Anna Skorska

Identification of noncytotoxic and IL-10-producing CD8+AT2R+ T cell population in response to ischemic heart injury.

Emerging evidence suggests a cardioprotective role of the angiotensin AT2R, albeit the underlying cellular mechanisms are not well understood. We aimed in this article to elucidate a potential role of cardiac angiotensin AT2R in regulating cellular immune response to ischemic heart injury. Seven days after myocardial infarction in rats, double-immunofluorescence staining showed that AT2R was detected in a fraction of CD8+ T cells infiltrating in the peri-infarct myocardium. We developed a method that allowed the isolation of myocardial infiltrating CD8+AT2R+ T cells using modified MACS, and further characterization and purification with flow cytometry. Although the CD8+AT2R− T cells exhibited potent cytotoxicity to both adult and fetal cardiomyocytes (CMs), the CD8+AT2R+ T cells were noncytotoxic to these CMs. The CD8+AT2R+ T cells were characterized by upregulated IL-10 and downregulated IL-2 and INF-γ expression when compared with CD8+AT2R− T cells. We further showed that IL-10 gene expression was enhanced in CD8+ T cells on in vitro AT2R stimulation. Importantly, in vivo AT2R activation engendered an increment of CD8+AT2R+ T cells and IL-10 production in the ischemic myocardium. In addition, intramyocardial transplantation of CD8+AT2R+ T cells (versus CD8+AT2R−) led to reduced ischemic heart injury. Moreover, the CD8+AT2R+ T cell population was also demonstrated in human peripheral blood. Thus, we have defined the cardioprotective CD8+AT2R+ T cell population, which increases during ischemic heart injury and contributes to maintaining CM viability and providing IL-10, hence revealing an AT2R-mediated cellular mechanism in modulating adaptive immune response in the heart.

Innovative Strategy for MicroRNA Delivery in Human Mesenchymal Stem Cells via Magnetic Nanoparticles

Bone marrow derived human mesenchymal stem cells (hMSCs) show promising potential in regeneration of defective tissue. Recently, gene silencing strategies using microRNAs (miR) emerged with the aim to expand the therapeutic potential of hMSCs. However, researchers are still searching for effective miR delivery methods for clinical applications. Therefore, we aimed to develop a technique to efficiently deliver miR into hMSCs with the help of a magnetic non-viral vector based on cationic polymer polyethylenimine (PEI) bound to iron oxide magnetic nanoparticles (MNP). We tested different magnetic complex compositions and determined uptake efficiency and cytotoxicity by flow cytometry. Additionally, we monitored the release, processing and functionality of delivered miR-335 with confocal laser scanning microscopy, real-time PCR and live cell imaging, respectively. On this basis, we established parameters for construction of magnetic non-viral vectors with optimized uptake efficiency (~75%) and moderate cytotoxicity in hMSCs. Furthermore, we observed a better transfection performance of magnetic complexes compared to PEI complexes 72 h after transfection. We conclude that MNP-mediated transfection provides a long term effect beneficial for successful genetic modification of stem cells. Hence, our findings may become of great importance for future in vivo applications.

The CD4(+)AT2R(+) T cell subpopulation improves post-infarction remodelling and restores cardiac function

Myocardial infarction (MI) is a major condition causing heart failure (HF). After MI, the renin angiotensin system (RAS) and its signalling octapeptide angiotensin II (Ang II) interferes with cardiac injury/repair via the AT1 and AT2 receptors (AT1R, AT2R). Our study aimed at deciphering the mechanisms underlying the link between RAS and cellular components of the immune response relying on a rodent model of HF as well as HF patients. Flow cytometric analyses showed an increase in the expression of CD4+ AT2R+ cells in the rat heart and spleen post‐infarction, but a reduction in the peripheral blood. The latter was also observed in HF patients. The frequency of rat CD4+ AT2R+ T cells in circulating blood, post‐infarcted heart and spleen represented 3.8 ± 0.4%, 23.2 ± 2.7% and 22.6 ± 2.6% of the CD4+ cells. CD4+ AT2R+ T cells within blood CD4+ T cells were reduced from 2.6 ± 0.2% in healthy controls to 1.7 ± 0.4% in patients. Moreover, we characterized CD4+ AT2R+ T cells which expressed regulatory FoxP3, secreted interleukin‐10 and other inflammatory‐related cytokines. Furthermore, intramyocardial injection of MI‐induced splenic CD4+ AT2R+ T cells into recipient rats with MI led to reduced infarct size and improved cardiac performance. We defined CD4+ AT2R+ cells as a T cell subset improving heart function post‐MI corresponding with reduced infarction size in a rat MI‐model. Our results indicate CD4+ AT2R+ cells as a promising population for regenerative therapy, via myocardial transplantation, pharmacological AT2R activation or a combination thereof.

Magnetic Nanoparticle Based Nonviral MicroRNA Delivery into Freshly Isolated CD105+ hMSCs

Genetic modifications of bone marrow derived human mesenchymal stem cells (hMSCs) using microRNAs (miRs) may be used to improve their therapeutic potential and enable innovative strategies in tissue regeneration. However, most of the studies use cultured hMSCs, although these can lose their stem cell characteristics during expansion. Therefore, we aimed to develop a nonviral miR carrier based on polyethylenimine (PEI) bound to magnetic nanoparticles (MNPs) for efficient miR delivery in freshly isolated hMSCs. MNP based transfection is preferable for genetic modifications in vivo due to improved selectivity, safety of delivery, and reduced side effects. Thus, in this study different miR/PEI and miR/PEI/MNP complex formulations were tested in vitro for uptake efficiency and cytotoxicity with respect to the influence of an external magnetic field. Afterwards, optimized magnetic complexes were selected and compared to commercially available magnetic vectors (Magnetofectamine, CombiMag). We found that all tested transfection reagents had high miR uptake rates (yielded over 60%) and no significant cytotoxic effects. Our work may become crucial for virus-free introduction of therapeutic miRs as well as other nucleic acids in vivo. Moreover, in the field of targeted stem cell therapy nucleic acid delivery prior to transplantation may allowfor initial cell modulation in vitro.

Improved transfection in human mesenchymal stem cells: effective intracellular release of pDNA by magnetic polyplexes

AIM Magnetically guided transfection has been shown as a promising approach for the genetic modification of cells. We observed that polyethylenimine (PEI)-condensed pDNA, combined with magnetic nanoparticles (MNPs) via biotin-streptavidin interactions could provide higher transfection efficiency than pDNA/PEI alone, even without the application of a magnetic force. Therefore, we intended to investigate the beneficial properties of MNP-based transfection. MATERIALS & METHODS We performed three-color fluorescent labeling of magnetic transfection complexes and traced them inside human mesenchymal stem cells over time using confocal microscopy in order to study pDNA release kinetics by colocalization studies. RESULTS We demonstrated that MNP-combined pDNA/PEI complexes provide more rapid and efficient release of pDNA than pDNA/PEI alone, which could be explained by the retention of PEI on the surface of the MNPs due to strong biotin-streptavidin interactions. CONCLUSION The process of pDNA liberation may significantly influence the efficiency of the transfection vector. Therefore, it should be carefully considered when creating novel gene delivery agents.

Mobilization of Bone Marrow-Derived Endothelial Progenitor Cells following Finnish Sauna: A Pilot Study

Background: Sauna bathing is claimed to provide benefits for patients suffering from cardiovascular diseases. The current study aims at analyzing the induction of potential regenerative processes by quantifying the mobilization of bone marrow-derived stem cells into the peripheral blood of healthy adults following Finnish sauna. Materials and Methods: Twenty healthy unbiased male volunteers (20-30 years old) were exposed to a Finnish sauna bath (3 × 10 min, 90°C). Venous blood samples were drawn before (baseline), immediately, and 6 h as well as 24 h after the sauna bath. Blood analysis included isolation of mononuclear cells, cell staining with mononuclear antibodies, and fluorescence-activated cell sorting (FACS). For baseline and 24 h post-sauna samples colony-forming unit-Hill assays were applied to quantify endothelial progenitor cells (EPC). Results: Flow cytometry revealed an upregulation of circulating CD45+/CD309+ progenitor cells immediately after the sauna bath, however without reaching statistical significance. Circulating cell numbers of the CD45+CD34+, CD45+CD34+CD133+, and CD45+CD34+CD117+ populations did not show clear enhancements following sauna. EPC colony formation tended to be enhanced after sauna as compared to baseline values. Conclusion: Peripheral EPC numbers exhibited a moderate increase following Finnish sauna in a cohort of healthy young men. Furthermore, sauna bathing tended to increase EPC colony-forming capacity. These rather weak responses to thermotherapy might indicate a ceiling effect. In individuals exhibiting cardiovascular risk factors the effects may be more pronounced.

Cardiac Function Improvement and Bone Marrow Response

Objective The phase III clinical trial PERFECT was designed to assess clinical safety and efficacy of intramyocardial CD133+ bone marrow stem cell treatment combined with CABG for induction of cardiac repair. Design Multicentre, double-blinded, randomised placebo controlled trial. Setting The study was conducted across six centres in Germany October 2009 through March 2016 and stopped due slow recruitment after positive interim analysis in March 2015. Participants Post-infarction patients with chronic ischemia and reduced LVEF (25–50%). Interventions: Eighty-two patients were randomised to two groups receiving intramyocardial application of 5 ml placebo or a suspension of 0.5–5 × 106 CD133+. Outcome Primary endpoint was delta (∆) LVEF at 180 days (d) compared to baseline measured in MRI. Findings (prespecified) Safety (n = 77): 180 d survival was 100%, MACE n = 2, SAE n = 49, without difference between placebo and CD133+. Efficacy (n = 58): The LVEF improved from baseline LVEF 33.5% by + 9.6% at 180 d, p = 0.001 (n = 58). Treatment groups were not different in ∆ LVEF (ANCOVA: Placebo + 8.8% vs. CD133+ + 10.4%, ∆ CD133+ vs placebo + 2.6%, p = 0.4). Findings (post hoc) Responders (R) classified by ∆ LVEF ≥ 5% after 180 d were 60% of the patients (35/58) in both treatment groups. ∆ LVEF in ANCOVA was + 17.1% in (R) vs. non-responders (NR) (∆ LVEF 0%, n = 23). NR were characterized by a preoperative response signature in peripheral blood with reduced CD133+ EPC (RvsNR: p = 0.005) and thrombocytes (p = 0.004) in contrast to increased Erythropoeitin (p = 0.02), and SH2B3 mRNA expression (p = 0.073). Actuarial computed mean survival time was 76.9 ± 3.32 months (R) vs. + 72.3 ± 5.0 months (NR), HR 0.3 [Cl 0.07–1.2]; p = 0.067.Using a machine learning 20 biomarker response parameters were identified allowing preoperative discrimination with an accuracy of 80% (R) and 84% (NR) after 10-fold cross-validation. Interpretation The PERFECT trial analysis demonstrates that the regulation of induced cardiac repair is linked to the circulating pool of CD133 + EPC and thrombocytes, associated with SH2B3 gene expression. Based on these findings, responders to cardiac functional improvement may be identified by a peripheral blood biomarker signature. TRIAL REGISTRATION: ClinicalTrials.govNCT00950274.

Applying 3D-FRAP microscopy to analyse gap junction-dependent shuttling of small antisense RNAs between cardiomyocytes

Small antisense RNAs like miRNA and siRNA are of crucial importance in cardiac physiology, pathology and, moreover, can be applied as therapeutic agents for the treatment of cardiovascular diseases. Identification of novel strategies for miRNA/siRNA therapy requires a comprehensive understanding of the underlying mechanisms. Emerging data suggest that small RNAs are transferred between cells via gap junctions and provoke gene regulatory effects in the recipient cell. To elucidate the role of miRNA/siRNA as signalling molecules, suitable tools are required that will allow the analysis of these small RNAs at the cellular level. In the present study, we applied 3 dimensional fluorescence recovery after photo bleaching microscopy (3D-FRAP) to visualise and quantify the gap junctional exchange of small RNAs between neonatal cardiomyocytes in real time. Cardiomyocytes were transfected with labelled miRNA and subjected to FRAP microscopy. Interestingly, we observed recovery rates of 21% already after 13min, indicating strong intercellular shuttling of miRNA, which was significantly reduced when connexin43 was knocked down. Flow cytometry analysis confirmed our FRAP results. Furthermore, using an EGFP/siRNA reporter construct we demonstrated that the intercellular transfer does not affect proper functioning of small RNAs, leading to marker gene silencing in the recipient cell. Our results show that 3D-FRAP microscopy is a straightforward, non-invasive live cell imaging technique to evaluate the GJ-dependent shuttling of small RNAs with high spatio-temporal resolution. Moreover, the data obtained by 3D-FRAP confirm a novel pathway of intercellular gene regulation where small RNAs act as signalling molecules within the intercellular network.

Mechanisms of stem cell based cardiac repair-gap junctional signaling promotes the cardiac lineage specification of mesenchymal stem cells

Different subtypes of bone marrow-derived stem cells are characterized by varying functionality and activity after transplantation into the infarcted heart. Improvement of stem cell therapeutics requires deep knowledge about the mechanisms that mediate the benefits of stem cell treatment. Here, we demonstrated that co-transplantation of mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs) led to enhanced synergistic effects on cardiac remodeling. While HSCs were associated with blood vessel formation, MSCs were found to possess transdifferentiation capacity. This cardiomyogenic plasticity of MSCs was strongly promoted by a gap junction-dependent crosstalk between myocytes and stem cells. The inhibition of cell-cell coupling significantly reduced the expression of the cardiac specific transcription factors NKX2.5 and GATA4. Interestingly, we observed that small non-coding RNAs are exchanged between MSCs and cardiomyocytes in a GJ-dependent manner that might contribute to the transdifferentiation process of MSCs within a cardiac environment. Our results suggest that the predominant mechanism of HSCs contribution to cardiac regeneration is based on their ability to regulate angiogenesis. In contrast, transplanted MSCs have the capability for intercellular communication with surrounding cardiomyocytes, which triggers the intrinsic program of cardiogenic lineage specification of MSCs by providing cardiomyocyte-derived cues.

Exploiting AT2R to Improve CD117 Stem Cell Function In Vitro and In Vivo - Perspectives for Cardiac Stem Cell Therapy

Background/Aims: CD117+ stem cell (SC) based therapy is considered an alternative therapeutic option for terminal heart disease. However, controversies exist on the effects of CD117+ SC implantation. In particular, the link between CD117+ SC function and angiotensin-II-type-2 receptor (AT2R) after MI is continuously discussed. We therefore asked whether 1) AT2R stimulation influences CD117+ SC properties in vitro and, 2) which effects can be ascribed to AT2R stimulation in vivo. Methods: We approached AT2R stimulation with Angiotensin II while simultaneously blocking its opponent receptor AT1 with Losartan. CD117 effects were dissected using a 2D-Matrigel assay and HL-1 co-culture in vitro. A model of myocardial infarction, in which we implanted EGFP+ CD117 SC, was further applied. Results: While we found indications for AT2R driven vasculogenesis in vitro, co-culture experiments revealed that CD117+ SC improve vitality of cardiomyocytes independently of AT2R function. Likewise, untreated CD117+ SC had a positive effect on cardiac function and acted cardioprotective in vivo. Conclusions: Therefore, our data show that transient AT2R stimulation does not significantly add to the beneficial actions of CD117+ SC in vivo. Yet, exploiting AT2R driven vasculogenis via an optimized AT2R stimulation protocol may become a promising tool for cardiac SC therapy.