title: Differentiation of neural progenitor cells in a microfluidic chip-generated cytokine gradient.
abstract: In early embryonic development, spatial gradients of diffusible signaling molecules play important roles in controlling differentiation of cell types or arrays in diverse tissues. Thus, the concentration of exogenous cytokines or growth factors at any given time is crucial to the formation of an enriched population of a desired cell type from primitive stem cells in vitro. Microfluidic technology has proven very useful in the creation of cell-friendly microenvironments. Such techniques are, however, currently limited to a few cell types. Improved versatility is required if these systems are to become practically applicable to stem cells showing various plasticity ranges. Here, we built a microfluidic platform in which cells can be exposed to stable concentration gradients of various signaling molecules for more than a week with only minimal handling and no external power source. To maintain stability of the gradient concentration, the osmotic pumping performance was optimized by balancing the capillary action and hydraulic pressure in the inlet reagent reservoirs. We cultured an enriched population of neural progenitors derived from human embryonic stem cells in our microfluidic chamber for 8 days under continuous cytokine gradients (sonic hedgehog, fibroblast growth factor 8, and bone morphogenetic protein 4). Neural progenitors successfully differentiated into neurons, generating a complex neural network. The average numbers of both neuronal cell body clusters and neurite bundles were directly proportional to sonic hedgehog concentrations in the gradient chip. The system was shown to be useful for both basic and translational research, with straightforward mechanisms and operational schemes.
authors.affiliation: Department of Biomedical Engineering, College of Health Science, Korea University, Seoul 136-703, Republic of Korea.
authors.forename: Joong Yull
authors.initials: JY
authors.lastname: Park
authors.forename: Suel-Kee
authors.initials: SK
authors.lastname: Kim
authors.forename: Dong-Hun
authors.initials: DH
authors.lastname: Woo
authors.forename: Eun-Joong
authors.initials: EJ
authors.lastname: Lee
authors.forename: Jong-Hoon
authors.initials: JH
authors.lastname: Kim
authors.forename: Sang-Hoon
authors.initials: SH
authors.lastname: Lee
mesh_terms: D055415:Bone Morphogenetic Protein 4 / Q000737:chemistry / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects*; D002478:Cells, Cultured; D016207:Cytokines / Q000737:chemistry / Q000494:pharmacology*; D053595:Embryonic Stem Cells / Q000166:cytology* / Q000187:drug effects*; D051524:Fibroblast Growth Factor 8 / Q000737:chemistry / Q000494:pharmacology; D005434:Flow Cytometry; D053823:Hedgehog Proteins / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D046210:Microfluidic Analytical Techniques / Q000379:methods*; D008962:Models, Theoretical; D009474:Neurons / Q000166:cytology* / Q000187:drug effects; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects
chemical_list: D055415:Bone Morphogenetic Protein 4; D016207:Cytokines; D053823:Hedgehog Proteins; D051524:Fibroblast Growth Factor 8