Recent Advances of Biologically Inspired 3D Microfluidic Hydrogel Cell Culture Systems

Abstract

Application of Microfluidics in Life SciencesMicrofluidics can be defined as the study of fluid and air flows in microchannels and was initially introduced to facilitate liquid handling and sample preparations. Early work dates back to 1969 with Lew's work on a theoretical solution for mimicking blood and air flow in a microcirculatory system of the lung [1]. In this precursor stage of microfluidics the aim was to create a biomimetic system, which facilitated the study of biological pathways in vitro. It was not until the 1990s that the field of microfluidics emerged from miniaturization efforts and Micro-Electro-Mechanical Systems (MEMS) as an enabling technology platform for dispensing systems, analytical separations, chemical reactions, and bioanalysis applications. Since then, microfluidics has evolved into an established technology ranging from medical solutions (e.g., microfluidic inhalers), in vitro diagnostics (e.g., point of care) and production applications (e.g., microreaction technologies) [2]. More recent research applications include microchips for genomics, proteomics and cell-based assays.These microfluidic cell cultures are considered potential candidates to provide next generation cell analysis systems. Starting from single cell analysis using miniaturized flow cytometers [3] a variety of microfluidic devices have been developed for cell studies to investigate cell transport and cultivation in the absence and presence of concentration and temperature gradients or shear force conditions. The main benefit of microfluidic systems for cell culture analysis is that they can perform a number of crucial liquid handling steps including cell loading, nutrient supply and waste removal under physiologically relevant shear force conditions, all while offering real time microscopy [4]. Microfluidics also enables precise regulation of soluble factors including drug candidates, growth factors at specific solution concentrations and gradients, thus providing robust and reproducible measurement conditions. An alternative application of microfluidics for cell analysis is micropatterning to (a) optimize control of cellular behavior [5], (b) allow cell migration [6], (c) spatially resolve co-cultures systems [7] and (d) define cell repulsive and adhesive areas [8].Despite recent achievements of microfluidic 2D cell culture systems [9], they still do not address the fact that in vivo cells coexist in 3D communities that are influenced by spatial orientation of cells and cell-to-cell contact within the extracellular matrix [10]. It has been repeatedly demonstrated that the presence of a 3D matrix promotes many biologically relevant functions otherwise not observed in 2D monolayer cell cultures [11]. Consequently a transition from 2D to 3D cell cultures has gained momentum as an increasing number of reports have confirmed significant differences in the morphology, protein expression, differentiation, migration, functionality and viability of cells between 3D and 2D cell cultures [12]; these non-microfluidic advances a...

Small Force, Big Impact: Next Generation Organ-on-a-Chip Systems Incorporating Biomechanical Cues

“…The combination of microfabrication-based technologies with complex biology has enabled the development of advanced in vitro models capable of culturing and analyzing cell and tissue constructs under physiologically relevant conditions ( Ertl, 2015 ; Rothbauer et al, 2015 , 2017 ). While microfluidic models for 2D mechanical stimulation involving stretch and strain has been widely investigated, the application of physiologically relevant axial strain in 3D cell culture systems is still in its infancy.…”

Musculoskeletal tissues-on-a-chip: role of natural polymers in reproducing tissue-specific microenvironments

“…Usually, 3D in vitro models employ wellestablished biomaterials or commercial ones as support matrix. For example, natural polymers have been employed in microfluidic devices in order to facilitate the screening of drugs and anticancer agents, to study cell-cell interactions or cell migration [4]. Aizel et al proposed a microfluidic system to study cell migration in a type I collagen-based 3D environment in response to a chemokine gradient [5].…”

Engineering of three-dimensional pre-vascular networks within fibrin hydrogel constructs by microfluidic control over reciprocal cell signaling

“…Microfluidic cell culture systems are ideally suited to study vascular biology due to the inherent ability to control the respective microenvironment. [12][13][14][15][16][17] For instance, 2D microfluidic endothelial cell cultures systems have been used to elucidate the impact of growth factor gradients in intra-and extravasation of cancer cells [18][19][20] as well as VEGF 21,22 and angiopoietin-1 (ANG-1) gradients in endothelial cell sprouting. 21 In addition to demonstrating the importance of VEGF gradients for the formation of blood vessels, 23,24 microfluidic devices are routinely employed to provide physiologically relevant shear and interstitial flow regimes.…”