Hypoxia-stressed cardiomyocytes promote early cardiac differentiation of cardiac stem cells through HIF-1/Jagged1/Notch1 signaling

Hypoxia is beneficial for the differentiation of stem cells transplanted for myocardial injury, but mechanisms underlying this benefit remain unsolved. Here, we report the impact of hypoxia-induced Jagged1 expression in cardiomyocytes (CMs) for driving the differentiation of cardiac stem cells (CSCs). Forced hypoxia-inducible factor 1 (HIF-1) expression and physical hypoxia (5% O) treatment could induce Jagged1 expression in neonatal rat CMs. Pharmacological inhibition of HIF-1 by YC-1 attenuated hypoxia-promoted Jagged1 expression in CMs. An ERK inhibitor (PD98059), but not inhibitors of JNK (SP600125), Notch (DAPT), NF-B (PTDC), JAK (AG490), or STAT3 (Stattic) suppressed hypoxia-induced Jagged1 protein expression in CMs. c-Kit CSCs isolated from neonatal rat hearts using a magnetic-activated cell sorting method expressed GATA4, SM22 or vWF, but not Nkx2.5 and cTnI. Moreover, 87.3% of freshly isolated CSCs displayed Notch1 receptor expression. Direct co-culture of CMs with BrdU-labeled CSCs enhanced CSCs differentiation, as evidenced by an increased number of BrdU/Nkx2.5 cells, while intermittent hypoxia for 21 days promoted co-culture-triggered differentiation of CSCs into CM-like cells. Notably, YC-1 and DAPT attenuated hypoxia-induced differentiation. Our results suggest that hypoxia induces Jagged1 expression in CMs primarily through ERK signaling, and facilitates early cardiac lineage differentiation of CSCs in CM/CSC co-cultures HIF-1/Jagged1/Notch signaling.

Células madre: buscando marcadores de superficie celular que predispongan compromiso de diferenciación cardiaca / Stem cells: searching predisposition to cardiac commitment by surface markers expression

Resumen Actualmente las enfermedades cardiovasculares se han convertido en un serio problema para los sistemas de salud de todo el mundo, ya que son la principal causa de muerte y representan una enorme carga económica. Este problema ha sido abordado con diferentes estrategias, entre ellas con la ayuda de terapia celular, aunque sin resultados contundentes. Durante más de 20 años, se ha utilizado una gran variedad de células madre en diferentes modelos de infarto del miocardio. El uso de células madre cardiacas (CSC) parece ser la mejor opción, pero la inaccesibilidad y la escasez de estas células hacen que su uso sea muy limitado. Además, existe un riesgo elevado pues tienen que obtenerse directamente del corazón del paciente. A diferencia de las CSC, las células madre adultas derivadas de médula ósea o tejido adiposo, entre otras, representan una opción atractiva debido a su fácil accesibilidad y abundancia, pero sobre todo a la probable existencia de progenitores cardiacos entre sus diferentes subpoblaciones. En esta revisión hacemos un análisis de los marcadores de superficie presentes en CSC en comparación con otras células madre adultas, y sugerimos la preexistencia de células que comparten marcadores de superficie específicos con CSC, la presencia de un inmunofenotipo predecible, aunque en proporciones bajas, pero con un potencial de diferenciación cardiaca similar a las CSC, lo cual podría aumentar su valor terapéutico. Este estudio revela las nuevas perspectivas con respecto a la presencia de dichos marcadores, los cuales comprometerían algunas de estas subpoblaciones a diferenciarse a tejido cardiaco.

Abstract It is well-known that cardiovascular diseases are the leading cause of death world- wide, and represent an important economic burden to health systems. In an attempt to solve this problem, stem cell therapy has emerged as a therapeutic option. Within the last 20 years, a great variety of stem cells have been used in different myocardial infarction models. Up until now, the use of cardiac stem cells (CSCs) has seemed to be the best option, but the inaccessibility and scarcity of these cells make their use unreliable. Additionally, there is a high risk as they have to be obtained directly from the heart of the patient. Unlike CSCs, adult stem cells originating from bone marrow or adipose tissue, among others, appear to be an attractive option due to their easier accessibility and abundance, but particularly due to the probable existence of cardiac progenitors among their different sub-populations. In this review an analysis is made of the surface markers present in CSCs compared with other adult stem cells. This suggested the pre-existence of cells sharing specific surface markers with CSCs, a predictable immunophenotype present in some cells, although in low proportions, and with a potential of cardiac differentiation that could be similar to CSCs, thus increasing their therapeutic value. This study highlights new perspectives regarding MSCs that would enable some of these sub-populations to be differentiated at cardiac tissue level.

The advances of cardiac stem cell for the treatment of cardiovascular disease / 中国胸心血管外科临床杂志

@#With the discovery of cardiac stem cell, the conception of the heart considered to be a terminally differentiated organ was changed. Cardiac stem cells possess the common characteristics of self-renew, clone formation and differentiating into cardiomyocyte, smooth muscle cell, and endothelial cell. Because of the properties of tissue specificity and lineage commitment, cardiac stem cells are considered to have great advantages over other stem cells in the treatment of cardiovascular disease. However, the low rate of engraftment still remains a problem to be solved. In recent years, people attempted to combine stem cell therapy with other ways, such as tissue engineering, gene therapy, exosome therapy, to cure cardiovascular diseases, aiming at finding better ways to treat the cardiovascular disease. This article is mainly for the reviewing of the mechanisms underlying the stem cell therapy and the combinatory use of new technology emerged these years.

Construction of the full length and N-terminal fragment of serum response factor over-expressing lentiviral plasmid and its impacts on cardiac stem cell differentiation / 临床与实验病理学杂志

Purpose To analyze the effects of full length and N-terminal fragment of serum response factor (SRF-Full and SRF-N) on TGF-β1-induced differentiation in c-Kit + cardiac stem cells (CSC).Methods Rat SRF-Full and SRF-N (1-254 aa) coding sequences were obtained from cDNA library and cloned into the linearized lentviral vector GV358 (Ubi-MCS3FLAG-SV40-EGFP-IRES-puromycin) to generate the recombinant vectors,and then positive clones were selected and sequenced after transducing the competent cells with recombinant vectors.The recombinant lentvirus were packaged through transfecting the HEK293T cells with SRF-Full,SRF-N overexpressing plasmids and viral packaging plasmids.Neonatal SD rat cKit + CSCs were isolated via magnetic activated cell sorting,and TGF-β1-induced differentiation in SRF-Full and SRF-N overexpression virus-infected CSCs was assessed by quantitative PCR.Results SRF-Full and SRF-N coding sequences were successfully obtained and properly cloned into the linearized GV358.The positive clones were selected and further confirmed by sequencing.With the help of packaging plasmids,the SRFFull and SRF-N overexpressing plasmids-transfected HEK293T cells successfully produced the lentiviral particles with the titer of 2 × 108 TU/mL,and the SRF-Full-Flag and SRF-N-Flag fusion protein were detected by Western blot in virus-infected HEK293T cells.Addition of TGF-β1 significantly induced upregulated mRNAs in cardiomyocyte markers (Nkx2.5,Gata4,cTnI) and smooth muscle cell marker (SM22α) but not the epithelia cell marker (vWF) in CSCs.Overexpression of SRF-Full facilitated TGF-β1-triggered cardiomyocyte differentiation.However,SRF-N exerted anti-differentiation effects in TGF-β1-treated cells.Conclusion The SRF-Full and SRF-N overexpressing recombinant lentiviral vectors are successfully constructed.SRF-Full facilitates while SRF-N suppresses TGF-β1-induced cardiomyocyte differentiation in c-Kit + CSCs.

Transfection of calcitonin gene-related peptide mediated by lentivirus vec-tor in vitro and its effects on cardiac stem cell viability / 中国病理生理杂志

AIM:To investigate the effect of calcitonin gene-related peptide (CGRP)transfection into c-kitpos cardiac stem cells (c-kit+CSCs) on the cell viability.METHODS: Under the sterile condition, the auricles of SD rats were taken out , and then c-kit +CSCs were collected through enzyme digestion and immunomagnetic bead separation (MACS).The cells were identified by flow cytometry .c-kit +CSCs were transfected with enhanced green fluorescent pro-tein CGRP lentiviral vector ( Lv-EGFP-CGRP) or enhanced green fluorescent protein lentiviral vector ( Lv-EGFP).The cells were randomly divided into Lv-EGFP-CGRP-CSCs group , Lv-EGFP-CSCs group and CSCs group .The transfection was observed under the fluorescence microscope .The transfection efficiency was detected by flow cytometry .The CGRP protein secretion in the cell culture supernatants was detected by ELISA .The viability of c-kit+CSCs transfected with Lv-EGFP-CGRP or Lv-EGFP was measured by CCK-8 assay.RESULTS:c-kit+CSCs were isolated and cultured successfully .The expression positive rate of c-kit was 91.0%and the expression positive rates of CD 45 and CD34 were 4.5% and 4.0%, respectively.After transfected with lentivirus for 48 h, the stable fluorescence in c-kit +CSCs was observed under fluores-cence microscope .The transfection efficiency were 80%when MOI was 20.The level of CGRP was significantly increased in Lv-ECFP-CGRP-CSCs group compared with Lv-EGFP-CSCs group and CSCs group (P<0.05).Meanwhile, transfection with lentiviral vector in each group did not affect the viability of c-kit+CSCs.CONCLUSION:Transfection of Lv-EGFP-CGRP into c-kit+CSCs was successful .The secretion of CGRP was found in the transfected c-kit+CSCs and the viability was not changed after transfection .CGRP-modified c-kit+CSCs may play a role in treating myocardial infarction .

Induction effect of hepatocyte growth factor and insulin-like growth factor on cardiac stem cells / 解剖学报

Objective To investigate whether hepatocyte growth factor ( HGF ) and insulin-like growth factor (IGF1) induce cardiac stem cells (CSCs) to proliferate and directly differentiate into cardiomyocytes in vitro.Methods The myocardial tissues were dissected for primary culture of CSCs with the method of explants .The expressions of c-kit and CD34 were examined with immunofluorescence .Primary cells were purified with c-kit by flow cytometry.CFDA SE fluorescent probe was used to detect the proliferation of c-kit+CSCs.C-kit +CSCs were divided into two groups , and cardiac stem cells group and co-cultured with cardiomyocytes group , both group were cultured with HGF and IGF 1.An inverted microscope was used to observe changes in cell number and morphology in different periods .Living cells workstation was used to observe CFDA SE fluorescence intensity , to acquire images and do statistical analysis .Immunofluorescence technique was used to detect the expression of Nkx 2.5 and cardiac troponin T .Results In cardiac stem cells group ,CSCs had no obvious changes in cell number .In co-cultured with cardiomyocytes group , CSCs proliferated and had changes in morphology .Nkx2.5 and cTnT were positively expressed . Several CSCs differentiated into beating cardiomyocytes . Conclusion In co-cultured with cardiomyocytes condition , HGF and IGF1 may promote CSCs to proliferate and differentiate into beating cardiomyocytes .