The objective of this project is to develop a tissue-engineered construct including an engineered nucleus pulposus and annulus fibrosus to treat defects of the annulus fibrosus (AF) and degenerative changes of the intervertebral disc (IVD).
Three Specific Aims are pursued:
Specific Aim 1 will consist of establishing in vitro tissue engineered NP fabrication from rabbit and human NP and MSC cells in hyaluronic acid (HA)-based hydrogel constructs, and evaluation of cell viability, gene regulation, ECM production, and biomechanical properties as a function of gel biophysical properties, cell seeding density, and extended culture in a disc-like environment.
Specific Aim 2 will entail establishing and evaluating cellular infiltration and functional maturation engineered AF-like structures starting from rabbit and human AF and MSC seeded nanofibrous scaffolds in vitro.
Specific Aim 3 will combine the tissue-engineered NP and AF developed in Aims 1 and 2 to form a composite disc-like construct, and to then apply this construct to an in vivo rabbit disc model of total discectomy. Efficacy will be assesse via MRI T2 mapping and subsequent ex vivo analysis of motion segment mechanical, biochemical, and histologic properties. Research Design: This study will utilize in vitro tissue culture for Specific Aims 1-2;
Specific Aim 3 will utilize a rabbit animal model and magnetic resonance imaging (MRI). Methodology:
Specific Aims 1 and 2 are laboratory-based studies that will utilize in vitro tissue culture.
Specific Aim 3 will be performed in vivo with a rabbit mdel for discectomy and tissue-engineered disc implantation with subsequent ex vivo MRI of the spine and tissue analysis. The primary study outcome measures for Specific Aims 1-3 are biochemical analysis of tissue culture and biomechanical analysis of tissue-engineered constructs. Additionally, Specific Aim 3 will utilize these same outcomes, as well as implement quantitative MRI T2 maps of the implanted tissue-engineered constructs with comparisons made to control (non-treated discectomy) and adjacent normal discs. Findings: n/a at this time. Clinical Relationships: The goal of this project is to develop tissue-engineered constructs to trea degenerative disc disease as well as to validate radiologic methods to noninvasively assess potential therapeutic treatments of degenerative disc disease. Impact/Significance: It is anticipated that the proposed study will offer an increased understanding of degenerative disc disease and potential novel therapeutic treatment to both reverse degenerative changes as well as decrease risk of recurrent disc herniation. Further, it will provide critical support for the applicant as he develops a research-intensive clinical practice in spine surgery at the Philadelphia VA Medical Center and the University of Pennsylvania.

Public Health Relevance

This Career Development Award proposal builds on the applicant's prior experience in intervertebral disc biology research, including his experience with tissue culture, small animal surgery, and advanced imaging techniques. In this proposed project, the applicant will form a core mentorship team to develop a translational research program focused on treatment strategies for degenerative disc disease. This strategy will entail the application of tissue-engineered constructs to a rabbit model of intervertebral discectomy. In addition to the research, a core component of this project is the mentoring team supporting the applicant in developing a research foundation that will lead to independent funding and independence as a VA investigator and surgeon-scientist.

National Institute of Health (NIH)
Veterans Affairs (VA)
Veterans Administration (IK2)
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Philadelphia VA Medical Center
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Gullbrand, Sarah E; Ashinsky, Beth G; Bonnevie, Edward D et al. (2018) Long-term mechanical function and integration of an implanted tissue-engineered intervertebral disc. Sci Transl Med 10:
Piazza, Matthew; Peck, Sun H; Gullbrand, Sarah E et al. (2018) Quantitative MRI correlates with histological grade in a percutaneous needle injury mouse model of disc degeneration. J Orthop Res 36:2771-2779
Gullbrand, Sarah E; Kim, Dong Hwa; Bonnevie, Edward et al. (2018) Towards the scale up of tissue engineered intervertebral discs for clinical application. Acta Biomater 70:154-164
Martin, John T; Kim, Dong Hwa; Milby, Andrew H et al. (2017) In vivo performance of an acellular disc-like angle ply structure (DAPS) for total disc replacement in a small animal model. J Orthop Res 35:23-31
Tong, Wei; Lu, Zhouyu; Qin, Ling et al. (2017) Cell therapy for the degenerating intervertebral disc. Transl Res 181:49-58
Martin, J T; Gullbrand, S E; Kim, D H et al. (2017) In Vitro Maturation and In Vivo Integration and Function of an Engineered Cell-Seeded Disc-like Angle Ply Structure (DAPS) for Total Disc Arthroplasty. Sci Rep 7:15765
Martin, John T; Gullbrand, Sarah E; Mohanraj, Bhavana et al. (2017) * Optimization of Preculture Conditions to Maximize the In Vivo Performance of Cell-Seeded Engineered Intervertebral Discs. Tissue Eng Part A 23:923-934
Zhang, Yejia; Chee, Ana; Shi, Peng et al. (2016) Intervertebral Disc Cells Produce Interleukins Found in Patients with Back Pain. Am J Phys Med Rehabil 95:407-15
Gullbrand, Sarah E; Ashinsky, Beth G; Martin, John T et al. (2016) Correlations between quantitative T2 and T1? MRI, mechanical properties and biochemical composition in a rabbit lumbar intervertebral disc degeneration model. J Orthop Res 34:1382-8
Martin, John T; Collins, Christopher M; Ikuta, Kensuke et al. (2015) Population average T2 MRI maps reveal quantitative regional transformations in the degenerating rabbit intervertebral disc that vary by lumbar level. J Orthop Res 33:140-8

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