title: A novel concept for scaffold-free vessel tissue engineering: self-assembly of microtissue building blocks.
abstract: Current scientific attempts to generate in vitro tissue-engineered living blood vessels (TEBVs) show substantial limitations, thereby preventing routine clinical use. In the present report, we describe a novel biotechnology concept to create living small diameter TEBV based exclusively on microtissue self-assembly (living cellular re-aggregates). A novel bioreactor was designed to assemble microtissues in a vascular shape and apply pulsatile flow and circumferential mechanical stimulation. Microtissues composed of human artery-derived fibroblasts (HAFs) and endothelial cells (HUVECs) were accumulated and cultured for 7 and 14 days under pulsatile flow/mechanical stimulation or static culture conditions with a diameter of 3mm and a wall thickness of 1mm. The resulting vessels were analyzed by immunohistochemistry for extracellular matrix (ECM) and cell phenotype (von Willebrand factor, alpha-SMA, Ki67, VEGF). Self-assembled microtissues composed of fibroblasts displayed significantly accelerated ECM formation compared to monolayer cell sheets. Accumulation of vessel-like tissue occurred within 14 days under both, static and flow/mechanical stimulation conditions. A layered tissue formation was observed only in the dynamic group, as indicated by luminal aligned alpha-SMA positive fibroblasts. We could demonstrate that self-assembled cell-based microtissues can be used to generate small diameter TEBV. The significant enhancement of ECM expression and maturation, together with the pre-vascularization capacity makes this approach highly attractive in terms of generating functional small diameter TEBV devoid of any foreign material.
authors.affiliation: Regenerative Medicine Program, Department of Surgical Research, University of Zürich, CH-8091 Zürich, Switzerland. jens.kelm@cabmm.uzh.ch
authors.forename: Jens M
authors.initials: JM
authors.lastname: Kelm
authors.forename: Volker
authors.initials: V
authors.lastname: Lorber
authors.forename: Jess G
authors.initials: JG
authors.lastname: Snedeker
authors.forename: Dörthe
authors.initials: D
authors.lastname: Schmidt
authors.forename: Angela
authors.initials: A
authors.lastname: Broggini-Tenzer
authors.forename: Martin
authors.initials: M
authors.lastname: Weisstanner
authors.forename: Bernhard
authors.initials: B
authors.lastname: Odermatt
authors.forename: Anita
authors.initials: A
authors.lastname: Mol
authors.forename: Gregor
authors.initials: G
authors.lastname: Zünd
authors.forename: Simon P
authors.initials: SP
authors.lastname: Hoerstrup
mesh_terms: D000199:Actins / Q000378:metabolism; D001158:Arteries / Q000166:cytology*; D001696:Biomechanical Phenomena; D019149:Bioreactors; D001807:Blood Vessel Prosthesis; D024141:Collagen Type IV / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology; D005347:Fibroblasts / Q000166:cytology; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D008955:Models, Cardiovascular; D046509:Tissue Culture Techniques / Q000295:instrumentation / Q000379:methods; D023822:Tissue Engineering / Q000295:instrumentation / Q000379:methods; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D014841:von Willebrand Factor / Q000378:metabolism
chemical_list: D000199:Actins; D024141:Collagen Type IV; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D014841:von Willebrand Factor