scholarly journals Cardiac Pacemaker Cells Generate Cardiomyocytes from Fibroblasts in Long-Term Cultures

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Shigeki Kiuchi ◽  
Akino Usami ◽  
Tae Shimoyama ◽  
Fuminori Otsuka ◽  
Sachiko Yamaguchi ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Cardiac Fibroblasts ◽  
Cluster Formation ◽  
Cardiac Pacemaker ◽  
Pacemaker Cells ◽  
Intracellular Ca ◽  
Specific Proteins ◽  
Cell Densities

Abstract Because cardiomyocyte generation is limited, the turnover of cardiomyocytes in adult heart tissues is much debated. We report here that cardiac pacemaker cells can generate cardiomyocytes from fibroblasts in vitro. Sinoatrial node cells (SANCs) were isolated from adult guinea pig hearts and were cultured at relatively low cell densities. Within a week, a number of fibroblast-like cells were observed to gather around SANCs, and these formed spontaneously beating clusters with cardiomyocyte structures. The clusters expressed genes and proteins that are characteristic of atrial cardiomyocytes. Pharmacological blocking of pacemaker currents inhibited generation of action potentials, and the spontaneous beating were ceased by physically destroying a few central cells. Inhibition of beating during culture also hampered the cluster formation. Moreover, purified guinea pig cardiac fibroblasts (GCFs) expressed cardiac-specific proteins in co-culture with SANCs or in SANC-preconditioned culture medium under electrical stimulation. These results indicate that SANCs can generate cardiomyocytes from cardiac fibroblasts through the influence of humoral factor(s) and electrophysiological activities followed by intracellular Ca2+ oscillations. This potential of SANCs to generate cardiomyocytes indicates a novel mechanism by which cardiomyocytes turns over in the vicinity of pacemaker cells and could be exploited in the development of strategies for cardiac regenerative therapy in adult hearts.

Differential modulation of caffeine- and IP3-induced calcium release in cultured arterial tissue

1999 ◽  
Vol 276 (5) ◽  
pp. C1115-C1120 ◽  
Author(s):  
Karl Dreja ◽  
Per Hellstrand
Keyword(s):  
Calcium Release ◽  
Cyclopiazonic Acid ◽  
Differential Modulation ◽  
Transient Responses ◽  
Inositol 1,4,5 Trisphosphate ◽  
Arterial Tissue ◽  
Intracellular Ca ◽  
Rat Tail

To investigate the Ca2+-dependent plasticity of sarcoplasmic reticulum (SR) function in vascular smooth muscle, transient responses to agents releasing intracellular Ca2+ by either ryanodine (caffeine) ord- myo-inositol 1,4,5-trisphosphate [IP3; produced in response to norepinephrine (NE), 5-hydroxytryptamine (5-HT), arginine vasopressin (AVP)] receptors in rat tail arterial rings were evaluated after 4 days of organ culture. Force transients induced by all agents were increased compared with those induced in fresh rings. Stimulation by 10% FCS during culture further potentiated the force and Ca2+ responses to caffeine (20 mM) but not to NE (10 μM), 5-HT (10 μM), or AVP (0.1 μM). The effect was persistent, and SR capacity was not altered after reversible depletion of stores with cyclopiazonic acid. The effects of serum could be mimicked by culture in depolarizing medium (30 mM K+) and blocked by the addition of verapamil (1 μM) or EGTA (1 mM) to the medium, lowering intracellular Ca2+ concentration ([Ca2+]i) during culture. These results show that modulation of SR function can occur in vitro by a mechanism dependent on long-term levels of basal [Ca2+]iand involving ryanodine- but not IP3 receptor-mediated Ca2+release.

Electrotonic interactions between aggregates of chick embryo cardiac pacemaker cells

1986 ◽  
Vol 250 (3) ◽  
pp. H453-H463 ◽  
Author(s):  
R. D. Veenstra ◽  
R. L. DeHaan
Keyword(s):  
Electrical Coupling ◽  
Cardiac Pacemaker ◽  
Heart Cell ◽  
Embryonic Chick ◽  
Phase Resetting ◽  
Pacemaker Cells ◽  
Beat Rate ◽  
Electrotonic Interactions ◽  
External K

Synchronization of spontaneously active heart cell aggregates occurs shortly after they are brought into contact. The synchronous rate is determined by pacemaker phase resetting and passive subthreshold electrotonic interactions. To further study the effects of passive electrical interactions, we have used 150-microns diameter aggregates prepared from cells of 4d (4-day ventricle + 1 day in vitro), 7d, and 14d embryonic chick ventricle as models of primary, latent, and nonpacemaker tissues, respectively. Coupling of 4d and 7d aggregates (4d/7d pairs) leads to intermediate synchronous rates. We show here that elevating external K+ from 1.3 to 2.8 mM, which has no effect on 4d/4d pairs but selectively reduces the beat rate of 7d/7d pairs by 42%, slows the synchronous beat rate of 4d/7d pairs by 23%. Increases in electrical coupling in newly joined 4d/14d pairs cause the 4d rate to slow to a minimum value (16 +/- 13 beats/min, n = 16) just prior to the onset of synchronous activity. The rate slowly recovers to a final value of 40 +/- 12 beat/min. We conclude that the spontaneous beat rate of a primary pacemaker is modulated by both active and passive interactions with latent or nonpacemaker tissues.

Self-Assembling Peptide Nanofibers for MMP Delivery and Cardiac Regeneration in Diabetes

2011 ◽  
Author(s):  
Jennifer R. Hurley ◽  
Abdul Q. Sheikh ◽  
Meredith Beckenhaupt ◽  
Cameron Ingram ◽  
Andrew Mutchler ◽  
...  
Keyword(s):  
Cardiac Fibrosis ◽  
Cardiac Fibroblasts ◽  
Cardiac Regeneration ◽  
The United States ◽  
Matrix Remodeling ◽  
Self Assembling ◽  
Peptide Nanofibers ◽  
Novel Target

Diabetes is a serious problem in the United States, afflicting 7.8% of the population with annual medical costs estimated at $116B in 2007 (1). Diabetic cardiomyopathy (DCM) is a cardiovascular complication of diabetes resulting in pathological alterations to the myocardium including circulatory defects, impaired heart muscle contraction, and progressive fibrosis. Cardiac fibrosis is associated with an imbalance between the deposition of the extracellular matrix (ECM) proteins by cardiac fibroblasts and the ECM proteolytic degradation via matrix metalloproteinases (MMPs). Recent studies have demonstrated that in the diabetic heart, expression and activity of MMP-2 are reduced, resulting in increased collagen accumulation and cardiac dysfunction (2). These observations suggest that a MMP-related mechanism may contribute to cardiac fibrosis, and that it may be attenuated through stimulation of native MMP-2 expression or delivery of exogenous MMP-2. Therefore, reduced MMP-2 activity in DCM may represent a novel target for therapeutic treatment (3). To achieve this, a special proteolytically-stable delivery scaffold would be needed, because native ECM is rapidly degraded by MMPs. The goal of this study is to determine if self-assembling peptide nanofibers can be used for long-term (several weeks) MMP delivery and enhancement of cardiac remodeling. This study tests the hypothesis that increased MMP-2 concentration (native or exogenous) in the nanofiber environment will promote matrix remodeling in diabetic cardiac fibroblasts in vitro.

scholarly journals Mesenchymal Stem Cells as a Gene Delivery System to Create Biological Pacemaker Cells in vitro

2008 ◽  
Vol 36 (5) ◽  
pp. 1049-1055 ◽  
Author(s):  
X-J Yang ◽  
Y-F Zhou ◽  
H-X Li ◽  
L-H Han ◽  
W-P Jiang
Keyword(s):  
Stem Cells ◽  
Mesenchymal Stem Cells ◽  
Protein A ◽  
Cardiac Pacemaker ◽  
Genetically Engineered ◽  
Hcn Channels ◽  
Pacemaker Cells ◽  
Diastolic Phase ◽  
Biological Pacemaker

Pacemaker cells differ from common cardiomyocytes due to the presence of a spontaneous depolarization process during the diastolic phase of the cardiac cycle. This is due to hyperpolarization-activated cyclic nucleotide-gated ( HCN) channels, which are responsible for providing an inward current. Genetically engineered mesenchymal stem cells (MSCs) were transfected with hHCN4 genes using lentiviral transfection, and their potential use as biological pacemaker cells was investigated. In addition to expressing an anticipated high level of the hHCN4 gene, MSCs transfected with hHCN4 genes also expressed characteristic hHCN4 protein, a cardiac pacemaker-like current and were capable of increasing the spontaneous beating rate of co-cultured cardiac myocytes. Control MSCs did not exert these effects. It is hypothesized that genetically engineered MSCs transfected with hHCN4 genes by lentiviral transfection can be modified to be cardiac pacemaker cells in vitro.

Long-term regulation of contractility and calcium current in smooth muscle

1997 ◽  
Vol 273 (5) ◽  
pp. C1714-C1720 ◽  
Author(s):  
Maria Gomez ◽  
Karl Swärd
Keyword(s):  
Smooth Muscle ◽  
Calf Serum ◽  
Cell Voltage ◽  
High K ◽  
Intracellular Ca ◽  
The Right ◽  
The Relationship ◽  
Cell Capacitance

Longitudinal smooth muscle strips from guinea pig ileum were cultured in vitro for 5 days, and the relationship between extracellular Ca2+ and force in high-K+ medium was evaluated. In strips cultured with 10% fetal calf serum (FCS), this relationship was shifted to the right (50% effective concentration changed by 2–3 mM) compared with strips cultured without FCS. The shift was prevented by inclusion of verapamil (1 μM) during culture and mimicked by ionomycin in the absence of FCS. The intracellular Ca2+ concentration ([Ca2+]i) during stimulation with high-K+solution or carbachol was reduced after culture with FCS, whereas the [Ca2+]i-force relationship was unaffected. Cells were isolated from cultured strips, and whole cell voltage-clamp experiments were performed. Maximum inward Ca2+ current (10 mM Ba2+), normalized to cell capacitance, was almost three times smaller in cells isolated from strips cultured with FCS. Culture with 1 μM verapamil prevented this reduction. These results suggest that increased [Ca2+]iduring culture downregulates Ca2+current density, with associated effects on contractility.

Protein Synthesis In Megakaryocytes Stimulated By Thrombo- Poietin In Vitro

1981 ◽  
Author(s):  
K L Kellar ◽  
B L Evatt ◽  
C R McGrath ◽  
R B Ramsey
Keyword(s):  
Protein Synthesis ◽  
Guinea Pig ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Leucine Incorporation ◽  
Ploidy Levels ◽  
Percoll Gradients ◽  
Specific Proteins ◽  
Phosphate Buffered Saline

Studies in our laboratories have been concerned with the responses of megakaryocytes to thrombopoietin in vitro. We have shown that preparations of thrombopoietin stimulate DNA synthesis in guinea pig megakaryocytes. The increase in 3H-thymidihe incorporation correlates with an increase in the labeling index of the megakaryocytes. After 2 and 3 days of incubation an increase in the ploidy levels of the megakaryocytes has been observed in thrombo- poietin-supplemented cultures compared to controls.Recent studies have examined the incorporation of 3H-leucine in megakaryocyte cultures. Megakaryocytes were prepared on BSA or Percoll gradients to purities of 70-95%. 3H-leucine incorporation was measured after a 15 hr incubation of the megakaryocytes in medium containing 10% thrombopoietin or control preparations of normal plasma or phosphate-buffered saline. Utilization of isotope increased over a 24 hr period and was higher in the thrombopoietin-supplemented cultures. In addition, synthesis of specific proteins was analyzed by using SDS- polyacrylamide gel electrophoresis and quantitation was achieved by employing rocket immunoelectrophoresis. The results indicate that thrombopoietin stimulates endoredu- plication and protein synthesis in megakaryocytes in vitro and that this system may serve as a model for studying the mechanism of action of thrombopoietin in megakaryocytopoiesis.

Different Drug-Susceptibilities of long-term potentiation in three input systems to the CA3 region of the guinea pig hippocampus in vitro

1990 ◽  
Vol 29 (5) ◽  
pp. 487-492 ◽  
Author(s):  
K. Ishihara ◽  
H. Katsuki ◽  
M. Sugimura ◽  
S. Kaneko ◽  
M. Satoh
Keyword(s):  
Guinea Pig ◽  
Long Term Potentiation ◽  
Term Potentiation ◽  
Ca3 Region
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