Extracellular vesicles from human cardiac progenitor cells inhibit cardiomyocyte apoptosis and improve cardiac function after myocardial infarction

Aims Recent evidence suggests that cardiac progenitor cells (CPCs) may improve cardiac function after injury. The underlying mechanisms are indirect, but their mediators remain unidentified. Exosomes and other secreted membrane vesicles, hereafter collectively referred to as extracellular vesicles (EVs), act as paracrine signalling mediators. Here, we report that EVs secreted by human CPCs are crucial cardioprotective agents. Methods and results CPCs were derived from atrial appendage explants from patients who underwent heart valve surgery. CPC-conditioned medium (CM) inhibited apoptosis in mouse HL-1 cardiomyocytic cells, while enhancing tube formation in human umbilical vein endothelial cells. These effects were abrogated by depleting CM of EVs. They were reproduced by EVs secreted by CPCs, but not by those secreted by human dermal fibroblasts. Transmission electron microscopy and nanoparticle tracking analysis showed most EVs to be 30-90 nm in diameter, the size of exosomes, although smaller and larger vesicles were also present. MicroRNAs most highly enriched in EVs secreted by CPCs compared with fibroblasts included miR-210, miR-132, and miR-146a-3p. miR-210 down-regulated its known targets, ephrin A3 and PTP1b, inhibiting apoptosis in cardiomyocytic cells. miR-132 down-regulated its target, RasGAP-p120, enhancing tube formation in endothelial cells. Infarcted hearts injected with EVs from CPCs, but not from fibroblasts, exhibited less cardiomyocyte apoptosis, enhanced angiogenesis, and improved LV ejection fraction (0.8 ± 6.8 vs. −21.3 ± 4.5%; P < 0.05) compared with those injected with control medium. Conclusion EVs are the active component of the paracrine secretion by human CPCs. As a cell-free approach, EVs could circumvent many of the limitations of cell transplantatio

Erratum: Inflammatory extracellular vesicles prompt heart dysfunction via TLR4-dependent NF-κB activation: Erratum.

[This corrects the article DOI: 10.7150/thno.39072.]

ALDH1A3 Is the Key Isoform That Contributes to Aldehyde Dehydrogenase Activity and Affects <i>in Vitro</i> Proliferation in Cardiac Atrial Appendage Progenitor Cells.

High aldehyde dehydrogenase (ALDH &lt;sup&gt;hi&lt;/sup&gt; ) activity has been reported in normal and cancer stem cells. We and others have shown previously that human ALDH &lt;sup&gt;hi&lt;/sup&gt; cardiac atrial appendage cells are enriched with stem/progenitor cells. The role of ALDH in these cells is poorly understood but it may come down to the specific ALDH isoform(s) expressed. This study aimed to compare ALDH &lt;sup&gt;hi&lt;/sup&gt; and ALDH &lt;sup&gt;lo&lt;/sup&gt; atrial cells and to identify the isoform(s) that contribute to ALDH activity, and their functional role. &lt;b&gt;Methods and Results:&lt;/b&gt; Cells were isolated from atrial appendage specimens from patients with ischemic and/or valvular heart disease undergoing heart surgery. ALDH &lt;sup&gt;hi&lt;/sup&gt; activity assessed with the Aldefluor reagent coincided with primitive surface marker expression (CD34 &lt;sup&gt;+&lt;/sup&gt; ). Depending on their ALDH activity, RT-PCR analysis of ALDH &lt;sup&gt;hi&lt;/sup&gt; and ALDH &lt;sup&gt;lo&lt;/sup&gt; cells demonstrated a differential pattern of pluripotency genes (Oct 4, Nanog) and genes for more established cardiac lineages (Nkx2.5, Tbx5, Mef2c, GATA4). ALDH &lt;sup&gt;hi&lt;/sup&gt; cells, but not ALDH &lt;sup&gt;lo&lt;/sup&gt; cells, formed clones and were culture-expanded. When cultured under cardiac differentiation conditions, ALDH &lt;sup&gt;hi&lt;/sup&gt; cells gave rise to a higher number of cardiomyocytes compared with ALDH &lt;sup&gt;lo&lt;/sup&gt; cells. Among 19 ALDH isoforms known in human, ALDH1A3 was most highly expressed in ALDH &lt;sup&gt;hi&lt;/sup&gt; atrial cells. Knocking down ALDH1A3, but not ALDH1A1, ALDH1A2, ALDH2, ALDH4A1, or ALDH8A1 using siRNA decreased ALDH activity and cell proliferation in ALDH &lt;sup&gt;hi&lt;/sup&gt; cells. Conversely, overexpressing ALDH1A3 with a retroviral vector increased proliferation in ALDH &lt;sup&gt;lo&lt;/sup&gt; cells. &lt;b&gt;Conclusions:&lt;/b&gt; ALDH1A3 is the key isoform responsible for ALDH activity in ALDH &lt;sup&gt;hi&lt;/sup&gt; atrial appendage cells, which have a propensity to differentiate into cardiomyocytes. ALDH1A3 affects &lt;i&gt;in vitro&lt;/i&gt; proliferation of these cells

Conditioned Medium From Human Amniotic Mesenchymal Stromal Cells Limits Infarct Size and Enhances Angiogenesis

The paracrine properties of human amniotic membrane-derived mesenchymal stromal cells (hAMCs) have not been fully elucidated. The goal of the present study was to elucidate whether hAMCs can exert beneficial paracrine effects on infarcted rat hearts, in particular through cardioprotection and angiogenesis. Moreover, we aimed to identify the putative active paracrine mediators. hAMCs were isolated, expanded, and characterized. In vitro, conditioned medium from hAMC (hAMC-CM) exhibited cytoprotective and proangiogenic properties. In vivo, injection of hAMC-CM into infarcted rat hearts limited the infarct size, reduced cardiomyocyte apoptosis and ventricular remodeling, and strongly promoted capillary formation at the infarct border zone. Gene array analysis led to the identification of 32 genes encoding for the secreted factors overexpressed by hAMCs. Among these, midkine and secreted protein acidic and rich in cysteine were also upregulated at the protein level. Furthermore, high amounts of several proangiogenic factors were detected in hAMC-CM by cytokine array. Our results strongly support the concept that the administration of hAMC-CM favors the repair process after acute myocardial infarction

Exosomes for Intramyocardial Intercellular Communication

Cross-talk between different cell types plays central roles both in cardiac homeostasis and in adaptive responses of the heart to stress. Cardiomyocytes (CMs) send biological messages to the other cell types present in the heart including endothelial cells (ECs) and fibroblasts. In turn, CMs receive messages from these cells. Recent evidence has now established that exosomes, nanosized secreted extracellular vesicles, are crucial mediators of such messages. CMs, ECs, cardiac fibroblasts, and cardiac progenitor cells (CPCs) release exosomes carrying nonrandom subsets of proteins, lipids, and nucleic acids present in their cells of origin. Exosomes secreted from CMs are internalized by fibroblasts and regulate gene expression in these cells as well as in ECs. CPC-derived exosomes protect CMs against apoptosis while also stimulating angiogenesis. They are rich in cardioprotective and proangiogenic microRNAs such as miR-146, miR-210, and miR-132. When injected into infracted hearts in vivo, CPC-derived exosomes reduce infarct size and improve cardiac function. Thus, exosomes are emerging both as key mediators of intercellular communication in the heart and as therapeutic candidates for heart disease

Concomitant overexpression of IGF1 and BMP2 in mesenchymal stem cells mediates cytoprotection through both autocrine and paracrine activation of Akt, Erk1/2 and SMAD1/5/8 pathways.

Background. Bone marrow mesenchymal stem cells (BM-MSC) are valuable tools for cardiac repair, acting mainly through release of paracrine factors. However, the effects of BM-MSC are limited by poor engraftment and low rate of differentiation events. To overcome these limitations, we genetically engineered BM-MSC with a novel bicistronic lentivirus co-expressing IGF1 and BMP2 (IB), two factors known to be involved in both cardiac differentiation and cytoprotection. Methods. Rat BM-MSC were transduced with a control virus (GFP-MSC) or IB virus (IB-MSC). Autocrine and paracrine cytoprotection was evaluated in transduced MSC or in H9c2 cells treated with unconditioned (CTRL-M) or conditioned media (GFP-CM or IB-CM), after 24h of hypoxia. Cell viability was measured by MTS assay. Apoptosis was evaluated through caspase-3 activation. Transcriptional levels of pro and anti-apoptotic genes in H9c2 were measured by RT-PCR. Activation of IGF1 and BMP2 pro-survival pathways (Akt, ERK1/2, and SMAD1/5/8) in both MSC and H9c2 were assessed by western blot. Results. IB-MSC showed a marked reduction of apoptosis (-50% p<0.001) vs GFP-MSC after 24h of hypoxia. IB-CM increased H9c2 viability (+32,1% p<0.001) compared with CTRL-M, while GFP-CM had no effect. Caspase-3 activation was reduced in the presence of IB-CM of 63,9% vs CTRL-M (p<0.001) and of 49,7 % vs GFP-MSC (p<0.05). H9c2 treated with IB-CM showed enhanced expression of Bcl-2 and Stat3 pro-survival genes, and inhibition of FasL and TNFalpha pro-apoptotic genes. Both IB-MSC or IB-CM treated-H9c2 showed a strong activation of Akt, ERK1/2 and SMAD1/5/8 pathways, confirming that IGF1 and BMP2 transgenes are acting both in autocrine and paracrine manner. Conclusions. IGF1 and BMP2 transgene overexpression in MSC increases cell survival and cytoprotective paracrine properties. In particular, these effects are mediated by the activation of pathways known to be involved in cell survival

L’esposizione a persolfato d’ammonio riduce il controllo non adrenergico, non colinergico inibitorio (NANC-i) nelle vie aeree di cavia

To evaluate the effect of repeated exposure to ammonium persulphate (AP) on NANC inhibitory innervation of guinea-pig airways, we exposed male guinea-pigs to AP, by aerosol inhalation at a concentration of 1 mg/m3 for 30 minutes for 5 days for three weeks. Control animals inhaled saline aerosol. After the last exposure, the animals were killed and the isolated whole trachea was cannulated at each extremity and mounted in an organ bath. Intraluminal pressure variations were measured by means of a pressure transducer. The inhibitory NANC responses to electrical field stimulation (3 and 10 Hz) were evaluated in the presence of hyoscine, piperoxane and propranolol. To evaluate both the amplitude and the duration of the responses, the area under the curve (AUC) was measured as Pa · seconds. Statistical analysis, was performed by analysis of variance. In the exposed animals, the in vitro NANC relaxations at 3 and 10 Hz were significantly reduced (P < 0.01). In particular, the AUC was 45.9 ± 12.1%, as compared to control at 3 Hz and 52.7 ± 14.1% at 10 Hz. In conclusion, the impairment in NANC relaxation may represent one of the mechanisms subserving airway hyperreactivity induced by AP esposure

Recent insights into the pathogenesis of abdominal symptoms in functional bowel disorders

In the gut, 5-HT acts as a paracrine signalling molecule released by enterochromaffin cells and as a transmitter released by some descending serotonergic interneurons. It has a prominent role in the regulation of motility, vascular tone, secretion and perception both in normal and under certain pathophysiological conditions, such as the carcinoid syndrome and the irritable bowel syndrome (IBS). Serotonin is known to markedly influence bowel function by activating at least five receptor types (5-HT(1,2,3,4,7)). Among all 5-HT receptors, those belonging to the 5-HT3 (a ionotropic receptor) and 5-HT4 (a metabotropic receptor) type are the most extensively studied in gastroenterology, resulting in commercially available (although not worldwide) serotonergic agents for the treatment of IBS and functional dyspepsia. Recently, 5-HT7 receptors have been found to participate in the accommodation process of the circular muscle during the preparatory phase of ileal peristalsis. Since an exaggerated accommodation of the gut wall may contribute to abdominal distension and bloating, 5-HT7 receptor ligands may offer innovative opportunities for the pharmacological treatment of functional bowel disorders