miR-19a-3p containing exosomes improve function of ischemic myocardium upon shock wave therapy

AIMS: As many current approaches for heart regeneration exert unfavorable side-effects, the induction of endogenous repair mechanisms in ischemic heart disease is of particular interest. Recently, exosomes carrying angiogenic miRNAs have been described to improve heart function. However, it remains challenging to stimulate specific release of reparative exosomes in ischemic myocardium. In the present study, we sought to test the hypothesis that the physical stimulus of shock wave therapy (SWT) causes the release of exosomes. We aimed to substantiate the pro-angiogenic impact of the released factors, to identify the nature of their cargo, and to test their efficacy in vivo supporting regeneration and recovery after myocardial ischemia. METHODS AND RESULTS: Mechanical stimulation of ischemic muscle via SWT caused extracellular vesicle (EV) release from endothelial cells both in vitro and in vivo. Characterization of EVs via electron microscopy, nanoparticle tracking analysis and flow cytometry revealed specific exosome morphology and size with presence of exosome markers CD 9, CD81 and CD63. Exosomes exhibited angiogenic properties activating protein kinase b (Akt) and extracellular-signal regulated kinase (ERK) resulting in enhanced endothelial tube formation and proliferation. A miRNA array and transcriptome analysis via next-generation sequencing were performed to specify exosome content. miR-19a-3p was identified as responsible cargo, antimir-19a-3p antagonized angiogenic exosome effects. Exosomes and target miRNA were injected intramyocardially in mice after left anterior descending artery (LAD) ligation. Exosomes resulted in improved vascularization, decreased myocardial fibrosis and increased left ventricular ejection fraction as shown by transthoracic echocardiography. CONCLUSIONS: The mechanical stimulus of SWT causes release of angiogenic exosomes. miR-19a-3p is the vesicular cargo responsible for the observed effects. Released exosomes induce angiogenesis, decrease myocardial fibrosis and improve left ventricular function after myocardial ischemia. Exosome release via SWT could develop an innovative approach for the regeneration of ischemic myocardium

Incongruence between transcriptional and vascular pathophysiological cell states

Research in R.B.’s laboratory was supported by the European Research Council Starting Grant AngioGenesHD (638028) and Consolidator Grant AngioUnrestUHD (101001814), the CNIC Intramural Grant Program Severo Ochoa (11-2016-IGP-SEV-2015-0505), the Ministerio de Ciencia e Innovación (MCIN) (SAF2013-44329-P, RYC-2013- 13209, and SAF2017-89299-P) and ‘La Caixa’ Banking Foundation (HR19-00120). J.V.’s laboratory was supported by MCIN (PGC2018- 097019-B-I00 and PID2021-122348NB-I00) and La Caixa (HR17-00247 and HR22-00253). K.G.’s laboratory was supported by Knut and Alice Wallenberg Foundation (2020.0057) and Vetenskapsrådet (2021-04896). The CNIC is supported by Instituto de Salud Carlos III, MCIN, and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (grant CEX2020-001041-S funded by MCIN/ AEI/10.13039/501100011033). Microscopy experiments were performed at the Microscopy and Dynamic Imaging Unit, CNIC, ICTS-ReDib, co-funded by MCIN/AEI/10.13039/501100011033 and FEDER ‘Una manera de hacer Europa’ (ICTS-2018-04-CNIC-16). M.F.-C. was supported by PhD fellowships from La Caixa (CX_E-2015-01) and Boehringer Ingelheim travel grants. S.M. was supported by the Austrian Science Fund (J4358). A.R. was supported by the Youth Employment Initiative (PEJD-2019-PRE/BMD-16990). L.G.-O. was supported by the Spanish Ministry of Economy and Competitiveness (PRE2018-085283). We thank S. Bartlett (CNIC) for English editing, as well as the members of the Transgenesis, Microscopy, Genomics, Citometry and Bioinformatic units at CNIC. We also thank F. Radtke (Swiss Institute for Experimental Cancer Research), R. H. Adams (Max Planck Institute for Molecular Biomedicine), F. Alt (Boston Children’s Hospital, Harvard Medical School), T. Honjo (Kyoto University Institute for Advanced Studies), I. Flores (CNIC), J. Lewis (Cancer Research UK London Research Institute), S. Habu (Tokai University School of Medicine), T. Gridley (Maine Health Institute for Research) and C. Brakebusch (Biotech Research and Innovation Centre) for sharing the Dll4floxed, Notch1floxed, Notch2floxed, Cdh5(PAC)-creERT2, Myc floxed, Rbpj floxed, p21−/−, Jag1floxed, Dll1floxed, Jag2floxed and Rac1floxed mice.S

Microvascular networks from endothelial cells and mesenchymal stromal cells from adipose tissue and bone marrow:A comparison

\u3cp\u3eA promising approach to overcome hypoxic conditions in tissue engineered constructs is to use the potential of endothelial cells (EC) to form networks in vitro when co-cultured with a supporting cell type in a 3D environment. Adipose tissue-derived stromal cells (ASC) as well as bone marrow-derived stromal cells (BMSC) have been shown to support vessel formation of EC in vitro, but only very few studies compared the angiogenic potential of both cell types using the same model. Here, we aimed at investigating the ability of ASC and BMSC to induce network formation of EC in a co-culture model in fibrin. While vascular structures of BMSC and EC remained stable over the course of 3 weeks, ASC-EC co-cultures developed more junctions and higher network density within the same time frame. Both co-cultures showed positive staining for neural glial antigen 2 (NG2) and basal lamina proteins. This indicates that vessels matured and were surrounded by perivascular cells as well as matrix molecules involved in stabilization. Gene expression analysis revealed a significant increase of vascular endothelial growth factor (VEGF) expression in ASC-EC co-culture compared to BMSC-EC co-culture. These observations were donor-independent and highlight the importance of organotypic cell sources for vascular tissue engineering.\u3c/p\u3

Arterialization requires the timely suppression of cell growth

The formation of arteries is thought to occur by the induction of a highly conserved arterial genetic programme in a subset of vessels that will later experience an increase in oxygenated blood flow. The initial steps of arterial specification require both the VEGF and Notch signalling pathways. Here, we combine inducible genetic mosaics and transcriptomics to modulate and define the function of these signalling pathways in cell proliferation, arteriovenous differentiation and mobilization. We show that endothelial cells with high levels of VEGF or Notch signalling are intrinsically biased to mobilize and form arteries; however, they are not genetically pre-determined, and can also form veins. Mechanistically, we found that increased levels of VEGF and Notch signalling in pre-arterial capillaries suppresses MYC-dependent metabolic and cell-cycle activities, and promotes the incorporation of endothelial cells into arteries. Mosaic lineage-tracing studies showed that endothelial cells that lack the Notch–RBPJ transcriptional activator complex rarely form arteries; however, these cells regained the ability to form arteries when the function of MYC was suppressed. Thus, the development of arteries does not require the direct induction of a Notch-dependent arterial differentiation programme, but instead depends on the timely suppression of endothelial cell-cycle progression and metabolism, a process that precedes arterial mobilization and complete differentiation

Laser photofabrication of cell-containing hydrogel constructs

The two-photon polymerization (2PP) of photosensitive gelatin in the presence of living cells is reported. The 2PP technique is based on the localized cross-linking of photopolymers induced by femtosecond laser pulses. The availability of water-soluble photo-initiators (PI) suitable for 2PP is crucial for applying this method to cell-containing materials. Novel Pis developed by our group allow 2PP of formulations with up to 80% cell culture medium. The cytocompatibility of these Pis was evaluated by an MTT assay. The results of cell encapsulation by 2PP show the occurrence of cell damage within the laser-exposed regions. However, some cells located in the immediate vicinity and even within the 2PP-produced structures remain viable and can further proliferate. The control experiments demonstrate that the laser radiation itself does not damage the cells at the parameters used for 2PP. On the basis of these findings and the reports by other groups, we conclude that such localized cell damage is of a chemical origin and can be attributed to reactive species generated during 2PP. The viable cells trapped within the 2PP structures but not exposed to laser radiation continued to proliferate. The live/dead staining after 3 weeks revealed viable cells occupying most of the space available within the 3D hydrogel constructs. While some of the questions raised by this study remain open, the presented results indicate the general practicability of 2PP for 3D processing of cell-containing materials. The potential applications of this highly versatile approach span from precise engineering of 3D tissue models to the fabrication of cellular microarrays