Development-on-chip: in vitro neural tube patterning with a microfluidic device

Abstract

Embryogenesis is a highly regulated process in which the precise spatial and temporal release of soluble cues directs differentiation of multipotent stem cells into discrete populations of specialized adult cell types. In the spinal cord, neural progenitor cells are directed to differentiate into adult neurons through the action of mediators released from nearby organizing centers, such as the floor plate and paraxial mesoderm. These signals combine to create spatiotemporal diffusional landscapes that precisely regulate the development of the central nervous system (CNS). Currently, in vivo and ex vivo studies of these signaling factors present some inherent ambiguity. In vitro methods are preferred for their enhanced experimental clarity but often lack the technical sophistication required for biological realism. In this article, we present a versatile microfluidic platform capable of mimicking the spatial and temporal chemical environments found in vivo during neural tube development. Simultaneous opposing and/or orthogonal gradients of developmental morphogens can be maintained, resulting in neural tube patterning analogous to that observed in vivo.

In Vitro Microfluidic Models for Neurodegenerative Disorders

“…They also showed that the opposing effects of agonist (SHH) and antagonist (BMP4) on the proliferation and differentiation of hESC‐derived neurons could be successfully recapitulated by means of concentration gradients in the microfluidic device. Demers et al demonstrated the generation of four different molecular gradients in multilayered microfluidic devices for the reconstruction of neural tube by means of mimicking the primary aspects of the diffusion‐based patterning of the neural tube . Flow channels running under the cell culture channels supply nutrients and desired guidance molecules to the cells.…”

Bioengineered microenvironment to culture early embryos

“…It not only helps to enhance our understanding of the early development of human embryos but also bypasses the bioethical issues related to human embryo research. Signal molecules control the differentiation of PSCs during embryonic development with specific spatial and temporal distributions . Demers et al designed a dual‐channel microfluidic system (Figure F), which can provide ESCs in the central culture chamber with signal molecules with concentration gradients, simulating the natural spatiotemporal distribution, thereby inducing the formation of neural tube patterns.…”

Spatiotemporal Control of Morphogen Delivery to Pattern Stem Cell Differentiation in Three‐Dimensional Hydrogels

“…At present, studies have demonstrated sustained morphogen gradients within geometrically small (sub‐millimeter) three‐dimensional cell culture over moderately short periods of time (days) (Kinney & McDevitt, ). Other prominent examples include delivering retinoic acid to a sheet of embryonic stem cells for neuronal differentiation (Cosson & Lutolf, ), and a microfluidic chip with four channels surrounding a cell‐laden hydrogel to pattern a neural tube with retinoic acid, sonic hedgehog, bone morphogenic protein, and fibroblast growth factor (Demers et al., ). Some systems even go as far as linking multiple tissue types together in one microfluidic circuit such that secreted morphogens feed each component tissue type to reflect whole organism physiology (Maschmeyer et al., ).…”

“…Morphogens are biological molecules that activate or repress biochemical pathways within cells during development of tissues and organs. Numerous research groups have explored how morphogens alter tissue growth and differentiation, including examples such as spatial patterning of the anteroposterior axis by retinoic acid and fibroblast growth factor, and mesoderm differentiation of cardiac tissue by transforming growth factor β (Birket et al., ; Buckingham, Meilhac, & Zaffran, ; Demers et al., ; Kinney & McDevitt, ; Sadler, ; Schneider, ). Morphogens have also been shown to maintain tissue homeostasis in adult organisms, as demonstrated in the intestine with bone morphogenic protein and wingless/integrated protein, where undifferentiated stem cells below the crypts provide an unlimited cell source to replace the epithelial lining responsible for both nutrient absorption and barrier function against harmful microbiota (Barker, ; Beaulieu, ; Lane, Williams, & Watt, ).…”