Comparison of the incidence of depression before and after endovascular treatment in patients with lower limb peripheral artery disease.

Depression is a chronic illness that affects mood, physical health, and overall vitality and quality of life. Depression has been associated with an increased risk of all-cause and cardiovascular mortality among patients with peripheral arterial disease (PAD). Therefore, this study aimed to compare the incidence of depression before and after endovascular treatment in patients with lower limb PAD. This is an important clinical issue considering the worldwide increase in PAD with the aging population and the known negative impact of depression on recovery. This was a retrospective sub-analysis of data from the Tokyo Peripheral Vascular Intervention Study using the TOMA-CODE registry. The presence and extent of depressive symptoms were evaluated using the patient health questionnaire (PHQ-9), with a depressive tendency score of ≥ 5. The PHQ-9 score was evaluated before endovascular treatment (EVT) and at 4 (± 1) weeks after EVT. The study population consisted of 87 patients who completed the PHQ-9 before EVT, with 76 completing the post-EVT PHQ-9. Of these 76, 19 had a pre-EVT score ≥ 5. Overall, there was no difference in the pre- and post-EVT scores (P = 0.091). There was no significant change in the 19 patients with a pre-EVT score ≥ 5 (mean 9.2 ± 4.4); however, there was a tendency to improve in the pre- to post-EVT score (mean, 6.9 ± 5.2; P = 0.059). Diabetes was a significant negative factor for pre- to post-EVT score improvement (P = 0.023). Overall, symptoms of depression showed the tendency to improve at 30 days post-EVT. However, diabetes was associated with lower improvement in symptoms.

Effects of methylglyoxal on human cardiac fibroblast: roles of transient receptor potential ankyrin 1 (TRPA1) channels.

Cardiac fibroblasts contribute to the pathogenesis of cardiac remodeling. Methylglyoxal (MG) is an endogenous carbonyl compound produced under hyperglycemic conditions, which may play a role in the development of pathophysiological conditions including diabetic cardiomyopathy. However, the mechanism by which this occurs and the molecular targets of MG are unclear. We investigated the effects of MG on Ca(2+) signals, its underlying mechanism, and cell cycle progression/cell differentiation in human cardiac fibroblasts. The conventional and quantitative real-time RT-PCR, Western blot, immunocytochemical analysis, and intracellular Ca(2+) concentration [Ca(2+)]i measurement were applied. Cell cycle progression was assessed using the fluorescence activated cell sorting. MG induced Ca(2+) entry concentration dependently. Ruthenium red (RR), a general cation channel blocker, and HC030031, a selective transient receptor potential ankyrin 1 (TRPA1) antagonist, inhibited MG-induced Ca(2+) entry. Treatment with aminoguanidine, a MG scavenger, also inhibited it. Allyl isothiocyanate, a selective TRPA1 agonist, increased Ca(2+) entry. The use of small interfering RNA to knock down TRPA1 reduced the MG-induced Ca(2+) entry as well as TRPA1 mRNA expression. The quantitative real-time RT-PCR analysis showed the prominent existence of TRPA1 mRNA. Expression of TRPA1 protein was confirmed by Western blotting and immunocytochemical analyses. MG promoted cell cycle progression from G0/G1 to S/G2/M, which was suppressed by HC030031 or RR. MG also enhanced α-smooth muscle actin expression. The present results suggest that methylglyoxal activates TRPA1 and promotes cell cycle progression and differentiation in human cardiac fibroblasts. MG might participate the development of pathophysiological conditions including diabetic cardiomyopathy via activation of TRPA1.

Nongenetic method for purifying stem cell-derived cardiomyocytes.

Several applications of pluripotent stem cell (PSC)-derived cardiomyocytes require elimination of undifferentiated cells. A major limitation for cardiomyocyte purification is the lack of easy and specific cell marking techniques. We found that a fluorescent dye that labels mitochondria, tetramethylrhodamine methyl ester perchlorate, could be used to selectively mark embryonic and neonatal rat cardiomyocytes, as well as mouse, marmoset and human PSC-derived cardiomyocytes, and that the cells could subsequently be enriched (>99% purity) by fluorescence-activated cell sorting. Purified cardiomyocytes transplanted into testes did not induce teratoma formation. Moreover, aggregate formation of PSC-derived cardiomyocytes through homophilic cell-cell adhesion improved their survival in the immunodeficient mouse heart. Our approaches will aid in the future success of using PSC-derived cardiomyocytes for basic and clinical applications.

Wnt2 accelerates cardiac myocyte differentiation from ES-cell derived mesodermal cells via non-canonical pathway.

The efficient induction of cardiomyocyte differentiation from embryonic stem (ES) cells is crucial for cardiac regenerative medicine. Although Wnts play important roles in cardiac development, complex questions remain as to when, how and what types of Wnts are involved in cardiogenesis. We found that Wnt2 was strongly up-regulated during cardiomyocyte differentiation from ES cells. Therefore, we investigated when and how Wnt2 acts in cardiogenesis during ES cell differentiation. Wnt2 was strongly expressed in the early developing murine heart. We applied this embryonic Wnt2 expression pattern to ES cell differentiation, to elucidate Wnt2 function in cardiomyocyte differentiation. Wnt2 knockdown revealed that intrinsic Wnt2 was essential for efficient cardiomyocyte differentiation from ES cells. Moreover, exogenous Wnt2 increased cardiomyocyte differentiation from ES cells. Interestingly, the effects on cardiogenesis of intrinsic Wnt2 knockdown and exogenous Wnt2 addition were temporally restricted. During cardiomyocyte differentiation from ES cells, Wnt2 didn't activate canonical Wnt pathway but utilizes JNK/AP-1 pathway which is required for cardiomyocyte differentiation from ES cells. Therefore we conclude that Wnt2 plays strong positive stage-specific role in cardiogenesis through non-canonical Wnt pathway in murine ES cells.

Proportion of flat- and depressed-type and laterally spreading tumor among advanced colorectal neoplasia.

BACKGROUND & AIMS: Flat- and depressed-type neoplasias along with laterally spreading tumors (LSTs) have been reported in colorectal neoplasias. We estimated the prevalence of flat and depressed types and LSTs along with their proportion among advanced neoplasias in a large average-risk population undergoing screening colonoscopy. METHODS: This was a cross-sectional study performed at a single, general community institution, with subjects who were 40 to 79 years old, asymptomatic, and who had undergone their first colonoscopy for screening between 2003 and 2009 (n = 4910). Among the neoplasias detected, advanced neoplasias were morphologically classified as the polypoid type, flat and depressed type, or LST. We determined the prevalence and proportion for each type among the advanced neoplasias, with morphologies defined according to the Japanese endoscopic classification. RESULTS: Advanced neoplasias were detected in 7.9% of men, 4.7% of women, and 6.1% of overall subjects. The polypoid type, the flat and depressed types, and the LSTs accounted for 75.3%, 7.5%, and 17.2% of advanced neoplasia, respectively. There was a high proportion of T1 cancers among the depressed types (40%). Approximately 80% of LSTs were located on the right side of the colon and more than 30% of LSTs showed high-grade dysplasia or T1 cancer. CONCLUSIONS: Most advanced neoplasias detected were of the polypoid type. LSTs accounted for a considerable proportion among advanced neoplasia and tended to be located on the right side of the colon. The influences of any LSTs need to be taken into consideration for preventing colorectal cancer.

Maternal-effect gene Ces5/Ooep/Moep19/Floped is essential for oocyte cytoplasmic lattice formation and embryonic development at the maternal-zygotic stage transition.

In a search for genes specifically expressed in mouse embryonic stem cells, we identified one we called Ces5. We found that it corresponded to the Ooep gene, which was recently reported to be expressed specifically in oocytes. Mouse Ces5/Ooep, also called Moep19 or Floped, encoded a 164-amino acid protein, which was detected in the cytoplasm of developing and mature oocytes and in embryos throughout the preimplantation period. To examine its function, we carried out targeted disruption of this gene. The Ces5/Ooep-null mice were grossly normal, but the females were infertile. Although the ovaries and ovulation appeared normal, the embryos from Ces5/Ooep-null females mated with wild-type males showed developmental arrest at the two- or four-cell stage. In addition, their first cleavage was considerably delayed and often asymmetrical. Thus, Ces5/Ooep is a maternal-effect gene. By electron microscopy, we found that the eggs from Ces5/Ooep-null females lacked oocyte cytoplasmic lattices (CPLs), which have long been predicted to function as a storage form for components that are maternally contributed to the early embryo. Further analysis showed that CES5/OOEP was directly associated with the CPLs. These results indicate that CES5/OOEP is an essential component of the CPLs and is required for embryonic development at the maternal-zygotic stage transition.

Effects of serum amyloid a and lysophosphatidylcholine on intracellular calcium concentration in human coronary artery smooth muscle cells.

Serum amyloid A (SAA), an acute-phase protein, and lysophosphatidylcholine (LPC), an oxidized LDL component, contribute to the physiological processes of atherosclerosis and cardiovascular disease. However, the effects of SAA/LPC on human coronary artery smooth muscle cells (hCASMCs) have not been fully investigated. Therefore, we examined the effects of SAA/LPC on Ca(2+)/Mg(2+) mobilization and its underlying mechanisms in hCASMCs. Intracellular Ca(2+)/Mg(2+) concentration ([Ca(2+)](i) / [Mg(2+)](i)) was measured with fura-2 AM/mag-fura-2 AM. Conventional RT-PCR analysis was also performed. Both SAA and LPC increased [Ca(2+)](i) by Ca(2+) entry. The SAA-induced Ca(2+) entry was inhibited by Gd(3+), SKF96365, and 2-aminoethoxydiphenyl borate (2-APB), a nonselective transient receptor potential (TRP) channel blocker, but not nifedipine. The LPC-induced Ca(2+) entry was blocked by Gd(3+), but not nifedipine, SKF96365 and 2-APB. U-73122 and PTX prevented the activation of SAA-, but not LPC-induced Ca(2+) influx. LPC, but not SAA, increased [Mg(2+)](i) as well as [Ca(2+)](i). The RT-PCR analysis revealed the expression of TRPC1/4, TRPV1/2/4, and TRPM7/8 mRNA. These results suggest that SAA/LPC activate Ca(2+) influx in hCASMCs; SAA activates it via PTX-sensitive G-protein, PLC and TRPC pathways, while LPC activates it independently of these pathways, where TRPM7 may be partly involved. Thus, TRP protein appears to be a target molecule of Ca(2+) signaling in hCASMCs elicited by SAA/LPC, which may play roles in coronary muscle dysfunction under pathophysiological and inflammatory conditions such as atherosclerosis.

Involvement of CaV3.1 T-type calcium channels in cell proliferation in mouse preadipocytes.

Voltage-gated Ca(2+) channels (Ca(V)) are ubiquitously expressed in various cell types and play vital roles in regulation of cellular functions including proliferation. However, the molecular identities and function of Ca(V) remained unexplored in preadipocytes. Therefore, whole cell voltage-clamp technique, conventional/quantitative real-time RT-PCR, Western blot, small interfering RNA (siRNA) experiments, and immunohistochemical analysis were applied in mouse primary cultured preadipocytes as well as mouse 3T3-L1 preadipocytes. The effects of Ca(V) blockers on cell proliferation and cell cycle were also investigated. Whole cell recordings of 3T3-L1 preadipocytes showed low-threshold Ca(V), which could be inhibited by mibefradil, Ni(2+) (IC(50) of 200 muM), and NNC55-0396. Dominant expression of alpha(1G) mRNA was detected among Ca(V) transcripts (alpha(1A)-alpha(1I)), supported by expression of Ca(V)3.1 protein encoded by alpha(1G) gene, with immunohistochemical studies and Western blot analysis. siRNA targeted for alpha(1G) markedly inhibited Ca(V). Dominant expression of alpha(1G) mRNA and expression of Ca(V)3.1 protein were also observed in mouse primary cultured preadipocytes. Expression level of alpha(1G) mRNA and Ca(V)3.1 protein significantly decreased in differentiated adipocytes. Mibefradil, NNC55-0396, a selective T-type Ca(V) blocker, but not diltiazem, inhibited cell proliferation in response to serum. NNC55-0396 and siRNA targeted for alpha(1G) also prevented cell cycle entry/progression. The present study demonstrates that the Ca(V)3.1 T-type Ca(2+) channel encoded by alpha(1G) subtype is the dominant Ca(V) in mouse preadipocytes and may play a role in regulating preadipocyte proliferation, a key step in adipose tissue development.

Anomalous origin of the coronary artery coursing between the great vessels presenting with a cardiovascular event (J-CONOMALY Registry).

AIMS: Anomalous origin of the coronary artery (AOCA) with an inter-arterial course (IAC) between the great vessels poses a risk for a life-threatening cardiovascular event. We assessed, in a registry-based study, the clinical features, treatment strategies, and prognoses of life-threatening cardiovascular events ensuant to AOCA. METHODS AND RESULTS: Included were 65 AOCA patients (48 men/17 women, aged 41 ± 23 years) from 40 clinical centres who had experienced sudden cardiac arrest (SCA) (n = 30), acute myocardial infarction (AMI) (n = 5), angina (n = 23), or syncope (n = 7). The anomalous vessel was the right coronary artery in 72% of patients and left coronary artery in 28%; the ostium was slit-like in 42%. Coronary luminal narrowing ≥75% was absent in patients with SCA or syncope (86% and 57%, respectively), but occlusion or narrowing was seen in those with AMI (100%) or angina (52%). Age ≤40 years, male sex, sporting activity, absence of prodromal symptoms, acutely angled (≤30°) take-off from the aorta, and absence of luminal narrowing of the IAC segment were associated with SCA in this patient group. Coronary vasospasm was inducible in 12 of 17 patients without coronary narrowing. Management included surgical revascularization (n = 26) percutaneous coronary intervention (n = 9), and medical treatment (n = 26). Four SCA patients died while hospitalized; no others died during the median 5.0 (range, 1.8-7.0)-year follow-up period. CONCLUSIONS: In patients with AOCA, age ≤40 years, male sex, sporting activity, and an acute take-off angle appear to be risk factors for SCA. Appropriate management can be beneficial. Confirmation in a large-scale study is warranted.

In vitro pharmacologic testing using human induced pluripotent stem cell-derived cardiomyocytes.

The lethal ventricular arrhythmia Torsade de pointes (TdP) is the most common reason for the withdrawal or restricted use of many cardiovascular and non-cardiovascular drugs. The lack of an in vitro model to detect pro-arrhythmic effects on human heart cells hinders the development of new drugs. We hypothesized that recently established human induced pluripotent stem (hiPS) cells could be used in an in vitro drug screening model. In this study, hiPS cells were driven to differentiate into functional cardiomyocytes, which expressed cardiac markers including Nkx2.5, GATA4, and atrial natriuretic peptide. The hiPS-derived cardiomyocytes (hiPS-CMs) were analyzed using a multi electrode assay. The application of ion channel inhibitors resulted in dose-dependent changes to the field potential waveform, and these changes were identical to those induced in the native cardiomyocytes. This study shows that hiPS-CMs represent a promising in vitro model for cardiac electrophysiologic studies and drug screening.

Transient inhibition of BMP signaling by Noggin induces cardiomyocyte differentiation of mouse embryonic stem cells.

Embryonic stem (ES) cells are a promising source of cardiomyocytes, but clinical application of ES cells has been hindered by the lack of reliable selective differentiation methods. Differentiation into any lineage is partly dependent on the regulatory mechanisms of normal early development. Although several signals, including bone morphogenetic protein (BMP), Wnt and FGF, are involved in heart development, scarce evidence is available about the exact signals that mediate cardiomyocyte differentiation. While investigating the involvement of BMP signaling in early heart formation in the mouse, we found that the BMP antagonist Noggin is transiently but strongly expressed in the heart-forming region during gastrulation and acts at the level of induction of mesendoderm to establish conditions conducive to cardiogenesis. We applied this finding to develop an effective protocol for obtaining cardiomyocytes from mouse ES cells by inhibition of BMP signaling.

Immunoglobulin G4-related Coronary Periarteritis and Luminal Stenosis in a Patient with a History of Autoimmune Pancreatitis.

Immunoglobulin G4 (IgG4)-related disease is a systemic inflammatory disorder that was first described in patients with autoimmune pancreatitis. Although IgG4-related disease is thought to involve the cardiovascular system, case reports describing coronary artery involvement are relatively rare. We describe a patient who was previously diagnosed with autoimmune pancreatitis and found to have coronary periarteritis and luminal narrowing. After the initiation of steroid treatment, the patient's coronary periarteritis and luminal stenosis were both ameliorated with an improvement in the serum IgG4 concentration. The present findings collectively suggest that IgG4-related immuno-inflammation may have a role in the development of coronary periarteritis and luminal atherosclerosis.

Impact of the distance from the stent edge to the residual plaque on edge restenosis following everolimus-eluting stent implantation.

OBJECTIVES: This study aimed to assess the relation between stent edge restenosis (SER) and the distance from the stent edge to the residual plaque using quantitative intravascular ultrasound. BACKGROUND: Although percutaneous coronary intervention with drug-eluting stents has improved SER rates, determining an appropriate stent edge landing zone can be challenging in cases of diffuse plaque lesions. It is known that edge vascular response can occur within 2 mm from the edge of a bare metal stent, but the distance to the adjacent plaque has not been evaluated for drug-eluting stents. METHODS: A total of 97 proximal residual plaque lesions (plaque burden [PB] >40%) treated with everolimus-eluting stents were retrospectively evaluated to determine the distance from the stent edge to the residual plaque. RESULTS: The SER group had significantly higher PB (59.1 ± 6.1% vs. 51.9 ± 9.1% for non-SER; P = 0.04). Higher PB was associated with SER, with the cutoff value of 54.74% determined using receiver operating characteristic (ROC) curve analysis. At this cutoff value of PB, the distance from the stent edge to the lesion was significantly associated with SER (odds ratio = 2.05, P = 0.035). The corresponding area under the ROC curve was 0.725, and the cutoff distance value for predicting SER was 1.0 mm. CONCLUSION: An interval less than 1 mm from the proximal stent edge to the nearest point with the determined PB cutoff value of 54.74% was significantly associated with SER in patients with residual plaque lesions.

Midterm follow-up after retrievable inferior vena cava filter placement in venous thromboembolism patients with or without malignancy.

BACKGROUND: A clear indication and strategy for placement of retrievable inferior vena cava filters (IVCFs) have not been established. This study was designed to evaluate the efficacy and disadvantages of the retrievable IVCF use particularly in venous thromboembolism (VTE) patients with malignancy. HYPOTHESIS: Retrievable IVCFs might be safe and useful in VTE patients with malignancy. METHODS: The study population consisted of 56 consecutive patients undergoing IVCF placement at our institution from January 1, 2008 to December 31, 2011. Prognostic data were retrospectively reviewed in April 2013. RESULTS: Mean follow-up period was 584.6 (range, 1-1857) days. Twenty-six of the 56 patients had a malignancy. In 16 of the 30 patients without malignancy, the filter was retrieved, whereas the other 14 patients eventually received permanent implantation. There was no significant difference in the survival rate between the retrieval group and the nonretrieval group in the nonmalignancy patients (1-year survival rates, 94% vs 85%). In patients with malignancy, the nonretrieval group showed a significantly lower survival rate (P < 0.01). The 1-year and 2-year survival rates were 100% vs 46% and 100% vs 18%, respectively. There was no medical record of pulmonary thromboembolism occurrence or recurrence. All deaths in the patients with malignancy were malignancy related. In 4 of 5 malignancy patients who could undergo tumor resection surgery, adequate thrombus regression enabled us to retrieve the IVCF after surgery. CONCLUSIONS: Permanent use of a retrievable IVCF is relatively safe in short- or midterm follow-up regardless of malignancy status. Retrievable filter use might be reasonable in malignancy patients.

Functional analysis of Tcl1 using Tcl1-deficient mouse embryonic stem cells.

Tcl1 is highly expressed in embryonic stem (ES) cells, but its expression rapidly decreases following differentiation. To assess Tcl1's roles in ES cells, we generated Tcl1-deficient and -overexpressing mouse ES cell lines. We found that Tcl1 was neither essential nor sufficient for maintaining the undifferentiated state. Tcl1 is reported to activate Akt and to enhance cell proliferation. We found that Tcl1 expression levels correlated positively with the proliferation rate and negatively with the apoptosis of ES cells, but did not affect Akt phosphorylation. On the other hand, the phosphorylation level of ß-catenin decreased in response to Tcl1 overexpression. We measured the ß-catenin activity using the TOPflash reporter assay, and found that wild-type ES cells had low activity, which Tcl1 overexpression enhanced 1.8-fold. When the canonical Wnt signaling is activated by ß-catenin stabilization, it reportedly helps maintain ES cells in the undifferentiated state. We then performed DNA microarray analyses between the Tcl1-deficient and -expressing ES cells. The results revealed that Tcl1 expression downregulated a distinct group of genes, including Ndp52, whose expression is very high in blastocysts but reduced in the primitive ectoderm. Based on these results, we discuss the possible roles of Tcl1 in ES cells.

Amiodarone inhibits tissue factor expression in monocytic THP-1 cells.

There is a possibility thrombus formation is closely involved in sudden cardiac death. Amiodarone, a potassium channel inhibitor, is known to reduce mortality in patients with coronary artery disease or low ejection fraction, having antithrombotic actions. Using human monocytic THP-1 cells, we investigated the effects of amiodarone on tissue factor mRNA and protein expression. The involvement of the two main potassium channels existing in THP-1 cells was also investigated. Amiodarone (10µM) significantly and almost completely inhibited the increase of tissue factor mRNA and protein expression induced by tumor necrosis factor-α (100ng/ml). The inhibitory effects of amiodarone on tissue factor mRNA expression showed dose-dependency. Margatoxin (1nM), a selective blocker of voltage-dependent potassium channel Kv1.3, also inhibited tissue factor protein expression, but didn't significantly inhibit mRNA expression. Ba(2+), a blocker of inwardly rectifying potassium channel Kir2.1, partly inhibited the increase of tissue factor mRNA and protein expression. This is the first study that shows amiodarone inhibits tissue factor expression in monocytic cells, by inhibiting mRNA transcription. The result may correlate with the facts amiodarone has antithrombotic actions in patients under extraordinary conditions where thrombus formation is enhanced. The inhibitory effects of amiodarone on tissue factor expression are drastic, different from those of margatoxin and Ba(2+). The result suggests amiodarone has an underlying mechanism to intensely inhibit tissue factor expression other than blocking Kv1.3 and Kir2.1.

Roles of transient receptor potential canonical (TRPC) channels and reverse-mode Na+/Ca2+ exchanger on cell proliferation in human cardiac fibroblasts: effects of transforming growth factor ß1.

Expression of transient receptor potential canonical channels (TRPC) and the effects of transforming growth factor-ß1 (TGF-ß1) on Ca2+ signals and fibroblast proliferation were investigated in human cardiac fibroblasts. The conventional and quantitative real-time RT-PCR, western blot, immunocytochemical analysis, and intracellular Ca2+ concentration [Ca2+]i measurement were applied. Cell proliferation and cell cycle progression were assessed using MTT assays and fluorescence activated cell sorting. Human cardiac fibroblasts have the expression of TRPC1,3,4,6 mRNA and proteins. 1-oleoyl-2-acetyl-sn-glycerol (OAG) and thapsigargin induced extracellular Ca(2+)-mediated [Ca2+]i rise. siRNA for knock down of TRPC6 reduced OAG-induced Ca2+ entry. Hyperforin as well as angiotensin II (Ang II) induced Ca2+ entry. KB-R7943, a reverse-mode Na+/Ca2+ exchanger (NCX) inhibitor, and/or replacement of Na+ with NMDG+ inhibited thapsigargin-, OAG- and Ang II-induced Ca2+ entry. Treatment with TGF-ß1 increased thapsigargin-, OAG- and Ang II-induced Ca2+ entry with an enhancement of TRPC1,6 protein expression, suppressed by KB-R7943. TGF-ß1 and AngII promoted cell cycle progression from G0/G1 to S/G2/M and cell proliferation. A decrease of the extracellular Ca2+ and KB-R7943 suppressed it. Human cardiac fibroblasts contain several TRPC-mediated Ca2+ influx pathways, which activate the reverse-mode NCX. TGF-ß1 enhances the Ca2+ influx pathways requiring Ca2+ signals for its effect on fibroblast proliferation.

Distinct metabolic flow enables large-scale purification of mouse and human pluripotent stem cell-derived cardiomyocytes.

Heart disease remains a major cause of death despite advances in medical technology. Heart-regenerative therapy that uses pluripotent stem cells (PSCs) is a potentially promising strategy for patients with heart disease, but the inability to generate highly purified cardiomyocytes in sufficient quantities has been a barrier to realizing this potential. Here, we report a nongenetic method for mass-producing cardiomyocytes from mouse and human PSC derivatives that is based on the marked biochemical differences in glucose and lactate metabolism between cardiomyocytes and noncardiomyocytes, including undifferentiated cells. We cultured PSC derivatives with glucose-depleted culture medium containing abundant lactate and found that only cardiomyocytes survived. Using this approach, we obtained cardiomyocytes of up to 99% purity that did not form tumors after transplantation. We believe that our technological method broadens the range of potential applications for purified PSC-derived cardiomyocytes and could facilitate progress toward PSC-based cardiac regenerative therapy.