title: In vivo performance of an acellular disc-like angle ply structure (DAPS) for total disc replacement in a small animal model.
abstract: Total intervertebral disc replacement with a biologic engineered disc may be an alternative to spinal fusion for treating end-stage disc disease. In previous work, we developed disc-like angle ply structures (DAPS) that replicate the structure and function of the native disc and a rat tail model to evaluate DAPS in vivo. Here, we evaluated a strategy in which, after in vivo implantation, endogenous cells could colonize the acellular DAPS and form an extracellular matrix organized by the DAPS topographical template. To do so, acellular DAPS were implanted into the caudal spines of rats and evaluated over 12 weeks by mechanical testing, histology, and microcomputed tomography. An external fixation device was used to stabilize the implant site and various control groups were included to evaluate the effect of immobilization. There was robust tissue formation within the DAPS after implantation and compressive mechanical properties of the implant matched that of the native motion segment. Immobilization provided a stable site for fibrous tissue formation after either a discectomy or a DAPS implantation, but bony fusion eventually resulted, with segments showing intervertebral bridging after long-term implantation, a process that was accelerated by the implanted DAPS. Thus, while compressive mechanical properties were replicated after DAPS implantation, methods to actively prevent fusion must be developed. Future work will focus on limiting fusion by remobilizing the motion segment after a period of integration, delivering pro-chondrogenic factors, and pre-seeding DAPS with cells prior to implantation. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:23-31, 2017.
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania, 426 B Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, 19104-6081, Pennsylvania.|Translational Musculoskeletal Research Center, Philadelphia VA Medical Center, Philadelphia, Pennsylvania.|Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: John T
authors.initials: JT
authors.lastname: Martin
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania, 426 B Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, 19104-6081, Pennsylvania.
authors.forename: Dong Hwa
authors.initials: DH
authors.lastname: Kim
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania, 426 B Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, 19104-6081, Pennsylvania.|Translational Musculoskeletal Research Center, Philadelphia VA Medical Center, Philadelphia, Pennsylvania.
authors.forename: Andrew H
authors.initials: AH
authors.lastname: Milby
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania, 426 B Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, 19104-6081, Pennsylvania.|Translational Musculoskeletal Research Center, Philadelphia VA Medical Center, Philadelphia, Pennsylvania.|Department of Trauma Surgery, Regensburg University Medical Center, Regensburg, Germany.
authors.forename: Christian G
authors.initials: CG
authors.lastname: Pfeifer
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania, 426 B Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, 19104-6081, Pennsylvania.|Translational Musculoskeletal Research Center, Philadelphia VA Medical Center, Philadelphia, Pennsylvania.|Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Lachlan J
authors.initials: LJ
authors.lastname: Smith
authors.affiliation: Department of Biomedical Engineering, University of Delaware, Newark, Delaware.
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Elliott
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania, 426 B Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, 19104-6081, Pennsylvania.|Translational Musculoskeletal Research Center, Philadelphia VA Medical Center, Philadelphia, Pennsylvania.|Department of Neurosurgery, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Harvey E
authors.initials: HE
authors.lastname: Smith
authors.affiliation: Department of Orthopaedic Surgery, University of Pennsylvania, 426 B Stemmler Hall, 36th Street and Hamilton Walk, Philadelphia, 19104-6081, Pennsylvania.|Translational Musculoskeletal Research Center, Philadelphia VA Medical Center, Philadelphia, Pennsylvania.|Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania.|Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Mauck
mesh_terms: D000818:Animals; D008297:Male; D023421:Models, Animal; D017207:Rats, Sprague-Dawley; D059145:Total Disc Replacement / Q000295:instrumentation*
keywords: acellular biomaterials; intervertebral disc; tissue engineering; total disc replacement