Characterization of functional ion channels in human cardiac c-kit+ progenitor cells

Bradykinin-pretreated Human cardiac-specific c-kit+ Cells Enhance Exosomal miR-3059-5p and Promote Angiogenesis Against Hindlimb Ischemia in mice

BACKGROUND

Protection of cardiac function following myocardial infarction was largely enhanced by bradykinin-pretreated cardiac-specific c-kit+ (BK-c-kit+) cells, even without significant engraftment, indicating that paracrine actions of BK-c-kit+ cells play a pivotal role in angiogenesis. Nevertheless, the active components of the paracrine actions of BK-c-kit+ cells and the underlying mechanisms remain unknown. This study aimed to define the active components of exosomes from BK-c-kit+ cells and elucidate their underlying protective mechanisms.

METHODS

Matrigel tube formation assay, cell cycle, and mobility in human umbilical vein endothelial cells (HUVECs) and hindlimb ischemia (HLI) in mice were applied to determine the angiogenic effect of condition medium (CM) and exosomes. Proteome profiler, microRNA sponge, Due-luciferase assay, microRNA-sequencing, qRT-PCR, and Western blot were used to determine the underlying mechanism of the angiogenic effect of exosomes from BK-c-kit+.

RESULTS

As a result, BK-c-kit+ CM and exosomes promoted tube formation in HUVECs and the repair of HLI in mice. Angiogenesis-related proteomic profiling and microRNA sequencing revealed highly enriched miR-3059-5p as a key angiogenic component of BK-c-kit+ exosomes. Meanwhile, loss- and gain-of-function experiments revealed that the promotion of angiogenesis by miR-3059-5p was mainly through suppression of TNFSF15-inhibited effects on vascular tube formation, cell proliferation and cell migration. Moreover, enhanced angiogenesis of miR-3059-5p-inhibited TNFSF15 has been associated with Akt/Erk1/2/Smad2/3-modulated signaling pathway.

CONCLUSION

Our results demonstrated a novel finding that BK-c-kit+ cells enrich exosomal miR-3059-5p to suppress TNFSF15 and promote angiogenesis against hindlimb ischemia in mice.

Computational design of custom therapeutic cells to correct failing human cardiomyocytes

Background

Myocardial delivery of non-excitable cells-namely human mesenchymal stem cells (hMSCs) and c-kit⁺ cardiac interstitial cells (hCICs)-remains a promising approach for treating the failing heart. Recent empirical studies attempt to improve such therapies by genetically engineering cells to express specific ion channels, or by creating hybrid cells with combined channel expression. This study uses a computational modeling approach to test the hypothesis that custom hypothetical cells can be rationally designed to restore a healthy phenotype when coupled to human heart failure (HF) cardiomyocytes.

Methods

Candidate custom cells were simulated with a combination of ion channels from non-excitable cells and healthy human cardiomyocytes (hCMs). Using a genetic algorithm-based optimization approach, candidate cells were accepted if a root mean square error (RMSE) of less than 50% relative to healthy hCM was achieved for both action potential and calcium transient waveforms for the cell-treated HF cardiomyocyte, normalized to the untreated HF cardiomyocyte.

Results

Custom cells expressing only non-excitable ion channels were inadequate to restore a healthy cardiac phenotype when coupled to either fibrotic or non-fibrotic HF cardiomyocytes. In contrast, custom cells also expressing cardiac ion channels led to acceptable restoration of a healthy cardiomyocyte phenotype when coupled to fibrotic, but not non-fibrotic, HF cardiomyocytes. Incorporating the cardiomyocyte inward rectifier K⁺ channel was critical to accomplishing this phenotypic rescue while also improving single-cell action potential metrics associated with arrhythmias, namely resting membrane potential and action potential duration. The computational approach also provided insight into the rescue mechanisms, whereby heterocellular coupling enhanced cardiomyocyte L-type calcium current and promoted calcium-induced calcium release. Finally, as a therapeutically translatable strategy, we simulated delivery of hMSCs and hCICs genetically engineered to express the cardiomyocyte inward rectifier K⁺ channel, which decreased action potential and calcium transient RMSEs by at least 24% relative to control hMSCs and hCICs, with more favorable single-cell arrhythmia metrics.

Conclusion

Computational modeling facilitates exploration of customizable engineered cell therapies. Optimized cells expressing cardiac ion channels restored healthy action potential and calcium handling phenotypes in fibrotic HF cardiomyocytes and improved single-cell arrhythmia metrics, warranting further experimental validation studies of the proposed custom therapeutic cells.

In silico Cell Therapy Model Restores Failing Human Myocyte Electrophysiology and Calcium Cycling in Fibrotic Myocardium

Myocardial delivery of human c-kit+ cardiac interstitial cells (hCICs) and human mesenchymal stem cells (hMSCs), an emerging approach for treating the failing heart, has been limited by an incomplete understanding of the effects on host myocardium. This computational study aims to model hCIC and hMSC effects on electrophysiology and calcium cycling of healthy and diseased human cardiomyocytes (hCM), and reveals a possible cardiotherapeutic benefit independent of putative regeneration processes. First, we developed an original hCIC mathematical model with an electrical profile comprised of distinct experimentally identified ion currents. Next, we verified the model by confirming it is representative of published experiments on hCIC whole-cell electrophysiology and on hCIC co-cultures with rodent cardiomyocytes. We then used our model to compare electrophysiological effects of hCICs to other non-excitable cells, as well as clinically relevant hCIC-hMSC combination therapies and fused hCIC-hMSC CardioChimeras. Simulation of direct coupling of hCICs to healthy or failing hCMs through gap junctions led to greater increases in calcium cycling with lesser reductions in action potential duration (APD) compared with hMSCs. Combined coupling of hCICs and hMSCs to healthy or diseased hCMs led to intermediate effects on electrophysiology and calcium cycling compared to individually coupled hCICs or hMSCs. Fused hCIC-hMSC CardioChimeras decreased healthy and diseased hCM APD and calcium transient amplitude compared to individual or combined cell treatments. Finally, to provide a theoretical basis for optimizing cell-based therapies, we randomized populations of 2,500 models incorporating variable hMSC and hCIC interventions and simulated their effects on restoring diseased cardiomyocyte electrophysiology and calcium handling. The permutation simulation predicted the ability to correct abnormal properties of heart failure hCMs in fibrotic, but not non-fibrotic, myocardium. This permutation experiment also predicted paracrine signaling to be a necessary and sufficient mechanism for this correction, counteracting the fibrotic effects while also restoring arrhythmia-related metrics such as upstroke velocity and resting membrane potential. Altogether, our in silico findings suggest anti-fibrotic effects of paracrine signaling are critical to abrogating pathological cardiomyocyte electrophysiology and calcium cycling in fibrotic heart failure, and support further investigation of delivering an optimized cellular secretome as a potential strategy for improving heart failure therapy.

Pretreatment of cardiac progenitor cells with bradykinin attenuates H2O2-induced cell apoptosis and improves cardiac function in rats by regulating autophagy

Background

Previous studies have demonstrated that human cardiac c-Kit⁺ progenitor cells (hCPCs) can effectively improve ischemic heart disease. However, the major challenge in applying hCPCs to clinical therapy is the low survival rate of graft hCPCs in the host heart, which limited the benefit of transplanted hCPCs. Bradykinin (BK) is a principal active agent of the tissue kinin-kallikrein system. Our previous studies have highlighted that BK mediated the growth and migration of CPCs by regulating Ca²⁺ influx. However, the protective effect of BK on CPCs, improvement in the survival rate of BK-pretreated hCPCs in the infarcted heart, and the related mechanism remain elusive.

Methods

HCPCs were treated with H₂O₂ to induce cell apoptosis and autophagy, and different concentration of BK was applied to rescue the H₂O₂-induced injury detected by MTT assay, TUNEL staining, flow cytometry, western blotting, and mitoSOX assays. The role of autophagy in the anti-apoptotic effect of BK was chemically activated or inhibited using the autophagy inducer, rapamycin, or the inhibitor, 3-methyladenine (3-MA). To explore the protective effect of BK on hCPCs, 3-MA or BK-pretreated hCPCs were transplanted into the myocardial infarcted rats. An echocardiogram was used to determine cardiac function, H&E and Masson staining were employed to assess pathological characteristics, HLA gene expression was quantified by qRT-PCR, and immunostaining was applied to examine neovascularization using confocal microscopy.

Results

The in vitro results showed that BK suppressed H₂O₂-induced hCPCs apoptosis and ROS production in a concentration-dependent manner by promoting pAkt and Bcl-2 expression and reducing cleaved caspase 3 and Bax expression. Moreover, BK restrained the H₂O₂-induced cell autophagy by decreasing LC3II/I, Beclin1, and ATG5 expression and increasing P62 expression. In the in vivo experiment, the transplanted BK- or 3-MA-treated hCPCs were found to be more effectively improved cardiac function by decreasing cardiomyocyte apoptosis, inflammatory infiltration, and myocardial fibrosis, and promoting neovascularization in the infarcted heart, compared to untreated-hCPCs or c-kit^- cardiomyocytes (CPC^- cells).

Conclusions

Our present study established a new method to rescue transplanted hCPCs in the infarcted cardiac area via regulating cell apoptosis and autophagy of hCPCs by pretreatment with BK, providing a new therapeutic option for heart failure.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02503-6.

Chemotherapy-Induced Peripheral Neuropathy: Nursing Implications

Chemotherapy-induced peripheral neuropathy (CIPN) is an unsolved and potentially life-compromising problem for most patients receiving neurotoxic chemotherapy. It manifests with numbness, tingling, and possibly neuropathic pain and motor and autonomic symptoms. This review aims to provide an evidence synthesis that prepares nurses to comprehensively assess, provide supportive care for, and critically evaluate the literature on CIPN. The prevalence, significance, characteristics, mechanisms, and risk factors of CIPN will be discussed, as well as nursing-relevant evidence on the assessment, prevention, and management of CIPN. The importance of critical literature evaluation before clinical implementation to reduce physical and financial harms to patients will also be highlighted.

The anesthetic bupivacaine induces cardiotoxicity by targeting L-type voltage-dependent calcium channels

Objective

Bupivacaine is an amide local anesthetic with possible side effects that include an irregular heart rate. However, the mechanism of bupivacaine-induced cardiotoxicity has not been fully elucidated, thus we aimed to examine this mechanism.

Methods

We performed electrocardiogram recordings to detect action potential waveforms in Sprague Dawley rats after application of bupivacaine, while calcium (Ca²⁺) currents in neonatal rat ventricular cells were examined by patch clamp recording. Western blot and quantitative real-time polymerase chain reaction assays were used to detect the expression levels of targets of interest.

Results

In the present study, after application of bupivacaine, abnormal action potential waveforms were detected in Sprague Dawley rats by electrocardiogram recordings, while decreased Ca²⁺ currents were confirmed in neonatal rat ventricular cells by patch clamp recording. These alterations may be attributed to a deficiency of Ca_V1.3 (L-type) Ca²⁺ channels, which may be regulated by the multifunctional protein calreticulin.

Conclusions

The present study identifies a possible role of the calreticulin–Ca_V1.3 axis in bupivacaine-induced abnormal action potentials and Ca²⁺ currents, which may lead to a better understanding anesthetic drug-induced cardiotoxicity.

Metabolomics markers in Neurology: current knowledge and future perspectives for therapeutic targeting

INTRODUCTION

Metabolomics is an emerging approach providing new insights into the metabolic changes and underlying mechanisms involved in the pathogenesis of neurological disorders.

AREAS COVERED

Here, the authors present an overview of the current knowledge of metabolic profiling (metabolomics) to provide critical insight on the role of biochemical markers and metabolic alterations in neurological diseases.

EXPERT OPINION

Elucidation of characteristic metabolic alterations in neurological disorders is crucial for a better understanding of their pathogenesis, and for identifying potential biomarkers and drug targets. Nevertheless, discrepancies in diagnostic criteria, sample handling protocols, and analytical methods still affect the generalizability of current study results.

Wen-Luo-Tong Decoction Attenuates Paclitaxel-Induced Peripheral Neuropathy by Regulating Linoleic Acid and Glycerophospholipid Metabolism Pathways

Chemotherapy-induced peripheral neuropathy (CIPN) is a serious dose-limiting toxicity of many anti-neoplastic agents, especially paclitaxel, and oxaliplatin. Up to 62% of patients receiving paclitaxel regimens turn out to develop CIPN. Unfortunately, there are so few agents proved effective for prevention or management of CIPN. The reason for the current situation is that the mechanisms of CIPN are still not explicit. Traditional Chinese Medicine (TCM) has unique advantages for dealing with complex diseases. Wen-Luo-Tong (WLT) is a TCM ointment for topical application. It has been applied for prevention and management of CIPN clinically for more than 10 years. Previous animal experiments and clinical studies had manifested the availability of WLT. However, due to the unclear mechanisms of WLT, further transformation has been restricted. To investigate the therapeutic mechanisms of WLT, a metabolomic method on the basis of UPLC- MS was developed in this study. Multivariate analysis techniques, such as principal component analysis (PCA) and partial least squares discriminate analysis (PLS-DA), were applied to observe the disturbance in the metabolic state of the paclitaxel-induced peripheral neuropathy (PIPN) rat model, as well as the recovering tendency of WLT treatment. A total of 19 significant variations associated with PIPN were identified as biomarkers. Results of pathway analysis indicated that the metabolic disturbance of pathways of linoleic acid (LA) metabolism and glycerophospholipid metabolism. WLT attenuated mechanical allodynia and rebalanced the metabolic disturbances of PIPN by primarily regulating LA and glycerophospholipid metabolism pathway. Further molecular docking analysis showed some ingredients of WLT, such as hydroxysafflor yellow A (HSYA), icariin, epimedin B and 4-dihydroxybenzoic acid (DHBA), had high affinity to plenty of proteins within these two pathways.

Bradykinin-mediated Ca2+ signalling regulates cell growth and mobility in human cardiac c-Kit+ progenitor cells

Our recent study showed that bradykinin increases cell cycling progression and migration of human cardiac c‐Kit⁺ progenitor cells by activating pAkt and pERK1/2 signals. This study investigated whether bradykinin‐mediated Ca²⁺ signalling participates in regulating cellular functions in cultured human cardiac c‐Kit⁺ progenitor cells using laser scanning confocal microscopy and biochemical approaches. It was found that bradykinin increased cytosolic free Ca²⁺ (Cai2+) by triggering a transient Ca²⁺ release from ER IP3Rs followed by sustained Ca²⁺ influx through store‐operated Ca²⁺ entry (SOCE) channel. Blockade of B2 receptor with HOE140 or IP3Rs with araguspongin B or silencing IP3R3 with siRNA abolished both Ca²⁺ release and Ca²⁺ influx. It is interesting to note that the bradykinin‐induced cell cycle progression and migration were not observed in cells with siRNA‐silenced IP3R3 or the SOCE component TRPC1, Orai1 or STIM1. Also the bradykinin‐induced increase in pAkt and pERK1/2 as well as cyclin D1 was reduced in these cells. These results demonstrate for the first time that bradykinin‐mediated increase in free Cai2+ via ER‐IP3R3 Ca²⁺ release followed by Ca²⁺ influx through SOCE channel plays a crucial role in regulating cell growth and migration via activating pAkt, pERK1/2 and cyclin D1 in human cardiac c‐Kit⁺ progenitor cells.

Calcium-dependent potassium channels control proliferation of cardiac progenitor cells and bone marrow-derived mesenchymal stem cells

KEY POINTS

Ex vivo proliferated c-Kit⁺ endogenous cardiac progenitor cells (eCPCs) obtained from mouse and human cardiac tissues have been reported to express a wide range of functional ion channels. In contrast to previous reports in cultured c-Kit⁺ eCPCs, we found that ion currents were minimal in freshly isolated cells. However, inclusion of free Ca²⁺ intracellularly revealed a prominent inwardly rectifying current identified as the intermediate conductance Ca²⁺ -activated K⁺ current (KCa3.1) Electrical function of both c-Kit⁺ eCPCs and bone marrow-derived mesenchymal stem cells is critically governed by KCa3.1 calcium-dependent potassium channels. Ca²⁺ -induced increases in KCa3.1 conductance are necessary to optimize membrane potential during Ca²⁺ entry. Membrane hyperpolarization due to KCa3.1 activation maintains the driving force for Ca²⁺ entry that activates stem cell proliferation. Cardiac disease downregulates KCa3.1 channels in resident cardiac progenitor cells. Alterations in KCa3.1 may have pathophysiological and therapeutic significance in regenerative medicine.

ABSTRACT

Endogenous c-Kit⁺ cardiac progenitor cells (eCPCs) and bone marrow (BM)-derived mesenchymal stem cells (MSCs) are being developed for cardiac regenerative therapy, but a better understanding of their physiology is needed. Here, we addressed the unknown functional role of ion channels in freshly isolated eCPCs and expanded BM-MSCs using patch-clamp, microfluorometry and confocal microscopy. Isolated c-Kit⁺ eCPCs were purified from dog hearts by immunomagnetic selection. Ion currents were barely detectable in freshly isolated c-Kit⁺ eCPCs with buffering of intracellular calcium (Ca²⁺_i ). Under conditions allowing free intracellular Ca²⁺ , freshly isolated c-Kit⁺ eCPCs and ex vivo proliferated BM-MSCs showed prominent voltage-independent conductances that were sensitive to intermediate-conductance K⁺ -channel (KCa3.1 current, I_KCa3.1 ) blockers and corresponding gene (KCNN4)-expression knockdown. Depletion of Ca²⁺_i induced membrane-potential (V_mem ) depolarization, while store-operated Ca²⁺ entry (SOCE) hyperpolarized V_mem in both cell types. The hyperpolarizing SOCE effect was substantially reduced by I_KCa3.1 or SOCE blockade (TRAM-34, 2-APB), and I_KCa3.1 blockade (TRAM-34) or KCNN4-knockdown decreased the Ca²⁺ entry resulting from SOCE. I_KCa3.1 suppression reduced c-Kit⁺ eCPC and BM-MSC proliferation, while significantly altering the profile of cyclin expression. I_KCa3.1 was reduced in c-Kit⁺ eCPCs isolated from dogs with congestive heart failure (CHF), along with corresponding KCNN4 mRNA. Under perforated-patch conditions to maintain physiological [Ca²⁺ ]_i , c-Kit⁺ eCPCs from CHF dogs had less negative resting membrane potentials (-58 ± 7 mV) versus c-Kit⁺ eCPCs from control dogs (-73 ± 3 mV, P < 0.05), along with slower proliferation. Our study suggests that Ca²⁺ -induced increases in I_KCa3.1 are necessary to optimize membrane potential during the Ca²⁺ entry that activates progenitor cell proliferation, and that alterations in KCa3.1 may have pathophysiological and therapeutic significance in regenerative medicine.

Qualitative and Quantitative Analysis of Cardiac Progenitor Cells in Cases of Myocarditis and Cardiomyopathy

We aimed to identify and quantify CD117⁺ and CD90⁺ endogenous cardiac progenitor cells (CPC) in human healthy and diseased hearts. We hypothesize that these cells perform a locally acting, contributing function in overcoming medical conditions of the heart by endogenous means. Human myocardium biopsies were obtained from 23 patients with the following diagnoses: Dilatative cardiomyopathy (DCM), ischemic cardiomyopathy (ICM), myocarditis, and controls from healthy cardiac patients. High-resolution scanning microscopy of the whole slide enabled a computer-based immunohistochemical quantification of CD117 and CD90. Those signals were evaluated by Definiens Tissue Phenomics® Technology. Co-localization of CD117 and CD90 was determined by analyzing comparable serial sections. CD117⁺/CD90⁺ cardiac cells were detected in all biopsies. The highest expression of CD90 was revealed in the myocarditis group. CD117 was significantly higher in all patient groups, compared to healthy specimens (^*p < 0.05). The highest co-expression was found in the myocarditis group (6.75 ± 3.25 CD90⁺CD117⁺ cells/mm²) followed by ICM (4 ± 1.89 cells/mm²), DCM (1.67 ± 0.58 cells/mm²), and healthy specimens (1 ± 0.43 cells/mm²). We conclude that the human heart comprises a fraction of local CD117⁺ and CD90⁺ cells. We hypothesize that these cells are part of local endogenous progenitor cells due to the co-expression of CD90 and CD117. With novel digital image analysis technologies, a quantification of the CD117 and CD90 signals is available. Our experiments reveal an increase of CD117 and CD90 in patients with myocarditis.

Preferential myofibroblast differentiation of cardiac mesenchymal progenitor cells in the presence of atrial fibrillation

Atrial fibrillation (AF) is characterized by electrical, contractile, and structural remodeling mediated by interstitial fibrosis. It has been shown that human cardiac mesenchymal progenitor cells (CMPCs) can be differentiated into endothelial, smooth muscle, and fibroblast cells. Here, we have investigated, for the first time, the contribution of CMPCs in the fibrotic process occurring in AF. As expected, right auricolae samples displayed significantly higher fibrosis in AF vs control (CTR) patients. In tissue samples of AF patients only, double staining for c-kit and the myofibroblast marker α-smooth muscle actin (α-SMA) was detected. The number of c-kit-positive CMPC was higher in atrial subepicardial regions of CTR than AF cells. AF-derived CMPC (AF-CMPC) and CTR-derived CMPC (Ctr-CMPC) were phenotypically similar, except for CD90 and c-kit, which were significantly more present in AF and CTR cells, respectively. Moreover, AF showed a lower rate of population doubling and fold enrichment vs Ctr-CMPC. When exogenously challenged with the profibrotic transforming growth factor-β1 (TGF-β1), AF-CMPC showed a significantly higher nuclear translocation of SMAD2 than Ctr-CMPC. In addition, TGF-β1 treatment induced the upregulation of COL1A1 and COL1A2 in AF-CMPC only. Further, both a marked production of soluble collagen and α-SMA upregulation have been observed in AF-CMPC only. Finally, electrophysiological studies showed that the inwardly rectifying potassium current (I_K1) was evenly present in AF- and Ctr-CMPC in basal conditions and similarly disappeared after TGF-β1 exposure. All together, these data suggest that AF steers the resident atrial CMPC compartment toward an electrically inert profibrotic phenotype.

Functional BKCa channel in human resident cardiac stem cells expressing W8B2

Recently, a new population of resident cardiac stem cells (CSCs) positive for the W8B2 marker has been identified. These CSCs are considered to be an ideal cellular source to repair myocardial damage after infarction. However, the electrophysiological profile of these cells has not been characterized yet. We first establish the conditions of isolation and expansion of W8B2⁺ CSCs from human heart biopsies using a magnetic sorting system followed by flow cytometry cell sorting. These cells display a spindle-shaped morphology, are highly proliferative, and possess self-renewal capacity demonstrated by their ability to form colonies. Besides, W8B2⁺ CSCs are positive for mesenchymal markers but negative for hematopoietic and endothelial ones. RT-qPCR and immunostaining experiments show that W8B2⁺ CSCs express some early cardiac-specific transcription factors but lack the expression of cardiac-specific structural genes. Using patch clamp in the whole-cell configuration, we show for the first time the electrophysiological signature of BKCa current in these cells. Accordingly, RT-PCR and western blotting analysis confirmed the presence of BKCa at both mRNA and protein levels in W8B2⁺ CSCs. Interestingly, BKCa channel inhibition by paxilline decreased cell proliferation in a concentration-dependent manner and halted cell cycle progression at the G0/G1 phase. The inhibition of BKCa also decreased the self-renewal capacity but did not affect migration of W8B2⁺ CSCs. Taken together, our results are consistent with an important role of BKCa channels in cell cycle progression and self-renewal in human cardiac stem cells.

Bradykinin regulates cell growth and migration in cultured human cardiac c-Kit+ progenitor cells

Bradykinin is a well-known endogenous vasoactive peptide. The present study investigated the bradykinin receptor expression in human cardiac c-Kit⁺ progenitor cells and the potential role of bradykinin in regulating cell cycling progression and mobility. It was found that mRNA and protein of bradykinin type 2 receptors, but not bradykinin type 1 receptors, were abundant in cultured human cardiac c-Kit⁺ progenitor cells. Bradykinin (1-10 nM) stimulated cell growth and migration in a concentration-dependent manner. The increase of cell proliferation was related to promoting G0/G1 transition into G2/M and S phase. Western blots revealed that bradykinin significantly increased pAkt and pERK1/2 as well as cyclin D1, which were countered by HOE140 (an antagonist of bradykinin type 2 receptors) or by silencing bradykinin type 2 receptors. The increase of pAkt, pERK1/2 and cyclin D1 by bradykinin was prevented by the PI3K inhibitor Ly294002, the PLC inhibitors U73122 and neomycin, and/or the PKC inhibitor chelerythrine and the MAPK inhibitor PD98059. Our results demonstrate the novel information that bradykinin promotes cell cycling progression and migration in human cardiac c-Kit⁺ progenitor cells via activating PI3K, PLC, PKC, cyclin D1, pERK1/2, and pAkt.

Functional TRPV2 and TRPV4 channels in human cardiac c-kit(+) progenitor cells

The cellular physiology and biology of human cardiac c-kit(+) progenitor cells has not been extensively characterized and remains an area of active research. This study investigates the functional expression of transient receptor potential vanilloid (TRPV) and possible roles for this ion channel in regulating proliferation and migration of human cardiac c-kit(+) progenitor cells. We found that genes coding for TRPV2 and TRPV4 channels and their proteins are significantly expressed in human c-kit(+) cardiac stem cells. Probenecid, an activator of TRPV2, induced an increase in intracellular Ca(2+) (Ca(2+) i ), an effect that may be attenuated or abolished by the TRPV2 blocker ruthenium red. The TRPV4 channel activator 4α-phorbol 12-13-dicaprinate induced Ca(2+) i oscillations, which can be inhibited by the TRPV4 blocker RN-1734. The alteration of Ca(2+) i by probenecid or 4α-phorbol 12-13-dicprinate was dramatically inhibited in cells infected with TRPV2 short hairpin RNA (shRNA) or TRPV4 shRNA. Silencing TRPV2, but not TRPV4, significantly reduced cell proliferation by arresting cells at the G0/G1 boundary of the cell cycle. Cell migration was reduced by silencing TRPV2 or TRPV4. Western blot revealed that silencing TRPV2 decreased expression of cyclin D1, cyclin E, pERK1/2 and pAkt, whereas silencing TRPV4 only reduced pAkt expression. Our results demonstrate for the first time that functional TRPV2 and TRPV4 channels are abundantly expressed in human cardiac c-kit(+) progenitor cells. TRPV2 channels, but not TRPV4 channels, participate in regulating cell cycle progression; moreover, both TRPV2 and TRPV4 are involved in migration of human cardiac c-kit(+) progenitor cells.

Chemotherapy-induced peripheral neurotoxicity and complementary and alternative medicines: progress and perspective

Chemotherapy-induced peripheral neurotoxicity (CIPN) is a severe and dose-limiting side effect of antineoplastic drugs. It can cause sensory, motor and autonomic system dysfunction, and ultimately force patients to discontinue chemotherapy. Until now, little is understood about CIPN and no consistent caring standard is available. Since CIPN is a multifactorial disease, the clinical efficacy of single pharmacological drugs is disappointing, prompting patients to seek alternative treatment options. Complementary and alternative medicines (CAMs), especially herbal medicines, are well known for their multifaceted implications and widely used in human health care. Up to date, several phytochemicals, plant extractions, and herbal formulas have been evaluated for their potential therapeutic benefit of preventing the onset and progression of CIPN in experimental models. Clinical acupuncture has also been shown to improve CIPN symptoms. In this review, we will give an outline of our current knowledge regrading the advanced research of CIPN, the role of CAMs in alleviating CIPN and possible lacunae in research that needs to be addressed.

Roles of store-operated Ca2+ channels in regulating cell cycling and migration of human cardiac c-kit+ progenitor cells

Cardiac c-kit(+) progenitor cells are important for maintaining cardiac homeostasis and can potentially contribute to myocardial repair. However, cellular physiology of human cardiac c-kit(+) progenitor cells is not well understood. The present study investigates the functional store-operated Ca(2+) entry (SOCE) channels and the potential role in regulating cell cycling and migration using confocal microscopy, RT-PCR, Western blot, coimmunoprecipitation, cell proliferation, and migration assays. We found that SOCE channels mediated Ca(2+) influx, and TRPC1, STIM1, and Orai1 were involved in the formation of SOCE channels in human cardiac c-kit(+) progenitor cells. Silencing TRPC1, STIM1, or Orai1 with the corresponding siRNA significantly reduced the Ca(2+) signaling through SOCE channels, decreased cell proliferation and migration, and reduced expression of cyclin D1, cyclin E, and/or p-Akt. Our results demonstrate the novel information that Ca(2+) signaling through SOCE channels regulates cell cycling and migration via activating cyclin D1, cyclin E, and/or p-Akt in human cardiac c-kit(+) cells.

Effects of BKCa and Kir2.1 Channels on Cell Cycling Progression and Migration in Human Cardiac c-kit+ Progenitor Cells

Our previous study demonstrated that a large-conductance Ca2+-activated K+ current (BKCa), a voltage-gated TTX-sensitive sodium current (INa.TTX), and an inward rectifier K+ current (IKir) were heterogeneously present in most of human cardiac c-kit+ progenitor cells. The present study was designed to investigate the effects of these ion channels on cell cycling progression and migration of human cardiac c-kit+ progenitor cells with approaches of cell proliferation and mobility assays, siRNA, RT-PCR, Western blots, flow cytometry analysis, etc. It was found that inhibition of BKCa with paxilline, but not INa.TTX with tetrodotoxin, decreased both cell proliferation and migration. Inhibition of IKir with Ba2+ had no effect on cell proliferation, while enhanced cell mobility. Silencing KCa.1.1 reduced cell proliferation by accumulating the cells at G0/G1 phase and decreased cell mobility. Interestingly, silencing Kir2.1 increased the cell migration without affecting cell cycling progression. These results demonstrate the novel information that blockade or silence of BKCa channels, but not INa.TTX channels, decreases cell cycling progression and mobility, whereas inhibition of Kir2.1 channels increases cell mobility without affecting cell cycling progression in human cardiac c-kit+ progenitor cells.

c-kit(+) cells: the tell-tale heart of cardiac regeneration?

Cardiovascular disease is the leading cause of morbidity and mortality in the developed world. Although ongoing therapeutic strategies ameliorate symptoms and prolong life for patients with cardiovascular diseases, they do not solve the critical issue related to the loss of cardiac tissue. Accordingly, stem/progenitor cell therapy has emerged as a paramount approach for cardiac repair and regeneration. In this regard, c-kit(+) cells have animated much interest and controversy. These cells are self-renewing, clonogenic, and multipotent and display a noteworthy potential to differentiate into all cardiovascular lineages. However, their functional contribution to cardiomyocyte turnover is one of the centrally debated issues concerning their regenerative potential. Regardless, plentiful preclinical and clinical studies have been conducted which provide evidence for the capacity of c-kit(+) cells to improve cardiac function. The purpose of this review is to give a comprehensive, impartial, critical description and evaluation of the literature on c-kit(+) cells from bench to bedside in order to address their true potential, benefits and controversies.

Chemotherapy-induced peripheral neuropathy: What do we know about mechanisms?

Cisplatin, oxaliplatin, paclitaxel, vincristine and bortezomib are some of the most effective drugs successfully employed (alone or in combinations) as first-line treatment for common cancers. However they often caused severe peripheral neurotoxicity and neuropathic pain. Structural deficits in Dorsal Root Ganglia and sensory nerves caused symptoms as sensory loss, paresthesia, dysaesthesia and numbness that result in patient' suffering and also limit the life-saving therapy. Several scientists have explored the various mechanisms involved in the onset of chemotherapy-related peripheral neurotoxicity identifying molecular targets useful for the development of selected neuroprotective strategies. Dorsal Root Ganglia sensory neurons, satellite cells, Schwann cells, as well as neuronal and glial cells in the spinal cord, are the preferential sites in which chemotherapy neurotoxicity occurs. DNA damage, alterations in cellular system repairs, mitochondria changes, increased intracellular reactive oxygen species, alterations in ion channels, glutamate signalling, MAP-kinases and nociceptors ectopic activation are among the events that trigger the onset of peripheral neurotoxicity and neuropathic pain. In the present work we review the role of the main players in determining the pathogenesis of anticancer drugs-induced peripheral neuropathy.