title: Endothelial pattern formation in hybrid constructs of additive manufactured porous rigid scaffolds and cell-laden hydrogels for orthopedic applications.
abstract: Vascularization of tissue engineering constructs (TECs) in vitro is of critical importance for ensuring effective and satisfactory clinical outcomes upon implantation of TECs. Biomechanical properties of TECs have remarkable influence on the in vitro vascularization of TECs. This work utilized in vitro experiments and finite element analysis to investigate endothelial patterns in hybrid constructs of soft collagen gels and rigid macroporous poly(ε-caprolactone)-β-tricalcium phosphate (PCL-β-TCP) scaffold seeded/embedded with human umbilical vein endothelial cells (HUVECs) for bone tissue engineering applications. We first fabricated and characterized well-defined porous PCL-β-TCP scaffolds with identical pore size (500µm) but different strut sizes (200 and 400µm) using additive manufacturing (AM) technology, and then assessed the HUVEC׳s proliferation and morphogenesis within collagen, PCL-β-TCP scaffold, and the collagen-scaffold hybrid construct. Results showed that, in the hybrid construct, the cell population in the collagen component dropped by day 7 but then increased by day 14. Also, cells migrated onto the struts of the scaffold component, proliferated over time, and formed networks on the thinner struts (i.e., 200µm). Also, the thinner struts resulted in formation of long linear cellular cords structures within the pores. Finite element simulation demonstrated principal stress patterns similar to the observed cell-network pattern. It is probable that the scaffold component modulated patterns of principal stresses in the collagen component as biomechanical cues for reorganization of cell network patterns. Also, the scaffold component significantly improved the mechanical integrity of hydrogel component in the hybrid construct for weight-bearing applications. These results have collectively indicated that the manipulation of micro-architecture of scaffold could be an effective means to further regulate and guide desired cellular response in hybrid constructs.
authors.affiliation: Department of Orthopedic Surgery, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA.
authors.forename: Yaser
authors.initials: Y
authors.lastname: Shanjani
authors.affiliation: Department of Orthopedic Surgery, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA.
authors.forename: Yunqing
authors.initials: Y
authors.lastname: Kang
authors.affiliation: Department of Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA.
authors.forename: Livia
authors.initials: L
authors.lastname: Zarnescu
authors.affiliation: Department of Electrical Engineering, Stanford University, 348 Via Pueblo, Stanford, CA 94305, USA.
authors.forename: Audrey K
authors.initials: AK
authors.lastname: Ellerbee Bowden
authors.affiliation: School of Dentistry, Chonnam National University, 77 Yongbong-ro, Buk-gu, Gwangju 500-757, Republic of Korea.
authors.forename: Jeong-Tae
authors.initials: JT
authors.lastname: Koh
authors.affiliation: Department of Orthopedic Surgery, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA.
authors.forename: Dai Fei Elmer
authors.initials: DFE
authors.lastname: Ker
authors.affiliation: Department of Orthopedic Surgery, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA; Department of Bioengineering, Stanford University, 318 Campus Drive, Stanford, CA 94305, USA; Department of Materials Science and Engineering, Stanford University, 300 Pasteur Drive, Stanford, CA 94305, USA. Electronic address: ypyang@stanford.edu.
authors.forename: Yunzhi
authors.initials: Y
authors.lastname: Yang
mesh_terms: D002130:Calcium Phosphates; D002478:Cells, Cultured; D003094:Collagen; D061307:Human Umbilical Vein Endothelial Cells / Q000166:cytology*; D006801:Humans; D020100:Hydrogels / Q000032:analysis*; D011091:Polyesters; D023822:Tissue Engineering; D054457:Tissue Scaffolds
chemical_list: D002130:Calcium Phosphates; D020100:Hydrogels; D011091:Polyesters; C485817:beta-tricalcium phosphate; C016240:polycaprolactone; D003094:Collagen
keywords: Additive manufacturing; Cell network pattern; Endothelial cell; Hydrogel; Scaffold