title: Short-range cytokine gradients to mimic paracrine cell interactions in vitro.
abstract: Cell fate decisions in many physiological processes, including embryogenesis, stem cell niche homeostasis and wound healing, are regulated by secretion of small signaling proteins, called cytokines, from source cells to their neighbors or into the environment. Concentration level and steepness of the resulting paracrine gradients elicit different cell responses, including proliferation, differentiation or chemotaxis. For an in-depth analysis of underlying mechanisms, in vitro models are required to mimic in vivo cytokine gradients. We set up a microparticle-based system to establish short-range cytokine gradients in a three-dimensional extracellular matrix context. To provide native binding sites for cytokines, agarose microparticles were functionalized with different glycosaminoglycans (GAG). After protein was loaded onto microparticles, its slow release was quantified by confocal microscopy and fluorescence correlation spectroscopy. Besides the model protein lysozyme, SDF-1 was used as a relevant chemokine for hematopoietic stem and progenitor cell (HSPC) chemotaxis. For both proteins we found gradients ranging up to 50μm from the microparticle surface and concentrations in the order of nM to pM in dependence on loading concentration and affinity modulation by the GAG functionalization. Directed chemotactic migration of cells from a hematopoietic cell line (FDCPmix) and primary murine HSPC (Sca-1(+) CD150(+) CD48(-)) toward the SDF-1-laden microparticles proved functional short-range gradients in a two-dimensional and three-dimensional setting over time periods of many hours. The approach has the potential to be applied to other cytokines mimicking paracrine cell-cell interactions in vitro.
authors.affiliation: Institute of Biochemistry, Universität Leipzig, Johannisallee 21/23, 04103 Leipzig, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Ansorge
authors.affiliation: Institute of Biochemistry, Universität Leipzig, Johannisallee 21/23, 04103 Leipzig, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Rastig
authors.affiliation: Institute of Biochemistry, Universität Leipzig, Johannisallee 21/23, 04103 Leipzig, Germany.
authors.forename: Ralph
authors.initials: R
authors.lastname: Steinborn
authors.affiliation: Institute of Biochemistry, Universität Leipzig, Johannisallee 21/23, 04103 Leipzig, Germany.
authors.forename: Tina
authors.initials: T
authors.lastname: König
authors.affiliation: Institute of Biochemistry, Universität Leipzig, Johannisallee 21/23, 04103 Leipzig, Germany.
authors.forename: Lars
authors.initials: L
authors.lastname: Baumann
authors.affiliation: Biomaterials Department, INNOVENT e. V., Prüssingstraße 27B, 07745 Jena, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Möller
authors.affiliation: Biomaterials Department, INNOVENT e. V., Prüssingstraße 27B, 07745 Jena, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Schnabelrauch
authors.affiliation: Department of Hematology, Oncology and Hemostasiology, Universität Leipzig, Johannisallee 32A, 04103 Leipzig, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Cross
authors.affiliation: Max Bergmann Center of Biomaterials, Leibniz Institute of Polymer Research Dresden, Budapester Straße 27, 01069 Dresden, Germany; Center for Regenerative Therapies Dresden, Technische Universität Dresden, Fetscherstraße 105, 01307 Dresden, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Werner
authors.affiliation: Institute of Biochemistry, Universität Leipzig, Johannisallee 21/23, 04103 Leipzig, Germany.
authors.forename: Annette G
authors.initials: AG
authors.lastname: Beck-Sickinger
authors.affiliation: Institute of Biochemistry, Universität Leipzig, Johannisallee 21/23, 04103 Leipzig, Germany; Max Bergmann Center of Biomaterials, Leibniz Institute of Polymer Research Dresden, Budapester Straße 27, 01069 Dresden, Germany. Electronic address: tilo.pompe@uni-leipzig.de.
authors.forename: Tilo
authors.initials: T
authors.lastname: Pompe
mesh_terms: D000465:Algorithms; D000818:Animals; D002450:Cell Communication; D002460:Cell Line; D054377:Chemokine CXCL12 / Q000008:administration & dosage; D002633:Chemotaxis / Q000187:drug effects; D016207:Cytokines / Q000378:metabolism*; D005109:Extracellular Matrix / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000187:drug effects; D051379:Mice; D009113:Muramidase / Q000032:analysis; D053758:Nanoparticles; D019899:Paracrine Communication; D013234:Stem Cells / Q000187:drug effects
chemical_list: D054377:Chemokine CXCL12; C515256:Cxcl12 protein, mouse; D016207:Cytokines; D009113:Muramidase
keywords: Affinity-based release; Agarose; Chemokine; Chemotaxis; Glycosaminoglycan; Gradients; Microparticle