Micromanaging cardiac regeneration:Targeted delivery of microRNAs for cardiac repair and regeneration

The loss of cardiomyocytes during injury and disease can result in heart failure and sudden death, while the adult heart has a limited capacity for endogenous regeneration and repair. Current stem cell-based regenerative medicine approaches modestly improve cardiomyocyte survival, but offer neglectable cardiomyogenesis. This has prompted the need for methodological developments that crease de novo cardiomyocytes. Current insights in cardiac development on the processes and regulatory mechanisms in embryonic cardiomyocyte differentiation provide a basis to therapeutically induce these pathways to generate new cardiomyocytes. Here, we discuss the current knowledge on embryonic cardiomyocyte differentiation and the implementation of this knowledge in state-of-the-art protocols to the direct reprogramming of cardiac fibroblasts into de novo cardiomyocytes in vitro and in vivo with an emphasis on microRNA-mediated reprogramming. Additionally, we discuss current advances on state-of-the-art targeted drug delivery systems that can be employed to deliver these microRNAs to the damaged cardiac tissue. Together, the advances in our understanding of cardiac development, recent advances in microRNA-based therapeutics, and innovative drug delivery systems, highlight exciting opportunities for effective therapies for myocardial infarction and heart failure

Responses of retinal and brain microvasculature to streptozotocin induced diabetes revealed by global expression profiling

This study aims to determine the effects of diabetes in the retinal and brain microvasculature through gene expression profiling. Twelve male Wistar rats were randomly divided into two groups: streptozotocin-induced diabetic rats and time-matched nondiabetic rats. The retinal microvessels (RMVs) and brain microvessels (BMVs) were mechanically isolated from individual rats. Differentially expressed genes (DEGs) in diabetic and nondiabetic microvessels were identified by cDNA microarrays analysis. In RMVs, we identified 43 DEGs, of which 20 were upregulated while 23 were downregulated by diabetes. In BMVs, 35 genes DEGs were identified, of which 22 were upregulated and 13 were downregulated by diabetes. Altered expression of the Nars, Gars, Mars, Iars, Yars, Bcl2, Nqo1, NR4A3, Gpd1, Stc1, Tsc22d3, Tnfrsf21 mRNA as observed in the microarray analyses, was confirmed by quantitative RT-PCR. The aminoacyl-tRNA synthetases (aaRSs) pathway in RMVs was significantly overrepresented as compared to BMVs. Our study demonstrates for the first time that in the brain microvasculature multiple compensatory mechanisms exists, serving to protect brain tissue from diabetic insults, whereas these mechanisms are not activated in the retinal microvasculature. This provides new insights as to why brain microvasculature is less susceptible to diabetes.</p

Development of a Combined Lipid-Based Nanoparticle Formulation for Enhanced siRNA Delivery to Vascular Endothelial Cells

Low transfection efficiency in endothelial cells (EC) is still a bottleneck for the majority of siRNA-based vascular delivery approaches. In this work, we developed a lipid-based nanoparticle (LNP) formulation based on a combination of a permanently charged cationic lipid-DOTAP and a conditionally ionized cationic lipid-MC3 (DOTAP/MC3) for the enhanced delivery of siRNA into EC. Compared with a single DOTAP or MC3-based benchmark LNP, we demonstrated that the DOTAP/MC3 LNP formulation shows the best transfection efficiency both in primary EC in vitro and in endothelium in zebrafish. The high transfection activity of the DOTAP/MC3 LNP formulation is achieved by a combination of improved endothelial association mediated by DOTAP and MC3-triggered efficient siRNA intracellular release in EC. Furthermore, AbVCAM-1-coupled DOTAP/MC3 LNP-mediated siRNARelA transfection showed pronounced anti-inflammatory effects in inflammatory-activated primary EC by effectively blocking the NF-κB pathway. In conclusion, the combination of permanent and ionizable cationic lipids in LNP formulation provides an effective endothelial cell delivery of siRNA

Differential effects of oleate on vascular endothelial and liver sinusoidal endothelial cells reveal its toxic features in vitro

Several fatty acids, in particular saturated fatty acids like palmitic acid, cause lipotoxicity in the context of non-alcoholic fatty liver disease . Unsaturated fatty acids (e.g. oleic acid) protect against lipotoxicity in hepatocytes. However, the effect of oleic acid on other liver cell types, in particular liver sinusoidal endothelial cells (LSECs), is unknown. Human umbilical vein endothelial cells (HUVECs) are often used as a substitute for LSECs, however, because of the unique phenotype of LSECs, HUVECs cannot represent the same biological features as LSECs. In this study, we investigate the effects of oleate and palmitate (the sodium salts of oleic acid and palmitic acid) on primary rat LSECs in comparison to their effects on HUVECs. Oleate induces necrotic cell death in LSECs, but not in HUVECs. Necrotic cell death of LSECs can be prevented by supplementation of 2-stearoylglycerol, which promotes cellular triglyceride (TG) synthesis. Repressing TG synthesis, by knocking down DGAT1 renders HUVECs sensitive to oleate-induced necrotic death. Mechanistically, oleate causes a sharp drop of intracellular ATP level and impairs mitochondrial respiration in LSECs. The combination of oleate and palmitate reverses the toxic effect of oleate in both LSECs and HUVECs. These results indicate that oleate is toxic and its toxicity can be attenuated by stimulating TG synthesis. The toxicity of oleate is characterized by mitochondrial dysfunction and necrotic cell death. Moreover, HUVECs are not suitable as a substitute model for LSECs.</p

Targeting liposomes to endothelial cells in inflammatory diseases

The endothelium covers the vascular wall of all blood vessels in the body and comprises 1013 endothelial cells (ECs) in an adult (1). Their excellent accessibility for drugs present in the systemic circulation and their involvement in a large variety of physiological and pathophysiological processes make ECs ideal targets for targeted liposome-mediated drug delivery. The heterogeneity of the endothelium with respect to appearance and function allows for drug delivery approaches that are either organ and/or disease specific. Despite these features, research on liposome-mediated drug delivery to ECs is limited. This is undoubtedly related to the fact that ECs are generally refractory to liposome uptake (2) and that the use of specific targeting devices are a prerequisite for liposome uptake by selected cell subsets.</p

Targeting liposomes to endothelial cells in inflammatory diseases

The endothelium covers the vascular wall of all blood vessels in the body and comprises 1013 endothelial cells (ECs) in an adult (1). Their excellent accessibility for drugs present in the systemic circulation and their involvement in a large variety of physiological and pathophysiological processes make ECs ideal targets for targeted liposome-mediated drug delivery. The heterogeneity of the endothelium with respect to appearance and function allows for drug delivery approaches that are either organ and/or disease specific. Despite these features, research on liposome-mediated drug delivery to ECs is limited. This is undoubtedly related to the fact that ECs are generally refractory to liposome uptake (2) and that the use of specific targeting devices are a prerequisite for liposome uptake by selected cell subsets.</p

Targeting liposomes to endothelial cells in inflammatory diseases

The endothelium covers the vascular wall of all blood vessels in the body and comprises 1013 endothelial cells (ECs) in an adult (1). Their excellent accessibility for drugs present in the systemic circulation and their involvement in a large variety of physiological and pathophysiological processes make ECs ideal targets for targeted liposome-mediated drug delivery. The heterogeneity of the endothelium with respect to appearance and function allows for drug delivery approaches that are either organ and/or disease specific. Despite these features, research on liposome-mediated drug delivery to ECs is limited. This is undoubtedly related to the fact that ECs are generally refractory to liposome uptake (2) and that the use of specific targeting devices are a prerequisite for liposome uptake by selected cell subsets.</p

Targeting liposomes to endothelial cells in inflammatory diseases

The endothelium covers the vascular wall of all blood vessels in the body and comprises 1013 endothelial cells (ECs) in an adult (1). Their excellent accessibility for drugs present in the systemic circulation and their involvement in a large variety of physiological and pathophysiological processes make ECs ideal targets for targeted liposome-mediated drug delivery. The heterogeneity of the endothelium with respect to appearance and function allows for drug delivery approaches that are either organ and/or disease specific. Despite these features, research on liposome-mediated drug delivery to ECs is limited. This is undoubtedly related to the fact that ECs are generally refractory to liposome uptake (2) and that the use of specific targeting devices are a prerequisite for liposome uptake by selected cell subsets.</p