MicroRNA-489 Promotes the Apoptosis of Cardiac Muscle Cells in Myocardial Ischemia-Reperfusion Based on Smart Healthcare

With the development of information technology, the concept of smart healthcare has gradually come to the fore. Smart healthcare uses a new generation of information technologies, such as the Internet of Things (loT), big data, cloud computing, and artificial intelligence, to transform the traditional medical system in an all-around way, making healthcare more efficient, more convenient, and more personalized. miRNAs can regulate the proliferation, differentiation, and apoptosis of human cells. Relevant studies have also shown that miRNAs may play a key role in the occurrence and development of myocardial ischemia-reperfusion injury (MIRI). This study aims to explore the effects of miR-489 in MIRI. In this study, miR-489 expression in a myocardial ischemia-reperfusion animal model and H9C2 cells induced by H/R was detected by qRT-PCR. The release of lactate dehydrogenase (LDH) and the activity of creatine kinase (CK) was detected after miR-489 knockdown in H9C2 cells induced by H/R. The apoptosis of H9C2 cells and animal models were determined by ELISA. The relationship between miR-489 and SPIN1 was verified by a double fluorescence reporter enzyme assay. The expression of the PI3K/AKT pathway-related proteins was detected by Western blot. Experimental results showed that miR-489 was highly expressed in cardiac muscle cells of the animal model and in H9C2 cells induced by H/R of the myocardial infarction group, which was positively associated with the apoptosis of cardiac muscle cells with ischemia-reperfusion. miR-489 knockdown can reduce the apoptosis of cardiac muscle cells caused by ischemia-reperfusion. In downstream targeting studies, it was found that miR-489 promotes the apoptosis of cardiac muscle cells after ischemia-reperfusion by targeting the inhibition of the SPIN1-mediated PI3K/AKT pathway. In conclusion, high expression of miR-489 is associated with increased apoptosis of cardiac muscle cells after ischemia-reperfusion, which can promote the apoptosis after ischemia-reperfusion by targeting the inhibition of the SPIN1-mediated PI3K/AKT pathway. Therefore, miR-489 can be one of the potential therapeutic targets for reducing the apoptosis of cardiac muscle cells after ischemia-reperfusion.

Mechanisms for Cardiac Troponin Increase in Arterial Hypertension

Despite the fact that cardiac troponins (cTnI and cTnT) are cardiospecific, they can be elevated in many systemic and non-cardiac physiological and pathological conditions. The diagnostic value of cTnI and cTnT significantly depends on the method of their determination. Thus, previously used low- and moderate-sensitivity immunoassays detected only serious myocardial damage and did not determine troponins in patients suffering from certain chronic pathologies. High-sensitivity troponin assays can detect minor damage to cardiac muscle cells in many pathological conditions, and troponin levels have a high predictive value. Among the early pathological conditions requiring the attention of clinicians is arterial hypertension (AH), which is also accompanied by an increase in the levels of hsTn in serum and urine. Currently, mechanisms responsible for increased levels of cardiac troponins in the blood serum and urine in hypertension are not well covered in the scientific literature. This article discusses in detail the presumptive mechanisms that cause increased levels of cTnI and cTnT in AH.

Reawakening the Intrinsic Cardiac Regenerative Potential: Molecular Strategies to Boost Dedifferentiation and Proliferation of Endogenous Cardiomyocytes

Despite considerable efforts carried out to develop stem/progenitor cell-based technologies aiming at replacing and restoring the cardiac tissue following severe damages, thus far no strategies based on adult stem cell transplantation have been demonstrated to efficiently generate new cardiac muscle cells. Intriguingly, dedifferentiation, and proliferation of pre-existing cardiomyocytes and not stem cell differentiation represent the preponderant cellular mechanism by which lower vertebrates spontaneously regenerate the injured heart. Mammals can also regenerate their heart up to the early neonatal period, even in this case by activating the proliferation of endogenous cardiomyocytes. However, the mammalian cardiac regenerative potential is dramatically reduced soon after birth, when most cardiomyocytes exit from the cell cycle, undergo further maturation, and continue to grow in size. Although a slow rate of cardiomyocyte turnover has also been documented in adult mammals, both in mice and humans, this is not enough to sustain a robust regenerative process. Nevertheless, these remarkable findings opened the door to a branch of novel regenerative approaches aiming at reactivating the endogenous cardiac regenerative potential by triggering a partial dedifferentiation process and cell cycle re-entry in endogenous cardiomyocytes. Several adaptations from intrauterine to extrauterine life starting at birth and continuing in the immediate neonatal period concur to the loss of the mammalian cardiac regenerative ability. A wide range of systemic and microenvironmental factors or cell-intrinsic molecular players proved to regulate cardiomyocyte proliferation and their manipulation has been explored as a therapeutic strategy to boost cardiac function after injuries. We here review the scientific knowledge gained thus far in this novel and flourishing field of research, elucidating the key biological and molecular mechanisms whose modulation may represent a viable approach for regenerating the human damaged myocardium.

Abstract P318: Dna Tension Probes Show That Cardiomyocyte Maturation Is Sensitive To The Pico-Newton Traction Forces Transmitted By Integrins

Cardiac muscle cells (CMCs) are the unit cells that comprise the heart. CMCs go through different stages of differentiation and maturation pathways to fully mature into beating cells. These cells can sense and respond to mechanical cues through receptors such as integrins which influence maturation pathways. For example, cell traction forces are important for the differentiation and development of functional CMCs, as CMCs cultured on varying substrate stiffness function differently. Most work in this area has focused on understanding the role of bulk ECM (extracellular matrix) stiffness in mediating the functional fate of CMC. Given that stiffness sensing mechanisms are mediated by individual integrin receptors, an important question in this area pertains to the specific magnitude of integrin piconewton (pN) forces that can trigger CMC functional maturation. To address this knowledge gap, we used DNA adhesion tethers that rupture at specific thresholds of force (~12, ~56, and ~160 pN) to test whether capping peak integrin tension to specific magnitudes affects CMC function. The work shows that adhesion tethers with greater force tolerance lead to functionally mature CMCs as determined by morphology, twitching frequency, transient calcium flux measurements and protein expression (F-actin, vinculin, α-actinin, YAP and SERCA2). Additionally, sacromeric actinin alignment and multinucleation were significantly enhanced as the mechanical tolerance of integrin tethers was increased. Taken together, the results show that CMCs harness defined pN integrin forces to influence early stage development. This study represents an important step toward biophysical characterization of the contribution of pN forces in early stage cardiac differentiation.

The influence of iron availability on the structural changes of skeletal muscle cells and cardiac muscle cells

In the presented study, the influence iron availability on the cell morphology and structure was examined in skeletal myocytes cultured under normoxic and hypoxic conditions. The study showed that iron deficiency in vitro (especially in combination with hypoxia) has a detrimental effect on skeletal myocytes. Cellular disfunction was manifested by atrophic changes in cell morphology, structural remodeling of cells and increased expression of muscle atrophy markers. Interestingly, increased iron availability appeared to have some protective properties in the context of aforementioned changes. Moreover, based on clinical data and recent transgenic models, structural and functional abnormalities in iron-deficient cardiac muscle were described and the potential pathomechanisms behind them have been discussed.

Hair-Follicle-Associated Pluripotent (HAP) Stem Cells Can Extensively Differentiate to Tyrosine-Hydroxylase-Expressing Dopamine-Secreting Neurons

Hair-follicle-associated pluripotent (HAP) stem cells are located in the bulge area of hair follicles from mice and humans and have been shown to differentiate to neurons, glia, keratinocytes, smooth muscle cells, melanocytes and beating cardiac muscle cells in vitro. Subsequently, we demonstrated that HAP stem cells could effect nerve and spinal-cord regeneration in mouse models, differentiating to Schwann cells and neurons in this process. HAP stem cells can be banked by cryopreservation and preserve their ability to differentiate. In the present study, we demonstrated that mouse HAP stem cells cultured in neural-induction medium can extensively differentiate to dopaminergic neurons, which express tyrosine hydroxylase and secrete dopamine. These results indicate that the dopaminergic neurons differentiated from HAP stem cells may be useful in the future to improve the symptoms of Parkinson’s disease in the clinic.

Effect of Verapamil, an L-Type Calcium Channel Inhibitor, on Caveolin-3 Expression in Septic Mouse Hearts

Sepsis-induced myocardial dysfunction considerably increases mortality risk in patients with sepsis. Previous studies from our group have shown that sepsis alters the expression of structural proteins in cardiac cells, resulting in cardiomyocyte degeneration and impaired communication between cardiac cells. Caveolin-3 (CAV3) is a structural protein present in caveolae, located in the membrane of cardiac muscle cells, which regulates physiological processes such as calcium homeostasis. In sepsis, there is a disruption of calcium homeostasis, which increases the concentration of intracellular calcium, which can lead to the activation of potent cellular enzymes/proteases which cause severe cellular injury and death. The purpose of the present study was to test the hypotheses that sepsis induces CAV3 overexpression in the heart, and the regulation of L-type calcium channels directly relates to the regulation of CAV3 expression. Severe sepsis increases the expression of CAV3 in the heart, as immunostaining in our study showed CAV3 presence in the cardiomyocyte membrane and cytoplasm, in comparison with our control groups (without sepsis) that showed CAV3 presence predominantly in the plasma membrane. The administration of verapamil, an L-type calcium channel inhibitor, resulted in a decrease in mortality rates of septic mice. This effect was accompanied by a reduction in the expression of CAV3 and attenuation of cardiac lesions in septic mice treated with verapamil. Our results indicate that CAV3 has a vital role in cardiac dysfunction development in sepsis and that the regulation of L-type calcium channels may be related to its expression.