Microfluidic systems: A new toolbox for pluripotent stem cells

Conventional culture systems are often limited in their ability to regulate the growth and differentiation of pluripotent stem cells. Microfluidic systems can overcome some of these limitations by providing defined growth conditions with user‐controlled spatiotemporal cues. Microfluidic systems allow researchers to modulate pluripotent stem cell renewal and differentiation through biochemical and mechanical stimulation, as well as through microscale patterning and organization of cells and extracellular materials. Essentially, microfluidic tools are reducing the gap between in vitro cell culture environments and the complex and dynamic features of the in vivo stem cell niche. These microfluidic culture systems can also be integrated with microanalytical tools to assess the health and molecular status of pluripotent stem cells. The ability to control biochemical and mechanical input to cells, as well as rapidly and efficiently analyze the biological output from cells, will further our understanding of stem cells and help translate them into clinical use. This review provides a comprehensive insignt into the implications of microfluidics on pluripotent stem cell research. Conventional culture systems are often limited in their ability to regulate the growth and differentiation of pluripotent stem cells. In this review, the authors describe technologies that move small volumes of fluids (on microscales) and how they can be used with stem cells. These technologies can provide precise signals that control stem cells, causing them to self‐renew (produce more stem cells) or differentiate (become any of the cells in the body). They can also be used to investigate the biology of stem cells and test their quality for medical applications. These powerful tools could one day be used to combat degenerative diseases.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96259/1/180_ftp.pd

384 hanging drop arrays give excellent Z ‐factors and allow versatile formation of co‐culture spheroids

We previously reported the development of a simple, user‐friendly, and versatile 384 hanging drop array plate for 3D spheroid culture and the importance of utilizing 3D cellular models in anti‐cancer drug sensitivity testing. The 384 hanging drop array plate allows for high‐throughput capabilities and offers significant improvements over existing 3D spheroid culture methods. To allow for practical 3D cell‐based high‐throughput screening and enable broader use of the plate, we characterize the robustness of the 384 hanging drop array plate in terms of assay performance and demonstrate the versatility of the plate. We find that the 384 hanging drop array plate performance is robust in fluorescence‐ and colorimetric‐based assays through Z ‐factor calculations. Finally, we demonstrate different plate capabilities and applications, including: spheroid transfer and retrieval for Janus spheroid formation, sequential addition of cells for concentric layer patterning of different cell types, and culture of a wide variety of cell types. Biotechnol. Bioeng. 2012; 109:1293–1304. © 2011 Wiley Periodicals, Inc. This paper characterizes the robustness of the high‐throughput 384 hanging drop array spheroid formation and culture plate in terms of assay performance. The versatility of the platform was further demonstrated through 3D patterning of multiple cell types into concentric layers and as Janus spheroids. The system is envisioned to deliver valuable insights into 3D cellular behavior as well as more accurate readouts from 3D cell‐based high‐throughput screening and testing.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90601/1/24399_ftp.pd

Application of Microfluidics in Stem Cell Culture

In this chapter, we review the recent developments, including our studies on the microfabricated devices applicable to stem cell culture. We will focus on the application of pluripotent stem cells including embryonic stem cells and induced pluripotent stem cells. In the first section, we provide a background on microfluidic devices, including their fabrication technology, characteristics, and the advantages of their application in stem cell culture. The second section outlines the use of micropatterning technology in stem cell culture. The use of microwell array technology in stem cell culture is explored in the third section. In the fourth section, we discuss the use of the microfluidic perfusion culture system for stem cell culture, and the last section is a summary of the current state of the art and perspectives of microfluidic technologies in stem cell culture

Microfluidic devices for cell cultivation and proliferation

Microfluidic technology provides precise, controlled-environment, cost-effective, compact, integrated, and high-throughput microsystems that are promising substitutes for conventional biological laboratory methods. In recent years, microfluidic cell culture devices have been used for applications such as tissue engineering, diagnostics, drug screening, immunology, cancer studies, stem cell proliferation and differentiation, and neurite guidance. Microfluidic technology allows dynamic cell culture in microperfusion systems to deliver continuous nutrient supplies for long term cell culture. It offers many opportunities to mimic the cell-cell and cell-extracellular matrix interactions of tissues by creating gradient concentrations of biochemical signals such as growth factors, chemokines, and hormones. Other applications of cell cultivation in microfluidic systems include high resolution cell patterning on a modified substrate with adhesive patterns and the reconstruction of complicated tissue architectures. In this review, recent advances in microfluidic platforms for cell culturing and proliferation, for both simple monolayer (2D) cell seeding processes and 3D configurations as accurate models of in vivo conditions, are examined

A multiple-funnels cell culture insert for the scale-up production of uniform cell spheroids

Introduction: Formation of cell spheres is an important procedure in biomedical research. A large number of high-quality cell spheres of uniform size and shape are required for basic studies and therapeutic applications. Conventional approaches, including the hanging drop method and suspension culture, are used for cell sphere production. However, these methods are time consuming, cell spheres cannot be harvested easily, and it is difficult to control the size and geometry of cell spheres. To resolve these problems, a novel multiple-funnel cell culture insert was designed for size controlling, easy harvesting, and scale-up production of cell spheres. Methods: The culture substrate has 680 micro-funnels with a 1-mm width top, 0.89 mm depth, and 0.5 mm square bottom. Mouse embryonic stem cells were used to test the newly developed device. The seeded embryonic stem cells settled at the downward medium surface toward the bottom opening and aggregated as embryoid bodies (EBs). For cell sphere harvest, the bottom of the culture insert was put in contact with the medium surface in another culture dish, and the medium in the device flowed down with cell spheres by hydrostatic pressure. Results: Compact cell spheres with uniform size and shape were collected easily. The diameter of the spheres could be controlled by adjusting the seeding cell density. Spontaneous neural differentiation (nestin and Tju1) and retinoic acid-induced endodermal differentiation (Pdx-1 and insulin I) were improved in the EBs produced using the new insert compared to those in EBs produced by suspension culture. Conclusions: This novel cell culture insert shall improve future studies of cell spheres and benefit clinical applications of cell therapy

Probing Embryonic Stem Cell Autocrine and Paracrine Signaling Using Microfluidics

Although stem cell fate is traditionally manipulated by exogenously altering the cells' extracellular signaling environment, the endogenous autocrine and paracrine signals produced by the cells also contribute to their two essential processes: self-renewal and differentiation. Autocrine and/or paracrine signals are fundamental to both embryonic stem cell self-renewal and early embryonic development, but the nature and contributions of these signals are often difficult to fully define using conventional methods. Microfluidic techniques have been used to explore the effects of cell-secreted signals by controlling cell organization or by providing precise control over the spatial and temporal cellular microenvironment. Here we review how such techniques have begun to be adapted for use with embryonic stem cells, and we illustrate how many remaining questions in embryonic stem cell biology could be addressed using microfluidic technologies.National Institutes of Health (U.S.) (EB007278)Singapore-MIT AllianceNational Science Foundation (U.S.) (0939511

Reproducible, Ultra High-Throughput Formation of Multicellular Organization from Single Cell Suspension-Derived Human Embryonic Stem Cell Aggregates

Background: Human embryonic stem cells (hESC) should enable novel insights into early human development and provide a renewable source of cells for regenerative medicine. However, because the three-dimensional hESC aggregates [embryoid bodies (hEB)] typically employed to reveal hESC developmental potential are heterogeneous and exhibit disorganized differentiation, progress in hESC technology development has been hindered. Methodology/Principal Findings: Using a centrifugal forced-aggregation strategy in combination with a novel centrifugalextraction approach as a foundation, we demonstrated that hESC input composition and inductive environment could be manipulated to form large numbers of well-defined aggregates exhibiting multi-lineage differentiation and substantially improved self-organization from single-cell suspensions. These aggregates exhibited coordinated bi-domain structures including contiguous regions of extraembryonic endoderm- and epiblast-like tissue. A silicon wafer-based microfabrication technology was used to generate surfaces that permit the production of hundreds to thousands of hEB per cm 2. Conclusions/Significance: The mechanisms of early human embryogenesis are poorly understood. We report an ultra high throughput (UHTP) approach for generating spatially and temporally synchronised hEB. Aggregates generated in this manner exhibited aspects of peri-implantation tissue-level morphogenesis. These results should advance fundamental studies into early human developmental processes, enable high-throughput screening strategies to identify conditions tha

Advanced 3D cell culture techniques in micro-bioreactors, Part II: Systems and applications

In this second part of our systematic review on the research area of 3D cell culture in micro-bioreactors we give a detailed description of the published work with regard to the existing micro-bioreactor types and their applications, and highlight important results gathered with the respective systems. As an interesting detail, we found that micro-bioreactors have already been used in SARS-CoV research prior to the SARS-CoV2 pandemic. As our literature research revealed a variety of 3D cell culture configurations in the examined bioreactor systems, we defined in review part one “complexity levels” by means of the corresponding 3D cell culture techniques applied in the systems. The definition of the complexity is thereby based on the knowledge that the spatial distribution of cell-extracellular matrix interactions and the spatial distribution of homologous and heterologous cell–cell contacts play an important role in modulating cell functions. Because at least one of these parameters can be assigned to the 3D cell culture techniques discussed in the present review, we structured the studies according to the complexity levels applied in the MBR systems