Biology subjects

Borem, R.

Publications and source records attributed to Borem, R..

4 recordsLinked to original sources

bioRxiv2020

Characterization of chondroitinase-induced lumbar intervertebral disc degeneration in a sheep model intended for assessing biomaterials

Intervertebral disc (IVD) degeneration (IVDD) leads to structural and functional changes. Biomaterials for restoring IVD function and promoting regeneration are currently being investigated; however, such approaches require validation using animal models that recapitulate clinical, biochemical, and biomechanical hallmarks of the human pathology. Herein, we comprehensively characterized a sheep model of chondroitinase-ABC (C-ABC) induced IVDD. Briefly, C-ABC (1U) was injected into the L1/2, L2/3, and L3/4 IVDs. Degeneration was assessed via longitudinal magnetic resonance (MR) and radiographic imaging. Additionally, kinematic, biochemical, and histological analyses were performed on explanted functional spinal units (FSUs). At 17-weeks, C-ABC treated IVDs demonstrated significant reductions in MR index (p=0.030) and disc height (p=0.009) compared to pre-operative values. Additionally, C-ABC treated IVDs exhibited significantly increased creep displacement (p=0.004) and axial range of motion (p=0.007) concomitant with significant decreases in tensile (p=0.034) and torsional (p=0.021) stiffnesses and long-term viscoelastic properties (p=0.016). C-ABC treated IVDs also exhibited a significant decrease in NP glycosaminoglycan: hydroxyproline ratio (p=0.002) and changes in microarchitecture, particularly in the NP and endplates, compared to uninjured IVDs. Taken together, this study demonstrated that intradiscal injection of C-ABC induces significant degeneration in sheep lumbar IVDs and its potential for use in evaluating biomaterials for IVD repair. Statement of SignificanceSelecting the appropriate model for assessing biomaterials to repair and/or support regeneration of the intervertebral disc (IVD) has been controversial, leading to the use of many methods of simulating IVD degeneration (IVDD) in multiple species. Many of these models lack thorough characterization of their fidelity to human IVDD, which could hinder the translation of novel biomaterials and therapies due to unknown confounding factors. Herein, further investigation of one such model was performed using the matrix-degrading enzyme chondroitinase-ABC to induce degeneration in sheep lumbar IVDs. Degenerative changes were quantified using outcome measures relevant to human IVDD, and this dosage and method induces an aggressive degeneration environment that could be used to assess biomaterials that mimic the structure and function of the entire composite IVD. These findings may aid investigators in their selection of an appropriate animal model for preclinical testing of biomaterials and other therapeutics.

bioengineering↗

bioRxiv2019

Differential Effector Response of Amnion- and Adipose-Derived Mesenchymal Stem Cells to Inflammation; Implications for Intradiscal Therapy

Intervertebral disc degeneration (IVDD) is a progressive condition marked by inflammation and tissue destruction. The effector functions of mesenchymal stem cells (MSCs) make them an attractive therapy for patients with IVDD. While several sources of MSCs exist, the optimal choice for use in the inflamed IVD remains a significant question. Adipose (AD)- and amnion (AM)-derived MSCs have several advantages compared to other sources, however, no study has directly compared the impact of IVDD inflammation on their effector functions. Human MSCs were cultured in media with or without supplementation of interleukin-1{beta} and tumor necrosis factor- at concentrations produced by IVDD cells. MSC proliferation and production of pro- and anti-inflammatory cytokines were quantified following 24- and 48-hours of culture. Additionally, the osteogenic and chondrogenic potential of AD- and AM-MSCs was characterized via histology and biochemical analysis following 28 days of culture. In inflammatory culture, AM-MSCs produced significantly more anti-inflammatory IL-10 (p=0.004) and larger chondrogenic pellets (p=0.04) with greater percent area staining positively for glycosaminoglycan (p<0.001) compared to AD-MSCs. Conversely, AD-MSCs proliferated more resulting in higher cell numbers (p=0.048) and produced higher concentrations of pro-inflammatory cytokines PGE2 (p=0.030) and IL-1{beta} (p=0.010) compared to AM-MSCs. Additionally, AD-MSCs produced more mineralized matrix (p<0.001) compared to AM-MSCs. These findings begin to inform researchers and clinicians as to which MSC source may be optimal for different IVD therapies including those that may promote regeneration or fusion. Further study is warranted evaluating these cells in systems which recapitulate the nutrient- and oxygen-deprived environment of the degenerate IVD.

bioengineering↗

bioRxiv2018

Multi-laminate Annulus Fibrosus Repair Scaffold with an Interlamellar Matrix Enhances Impact Resistance, Prevents Herniation and Assists in Restoring Spinal Kinematics

Focal defects in the annulus fibrosus (AF) of the intervertebral disc (IVD) from herniation or surgical injury have detrimental impacts on IVD mechanical function. Thus, biomaterial-based repair strategies, which can restore the mechanical integrity of the AF and support long-term tissue regeneration are needed. Accordingly, a collagen-based multi-laminate scaffold with an underlying \"angle-ply\" architecture has been previously reported demonstrating similar mechanical properties to native AF tissue. The objectives of this work were to: 1) enhance the biomaterials impact strength, 2) define its contribution to spinal kinematics, and 3) assess its ability to prevent IVD herniation. First, AFRPs were enriched with a glycosaminoglycan-based (GAG) interlamellar matrix (ILM), and then tested for its radially-directed impact resistance under physiological stresses. Subsequent kinematic testing was conducted using a characterized GAG-enriched AFRP as an AF focal defect closure device. In summary, AFRPs demonstrated 1) incorporation of a GAG-based ILM significantly increased radial impact strength, 2) restoration of axial FSU kinematics and 3) ability to prevent herniation of native IVD tissues. Together, these results suggest that the AFRP demonstrates the mechanical robustness and material properties to restore an IVDs physiological mechanical function through the adequate closure of an AF focal defect.

bioengineering↗

bioRxiv2018

A pilot investigation of chemonucleolysis-induced intervertebral disc degeneration in the ovine lumbar spine

Intervertebral disc (IVD) degeneration (IVDD) initiates in the nucleus pulposus (NP) and is marked by elevated levels of pro-inflammatory cytokines and matrix-degrading proteases, leading to structural and functional disruption. IVDD therapeutics are currently being investigated; however, such approaches require validation using large animal models that recapitulate clinical, biochemical, and biomechanical hallmarks of the human pathology. Others have previously utilized intradiscal administration of chondroitinase-ABC (C-ABC) to initiate IVDD in the NP of sheep lumbar IVDs. While these studies examined changes in IVD height, hydration, and tissue micro-architecture, changes in biochemical content and mechanical properties were not assessed. Thus, the objective herein was to comprehensively characterize this ovine model IVDD for salient features reported in human degenerate IVDs by evaluating biochemical, biomechanical, and histological changes. Briefly, C-ABC (1U) was administered via intradiscal injection into the L1/2, L2/3, and L3/4 IVDs, and degeneration was assessed at 6- and 10-weeks via longitudinal magnetic resonance (MR) imaging. After 6 weeks, degenerative samples showed significant reductions in IVD heights (p=0.048) and MR imaging index (p=0.048), which worsened at 10 weeks. Post-mortem degenerate and controls IVDs were evaluated for differences in interleukin-1{beta} concentration, axial and torsional functional spinal unit kinematics, and histological microarchitecture. Degenerate IVDs demonstrated significantly elevated concentrations of interleukin-1{beta} (p=0.002). Additionally, degenerative samples showed increased creep displacement (p=0.022) and compressive stiffnesss (p=0.007) concurrent with decreased long-term elastic (p=0.007) and viscous dampening coefficients (p=0.002). Histological analysis of degenerative IVDs showed changes in microarchitecture, including derangement of the nucleus pulposus and annulus fibrosus tissue as well as cartilaginous end-plate irregularities. This pilot study demonstrated that intradiscal injection of 1U C-ABC induces significant and progressive degeneration of sheep lumbar IVDs over the time course investigated. The changes observed in this pilots study small sample size resemble the hallmarks of moderate to severe IVD degeneration observed in humans. Further study is warranted on a larger sample size to further validate these findings.

bioengineering↗