title: Paracrine exchanges of molecular signals between alginate-encapsulated pericytes and freely suspended endothelial cells within a 3D protein gel.
abstract: Paracrine signals, essential for the proper survival and functioning of tissues, may be mimicked by delivery of therapeutic proteins within engineered tissue constructs. Conventional delivery methods are of limited duration and are unresponsive to the local environment. We developed a system for sustained and regulated delivery of paracrine signals by encapsulating living cells of one type in alginate beads and co-suspending these cell-loaded particles along with unencapsulated cells of a second type within a 3D protein gel. This system was applied to vascular tissue engineering by placing human placental microvascular pericytes (PCs) in the particulate alginate phase and human umbilical vein endothelial cells (HUVECs) in the protein gel phase. Particle characteristics were optimized to keep the encapsulated PCs viable for at least two weeks. Encapsulated PCs were bioactive in vitro, secreting hepatocyte growth factor, an angiogenic protein, and responding to externally applied HUVEC-derived signals. Encapsulated PCs influenced HUVEC behavior in the surrounding gel by enhancing the formation of vessel-like structures when compared to empty alginate bead controls. In vivo, encapsulated PCs modulated the process of vascular self-assembly by HUVECs in 3D gels following implantation into immunodeficient mice. We conclude that alginate encapsulated cells can provide functional paracrine signals within engineered tissues.
authors: Department of Biomedical Engineering, Yale University, New Haven, CT 06511, USA.
authors: Jillian W
authors: JW
authors: Andrejecsk
authors: Jiajia
authors: J
authors: Cui
authors: William G
authors: WG
authors: Chang
authors: Julie
authors: J
authors: Devalliere
authors: Jordan S
authors: JS
authors: Pober
authors: W Mark
authors: WM
authors: Saltzman
mesh_terms: D000464:Alginates / Q000737:chemistry*; D000818:Animals; D002460:Cell Line; D018914:Cells, Immobilized / Q000737:chemistry*; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism; D005782:Gels / Q000737:chemistry; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D008297:Male; D051379:Mice; D016513:Mice, SCID; D055806:Microvessels / Q000166:cytology / Q000378:metabolism; D019899:Paracrine Communication / Q000502:physiology*; D010316:Particle Size; D020286:Pericytes / Q000166:cytology* / Q000378:metabolism; D023822:Tissue Engineering / Q000379:methods
chemical_list: D000464:Alginates; D005782:Gels; D006603:Hexuronic Acids; D020723:Glucuronic Acid
keywords: Alginate; Cell encapsulation; Co-culture; Pericyte; Protein delivery; Vascular tissue engineering
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