Spaceflight-Associated Changes of snoRNAs in Peripheral Blood Mononuclear Cells and Plasma Exosomes—A Pilot Study

During spaceflight, astronauts are exposed to various physiological and psychological stressors that have been associated with adverse health effects. Therefore, there is an unmet need to develop novel diagnostic tools to predict early alterations in astronauts’ health. Small nucleolar RNA (snoRNA) is a type of short non-coding RNA (60–300 nucleotides) known to guide 2′-O-methylation (Nm) or pseudouridine (ψ) of ribosomal RNA (rRNA), small nuclear RNA (snRNA), or messenger RNA (mRNA). Emerging evidence suggests that dysregulated snoRNAs may be key players in regulating fundamental cellular mechanisms and in the pathogenesis of cancer, heart, and neurological disease. Therefore, we sought to determine whether the spaceflight-induced snoRNA changes in astronaut’s peripheral blood (PB) plasma extracellular vesicles (PB-EV) and peripheral blood mononuclear cells (PBMCs). Using unbiased small RNA sequencing (sRNAseq), we evaluated changes in PB-EV snoRNA content isolated from astronauts (n = 5/group) who underwent median 12-day long Shuttle missions between 1998 and 2001. Using stringent cutoff (fold change > 2 or log(2)-fold change >1, FDR < 0.05), we detected 21 down-and 9—up-regulated snoRNAs in PB-EVs 3 days after return (R + 3) compared to 10 days before launch (L-10). qPCR validation revealed that SNORA74A was significantly down-regulated at R + 3 compared to L-10. We next determined snoRNA expression levels in astronauts’ PBMCs at R + 3 and L-10 (n = 6/group). qPCR analysis further confirmed a significant increase in SNORA19 and SNORA47 in astronauts’ PBMCs at R + 3 compared to L-10. Notably, many downregulated snoRNA-guided rRNA modifications, including four Nms and five ψs. Our findings revealed that spaceflight induced changes in PB-EV and PBMCs snoRNA expression, thus suggesting snoRNAs may serve as potential novel biomarkers for monitoring astronauts’ health

Enhanced Cardiac Regenerative Ability of Stem Cells After Ischemia-Reperfusion Injury Role of Human CD34+ Cells Deficient in MicroRNA-377

AbstractBackgroundMicroRNA (miR) dysregulation in the myocardium has been implicated in cardiac remodeling after injury or stress.ObjectivesThe aim of this study was to explore the role of miR in human CD34+ cell (hCD34+) dysfunction in vivo after transplantation into the myocardium under ischemia-reperfusion (I-R) conditions.MethodsIn response to inflammatory stimuli, the miR array profile of endothelial progenitor cells was analyzed using a polymerase chain reaction–based miR microarray. miR-377 expression was assessed in myocardial tissue from human patients with heart failure (HF). We investigated the effect of miR-377 inhibition on an hCD34+ cell angiogenic proteome profile in vitro and on cardiac repair and function after I-R injury in immunodeficient mice.ResultsThe miR array data from endothelial progenitor cells in response to inflammatory stimuli indicated changes in numerous miR, with a robust decrease in the levels of miR-377. Human cardiac biopsies from patients with HF showed significant increases in miR-377 expression compared with nonfailing control hearts. The proteome profile of hCD34+ cells transfected with miR-377 mimics showed significant decrease in the levels of proangiogenic proteins versus nonspecific control–transfected cells. We also validated that serine/threonine kinase 35 is a target of miR-377 using a dual luciferase reporter assay. In a mouse model of myocardial I-R, intramyocardial transplantation of miR-377 silenced hCD34+ cells in immunodeficient mice, promoting neovascularization (at 28 days, post–I-R) and lower interstitial fibrosis, leading to improved left ventricular function.ConclusionsThese findings indicate that HF increased miR-377 expression in the myocardium, which is detrimental to stem cell function, and transplantation of miR-377 knockdown hCD34+ cells into ischemic myocardium promoted their angiogenic ability, attenuating left ventricular remodeling and cardiac fibrosis

Astronauts Plasma-Derived Exosomes Induced Aberrant EZH2-Mediated H3K27me3 Epigenetic Regulation of the Vitamin D Receptor

There are unique stressors in the spaceflight environment. Exposure to such stressors may be associated with adverse effects on astronauts\u27 health, including increased cancer and cardiovascular disease risks. Small extracellular vesicles (sEVs, i.e., exosomes) play a vital role in intercellular communication and regulate various biological processes contributing to their role in disease pathogenesis. To assess whether spaceflight alters sEVs transcriptome profile, sEVs were isolated from the blood plasma of 3 astronauts at two different time points: 10 days before launch (L-10) and 3 days after return (R+3) from the Shuttle mission. AC16 cells (human cardiomyocyte cell line) were treated with L-10 and R+3 astronauts-derived exosomes for 24 h. Total RNA was isolated and analyzed for gene expression profiling using Affymetrix microarrays. Enrichment analysis was performed using Enrichr. Transcription factor (TF) enrichment analysis using the ENCODE/ChEA Consensus TF database identified gene sets related to the polycomb repressive complex 2 (PRC2) and Vitamin D receptor (VDR) in AC16 cells treated with R+3 compared to cells treated with L-10 astronauts-derived exosomes. Further analysis of the histone modifications using datasets from the Roadmap Epigenomics Project confirmed enrichment in gene sets related to the H3K27me3 repressive mark. Interestingly, analysis of previously published H3K27me3-chromatin immunoprecipitation sequencing (ChIP-Seq) ENCODE datasets showed enrichment of H3K27me3 in the VDR promoter. Collectively, our results suggest that astronaut-derived sEVs may epigenetically repress the expression of the VDR in human adult cardiomyocytes by promoting the activation of the PRC2 complex and H3K27me3 levels

Long-Term Effects of Very Low Dose Particle Radiation on Gene Expression in the Heart: Degenerative Disease Risks

Compared to low doses of gamma irradiation (γ-IR), high-charge-and-energy (HZE) particle IR may have different biological response thresholds in cardiac tissue at lower doses, and these effects may be IR type and dose dependent. Three- to four-month-old female CB6F1/Hsd mice were exposed once to one of four different doses of the following types of radiation: γ-IR 137Cs (40-160 cGy, 0.662 MeV), 14Si-IR (4-32 cGy, 260 MeV/n), or 22Ti-IR (3-26 cGy, 1 GeV/n). At 16 months post-exposure, animals were sacrificed and hearts were harvested and archived as part of the NASA Space Radiation Tissue Sharing Forum. These heart tissue samples were used in our study for RNA isolation and microarray hybridization. Functional annotation of twofold up/down differentially expressed genes (DEGs) and bioinformatics analyses revealed the following: (i) there were no clear lower IR thresholds for HZE- or γ-IR; (ii) there were 12 common DEGs across all 3 IR types; (iii) these 12 overlapping genes predicted various degrees of cardiovascular, pulmonary, and metabolic diseases, cancer, and aging; and (iv) these 12 genes revealed an exclusive non-linear DEG pattern in 14Si- and 22Ti-IR-exposed hearts, whereas two-thirds of γ-IR-exposed hearts revealed a linear pattern of DEGs. Thus, our study may provide experimental evidence of excess relative risk (ERR) quantification of low/very low doses of full-body space-type IR-associated degenerative disease development

Establishment of a rat model of myocardial infarction with a high survival rate: A suitable model for evaluation of efficacy of stem cell therapy

The most common rat model of myocardial infarction (MI) is by ligation of left anterior descending (LAD) coronary artery but it is associated with high mortality and large variations in the infarct size. We evolved certain innovations/modifications in the existing technique including immobilization of the heart without exteriorization, identification of the LAD by pressing it proximal to the site of ligation by an ear-bud, and subsequently its ligation 8 mm from its origin, no touch technique of the lungs during surgery, removal of air from the chest cavity prior to its closure using an in-house tubing, and deflation of the lungs before extubation. We induced MI in 24 Sprague- Dawley (SD) rats using these modifications and carried out post-MI evaluation of hemodynamic parameters, serum cardiac enzymes and histological studies upto 90 days using 13 sham operated and 3 healthy SD rats as controls. Three of the 24 rats (13%) died <24 hours of MI, but thereafter no mortality was observed till the follow-up period of 90 days. The infarct size was consistent in all the rats (21±4% of left ventricular area).? This model with low early and no long-term mortality may be suitable for studying efficacy of stem cell therapy in MI, where a follow-up of at least 13 weeks is required to assess myocardial regeneration

Bidirectional ventricular tachycardia with myocardial infarction: A case report with insight on mechanism and treatment

Bidirectional ventricular tachycardia (BVT) is a rare variety of tachycardia with morphologically distinct presentation: The QRS axis and/or morphology is alternating in the frontal plane leads. Since its original description in association with digitalis,1 numerous cases of this fascinating tachycardia with disparate etiologies and mechanisms have been postulated. We report a patient with BVT in association with non-ST elevation myocardial infarction and severe cardiomyopathy in the absence of digoxin toxicity

Mesenchymal stem cells from fetal heart attenuate myocardial injury after infarction: an in vivo serial pinhole gated SPECT-CT study in rats.

Mesenchymal stem cells (MSC) have emerged as a potential stem cell type for cardiac regeneration after myocardial infarction (MI). Recently, we isolated and characterized mesenchymal stem cells derived from rat fetal heart (fC-MSC), which exhibited potential to differentiate into cardiomyocytes, endothelial cells and smooth muscle cells in vitro. In the present study, we investigated the therapeutic efficacy of intravenously injected fC-MSC in a rat model of MI using multi-pinhole gated SPECT-CT system. fC-MSC were isolated from the hearts of Sprague Dawley (SD) rat fetuses at gestation day 16 and expanded ex vivo. One week after induction of MI, 2×10(6) fC-MSC labeled with PKH26 dye (n = 6) or saline alone (n = 6) were injected through the tail vein of the rats. Initial in vivo tracking of 99mTc-labeled fC-MSC revealed a focal uptake of cells in the anterior mid-ventricular region of the heart. At 4 weeks of fC-MSC administration, the cells labeled with PKH26 were located in abundance in infarct/peri-infarct region and the fC-MSC treated hearts showed a significant increase in left ventricular ejection fraction and a significant decrease in the end diastolic volume, end systolic volume and left ventricular myo-mass in comparison to the saline treated group. In addition, fC-MSC treated hearts had a significantly better myocardial perfusion and attenuation in the infarct size, in comparison to the saline treated hearts. The engrafted PKH26-fC-MSC expressed cardiac troponin T, endothelial CD31 and smooth muscle sm-MHC, suggesting their differentiation into all major cells of cardiovascular lineage. The fC-MSC treated hearts demonstrated an up-regulation of cardio-protective growth factors, anti-fibrotic and anti-apoptotic molecules, highlighting that the observed left ventricular functional recovery may be due to secretion of paracrine factors by fC-MSC. Taken together, our results suggest that fC-MSC therapy may be a new therapeutic strategy for MI and multi-pinhole gated SPECT-CT system may be a useful tool to evaluate cardiac perfusion, function and cell tracking after stem cell therapy in acute myocardial injury setting