Fibrin, Bone Marrow Cells and macrophages interactively modulate cardiomyoblast fate.

Interactions between macrophages, cardiac cells and the extracellular matrix are crucial for cardiac repair following myocardial infarction (MI). The paracrine effects of cell-based treatments of MI might modulate these interactions and impact cardiac repair. The immunomodulatory capacity of the therapeutic cells is therefore of interest and could be modulated by the use of biomaterials. We first showed that bone marrow cells (BMC) associated with fibrin could treat MI. Then, we interrogated the influence of fibrin, as a biologically active scaffold, on the secretome of BMC and the impact of their association on macrophage fate and cardiomyoblast proliferation. Methods: In vivo, two weeks post-MI, rats were treated with epicardial implantation of BMC and fibrin or sham-operated. High-resolution echocardiography was performed to evaluate the heart function and structure changes after 4 weeeks. Histology and immunostaining were performed on harvested hearts. In vitro, BMC were first primed with fibrin. Second, non-polarized macrophages were differentiated toward either pro-inflammatory or anti-inflammatory phenotypes and stimulated with the conditioned medium of fibrin-primed BMC (F-BMC). Proteomic, cytokine levels quantification, and RT-PCR were performed. EdU incorporation and real-time cell analysis assessed cell proliferation. Results: The epicardial implantation of fibrin and BMC reduced the loss of cardiac function induced by MI, increased wall thickness and prevented the fibrotic scar expansion. After 4 and 12 weeks, the infarct content of CD68+ and CD206+ was similar in control and treated animals. In vitro, we showed that fibrin profoundly influenced the gene expression and the secretome of BMC, simultaneously upregulating both pro- and anti-inflammatory mediators. Furthermore, the conditioned medium from F-BMC significantly increased the proliferation of macrophages in a subsets dependent manner and modulated their gene expression and cytokines secretion. For instance, F-BMC significantly downregulated the expression of Nos2, Il6 and Ccl2/Mcp1 while Arg1, Tgfb and IL10 were upregulated. Interestingly, macrophages educated by F-BMC increased cardiomyoblast proliferation. In conclusion, our study provides evidence that BMC/fibrin-based treatment lowered the infarct extent and improved cardiac function. The macrophage content was unmodified when measured at a chronic stage. Nevertheless, acutely and in vitro, the F-BMC secretome promotes an anti-inflammatory response that stimulates cardiac cell growth. Finally, our study emphases the acute impact of F-BMC educated macrophages on cardiac cell fate.

COMPARISON OF TRANS-RIGHT ATRIAL VERSUS COMBINED (TRANS-RIGHT ATRIAL, TRANS-RIGHT VENTRICULAR) APPROACH FOR INTRA-CARDIAC REPAIR OF TETRALOGY OF FALLOT: SINGLE-CENTER EXPERIENCE

Background and Objective: We compared trans-right atrial (t-RA) versus combined (trans-right-atrial and trans-ventricular (t-RA/RV) approaches for intra-cardiac repair of Tetralogy of Fallot (TOF) for the pre-operative and post-operative right ventricular (RV) function. The RV function was calculated using a tricuspid annular plane systolic excursion (TAPSE) using two-dimensional (2-D) echocardiography. Materials and Methods: This was a retrospective study. Fifty-three patients operated for the intra-cardiac repair of TOF between August 2019 and March 2021 were included in the study and divided into two groups based on the approach for repair as follows: t-RA or combined (t-RA/RV) approach. The first group (t-RA) had twenty-one patients, and the second group (combined t-RA/RV approach) had thirty-two patients. The assessment of pre-operative and post-operative RV function was done using TAPSE. Records of follow-up at 1 month and 3 months were evaluated. Results: Age, body surface area (BSA), preoperative saturation, cardiopulmonary bypass time, aortic cross?clamp time, postoperative intensive care unit (ICU) stay, and hospital stay were similar in both groups. However, t?RA/RV group had more pleural effusions (9 vs. 1 patients, P < 0.05), but had more improvements in Right Ventricular outflow tract (RVOT) gradients. There were no differences in arrhythmias in either group. Pre-operative TAPSE for both groups was similar (1.46 ± 0.27 vs. 1.61 ± 0.31, P > 0.05) and so was the post?operative TAPSE at discharge (1.54 ± 0.31 vs. 1.49 ± 0.33, P > 0.05), at 1 months (1.64 ± 0.25 vs. 1.48 ± 0.32, P > 0.05) and 3months (1.75 ± 0.19 vs. 1.7 ± 0.15, P > 0.05). Conclusion: Both approaches provide adequate palliation with effective improvements in RVOT gradients for patients with TOF. A limited right ventriculotomy does not adversely affect early RV function or increase the incidence of arrhythmias at the immediate post-operative period and early follow-up. More extensive studies with prospective randomized design and longer follow-ups are needed to address these issues further. Keywords: Tetralogy of Fallot, transatrial approach, intracardiac repair.

Cardiac Remodeling and Repair: Recent Approaches, Advancements, and Future Perspective

The limited ability of mammalian adult cardiomyocytes to proliferate following an injury to the heart, such as myocardial infarction, is a major factor that results in adverse fibrotic and myocardial remodeling that ultimately leads to heart failure. The continued high degree of heart failure-associated morbidity and lethality requires the special attention of researchers worldwide to develop efficient therapeutics for cardiac repair. Recently, various strategies and approaches have been developed and tested to extrinsically induce regeneration and restoration of the myocardium after cardiac injury have yielded encouraging results. Nevertheless, these interventions still lack adequate success to be used for clinical interventions. This review highlights and discusses both cell-based and cell-free therapeutic approaches as well as current advancements, major limitations, and future perspectives towards developing an efficient therapeutic method for cardiac repair.

Combined administration of laminin-221 and prostacyclin agonist enhances endogenous cardiac repair in an acute infarct rat heart

Although endogenous cardiac repair by recruitment of stem cells may serve as a therapeutic approach to healing a damaged heart, how to effectively enhance the migration of stem cells to the damaged heart is unclear. Here, we examined whether the combined administration of prostacyclin agonist (ONO1301), a multiple-cytokine inducer, and stem cell niche laminin-221 (LM221), enhances regeneration through endogenous cardiac repair. We administered ONO1301- and LM221-immersed sheets, LM221-immersed sheets, ONO1301-immersed sheets, and PBS-immersed sheets (control) to an acute infarction rat model. Four weeks later, cardiac function, histology, and cytokine expression were analysed. The combined administration of LM221 and ONO1301 upregulated angiogenic and chemotactic factors in the myocardium after 4 weeks and enhanced the accumulation of ILB4 positive cells, SMA positive cells, and platelet-derived growth factor receptor alpha (PDGFRα) and CD90 double-positive cells, leading to the generation of mature microvascular networks. Interstitial fibrosis reduced and functional recovery was prominent in LM221- and ONO1301-administrated hearts as compared with those in ONO1301-administrated or control hearts. LM221 and ONO1301 combination enhanced recruitment of PDGFRα and CD90 double-positive cells, maturation of vessels, and functional recovery in rat acute myocardial infarction hearts, highlighting a new promising acellular approach for the failed heart.

Cardiac Repair With Echocardiography-Guided Multiple Percutaneous Left Ventricular Intramyocardial Injection of hiPSC-CMs After Myocardial Infarction

Objective: We investigated the potency of cardiac repair based on echocardiography-guided multiple percutaneous left ventricular intramyocardial injection of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) after myocardial infarction (MI).Methods: Mice with surgically induced MI were randomly divided into three groups (n = 8 in each group) and subjected to echocardiography-guided percutaneous left ventricular infarcted border injection of hiPSC-CMs (single dose; 10 μl 3 × 105 cells) or repeated injections of hiPSC-CMs at post-MI weeks 1 and 2 (multiple doses). The sham group of animals underwent all surgical procedures necessary for MI induction except for ligation. Then 4 weeks after MI, heart function was measured with transthoracic echocardiography. Engraftment was evaluated through the detection of human-specific cardiac troponin T. Infarct size and collagen volume were calculated with Sirius Red/Fast Green staining. Angiogenesis was evaluated with isolectin B4 staining. Cardiac remodeling was evaluated from the cardiomyocyte minimal fiber diameter in the infarcted border zone. Apoptosis was detected via TdT-mediated dUTP Nick-End Labeling (TUNEL) staining in cardiomyocytes from the infarcted border zone.Results: No mice died after echocardiography-guided percutaneous left ventricular intramyocardial injection. hiPSC-CMs were about nine-fold higher in the multiple-dose group at week 4 compared to the single-dose group. Multiple-dose transplantation was associated with significant improvement in left ventricular function, infarct size, angiogenesis, cardiac remodeling, and cardiomyocyte apoptosis.Conclusion: Echocardiography-guided multiple percutaneous left ventricular intramyocardial injection is a feasible, satisfactory, repeatable, relatively less invasive, and effective method of delivering cell therapy. The delivery of hiPSC-CMs indicates a novel therapy for MI.

Serine/Threonine‐Protein Kinase 3 Facilitates Myocardial Repair After Cardiac Injury Possibly Through the Glycogen Synthase Kinase‐3β/β‐Catenin Pathway

Background The neonatal heart maintains its entire regeneration capacity within days after birth. Using quantitative phosphoproteomics technology, we identified that SGK3 (serine/threonine‐protein kinase 3) in the neonatal heart is highly expressed and activated after myocardial infarction. This study aimed to uncover the function and related mechanisms of SGK3 on cardiomyocyte proliferation and cardiac repair after apical resection or ischemia/reperfusion injury. Methods and Results The effect of SGK3 on proliferation and oxygen glucose deprivation/reoxygenation– induced apoptosis in isolated cardiomyocytes was evaluated using cardiomyocyte‐specific SGK3 overexpression or knockdown adenovirus5 vector. In vivo, gain‐ and loss‐of‐function experiments using cardiomyocyte‐specific adeno‐associated virus 9 were performed to determine the effect of SGK3 in cardiomyocyte proliferation and cardiac repair after apical resection or ischemia/reperfusion injury. In vitro, overexpression of SGK3 enhanced, whereas knockdown of SGK3 decreased, the cardiomyocyte proliferation ratio. In vivo, inhibiting the expression of SGK3 shortened the time window of cardiac regeneration after apical resection in neonatal mice, and overexpression of SGK3 significantly promoted myocardial repair and cardiac function recovery after ischemia/reperfusion injury in adult mice. Mechanistically, SGK3 promoted cardiomyocyte regeneration and myocardial repair after cardiac injury by inhibiting GSK‐3β (glycogen synthase kinase‐3β) activity and upregulating β‐catenin expression. SGK3 also upregulated the expression of cell cycle promoting genes G1/S‐specific cyclin‐D1, c‐myc (cellular‐myelocytomatosis viral oncogene), and cdc20 (cell division cycle 20), but downregulated the expression of cell cycle negative regulators cyclin kinase inhibitor P 21 and cyclin kinase inhibitor P 27. Conclusions Our study reveals a key role of SGK3 on cardiac repair after apical resection or ischemia/reperfusion injury, which may reopen a novel therapeutic option for myocardial infarction.