[Show abstract][Hide abstract] ABSTRACT: Long-QT syndrome mutations can cause syncope and sudden death by prolonging the cardiac action potential (AP). Ion channels affected by mutations are various, and the influences of cellular calcium cycling on LQTS cardiac events are unknown. To better understand LQTS arrhythmias, we performed current-clamp and intracellular calcium ([Ca2+]i) measurements on cardiomyocytes differentiated from patient-derived induced pluripotent stem cells (iPS-CM). In myocytes carrying an LQT2 mutation (HERG-A422T), APs and [Ca2+]i transients were prolonged in parallel. APs were abbreviated by nifedipine exposure and further lengthened upon releasing intracellularly stored Ca2+. Validating this model, control iPS-CM treated with HERG-blocking drugs recapitulated the LQT2 phenotype. In LQT3 iPS-CM, expressing NaV1.5-N406K, APs and [Ca2+]i transients were markedly prolonged. AP prolongation was sensitive to tetrodotoxin and to inhibiting Na+-Ca2+ exchange. These results suggest that LQTS mutations act partly on cytosolic Ca2+ cycling, potentially providing a basis for functionally targeted interventions regardless of the specific mutation site.
[Show abstract][Hide abstract] ABSTRACT: Abnormal activation of endochondral bone formation in soft tissues causes significant medical diseases associated with disability and pain. Hyperactive mutations in the bone morphogenetic protein (BMP) type 1 receptor ACVR1 lead to fibrodysplasia ossificans progressiva (FOP), a rare genetic disorder characterized by progressive ossification in soft tissues. However, the specific cellular mechanisms are unclear. In addition, the difficulty obtaining tbissue samples from FOP patients and the limitations in mouse models of FOP hamper our ability to dissect the pathogenesis of FOP.
To address these challenges and develop a "disease model in a dish," we created human induced pluripotent stem cells (iPS cells) derived from normal and FOP dermal fibroblasts by two separate methods, retroviral integration or integration-free episomal vectors. We tested if the ability to contribute to different steps of endochondral bone formation was different in FOP vs. control iPS cells.
Remarkably, FOP iPS cells showed increased mineralization and enhanced chondrogenesis in vitro. The mineralization phenotypes could be suppressed with a small-molecule inhibitor of BMP signaling, DMH1. Our results indicate that the FOP ACVR1 R206H mutation favors chondrogenesis and increases mineral deposition in vitro.
Our findings establish a FOP disease cell model for in vitro experimentation and provide a proof-of-concept for using human iPS cell models to understand human skeletal disorders.
[Show abstract][Hide abstract] ABSTRACT: An infant with ventricular septal defect, atrial septal defect, and Down syndrome (trisomy 21) was referred to our institution. The patient gradually developed infantile lobar emphysema of the right upper lobe and became dependent on mechanical ventilator support. When the patient was five months of age, we successfully performed a total correction of cardiac anomalies combined with a right upper lobectomy. The resection of the right upper lobe was performed under cardiopulmonary bypass through a median sternotomy. There was no major airway bleeding or mediastinitis. The patient was extubated on postoperative day 12 and discharged on postoperative day 29.
[Show abstract][Hide abstract] ABSTRACT: A 5-day-old girl who had pulmonary atresia with ventricular septal defect, patent ductus arteriosus, intralobar pulmonary sequestration of the right lower lobe, and retroesophageal innominate vein, was referred to our institution. We successfully performed a systemic-to-pulmonary shunt. During cardiopulmonary bypass, the arteries supplying the sequestrated lung were ligated above the diaphragm through the median sternotomy, without a thoracotomy. The postoperative course was uneventful, and we avoided the potential complications of lung infection and ventricular overload.
Asian cardiovascular & thoracic annals 08/2013; 21(4):460-3. DOI:10.1177/0218492312456692
[Show abstract][Hide abstract] ABSTRACT: Congenital pulmonary arteriovenous fistula (PAVF) is a rare disease which causes hypoxemia by shunting deoxygenated blood from the pulmonary artery into pulmonary venous return. Lung transplantation is the most effective therapy to treat severe, diffuse PAVF. However, the availability of lungs for transplantation is limited in most parts in the world. For patients with diffuse PAVF affecting only one side of the lungs, ipsilateral pulmonary artery banding (PAB) is an effective treatment, but not yet standard of care. We report successful treatment of a patient with diffuse left-sided PAVF with PAB. We believe that PAB is an effective therapy for severe unilateral PAVF and may serve as a bridge to lung transplantation.
Journal of Cardiothoracic Surgery 08/2012; 7(1):77. DOI:10.1186/1749-8090-7-77 · 1.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Female human induced pluripotent stem cell (hiPSC) lines exhibit variability in X-inactivation status. The majority of hiPSC lines maintain one transcriptionally active X (Xa) and one inactive X (Xi) chromosome from donor cells. However, at low frequency, hiPSC lines with two Xas are produced, suggesting that epigenetic alterations of the Xi occur sporadically during reprogramming. We show here that X-inactivation status in female hiPSC lines depends on derivation conditions. hiPSC lines generated by the Kyoto method (retroviral or episomal reprogramming), which uses leukemia inhibitory factor (LIF)-expressing SNL feeders, frequently had two Xas. Early passage Xa/Xi hiPSC lines generated on non-SNL feeders were converted into Xa/Xa hiPSC lines after several passages on SNL feeders, and supplementation with recombinant LIF caused reactivation of some of X-linked genes. Thus, feeders are a significant factor affecting X-inactivation status. The efficient production of Xa/Xa hiPSC lines provides unprecedented opportunities to understand human X-reactivation and -inactivation.
[Show abstract][Hide abstract] ABSTRACT: The treatment of ES cells with trichostatin A (TSA), an HDAC inhibitor, induces the acetylation of GATA4 as well as histones, and facilitates their differentiation into cardiomyocytes. Recently, we demonstrated that cyclin-dependent kinase 9 (Cdk9), a core component of positive elongation factor-b, is a novel GATA4-binding partner. The present study examined whether Cdk9 forms a complex with GATA4 in mouse ES cells and is involved in their differentiation into cardiomyocytes. Mouse ES cells and Nkx2.5/GFP ES cells, in which green fluorescent protein (GFP) is expressed under the control of the cardiac-specific Nkx2.5 promoter, were induced to differentiate on feeder-free gelatin-coated plates. Immunoprecipitation/Western blotting in nuclear extracts from mouse ES cells demonstrated that Cdk9 as well as cyclin T1 interact with GATA4 during myocardial differentiation. TSA treatment increased Nkx2.5/GFP-positive cells and endogenous mRNA levels of Nkx2.5 and atrial natriuretic factor. To determine the role of Cdk9 in myocardial cell differentiation, we examined the effects of a dominant-negative form of Cdk9 (DN-Cdk9), which loses its kinase activity, and a Cdk9 kinase inhibitor, 5,6-dichloro-1-β-ribofuranosyl-benzimidazole (DRB) on TSA-induced myocardial cell differentiation. The introduction of the DN-Cdk9 inhibited TSA-induced increase in GFP expression in Nkx2.5/GFP ES cells. The administration of DRB into ES cells significantly inhibited TSA-induced increase of endogenous Nkx2.5 mRNA levels in ES cells as well as GFP expression in Nkx2.5/GFP ES cells. These findings demonstrate that Cdk9 is involved in the differentiation of mouse ES cells into cardiomyocytes by interacting with GATA4.
[Show abstract][Hide abstract] ABSTRACT: Mouse and human fibroblasts can be directly reprogrammed to pluripotency by the ectopic expression of four transcription factors (Oct3/4, Sox2, Klf4, and c-Myc) to yield induced pluripotent stem (iPS) cells. iPS cells can be generated even without the expression of c-Myc. The present study examined patterns of differentiation of mouse iPS cells into cardiomyocytes in three different cell lines reprogrammed by three or four factors.
During the induction of differentiation on feeder-free gelatinized dishes, genes involved in cardiogenesis were expressed as in embryonic stem cells and myogenic contraction occurred in two iPS cell lines. However, in one iPS cell line (20D17) generated by four factors, the expression of cardiac-specific genes and the beating activity were extremely low. Treating iPS cells with trichostatin A (TSA), a histone deacetylase (HDAC) inhibitor, increased Nkx2.5 expression in all iPS cell lines. While the basal Nkx2.5 expression was very low in 20D17, the TSA-induced increase was the greatest. TSA also induced the expression of contractile proteins in 20D17. Furthermore, we demonstrated the increased mRNA level of Oct3/4 and nuclear protein level of HDAC4 in 20D17 compared with the other two iPS cell lines. DNA microarray analysis identified genes whose expression is up- or down-regulated in 20D17.
Mouse iPS cells differentiate into cardiomyocytes in a cell line-dependent manner. TSA induces myocardial differentiation in mouse iPS cells and might be useful to overcome cell line variation in the differentiation efficiency.
Cardiovascular Research 11/2010; 88(2):314-23. DOI:10.1093/cvr/cvq189 · 5.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Multipotent germline stem (mGS) cells have been established from neonatal mouse testes. We previously reported that undifferentiated mGS cells are phenotypically similar to embryonic stem cells and that fetal liver kinase 1 (Flk1)(+) mGS cells have a similar potential to differentiate into cardiomyocytes and endothelial cells compared with Flk1(+) embryonic stem cells. Here, we transplanted these Flk1(+) mGS cells into an ischemic heart failure mouse model to evaluate the improvement in cardiac function. Significant increase in left ventricular wall thickness of the infarct area, left ventricular ejection fraction and left ventricular maximum systolic velocity was observed 4weeks after when sorted Flk1(+) mGS cells were transplanted directly into the hearts of the acute ischemic model mice. Although the number of cardiomyocytes derived from Flk1(+) mGS cells were too small to account for the improvement in cardiac function but angiogenesis around ischemic area was enhanced in the Flk1(+) mGS cells transplanted group than the control group and senescence was also remarkably diminished in the early phase of ischemia according to β-galactosidase staining assay. In conclusion, Flk1(+) mGS cell transplantation can improve the cardiac function of ischemic hearts by promoting angiogenesis and by delaying host cell death via senescence.
Biochemical and Biophysical Research Communications 09/2010; 400(1):27-33. DOI:10.1016/j.bbrc.2010.07.131 · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Cardiac resynchronization therapy (CRT) is a new treatment for refractory heart failure. However, most heart failure patients treated with CRT are middle-aged or old patients with idiopathic or ischemic dilated cardiomyopathy. We treated a 17 year 11 month old girl with dilated cardiomyopathy after mitral valve replacement (MVR) and septal anterior ventricular exclusion (SAVE). Seven years after the SAVE procedure, she presented complaining of palpitations and general fatigue with normal activity. Her echocardiogram showed reduced left ventricular function. Despite of optimal medical therapy, her left ventricular function continued to decline and she experienced regular arrhythmias such as premature ventricular contractions. We thus elected to perform cardiac resynchronization therapy with defibrillator (CRT-D). After CRT-D, her clinical symptoms improved dramatically and left ventricular ejection fraction (LVEF) improved from 31.2% to 51.3% as assessed by echocardiogram. Serum BNP levels decreased from 448.2 to 213.6 pg/ml. On ECG, arrhythmias were remarkably reduced and QRS duration was shortened from 174 to 152 msec. In conclusion, CRT-D is an effective therapeutic option for adolescent patients with refractory heart failure after left ventricular volume reduction surgery.
Journal of Cardiothoracic Surgery 06/2010; 5:47. DOI:10.1186/1749-8090-5-47 · 1.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Multipotent germline stem (mGS) cells derived from neonatal mouse testis, similar to embryonic stem (ES) cells, differentiate into various types of somatic cells in vitro and produce teratomas after inoculation into mice. In the present work, we examined mGS cells for hematopoietic progenitor potential in vitro and in vivo.
mGS cells were differentiated on OP9 stromal cells and induced into Flk1(+) cells. Flk1(+) cells were sorted and replated on OP9 stromal cells with various cytokines and emerging hematopoietic cells were analyzed for lineage marker expression by fluorescein-activated cell sorting, progenitor activity by colony assay, and stem cell transplantation assay.
mGS cells, like ES cells, produce hematopoietic progenitors, including both primitive and definitive erythromyeloid, megakaryocyte, and B- and T-cell lineages via Flk1(+) progenitors. When transplanted into the bone marrow (BM) of nonobese diabetic/severe combined immunodeficient (NOD/SCID) gammac(null) mice directly, mGS-derived green fluorescent protein (GFP)-positive cells were detected 4 months later in the BM and spleen. GFP(+) donor cells were also identified in the Hoechst33342 side population, a feature of hematopoietic stem cells. However, these mGS-derived hematopoietic cells did not proliferate in vivo, even after exposure to hematopoietic stressors, such as 5-fluorouracil (5FU) injection or serial transplantation.
mGS cells produced multipotent hematopoietic progenitor cells with myeloid and lymphoid lineage potential in vitro and localized in the BM after intra-BM injection but, like ES cells, failed to expand or show stem cell repopulating ability in vivo.
[Show abstract][Hide abstract] ABSTRACT: We treated a 10 year 11 month old girl with severe mitral valve regurgitation, stenosis and dilated cardiomyopathy, presented with New York Heart Association (NYHA) functional classification IV. She acutely developed cardiogenic shock with a dyskinetic anterior-septal left ventricle and entered a shock state during our consultation about heart transplantation. Septal-anterior ventricular exclusion and mitral valve replacement were performed emergently. She successfully recovered from cardiogenic shock. Left ventricular end-diastolic diameter and fractional shortening improved from 71.5 mm (188.0% of normal) to 62.5 mm (144.2% of normal) and 7.6% to 18.3% respectively. Furthermore, her serum BNP decreased from 2217.5 pg/ml to 112.0 pg/ml. Her cardiac function has remained stable for 7 years since the procedures were performed.
Journal of Cardiothoracic Surgery 09/2009; 4:53. DOI:10.1186/1749-8090-4-53 · 1.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Developing effective drug therapies for arrhythmic diseases is hampered by the fact that the same drug can work well in some individuals but not in others. Human induced pluripotent stem (iPS) cells have been vetted as useful tools for drug screening. However, cardioactive drugs have not been shown to have the same effects on iPS cell-derived human cardiomyocytes as on embryonic stem (ES) cell-derived cardiomyocytes or human cardiomyocytes in a clinical setting. Here we show that current cardioactive drugs affect the beating frequency and contractility of iPS cell-derived cardiomyocytes in much the same way as they do ES cell-derived cardiomyocytes, and the results were compatible with empirical results in the clinic. Thus, human iPS cells could become an attractive tool to investigate the effects of cardioactive drugs at the individual level and to screen for individually tailored drugs against cardiac arrhythmic diseases.
Biochemical and Biophysical Research Communications 08/2009; 387(3):482-8. DOI:10.1016/j.bbrc.2009.07.052 · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Although granulocyte colony-stimulating factor (G-CSF) reportedly plays a cardioprotective role in several models of cardiac injury, clinical use of this drug in cardiac patients has been controversial. Here, we tested, in vivo and in vitro, the effect of G-CSF on cardiac mitochondria, which play a key role in determining cardiac cellular fate and function. Mild stimulation of C57/BL6 mice with doxorubicin (Dox) did not induce cardiac apoptosis or fibrosis but did induce damage to mitochondrial organization of the myocardium as observed through an electron microscope. Cardiac catheterization and echocardiography revealed that Dox did not alter cardiac systolic function or left ventricular size but did reduce diastolic function, an early sign of cardiac damage. Treatment with G-CSF attenuated significantly the damage to mitochondrial organization and rescued diastolic function. In an in vitro model for rat neonatal cardiomyocytes, a subapoptotic dose of Dox induced severe mitochondrial damage, including marked swelling of the cardiac mitochondria and/or decreased mitochondrial membrane potential. These mitochondrial changes were completely blocked by pretreatment with G-CSF. In addition, G-CSF dramatically improved ATP generation, which rescued Dox-impaired mitochondrial electron transport and oxygen consumption mainly through complex IV. These findings clearly indicate that G-CSF protects cardiac mitochondria, which are key organelles in the determination of cardiac cellular fate, in the early phase of cardiac injury.
[Show abstract][Hide abstract] ABSTRACT: The liver has a high potential to regenerate however, the relation between oval cells and endothelial cells in the portal area during liver regeneration has not been adequately described. We have focused on sca-1+ endothelial cells (SPEC: sca-1+CD31+CD45- cells) and analyzed their localization, growth potential, and the role of these cells in damaged liver. SPECs are localized in the portal area and comprise approximately 20-30% of CD31+CD45- cells. These cells have higher growth potential than sca-1- endothelial cells and grow aggressively when the liver is severely damaged on the lateral side of the oval cells. In an in vivo study we show that when the liver is severely damaged in the presence of a VEGF (vascular endothelial growth factor)-inhibitor, the frequency of SPECs decreased and the recovery of liver volume was also delayed. These results strongly suggest that SPECs play important roles in the recovery of severely damaged liver.
Biochemical and Biophysical Research Communications 02/2008; 365(3):595-601. DOI:10.1016/j.bbrc.2007.10.150 · 2.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Flk1(+) cells derived from embryonic stem (ES) cells are known to differentiate into mesodermal lineages such as hematopoietic and endothelial cells. Here we demonstrate that they can develop into cardiomyocytes that support functional recovery in a dilated cardiomyopathy (DCM) C57/BL6 mouse model.
Flk1(+) and Flk1(-) cells were sorted at day 4 of differentiation, and cardiomyogenesis was assessed in vitro. Next, we transplanted these cells into the hearts of cardiomyopathy mice to assess improvement in cardiac function.
Flk1(+) cells, but not Flk1(-) cells, isolated on day 4 after differentiation were efficiently converted into contractile cardiomyocytes. RT-PCR analysis and immunohistological assays demonstrated that contractile cells derived from Flk1(+) cells in vitro expressed mature cardiac markers on day 10 after differentiation. Transplantation of sorted Flk1(+) cells into DCM model mouse hearts improved cardiac function, as determined by echocardiography and cardiac catheterization. The in vivo differentiated Flk1(+) cells expressed cardiac markers and had gap junctions, as demonstrated by immunohistochemistry. Furthermore, these cells generated ventricular type action potentials similar to those of adult ventricle.
These results indicate that Flk1 is a good marker for sorting cardiac stem/progenitor cells which can differentiate into mature cardiomyocytes both in vitro and in vivo.
Cardiovascular Research 11/2007; 76(1):119-31. DOI:10.1016/j.cardiores.2007.05.013 · 5.81 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Multipotent germline stem (mGS) cells have been established from neonatal mouse testes. Here, we compared mGS, embryonic stem (ES), and embryonic germ (EG) cells with regard to their ability to differentiate into mesodermal cells, namely, cardiomyocytes and endothelial cells. The in situ morphological appearances of undifferentiated mGS, ES, and EG cells were similar, and 4 days after being induced to differentiate, approximately 30%-40% of each cell type differentiated into Flk1(+) cells. The sorted Flk1(+) cells differentiated efficiently into cardiomyocytes and endothelial cells. By day 10 after differentiation induction, the three cell types generated equal number of endothelial colonies. However, by day 13 after differentiation induction, the Flk1(+) mGS cells generated more contractile colonies than did the Flk1(+) ES cells, whereas the Flk1(+) EG cells generated equivalent numbers as the Flk1(+) mGS cells. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis of differentiation markers such as Rex1, FGF-5, GATA-4, Brachyury, and Flk1 revealed that mGS cells expressed these markers more slowly during days 0-4 after differentiation induction than did ES cells, but that this mGS cell pattern was similar to that of the EG cells. RT-PCR analysis also revealed that the three differentiation cell types expressed various cardiac markers. Moreover, immunohistochemical analysis revealed that the contractile colonies derived from Flk1(+) mGS cells express mature cardiac cell-specific markers. In conclusion, mGS cells are phenotypically similar to ES and EG cells and have a similar potential to differentiate into cardiomyocytes and endothelial cells. Disclosure of potential conflicts of interest is found at the end of this article.
[Show abstract][Hide abstract] ABSTRACT: Few studies on the long-term culture of postnatal mouse hepatic stem/progenitor cells have been reported. We successfully adapted a serum-free culture system that we employed previously to expand fetal mouse hepatic stem/progenitor cells and maintained them in culture over long periods. The expanded postnatal cells contained immature alpha-fetoprotein-positive cells along with hepatocytic and cholangiocytic lineage-committed cells. These cells expressed CD49f but not CD45, CD34, Thy-1, c-kit, CD31, or flk-1, and oncostatin M induced their differentiation. This heterogeneous population contained side population (SP) cells, which express the ATP-binding cassette transporter ABCG2, and sca-1+ cells. As mice aged, the frequency of SP and sca-1+ cells decreased along with the ability of cultured cells to expand. Approximately 20%-40% of the SP cells expressed sca-1, but only a few sca-1+ cells were also SP cells. Analysis of colonies derived from single SP or sca-1+ cells revealed that, although both cells had dual differentiation potential and self-renewal ability, SP cells formed colonies more efficiently and gave rise to SP and sca-1+ cells, whereas sca-1+ cells generated only sca-1+ progeny. Thus, SP cells are more characteristic of stem cells than are sca-1+ cells. In regenerating livers, ABCG2+ cells and sca-1+ cells were detected around or in the portal area (the putative hepatic stem cell niche). The expanded cells share many features of fetal hepatic stem/progenitor cells or oval cells and may be useful in determining the mechanisms whereby hepatic stem cells self-renew and differentiate.
[Show abstract][Hide abstract] ABSTRACT: Sphere formation has been utilized as a way to isolate multipotent stem/progenitor cells from various tissues. However, very few studies on bone marrow-derived spheres have been published and assessed their multipotentiality. In this study, multipotent marrow cell populations were isolated using a three-step method. First, after elimination of hematopoietic cells, murine marrow-derived adherent cells were cultured in plastic dishes until small cells gradually appeared and multiplied. Cells were then cultured under non-adherent conditions and formed spheres that were immunopositive for a neural precursor marker, nestin. RT-PCR analysis also revealed that the spheres were positive for nestin in addition to PPARgamma, osf2, SOX9, and myoD, which are markers of precursors of adipocytic, osteoblastic, chondrocytic, and skeletal myeloblastic lineages, respectively. Finally, spheres were dissociated into single cells and expanded in adherent cultures. Under appropriate induction conditions, the sphere-derived cells acquired the phenotypic properties in vitro of neurons, skeletal myoblasts, and beating cardiomyocytes, as well as adipocytes, osteoblasts, and chondrocytes. Next, sphere-derived cells were transplanted into murine myocardial infarction models. One month later, they had become engrafted as cardiomyocytes, and cardiac catheterization showed significant functional improvements. Thus, sphere-derived cells represent a new approach to enhance the multi-differentiation potential of murine bone marrow.
Experimental Cell Research 04/2007; 313(5):1008-23. DOI:10.1016/j.yexcr.2006.12.017 · 3.37 Impact Factor