title: Engineering meniscus structure and function via multi-layered mesenchymal stem cell-seeded nanofibrous scaffolds.
abstract: Despite advances in tissue engineering for the knee meniscus, it remains a challenge to match the complex macroscopic and microscopic structural features of native tissue, including the circumferentially and radially aligned collagen bundles essential for mechanical function. To mimic this structural hierarchy, this study developed multi-lamellar mesenchymal stem cell (MSC)-seeded nanofibrous constructs. Bovine MSCs were seeded onto nanofibrous scaffolds comprised of poly(ε-caprolactone) with fibers aligned in a single direction (0° or 90° to the scaffold long axis) or circumferentially aligned (C). Multi-layer groups (0°/0°/0°, 90°/90°/90°, 0°/90°/0°, 90°/0°/90°, and C/C/C) were created and cultured for a total of 6 weeks under conditions favoring fibrocartilaginous tissue formation. Tensile testing showed that 0° and C single layer constructs had stiffness values several fold higher than 90° constructs. For multi-layer groups, the stiffness of 0°/0°/0° constructs was higher than all other groups, while 90°/90°/90° constructs had the lowest values. Data for collagen content showed a general positive interactive effect for multi-layers relative to single layer constructs, while a positive interaction for stiffness was found only for the C/C/C group. Collagen content and cell infiltration occurred independent of scaffold alignment, and newly formed collagenous matrix followed the scaffold fiber direction. Structural hierarchies within multi-lamellar constructs dictated biomechanical properties, and only the C/C/C constructs with non-orthogonal alignment within layers featured positive mechanical reinforcement as a consequence of the layered construction. These multi-layer constructs may serve as functional substitutes for the meniscus as well as test beds to understand the complex mechanical principles that enable meniscus function.
authors: McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Translational Musculoskeletal Research Center, Philadelphia VA Medical Center, Philadelphia, PA 19104, USA; Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina 27599, USA and North Carolina State University, Raleigh, North Carolina 27695, USA.
authors: Matthew B
authors: MB
authors: Fisher
authors: McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Translational Musculoskeletal Research Center, Philadelphia VA Medical Center, Philadelphia, PA 19104, USA.
authors: Elizabeth A
authors: EA
authors: Henning
authors: McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors: Nicole
authors: N
authors: Söegaard
authors: McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
authors: Marc
authors: M
authors: Bostrom
authors: McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Translational Musculoskeletal Research Center, Philadelphia VA Medical Center, Philadelphia, PA 19104, USA.
authors: John L
authors: JL
authors: Esterhai
authors: McKay Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Translational Musculoskeletal Research Center, Philadelphia VA Medical Center, Philadelphia, PA 19104, USA; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA. Electronic address: lemauck@mail.med.upenn.edu.
authors: Robert L
authors: RL
authors: Mauck
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D055119:Elastic Modulus; D008422:Materials Testing; D008592:Menisci, Tibial / Q000473:pathology; D059630:Mesenchymal Stem Cells / Q000502:physiology*; D057139:Nanofibers / Q000737:chemistry; D011091:Polyesters / Q000737:chemistry; D023822:Tissue Engineering; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D011091:Polyesters; C016240:polycaprolactone; D003094:Collagen
keywords: Electrospinning; Mechanical properties; Meniscus; Nanofibrous scaffold; Tissue engineering