Delivery of small interfering RNA for inhibition of endothelial cell apoptosis by hypoxia and serum deprivation

RNA interference (RNAi) for anti-angiogenic or pro-apoptotic factors in endothelial cells (ECs) has great potential for the treatment of ischemic diseases by promoting angiogenesis or inhibiting apoptosis. Here, we report the utility of small interfering RNA (siRNA) in inhibiting EC apoptosis induced by tumor necrosis factor-α (TNF-α). siRNA was designed and synthesized targeting tumor necrosis factor-α receptor-1 (TNFR-1) and Src homology 2 domain-containing protein tyrosine phosphatase-1 (SHP-1). Human umbilical vein endothelial cells (HUVECs) were cultured under in vitro hypoxic and serum-deprived conditions to simulate in vivo ischemic conditions. Two days after liposomal delivery of siRNA targeting TNFR-1 and SHP-1, significant silencing of each target (TNFR-1; 76.5 % and SHP-1; 97.2 %) was detected. Under serum-deprived hypoxic (1% oxygen) conditions, TNF-α expression in HUVECs increased relative to normoxic (20% oxygen) and serum-containing conditions. Despite enhanced TNF-α expression, suppression of TNFR-1 or SHP-1 by siRNA delivery not only enhanced expression of angiogenic factors (KDR/Flk-1 and eNOS) and anti-apoptotic factor (Bcl-xL) but also reduced expression of a pro-apoptotic factor (Bax). Transfection of TNFR-1 or SHP-1 siRNA significantly decreased the HUVEC apoptosis while significantly enhancing HUVEC proliferation and capillary formation. The present study demonstrates that TNFR-1 and SHP-1 may be useful targets for the treatment of myocardial or hindlimb ischemia

Inhibition of HIF-1α Reduced Blood Brain Barrier Damage by Regulating MMP-2 and VEGF During Acute Cerebral Ischemia

Increase of blood brain barrier (BBB) permeability after acute ischemia stroke is a predictor to intracerebral hemorrhage transformation (HT) for tissue plasminogen activator (tPA) thrombolysis and post-endovascular treatment. Previous studies showed that 2-h ischemia induced damage of BBB integrity and matrix metalloproteinase-2 (MMP-2) made major contribution to this disruption. A recent study showed that blocking β2-adrenergic receptor (β2-AR) alleviated ischemia-induced BBB injury by reducing hypoxia-inducible factor-1 alpha (HIF-1α) level. In this study, we sought to investigate the interaction of HIF-1α with MMP-2 and vascular endothelial growth factor (VEGF) in BBB injury after acute ischemia stroke. Rat suture middle cerebral artery occlusion (MCAO) model was used to mimic ischemia condition. Our results showed that ischemia produced BBB damage and MMP-2/9 upregulation was colocalized with Rhodamine-dextran leakage. Pretreatment with YC-1, a HIF-1α inhibitor, alleviated 2-h ischemia-induced BBB injury significantly accompanied by decrease of MMP-2 upregulation. In addition, YC-1 also prevented VEGF-induced BBB damage. Of note, VEGF was shown to be colocalized with neurons but not astrocytes. Taken together, BBB damage was reduced by inhibition of interaction of HIF-1α with MMP-2 and VEGF during acute cerebral ischemia. These findings provide mechanisms underlying BBB damage after acute ischemia stroke and may help reduce thrombolysis- and post-endovascular treatment-related cerebral hemorrhage

Current Developments and Challenges of mRNA Vaccines

mRNA vaccines have brought about a great revolution in the vaccine fields owing to their simplicity and adaptability in antigen design, potential to induce both humoral and cell-mediated immune responses and demonstrated high efficacy, and rapid and low-cost production by using the same manufacturing platform for different mRNA vaccines. Multiple mRNA vaccines have been investigated for both infectious diseases and cancers, showing significant superiority to other types of vaccines. Although great success of mRNA vaccines has been achieved in the control of the coronavirus disease 2019 pandemic, there are still multiple challenges for the future development of mRNA vaccines. In this review, the most recent developments of mRNA vaccines against both infectious diseases and cancers are summarized for an overview of this field. Moreover, the challenges are also discussed on the basis of these developments. </jats:p

Neuronal Differentiation of Human Mesenchymal Stem Cells Using Exosomes Derived from Differentiating Neuronal Cells

<div><p>Exosomes deliver functional proteins and genetic materials to neighboring cells, and have potential applications for tissue regeneration. One possible mechanism of exosome-promoted tissue regeneration is through the delivery of microRNA (miRNA). In this study, we hypothesized that exosomes derived from neuronal progenitor cells contain miRNAs that promote neuronal differentiation. We treated mesenchymal stem cells (MSCs) daily with exosomes derived from PC12 cells, a neuronal cell line, for 1 week. After the treatment with PC12-derived exosomes, MSCs developed neuron-like morphology, and gene and protein expressions of neuronal markers were upregulated. Microarray analysis showed that the expression of miR-125b, which is known to play a role in neuronal differentiation of stem cells, was much higher in PC12-derived exosomes than in exosomes from B16-F10 melanoma cells. These results suggest that the delivery of miRNAs contained in PC12-derived exosomes is a possible mechanism explaining the neuronal differentiation of MSC.</p></div

miRNAs enriched in PC12 exosomes but not upregulated after NGF treatment.

<p>miRNAs enriched in PC12 exosomes but not upregulated after NGF treatment.</p

Size and morphology of exosomes.

<p>(A) Typical size distribution for an exosome sample derived from PC12 cells, measured with dynamic light scattering (DLS). (B) DLS analysis of exosome samples. <i>n</i> = 9. All error bars represent standard deviation. (C) Transmission electron microscopy (TEM) image of a typical exosome sample derived from B16-F10 cells. Scale bar, 100 nm.</p