Human Spred1 blocking peptide

The proresolution lipid mediator lipoxin (LX) A(4) bestows protective bioactions on endothelial cells. We examined the impact of LXA(4) on transcellular endothelial signaling via microRNA(miR)-containing microvesicles. We report LXA(4) inhibition of MV release by TNF-alpha-treated HUVECs, associated with the down-regulation of 18 miR in endothelial microvesicles (EMVs) and the up-regulation of miR-126-5p, both in HUVECs and in EMVs. LXA(4) upregulated miR-126-5p by similar to 5-fold in HUVECs and promoted a release of microvesicles (LXA(4)-EMVs) that enhanced miR-126-5p by similar to 7-fold in recipient HUVECs. In these cells, LXA(4)-EMVs abrogated the up-regulation of VCAM-1, induced in recipient HUVECs by EMVs released by untreated or TNF-alpha-treatedHUVECs. LXA(4)-EMVs also reduced by similar to 40% the expression of SPRED1, which we validated as an miR-126-5p target, whereas they stimulated monolayer repair in an in vitro wound assay. This effect was lost when the EMVs were depleted of miR-126-5p. These results provide evidence that changes in miR expression and microvesicle packaging and transfer represent a mechanism of action of LXA(4), which may be relevant in vascular biology and inflammation.-Codagnone, M., Recchiuti, A., Lanuti, P., Pierdomenico, A. M., Cianci, E., Patruno, S., Mari, V. C., Simiele, F., Di Tomo, P., Pandolfi, A., Romano, M. Lipoxin A(4) stimulates endothelial miR-126-5p expression and its transfer via microvesicles.

Increasing evidence has suggested that paracrine mechanisms might be involved in the underlying mechanism of mesenchymal stem cells (MSCs) transplantation, and exosomes are an important component of this paracrine role. However, MSCs are usually exposed to normoxia (21% O-2) in vitro but experience large differences in oxygen concentration in the body under hypoxia. Indeed, hypoxic precondition of MSCs can enhance their paracrine effects. The main purpose of this study was to determine whether exosomes derived from MSCs under hypoxia (Hypo-Exos) exhibit greater effects on bone fracture healing than those under normoxia (Exos). Using in vivo bone fracture model and in vitro experiments including cell proliferation assay, cell migration assay and so on, we confirmed that Hypo-Exos administration promoted angiogenesis, proliferation and migration to a greater extent when compared to Exos. Furthermore, utilizing a series in vitro and in vivo gain and loss of function experiments, we confirmed a functional role for exosomal miR-126 in the process of bone fracture healing. Meanwhile, we found that knockdown of hypoxia inducible factor 1 (HIF-1 alpha) resulted in a significant decrease of miR-126 in MSCs and exosomes, thereby abolishing the effects of Hypo-Exos. In conclusion, our results demonstrated a mechanism by which Hypo-Exos promote bone fracture healing through exosomal miR-126. Moreover, hypoxia preconditioning mediated enhanced production of exosomal miR-126 through the activation of HIF-1 alpha. Hypoxia preconditioning represents an effective and promising method for the optimization of the therapeutic actions of MSC-derived exosomes for bone fracture healing. Statement of significance Studies have confirmed that transplantation of exosomes exhibit similar therapeutic effects and functional properties to directly-transplanted stem cells but have less significant adverse effects. However, during in vitro culture conditions, MSCs are usually exposed to normoxia (21% O-2) which is very different to the oxygen concentrations found in the body under natural physiological conditions. Our results demonstrated a mechanism by which Hypo-Exos promote bone fracture healing through exosomal miR126 and the SPRED1/Ras/Erk signaling pathway. Moreover, hypoxia preconditioning mediated enhanced production of exosomal miR-126 through the activation of HIF-1 alpha. Hypoxia preconditioning represents an effective and promising method for the optimization of the therapeutic actions of MSC-derived exosomes for bone fracture healing. (C) 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.