Review articleHigh-throughput screening approaches and combinatorial development of biomaterials using microfluidics☆
Graphical abstract
Introduction
It is now becoming increasingly recognized that in vitro cell culture experimental set-ups in the conventional tissue culture plastics fall short in mimicking the natural in vivo microenvironment, which is considered one of the reasons for their limited predictive value. In addition to efforts required to overcome this issue, an increasing need exists for higher throughput of screening in the biomedical field, with the aim to accelerate the development of new and improved medical treatments against lower costs. In the field of pharmacology, high-throughput screening approaches were implemented relatively early, however, a large gap has been observed between the in vitro findings and the in vivo efficiency of the treatment, which is, for at least in a part, due to the use of oversimplistic conventional cell culture systems [1], [2]. This gap becomes even larger when biomaterials are introduced into the system. Indeed, conventional cell culture platforms were developed to study cell–cell interactions and cell responses to soluble stimuli such as growth factors, antibiotics, small molecules, etc. Interestingly, such platforms were implemented into biomaterials research field without significant modifications. As a consequence, many have shown that results on cell–material interactions obtained in such simplistic systems are also poorly representative of the interactions that occur in vivo [3]. These issues with research systems having poor predictability will undoubtedly continue to exist, since state-of-the-art solutions for clinical problems, such as regenerative strategies for damaged and diseased organs and tissues, are gaining on complexity. Indeed, modern regenerative solutions often include combined contributions from biomaterials of different types, cell- and tissue constructs, growth factors, etc. On the other hand, our society is ageing, requiring the efficiency of discovery of clinical treatments to be maintained at a high level. To keep up with these scientific and societal developments, it is therefore evident that efforts need to be invested in the development of research systems that allow both faster and more reliable screening for biomedical applications.
In the past 10 years, the wealth of developments in the field of microfluidics has helped to establish a new set of standards in the study of basic biological phenomena. Microfluidics is defined as the science and technology of systems that process and manipulate small (10−9–10−18 L) amounts of fluids by using channels with dimensions from tens to hundreds of micrometers [4]. Platforms based on microfluidics offer important advantages over classical in vitro cell culture systems such as close temporal and spatial control over fluids and physical parameters, integration of sensors for direct readout, and the possibility to increase throughput of screening by utilizing parallelization, multiplexing and automation. Furthermore, the micrometer scale makes microfluidic systems unique for having features in the range of a single cell size, which can be highly valuable in fundamental biological resarch, provided that also readouts are scaled down and their sensitivity reaches single cell resolution. Nevertheless, the validity of such assays, or the evidence that they are at least as reliable as conventional assays is needed for microfluidic platforms to be explored to the maximum extent. Alternatively to development of new assays, conventional analytical tools can be rendered applicable to microfluidic systems by means of customized interfacing [5].
Apart from the assays, the platforms as such, including the materials they are made from, and methods to produce them, need to prove their value for biomedical research. In early microfluidic systems for biomedical applications, rigid, inert materials such as silicon and glass, directly inherited from the field of microelectronics, reigned. However, current technology now allows the use of biopolymers that can be microfabricated to detail, tuned in their properties (e.g. stiffness, porosity, dielectric properties, hydrophilicity) by chemical changes, and biochemically decorated to better mimic the natural microenvironment [6]. These include photo- or heat-curable polymers such as SU-8 epoxy, polyimide photoresist, poly-dimethylsiloxane (PDMS) elastomer, as well as thermoplasts such as polymethylmethacrylate, polycarbonate, polystyrene, cyclic-olefin-copolymers and Teflon. Also the ever-lasting discussion between the PDMS-land engineers and polystyrenia kingdom biologists [7] has become further democratised, as a consequence of an exponentially increasing availability of complex materials that can be embedded in microfluidic devices, the on-demand delivery of smart hydrogels, and the nanometer-scale resolution printability of new scaffolding polymers and bioinorganics.
In this review, we aim to provide an overview of advances in the field of microfluidics that can aid biomedical research, with special emphasis on the field of biomaterials. We will do so by describing relevant examples of platforms that are developed with the aim of: (1) screening, in particular high-throughput and combinatorial screening, (2) mimicking of natural microenvironment ranging from 3D hydrogel-based cellular niches to organ-on-chip devices; and (3) production of a new generation of deliverable materials.
Section snippets
Screening cellular responses in microfluidic systems
A growing interest in microfluidic systems is largely derived from their proven versatility in biosensor applications. This multidisciplinary research field rapidly delivered point-of-care diagnostic devices, which are predominantly based on transducer mechanisms using biomolecules for sensitive and selective recognition of analytes in the bioenvironmental or biological samples. Oligonucleotides, peptides, enzymes and other bioprobes, adsorbed on, covalently bonded to or otherwise connected
Biomimetic microenvironments
Besides the so far highlighted possibilities of microfluidic technology to increase throughput of screening through parallelization and integration, expectations are at least as high when it comes to creating microenvironments that closely resemble the natural systems. Through compartmentalization in 3D, resulting from various multilayering options, initially developed within the microelectromechanical system (MEMS) field, complex microenvironments can now be created relatively easily at low
Biomaterial production using microfluidics
As is described thus far, screening of biological phenomena and generation of physiologically relevant biological models are by far the most important applications of microfluidic systems in biomedical science. Nevertheless, such systems can also be very useful as tools for fabricating, natural or synthetic, biomaterials. Three main applications of such microfluidics-produced biomaterials can be identified: delivery of (biological) compounds and/or cells; enrichment of rare primary cells; and
General conclusions and outlook
This review discussed a number of developments in the field of microfluidics relevant to biomedical research, with an emphasis on biomaterials. Microfluidics can support biomedical research by either accelerating the throughput of screening, or by increasing the complexity of in vitro models in order to more closely resemble the in vivo microenvironment. The development of high-throughput and combinatorial screening of physical and chemical cues, known to interfere in biological processes, was
Acknowledgements
D.B. gratefully acknowledges the financial support of the NIRM (Netherlands Institute of Regenerative Medicine). This research has been in part made possible with the support of the Dutch Province of Limburg.
References (210)
- et al.
Biomaterials meet microfluidics: building the next generation of artificial niches
Curr. Opin. Biotechnol.
(2011) - et al.
Microfluidic 3D bone tissue model for high-throughput evaluation of wound-healing and infection-preventing biomaterials
Biomaterials
(2012) - et al.
Characterization of 3D-printed microfluidic chip interconnects with integrated O-rings
Sens. Actuators, A
(2014) - et al.
Development of a multilayer microfluidic device integrated with a PDMS-cellulose composite film for sample pre-treatment and immunoassay
Sens. Actuators, A
(2013) - et al.
Microfluidic tools for cell biological research
Nano Today
(2010) - et al.
Single cells as experimentation units in lab-on-a-chip devices
Trends Biotechnol.
(2010) - et al.
A microfluidic array for quantitative analysis of human neural stem cell self-renewal and differentiation in three-dimensional hypoxic microenvironment
Biomaterials
(2013) - et al.
A microfluidic cell array with individually addressable culture chambers
Biosens. Bioelectron.
(2008) - et al.
A microfluidic approach for anticancer drug analysis based on hydrogel encapsulated tumor cells
Anal. Chim. Acta
(2010) - et al.
Biomaterials-based microfluidics for engineered tissue constructs
Soft Matter
(2010)
Predictive value of in vitro and in vivo assays in bone and cartilage repair–What do they really tell us about the clinical performance?
Adv. Exp. Med. Biol.
The origins and the future of microfluidics
Nature
Imitation of drug metabolism in human liver and cytotoxicity assay using a microfluidic device coupled to mass spectrometric detection
Lab Chip
Bio-microfluidics: biomaterials and biomimetic designs
Adv. Mater.
Engineers are from PDMS-land, biologists are from polystyrenia
Lab Chip
Integrated lab-on-chip biosensing systems based on magnetic particle actuation–a comprehensive review
Lab Chip
Microfluidic-based biosensors toward point-of-care detection of nucleic acids and proteins
Microfluid. Nanofluid.
Microfluidic-integrated biosensors: prospects for point-of-care diagnostics
Biotechnol. J.
Enabling systems biology approaches through microfabricated systems
Anal. Chem.
In vitro microvessels for the study of angiogenesis and thrombosis
Proc. Natl. Acad. Sci. U.S.A.
Mail-order microfluidics: evaluation of stereolithography for the production of microfluidic devices
Lab Chip
3D-printed microfluidic automation
Lab Chip
A simple method for fabricating multi-layer PDMS structures for 3D microfluidic chips
Lab Chip
Microbioreactor arrays for full factorial screening of exogenous and paracrine factors in human embryonic stem cell differentiation
PLoS One
Leakage-free bonding of porous membranes into layered microfluidic array systems
Anal. Chem.
Design and fabrication of a multilayered polymer microfluidic chip with nanofluidic interconnects via adhesive contact printing
Lab Chip
Fluidic communication between multiple vertically segregated microfluidic channels connected by nanocapillary array membranes
Electrophoresis
Microfluidic platforms for lab-on-a-chip applications
Lab Chip
Centrifugal microfluidic platforms: advanced unit operations and applications
Chem. Soc. Rev.
Microfluidic device for single-cell analysis
Anal. Chem.
Dynamic single cell culture array
Lab Chip
Cell chip array for microfluidic proteomics enabling rapid in situ assessment of intracellular protein phosphorylation
Biomicrofluidics
Multivariate analysis of apoptotic markers versus cell cycle phase in living human cancer cells by microfluidic cytometry
Proc. SPIE
Microfluidic single-cell analysis for systems immunology
Lab Chip
Microfluidic single-cell array cytometry for the analysis of tumor apoptosis
Anal. Chem.
Microfluidic high-throughput encapsulation and hydrodynamic self-sorting of single cells
Proc. Natl. Acad. Sci. U.S.A.
Ultrahigh-throughput mammalian single-cell reverse-transcriptase polymerase chain reaction in microfluidic drops
Anal. Chem.
Droplet microfluidic technology for single-cell high-throughput screening
Proc. Natl. Acad. Sci. U.S.A.
Integrated microfluidic array plate (iMAP) for cellular and molecular analysis
Lab Chip
Microfluidic array with integrated oxygenation control for real-time live-cell imaging: effect of hypoxia on physiology of microencapsulated pancreatic islets
Anal. Chem.
Development of a multi-layer microfluidic array chip to culture and replate uniform-sized embryoid bodies without manual cell retrieval
Lab Chip
Single-cell analysis of embryoid body heterogeneity using microfluidic trapping array
Biomed. Microdevices
A microfluidic array for large-scale ordering and orientation of embryos
Nat. Methods
Drosophila, the golden bug, emerges as a tool for human genetics
Nat. Rev. Genet.
Caenorhabditis elegans: an emerging model in biomedical and environmental toxicology
Toxicol. Sci.
The art and design of genetic screens: Drosophila melanogaster
Nat. Rev. Genet.
Microfluidic trap array for massively parallel imaging of Drosophila embryos
Nat. Protoc.
A microfluidic platform for high-sensitivity, real-time drug screening on C. elegans and parasitic nematodes
Lab Chip
Lifespan-on-a-chip: microfluidic chambers for performing lifelong observation of C. elegans
Lab Chip
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Screening as a strategy to drive regenerative medicine research
2021, MethodsCitation Excerpt :An extra layer of complexity can be introduced through compartmentalization, in which different separate cell systems are connected, which moves the platform more towards an organ-on-a-chip concept. These examples demonstrate that the microfluidic lab-on-a-chip concept is a highly versatile and attractive platform for high-throughput research in a regenerative medicine context [107]. Micro-fluidics research in a high-throughput setting often involves the use of compound gradients.
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Part of the High Throughput Approaches to Screening Biomaterials Special Issue, edited by Kristopher Kilian and Prabhas Moghe.
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Current affiliation: Maastricht University, MERLN Institute for Technology-Inspired Regenerative Medicine, P.O. Box 616, 6200 MD Maastricht, The Netherlands.