPBMCs ratios. The up-regulation of FasL mRNA levels in hDPSCs was also observed after indirect co-cultures only at later timepoints. Future studies aimed at deeply investigating the molecular mechanisms involved will corroborate these results. Conclusions: Our results pointed out that DPSCs can modulate the infl ammatory microenvironment by the activation of PD-1/PD-L1 pathway synergistically cooperating with other immune-regulatory pathways including Fas/FasL. These immunomodulatory properties are orchestrated by the infl ammatory microenvironment. Based on this evidence, these properties might be functional in controlling the inflammatory milieu typical of autoimmune diseases, such as rheumatoid arthritis. [ABSTRACT FROM AUTHOR]

Stress urinary incontinence (SUI), the most common type of urinary incontinence, is defined by an involuntary leakage of urine due to physical stress involving an increase in bladder pressure. It is associated with life quality issues, depressive symptoms and social discomfort. The pathophysiology is represented by tissue damage of the external urethral sphincter affecting both muscle and nerve tissues. The current therapies are mainly based on rehabilitating methods, pharmacological and/or surgical treatments. However, these therapies cannot resolve the primary cause of incontinence, indeed only symptoms can take relief by such treatments [1]. Mesenchymal stem cells might represent an alternative tool for therapy of SUI. The aim of the study was to evaluate the regenerative potential of human dental pulp stem cells (hDPSCs) in an animal model of SUI. As reported in literature, hDPSCs are easily accessible during routine tooth extraction procedures, own a wide differentiation potential and do not present ethical issues [2, 3]. The first phase of the study demonstrated that hDPSCs were able to reach the myogenic commitment in vitro; then, in the second phase, after surgically inducing urinary incontinence in female rats, we injected pre-differentiated hDPSCs in the urethral sphincter. Four weeks after cell injection the sphincter thickness was almost recovered, hDPSCs engrafted in the external urethral sphincter, committed towards myogenic lineage in vivo and promoted neo-angiogenesis. The urodynamic study showed an appreciable recovery of the continence in rats treated with hDPSCs which, interestingly, were also detected within the nerve, thus suggesting their participation in re-innervating the formerly injured nerve. Our findings, combined with further investigations on paracrine and immunomodulatory effects of hDPSCs, might allow to propose them as a promising tool for future alternative therapies in the treatment of SUI. [ABSTRACT FROM AUTHOR]

Human dental pulp, a soft connective tissue contained within the pulp chamber of the tooth, is considered an interesting source of adult stem cells, due to the low-invasive procedures required for cell isolation, high content of stem cells and its peculiar embryological origin from neural crest [1-2]. Based on previous findings from our group, a dental pulp stem cells (hDPSCs) population sorted for the expression of STRO-1, c-Kit and CD34 showed a higher commitment towards neurogenic and glial lineages. Moreover, in standard culture conditions STRO-1+/c-Kit+/CD34+ hDPSCS, at late passages, underwent an arrest in cell proliferation and senescence occurred. To this regard, the aim of the present study was to evaluate the ability of three dimensional sphere structures to preserve the biological and stemness properties of this sub-population. In addition, the ability to differentiate towards neurogenic lineage as well as the expression of Fas ligand were investigated. Our data demonstrated that hDPSCs-derived spheres were able to maintain their fibroblast-like morphology and preserved the expression of the stemness markers and their proliferative capability. At late passages, only few cells derived from spheres were positive for β-Galactosidase activity. Interestingly, the expression of neural crest markers was maintained along the whole culture time and the neurogenic commitment was successfully achieved, as confirmed by confocal immunofluorescence and electrophysiological analyses. The expression of FasL, a key molecule for the modulation of immune response, was observed in undifferentiated hDPSCs derived from sphere culture and, surprisingly, it was maintained even after the neurogenic differentiation was reached, whereas after the induction towards osteogenic and myogenic lineages the expression of FasL significantly decreased (P<0.05). These data demonstrated that 3D spheres obatained from STRO-1+/c- Kit+/CD34+ hDPSCs represent a suitable culture system to preserve the stemness properties and provide a favorable micro-environment for neural crest derived hDPSCs. [ABSTRACT FROM AUTHOR]