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Background: Cardiac regeneration after injury is limited by the low proliferative capacity of adult mammalian cardiomyocytes (CMs). However, certain animals readily regenerate lost myocardium through a process involving dedifferentiation, which unlocks their proliferative capacities. Methods: We bred mice with inducible, CM-specific expression of the Yamanaka factors, enabling adult CM reprogramming and dedifferentiation in vivo. Results: Two days after induction, adult CMs presented a dedifferentiated phenotype and increased proliferation in vivo. Microarray analysis revealed that upregulation of ketogenesis was central to this process. Adeno-associated virus-driven HMGCS2 overexpression induced ketogenesis in adult CMs and recapitulated CM dedifferentiation and proliferation observed during partial reprogramming. This same phenomenon was found to occur after myocardial infarction, specifically in the border zone tissue, and HMGCS2 knockout mice showed impaired cardiac function and response to injury. Finally, we showed that exogenous HMGCS2 rescues cardiac function after ischemic injury. Conclusions: Our data demonstrate the importance of HMGCS2-induced ketogenesis as a means to regulate metabolic response to CM injury, thus allowing cell dedifferentiation and proliferation as a regenerative response.

Considering the broad therapeutic potential of omega-3 polyunsaturated fatty acids such as docosahexaenoic acid (DHA), here we study the effect of PEGylation of DHA-incorporated hexosomes on their physicochemical characteristics and biodistribution following intravenous injection into mice. Hexosomes were formed from phosphatidylglycerol and DHA with a weight ratio of 3:2. PEGylation was achieved through the incorporation of either d-α-tocopheryl succinate poly(ethylene glycol)

Introduction: Injection of induced pluripotent stem cell-derived cardiomyocytes has been reported as a promising approach to regenerate loss myocardium and restore heart function after ischemic injury. However, immaturity of the transplanted cardiomyocytes and their poor survival rates caused by limited blood supply remain as major hurdles for clinical translation. Hypothesis: We tested the hypothesis that co-culture of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs) with hiPSC-derived endothelial cells (ECs) promotes CM maturation in vitro, and that co-transplantation of both hiPSC-CMs and hiPSC-ECs facilitates hiPSC-CM muscularization in myocardial ischemic injured mice and non-human primates. Methods and Results: We examined the therapeutic effect of co-transplantation of hiPSC-CMs and hiPSC-ECs in NOD-SCID mice undergoing myocardial infarction (N = 14 / group). Mice receiving co-transplantation had an improvement in ejection fraction compared to control (4.2 ± 1.2 % vs -8.4 ± 0.9 %, P < 0.0001), and even those receiving high-dose (-0.3 ± 0.9 %, P = 0.052) and low-dose (-2.4 ± 1.1 %, P = 0.001) hiPSC-CMs alone treatment. Moreover, less arrhythmic events were observed in co-transplantation using three-lead electrogram. To be more clinically relevant, we first showed in healthy non-human primates (N = 4) that hiPSC-CM engraftment, maturation, and integration was achieved when co-transplanted with hiPSC-ECs. Furthermore, we then examined the therapeutic effect of co-transplantation of hiPSC-CMs and hiPSC-ECs in rhesus macaques undergoing ischemia-reperfusion surgery (N = 3 / group). Consistent with the mouse model, co-transplantation in rhesus macaques significantly improved the ejection fraction (10 ± 1.3 % vs -1.8 ± 2.2 %, P = 0.010), accompanied by a reduced infarct size compared to control (16 ± 1.1 % vs 23 ± 3.3 %, P = 0.091). Conclusions: This study demonstrates the beneficial effects of co-transplantation of hiPSC-CMs with hiPSC-ECs, promoting hiPSC-CM maturation, enhancing neovascularization, and improving cardiac function in both mouse and non-human primate hearts. Delivery of this combined cell therapy holds promise for future clinical translation.

In this study, we establish a population-based human induced pluripotent stem cell (hiPSC) drug screening platform for toxicity assessment. After recruiting 1,000 healthy donors and screening for high-frequency human leukocyte antigen (HLA) haplotypes, we identify 13 HLA-homozygous "super donors" to represent the population. These "super donors" are also expected to represent at least 477,611,135 of the global population. By differentiating these representative hiPSCs into cardiomyocytes and neurons we show their utility in a high-throughput toxicity screen. To validate hit compounds, we demonstrate dose-dependent toxicity of the hit compounds and assess functional modulation. We also show reproducible in vivo drug toxicity results using mouse models with select hit compounds. This study shows the feasibility of using a population-based hiPSC drug screening platform to assess cytotoxicity, which can be used as an innovative tool to study inter-population differences in drug toxicity and adverse drug reactions in drug discovery applications.

Rationale: Long non-coding RNA (lncRNAs) has been identified as a pivotal novel regulators in cardiac development as well as cardiac pathogenesis. lncRNA H19 is known as a fetal gene but it is exclusively abundant in the heart and skeletal muscles in adulthood, and is evolutionarily conserved in humans and mice. It has been reported to possess a significant correlation with the risk of coronary artery diseases. However, the function of H19 is not well characterized in heart. Methods: Loss-of-function and gain-of-function mouse models with left anterior descending coronary artery-ligation surgery were utilized to evaluate the functionality of H19 in vivo. For mechanistic studies, hypoxia condition were exerted in in vitro models to mimic cardiac ischemic injury. Chromatin isolation by RNA immunoprecipitation (ChIRP) was performed to reveal the interacting protein of lncRNA H19. Results: lncRNA H19 was significantly upregulated in the infarct area post-surgery day 4 in mouse model. Ectopic expression of H19 in the mouse heart resulted in severe cardiac dilation and fibrosis. Several extracellular matrix (ECM) genes were significantly upregulated. While genetic ablation of H19 by CRISPR-Cas9 ameliorated post-MI cardiac remodeling with reduced expression in ECM genes. Through chromatin isolation by RNA purification (ChIRP), we identified Y-box-binding protein (YB)-1, a suppressor of Collagen 1A1, as an interacting protein of H19. Furthermore, H19 acted to antagonize YB-1 through direct interaction under hypoxia, which resulted in de-repression of Collagen 1A1 expression and cardiac fibrosis. Conclusions: Together these results demonstrate that lncRNA H19 and its interacting protein YB-1 are crucial for ECM regulation during cardiac remodeling.

Noncoding RNAs account for 80% of human transcripts, but functional studies on noncoding RNAs are relatively few and limited. Long noncoding RNAs (lncRNAs) are known to have an important role in cardiac development, and lately, high-throughput RNA sequencing has been extensively utilized to profile and explore the transcriptome landscape of lncRNAs in failing hearts. These studies have revealed that lncRNAs are mostly dysregulated in failing hearts and their expression signature can discriminate failing hearts of different etiologies. H19 is abundantly expressed in failing human hearts and its polymorphism was shown to possess a significant correlation with the risk of coronary artery diseases. In our study using murine hearts, we discovered that H19 was significantly up regulated in the heart after ischemic injury, with predominant expression in cardiac fibroblasts. This finding piqued our interest to further investigate the function of H19 in the heart. We demonstrated that ectopic overexpression of H19 using the AAV approach led to severe cardiac fibrosis in mouse hearts following myocardial infarction. In light of this finding, we generated H19 knockout mice to further investigate the functionality of H19 and we found that cardiac fibrosis was attenuated in these mice. Altogether, these findings suggested that H19 is a fibrosis regulator during cardiac remodeling process after infarction. Due to the multiple regulatory roles of lncRNAs, we then took advantage of chromatin isolation by RNA purification (ChIRP) to identify the H19-interacting protein, YB-1. Surprisingly, mice with YB-1 knockdown displayed severe cardiac fibrosis even without injury. Furthermore, we demonstrated that YB-1 is a transcriptional suppressor of collagen 1A1. Knockout of H19 in YB-1 knockdown partially suppressed Col1a1 expression, which suggests a negative regulatory role of H19 on YB-1 towards the expression of Col1a1. Taking into account all of these findings, we concluded that H19 mediates collagen expression in fibroblasts through the inhibition of YB-1 activity during cardiac remodeling.

Background: The impact of gut microbiota on the regulation of host physiology has recently garnered considerable attention, particularly in key areas such as the immune system and metabolism. These areas are also crucial for the pathophysiology of and repair after myocardial infarction (MI). However, the role of the gut microbiota in the context of MI remains to be fully elucidated. Methods: To investigate the effects of gut microbiota on cardiac repair after MI, C57BL/6J mice were treated with antibiotics 7 days before MI to deplete mouse gut microbiota. Flow cytometry was applied to examine the changes in immune cell composition in the heart. 16S rDNA sequencing was conducted as a readout for changes in gut microbial composition. Short-chain fatty acid (SCFA) species altered after antibiotic treatment were identified by high-performance liquid chromatography. Fecal reconstitution, transplantation of monocytes, or dietary SCFA or Lactobacillus probiotic supplementation was conducted to evaluate the cardioprotective effects of microbiota on the mice after MI. Results: Antibiotic-treated mice displayed drastic, dose-dependent mortality after MI. We observed an association between the gut microbiota depletion and significant reductions in the proportion of myeloid cells and SCFAs, more specifically acetate, butyrate, and propionate. Infiltration of CX3CR1+ monocytes to the peri-infarct zone after MI was also reduced, suggesting impairment of repair after MI. Accordingly, the physiological status and survival of mice were significantly improved after fecal reconstitution, transplantation of monocytes, or dietary SCFA supplementation. MI was associated with a reorganization of the gut microbial community such as a reduction in Lactobacillus. Supplementing antibiotic-treated mice with a Lactobacillus probiotic before MI restored myeloid cell proportions, yielded cardioprotective effects, and shifted the balance of SCFAs toward propionate. Conclusions: Gut microbiota–derived SCFAs play an important role in maintaining host immune composition and repair capacity after MI. This suggests that manipulation of these elements may provide opportunities to modulate pathological outcome after MI and indeed human health and disease as a whole.

The blood-brain barrier (BBB) selectively controls the passage of endogenous and exogenous molecules between systemic circulation and the brain parenchyma. Nanocarrier-based drugs such as liposomes and nanoparticles are an attractive prospect for cancer therapy since they can carry a drug payload and be modified to improve targeting and retention at the desired site. However, the BBB prevents most therapeutic drugs from entering the brain, including physically restricting the passage of liposomes and nanoparticles. In this paper, we show that a low dose of systemically injected recombinant human vascular endothelial growth factor induces a short period of increased BBB permeability. We have shown increased delivery of a range of nanomedicines to the brain including contrast agents for imaging, varying sizes of nanoparticles, small molecule chemotherapeutics, tracer dyes, and liposomal chemotherapeutics. However, this effect was not uniform across all brain regions, and permeability varied depending on the drug or molecule measured. We have found that this window of BBB permeability effect is transient, with normal BBB integrity restored within 4 h. This strategy, combined with liposomal doxorubicin, was able to significantly extend survival in a mouse model of human glioblastoma. We have found no evidence of systemic toxicity, and the technique was replicated in pigs, demonstrating that this technique could be scaled up and potentially be translated to the clinic, thus allowing the use of nanocarrier-based therapies for brain disorders.

The most high efficiency cadmium-free CIGS solar cell is zinc sulfide fabricated by chemical bath deposition. However, on account of the presence of Zn(OH)2 phase during chemical reaction, it leads to poor cell performance attributed in low fill factor and shows distorted I-V curve. The cell performance can be enhanced by continuous illumination, which has been found by many groups called light-soaking effect. In this paper, we compared two different chemical processes with and without ammonia hydroxide etching. The well-known ammonia etching effect for removing Zn(OH)2 phase has also been observed in this work. By comparing the different chemical processes with ammonia etching, we noticed the difference of compositions due to chemical reaction routes. Based on the research for chemical routes, we further to optimize CBD-ZnS process deposited on CIGS substrates. Owing to the decrease of Zn(OH)2 concentration by optimized CBD-ZnS, the cell efficiency can be improved in Voc and FF. Moreover, the time for lightsoaking treatment can be shortened to less than 20 minutes.