scholarly journals Rapid pacing by circulating traveling waves improves maturation of hiPSC-derived cardiomyocytes in self-organized tissue ring

2019 ◽  
Author(s):  
Junjun Li ◽  
Lu Zhang ◽  
Leqian Yu ◽  
Itsunari Minami ◽  
Marcel Hörning ◽  
...  
Keyword(s):  
Traveling Waves ◽  
Three Dimensional ◽  
Specific Gene ◽  
Excitable Cells ◽  
Self Organized ◽  
Rapid Pacing ◽  
Induced Pluripotent ◽  
Electrical Pacing ◽  
Long Term Behavior

AbstractDirected differentiation methods allow acquisition of high-purity cardiomyocytes (CMs) differentiated from human induced pluripotent stem cells (hiPSCs); however, their immaturity characteristic limits their application for drug screening and regenerative therapy. The rapid electrical pacing of cardiomyocytes have been used for efficiently promoting the maturation of cardiomyocytes, here we describe a simple device in modified culture plate on which hiPSC-derived CMs (hiPSC-CMs) can form three-dimensional self-organized tissue rings (SOTRs). Using calcium imaging, we show that within the ring, traveling waves (TWs) of action potential spontaneously originated and ran robustly at a frequency up to 4 Hz. After 2 weeks, SOTRs with TW training showed matured features including structural organization, increased cardiac-specific gene expression, enhanced Ca2+-handling properties, an increased oxygen-consumption rate, and enhanced contractile force. We subsequently used a mathematical model to interpret the origination, propagation, and long-term behavior of the TWs within the SOTRs. This new idea for spontaneous hiPSC-CM maturation also has potential for pacing the electrical excitable cells such as neuron and retina cells for various applications.

scholarly journals Circulating re-entrant waves promote maturation of hiPSC-derived cardiomyocytes in self-organized tissue ring

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Junjun Li ◽  
Lu Zhang ◽  
Leqian Yu ◽  
Itsunari Minami ◽  
Shigeru Miyagawa ◽  
...  
Keyword(s):  
Pluripotent Stem Cells ◽  
Consumption Rate ◽  
Three Dimensional ◽  
Specific Gene ◽  
Directed Differentiation ◽  
Self Organized ◽  
Induced Pluripotent ◽  
Electrical Pacing ◽  
Long Term Behavior

AbstractDirected differentiation methods allow acquisition of high-purity cardiomyocytes differentiated from human induced pluripotent stem cells (hiPSCs); however, their immaturity characteristic limits their application for drug screening and regenerative therapy. The rapid electrical pacing of cardiomyocytes has been used for efficiently promoting the maturation of cardiomyocytes, here we describe a simple device in modified culture plate on which hiPSC-derived cardiomyocytes can form three-dimensional self-organized tissue rings (SOTRs). Using calcium imaging, we show that within the ring, reentrant waves (ReWs) of action potential spontaneously originated and ran robustly at a frequency up to 4 Hz. After 2 weeks, SOTRs with ReWs show higher maturation including structural organization, increased cardiac-specific gene expression, enhanced Ca2+-handling properties, an increased oxygen-consumption rate, and enhanced contractile force. We subsequently use a mathematical model to interpret the origination, propagation, and long-term behavior of the ReWs within the SOTRs.

scholarly journals Cell Reprogramming, IPS Limitations, and Overcoming Strategies in Dental Bioengineering

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Gaskon Ibarretxe ◽  
Antonia Alvarez ◽  
Maria-Luz Cañavate ◽  
Enrique Hilario ◽  
Maitane Aurrekoetxea ◽  
...  
Keyword(s):  
Pluripotent Stem Cells ◽  
Ips Cells ◽  
Cell Reprogramming ◽  
Animal Cells ◽  
Ips Cell ◽  
Current State ◽  
Organ Systems ◽  
Induced Pluripotent ◽  
Long Term Behavior

The procurement of induced pluripotent stem cells, or IPS cells, from adult differentiated animal cells has the potential to revolutionize future medicine, where reprogrammed IPS cells may be used to repair disease-affected tissues on demand. The potential of IPS cell technology is tremendous, but it will be essential to improve the methodologies for IPS cell generation and to precisely evaluate each clone and subclone of IPS cells for their safety and efficacy. Additionally, the current state of knowledge on IPS cells advises that research on their regenerative properties is carried out in appropriate tissue and organ systems that permit a safe assessment of the long-term behavior of these reprogrammed cells. In the present paper, we discuss the mechanisms of cell reprogramming, current technical limitations of IPS cells for their use in human tissue engineering, and possibilities to overcome them in the particular case of dental regeneration.

Enhanced microvasculature formation and patterning in iPSC-derived kidney organoids cultured in physiological hypoxia

2021 ◽  
Author(s):  
Anika Schumacher ◽  
Nadia Roumans ◽  
Timo Rademakers ◽  
Virginie Joris ◽  
Maria Jose Eischen-Loges ◽  
...  
Keyword(s):  
Pluripotent Stem Cells ◽  
Three Dimensional ◽  
Culture Conditions ◽  
End Stage Kidney Disease ◽  
Whole Mount ◽  
Factor Expression ◽  
Induced Pluripotent ◽  
End Stage ◽  
Kidney Organoids

Functional kidney organoids have the potential to be used in implantable kidney grafts for patients with end-stage kidney disease, because they have been shown to self-organize from induced pluripotent stem cells into most important renal structures. To date, however, long-term kidney organoid culture has not succeeded, as nephrons lose their phenotype after approximately 25 days. Furthermore, the renal structures remain immature with diminishing endothelial networks with low connectivity and limited organoid invasion. We hypothesized that introducing long-term culture at physiological hypoxia, rather than the normally applied non-physiological, hyperoxic 21% O2, could initiate angiogenesis, lead to enhanced growth factor expression and improve the endothelial patterning. We therefore cultured the kidney organoids at 7% O2 instead of 21% O2 for up to 25 days and evaluated nephrogenesis, VEGF-A expression and vascularization. Whole mount imaging revealed a homogenous morphology of the endothelial network with enhanced sprouting and interconnectivity when the kidney organoids were cultured in hypoxia. Three-dimensional quantification confirmed that the hypoxic culture led to an increased average vessel length, likely due to the observed upregulation of proangiogenic VEGF-A189 mRNA and downregulation of the antiangiogenic protein VEGF-A165b measured in hypoxia. This research indicates the importance of optimization of oxygen availability in organoid systems and the potential of hypoxic culture conditions in improving the vascularization of organoids.

scholarly journals Microfabricated disk technology: rapid scale up in midbrain organoid generation

2021 ◽  
Author(s):  
Nguyen-Vi Mohamed ◽  
Paula Lepine ◽  
Maria Lacalle-Aurioles ◽  
Julien Sirois ◽  
Meghna Mathur ◽  
...  
Keyword(s):  
Scale Up ◽  
Three Dimensional ◽  
Require Time ◽  
Large Numbers ◽  
Midbrain Region ◽  
Brain Organoid ◽  
Induced Pluripotent ◽  
The Brain

By providing a three-dimensional in vitro culture system with key features of the substantia nigra region in the brain, 3D neuronal organoids derived from human induced pluripotent stem cells (iPSCs) provide living neuronal tissue resembling the midbrain region of the brain. However, a major limitation of conventional brain organoid culture is that it is often labor-intensive, requiring highly specialized personnel for moderate throughput. Additionally, the methods published for long-term cultures require time-consuming maintenance to generate brain organoids in large numbers. With the increasing need for human midbrain organoids (hMOs) to better understand and model Parkinson′s disease (PD) in a dish, there is a need to implement new workflows and methods to both generate and maintain hMOs, while minimizing batch to batch variation. In this study, we developed a method with microfabricated disks to scale up the generation of hMOs. This opens up the possibility to generate larger numbers of hMOs, in a manner that minimizes the amount of labor required, while decreasing variability and maintaining the viability of these hMOs over time. Taken together, producing hMOs in this manner opens up the potential for these to be used to further PD studies.

scholarly journals Microfluidics-enabled 96-well perfusion system for high-throughput tissue engineering and long-term all-optical electrophysiology

2020 ◽  
Author(s):  
Lai Wei ◽  
Weizhen Li ◽  
Emilia Entcheva ◽  
Zhenyu Li
Keyword(s):  
High Throughput ◽  
Pluripotent Stem Cell ◽  
Induced Pluripotent Stem Cell ◽  
Perfusion System ◽  
Excitable Cells ◽  
Hek Cells ◽  
All Optical ◽  
Electrophysiological Studies ◽  
Induced Pluripotent

ABSTRACTThis work demonstrates a novel high-throughput (HT) microfluidics-enabled uninterrupted perfusion system (HT-μUPS) and validates its use with chronic all-optical electrophysiology in human excitable cells. HT-μUPS consists of a soft multichannel microfluidic plate cover which could button on a commercial HT 96-well plate. Herein, we demonstrate the manufacturing process of the system and its usages in acute and chronic all-optical electrophysiological studies of human induced pluripotent stem-cell-derived cardiomyocytes (iPSC-CM) and engineered excitable (Spiking HEK) cells. HT-μUPS perfusion maintained functional voltage and calcium responses in iPSC-CM and Spiking HEK cells under spontaneous conditions and under optogenetic pacing. Long-term culture with HT-μUPS improved cell viability and optogenetically-tracked calcium responses in Spiking HEK cells. The scalability and simplicity of this design and its compatibility with HT all-optical electrophysiology can empower cell-based assays for personalized medicine using patient-derived cells.

scholarly journals Dynamic Behavior in Transition Zones and Long-Term Railway Track Performance

2021 ◽  
Vol 7 ◽  
Author(s):  
André Paixão ◽  
José Nuno Varandas ◽  
Eduardo Fortunato
Keyword(s):  
Three Dimensional ◽  
Structural Response ◽  
Railway Track ◽  
Train Track ◽  
3D Fem ◽  
Transition Zones ◽  
Complex Structural ◽  
Three Dimensional Finite Element ◽  
Long Term Behavior

Transition zones between embankments and bridges or tunnels are examples of critical assets of the railway infrastructure. These locations often exhibit higher degradations rates, mostly due to the development of differential settlements, which amplify the dynamic train-track interaction, thus further accelerating the development of settlements and deteriorating track components and vehicles. Despite the technical and scientific interest in predicting the long-term behavior of transition zones, few studies have been able to develop a robust approach that could accurately simulate this complex structural response. To address this topic, this work presents a three-dimensional finite element (3D FEM) approach to simulate the long-term behavior of railway tracks at transition zones. The approach considers both plastic deformation of the ballast layer using a high-cycle strain accumulation model and the non-linearity of the dynamic vehicle-track interaction that results from the evolution of the deformed states of the track itself. The results shed some light into the behavior of transition zones and evidence the complex long-term response of this structures and its interdependency with the transient response of the train-track interaction. Aspects that are critical when assessing the performance of these systems are analyzed in detail, which might be of relevance for researchers and practitioners in the design, construction, and maintenance processes.

Three Dimensional structure and organization of diploid chromosomes by optical section microscopy

1987 ◽  
Vol 45 ◽  
pp. 633-635
Author(s):  
David A. Agard ◽  
Yasushi Hiraoka ◽  
John W. Sedat
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Developmental State ◽  
Mitotic Cell ◽  
Biological Properties ◽  
Dimensional Structure ◽  
Specific Gene ◽  
Three Dimensional Structure ◽  
Complementary Techniques ◽  
Dynamic Structures

In an effort to understand the complex relationship between structure and biological function within the nucleus, we have embarked on a program to examine the three-dimensional structure and organization of Drosophila melanogaster embryonic chromosomes. Our overall goal is to determine how DNA and proteins are organized into complex and highly dynamic structures (chromosomes) and how these chromosomes are arranged in three dimensional space within the cell nucleus. Futher, we hope to be able to correlate structual data with such fundamental biological properties as stage in the mitotic cell cycle, developmental state and transcription at specific gene loci.Towards this end, we have been developing methodologies for the three-dimensional analysis of non-crystalline biological specimens using optical and electron microscopy. We feel that the combination of these two complementary techniques allows an unprecedented look at the structural organization of cellular components ranging in size from 100A to 100 microns.

Practical electron tomography

1995 ◽  
Vol 53 ◽  
pp. 742-743
Author(s):  
C.L. Woodcock
Keyword(s):  
Electron Tomography ◽  
Tomographic Reconstruction ◽  
Three Dimensional ◽  
3D Shape ◽  
Computational Resources ◽  
Shape Of Particles

Despite the potential of the technique, electron tomography has yet to be widely used by biologists. This is in part related to the rather daunting list of equipment and expertise that are required. Thanks to continuing advances in theory and instrumentation, tomography is now more feasible for the non-specialist. One barrier that has essentially disappeared is the expense of computational resources. In view of this progress, it is time to give more attention to practical issues that need to be considered when embarking on a tomographic project. The following recommendations and comments are derived from experience gained during two long-term collaborative projects.Tomographic reconstruction results in a three dimensional description of an individual EM specimen, most commonly a section, and is therefore applicable to problems in which ultrastructural details within the thickness of the specimen are obscured in single micrographs. Information that can be recovered using tomography includes the 3D shape of particles, and the arrangement and dispostion of overlapping fibrous and membranous structures.

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