MicroRNA-21 Exhibits Antiangiogenic Function by Targeting RhoB Expression in Endothelial Cells

BACKGROUND: MicroRNAs (miRNAs) are endogenously expressed small non-coding RNAs that regulate gene expression at post-transcriptional level. The recent discovery of the involvement of these RNAs in the control of angiogenesis renders them very attractive in the development of new approaches for restoring the angiogenic balance. Whereas miRNA-21 has been demonstrated to be highly expressed in endothelial cells, the potential function of this miRNA in angiogenesis has never been investigated. METHODOLOGY/PRINCIPAL FINDINGS: We first observed in endothelial cells a negative regulation of miR-21 expression by serum and bFGF, two pro-angiogenic factors. Then using in vitro angiogenic assays, we observed that miR-21 acts as a negative modulator of angiogenesis. miR-21 overexpression reduced endothelial cell proliferation, migration and the ability of these cells to form tubes whereas miR-21 inhibition using a LNA-anti-miR led to opposite effects. Expression of miR-21 in endothelial cells also led to a reduction in the organization of actin into stress fibers, which may explain the decrease in cell migration. Further mechanistic studies showed that miR-21 targets RhoB, as revealed by a decrease in RhoB expression and activity in miR-21 overexpressing cells. RhoB silencing impairs endothelial cell migration and tubulogenesis, thus providing a possible mechanism for miR-21 to inhibit angiogenesis. Finally, the therapeutic potential of miR-21 as an angiogenesis inhibitor was demonstrated in vivo in a mouse model of choroidal neovascularization. CONCLUSIONS/SIGNIFICANCE: Our results identify miR-21 as a new angiogenesis inhibitor and suggest that inhibition of cell migration and tubulogenesis is mediated through repression of RhoB

In Vitro Comparative Study of Platelets Treated with Two Pathogen-Inactivation Methods to Extend Shelf Life to 7 Days

Background and Objectives: Since 2015, platelet products have been pathogen-inactivated (PI) at the Luxemburgish Red Cross (LRC) using Riboflavin and UV light (RF-PI). As the LRC should respond to hospital needs at any time, platelet production exceeds the demand, generating a discard rate of 18%. To reduce this, we consider the extension of storage time from 5 to 7 days. This study’s objective was to evaluate the in vitro 7-day platelet-storage quality, comparing two PI technologies, RF-PI and amotosalen/UVA light (AM-PI), for platelet pools from whole-blood donations (PPCs) and apheresis platelets collected from single apheresis donation (APCs). Materials and Methods: For each product type, 6 double-platelet concentrates were prepared and divided into 2 units; one was treated with RF-PI and the other by AM-PI. In vitro platelet-quality parameters were tested pre- and post-PI, at days 5 and 7. Results: Treatment and storage lesions were observed in PPCs and APCs with both PI methods. We found a higher rate of lactate increase and glucose depletion, suggesting a stronger stimulation of the glycolytic pathway, a higher Annexin V binding, and a loss of swirling in the RF-PI-treated units from day 5. The platelet loss was significantly higher in the AM-PI compared with the RF-PI units. Conclusions: Results suggest that RF-PI treatment has a higher deleterious impact on in vitro platelet quality compared to AM-PI, but we observed higher loss of platelets with AM-PI due to the post-illumination amotosalen adsorption step. If 7-day storage is needed, it can only be achieved with AM-PI, based on our quality criteria

Antioxidant power measurement in platelet concentrates treated by two pathogen inactivation systems in different blood centres.

The antioxidant power measurement can be useful to validate the execution of the pathogen inactivation treatment of platelet concentrates. The aim of this study is to evaluate the technology on different blood preparations including INTERCEPT and Mirasol treatments that are in routine use in Belgium and Luxemburg. The antioxidant power measurement was tested on 78 apheresis platelet concentrates and 54 pools of buffy-coats-derived platelet concentrates before and after INTERCEPT treatment. In addition, 100 Reveos platelet pools were tested before and after Mirasol treatment. The antioxidant power was quantified electrochemically using disposable devices and was expressed as equivalent ascorbic acid concentration. Mean results for apheresis platelet concentrates were of 90 ± 14 and 35 ± 10 µmol/l eq. ascorbic acid before and after INTERCEPT treatment, respectively. The mean results for pools of buffy-coats-derived platelet concentrates were of 81 ± 10 and 29 ± 4 eq. µmol/l ascorbic acid before and after INTERCEPT treatment, respectively. For buffy-coats-derived platelet concentrates treated by Mirasol technology, the mean results were of 98 ± 11 and 32 ± 10 µmol/l eq. ascorbic acid before and after illumination, respectively. The antioxidant power significantly decreases with pathogen inactivation treatments for platelet concentrates treated by INTERCEPT or Mirasol technologies