Search

Established risk factors for osteoarthritis (OA) include obesity, joint injury, age, race, and genetics. However, the relationship between cigarette smoking and OA has yet to be established. In the present study, we have employed the use of cigarette smoke extract (CSE), the water‐soluble vapor phase of cigarette smoke, with porcine cartilage explants to investigate the effects of cigarette smoking on cartilage catabolism at the tissue level. Articular cartilage explants were first exposed to 2.5%, 5%, and 10% CSE to assess its effects on cartilage homeostasis. Following, the effects of CSE on OA‐like inflammation was observed by culturing explants with a combined treatment of IL‐1β and TNF‐α and 10% CSE (CSE + OA). Cartilage explants were assessed for changes in viability, biochemical composition, extracellular matrix (ECM) integrity, and equilibrium mechanical properties (aggregate modulus and hydraulic permeability). CSE alone leads to both a time‐ and dose‐dependent decrease in chondrocyte viability but does not significantly affect sGAG content, percent sGAG loss, or the ECM integrity of cartilage explants. When IL‐1β and TNF‐α were combined with 10% CSE, this led to a synergistic effect with more significant losses in viability, significantly more sGAG loss, and significantly higher production of ROS than OA‐like inflammation only. Cartilage explant equilibrium mechanical properties were unaffected. Within the timeframe of this study, CSE alone does not cause OA but when combined with OA‐like inflammation leads to worsened articular cartilage degeneration as measured by chondrocyte viability, sGAG loss, proteoglycan staining, and ROS production. [ABSTRACT FROM AUTHOR]

Intervertebral disc (IVD) degeneration (IVDD) has become increasingly prevalent and is a common contributing factor to low back pain. Current treatment options are limited to either symptom management or surgery. A promising treatment option being explored is intradiscal administration of mesenchymal stromal cells (MSCs). However, there remains a gap in knowledge as to whether MSCs from different tissue sources have similar responses to the low pH microenvironment of the IVD and the possible mechanisms governing these responses. To study this, MSCs from three different tissue sources: adipose (adipose‐derived mesenchymal stem cell), bone marrow (bone marrow mesenchymal stem cells), and amnion (amniotic membrane mesenchymal stem cell) were cultured at low pHs representative of IVDD. MSCs were assessed for survival, senescence, apoptosis, metabolic activity, and cytokine release profile. Additionally, western blot was utilized to assess acid sensing ion channel 1 and 3 expression. The results of this study indicated that MSC viability, cell proliferation, senescence, and metabolic activity is negatively affected by low pH and alters MSC cytokine production. This study also demonstrated that MSCs behavior is dependent on tissue source. Understanding how MSC behavior is altered by pH will allow further research aimed at increasing the efficacy of MSC therapy to promote in situ IVD tissue regeneration to combat IVDD. [ABSTRACT FROM AUTHOR]

Focal chondral defects (FCDs) significantly impede quality of life for patients and impose severe economic costs on society. One of the most promising treatment options—autologous matrix‐induced chondrogenesis (AMIC)—could benefit from a scaffold that contains both of the primary cartilage matrix components—sulfated glycosaminoglycans (sGAGs) and collagen type II. Here, 17 different protocols were evaluated to determine the most optimum strategy for decellularizing (decelling) the bovine nucleus pulposus (bNP) to yield a natural biomaterial with a cartilaginous constituency. The resulting scaffold was then characterized with respect to its biochemistry, biomechanics and cytocompatibility. Results indicated that the optimal decell protocol involved pre‐crosslinking the tissue prior to undergoing decell with trypsin and Triton X‐100. The residual DNA content of the scaffold was found to be 32.64 ± 9.26 ng/mg dry wt. of tissue with sGAG and hydroxyproline (HYP) contents of 72.53 ± 16.43. and 78.38 ± 8.46 μg/mg dry wt. respectively. The dynamic viscoelastic properties were found to be preserved (complex modulus: 17.92–16.62 kPa across a range of frequencies) while the equilibrium properties were found to have significantly decreased (aggregate modulus: 11.51 ± 9.19 kPa) compared to the non‐decelled fresh bNP tissue. Furthermore, the construct was also found to be cytocompatible with bone marrow stem cells (BMSCs). While it was not permissive of cellular infiltration, the BMSCs were still found to have lined the laser drilled channels in the scaffold. Taken together, the biomaterial developed herein could be a valuable addition to the AMIC family of scaffolds or serve as an off‐the‐shelf standalone option for cartilage repair. [ABSTRACT FROM AUTHOR]

The angle‐ply multilaminate structure of the annulus fibrosus is not reestablished following discectomy which leads to reherniation of the intervertebral disc (IVD). Biomimetic scaffolds developed to repair these defects should be evaluated for their ability to support tissue regeneration by endogenous and exogenous cells. Herein a collagen‐based, angle‐ply multilaminate patch designed to repair the outer annulus fibrosus was assessed for its ability to support mesenchymal stromal and annulus fibrosus cell viability, elongation, alignment, extracellular matrix gene expression, and scaffold remodeling. Results demonstrated that the cells remained viable, elongated, and aligned along the collagen fiber preferred direction of the scaffold, upregulated genes associated with annulus fibrosus matrix and produced collagen on the scaffold yielding biaxial mechanical properties that resembled native annulus fibrosus tissue. In conclusion, these scaffolds have demonstrated their potential to promote a living repair of defects in the annulus fibrosus and thus may be used to prevent recurrent IVD herniations. [ABSTRACT FROM AUTHOR]

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 (ChABC) induced IVDD. Briefly, ChABC (1 U) 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, ChABC treated IVDs demonstrated significant reductions in MR index (p = 0.030) and disc height (p = 0.009) compared with pre‐operative values. Additionally, ChABC 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). ChABC 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 with uninjured IVDs. Taken together, this study demonstrated that intradiscal injection of ChABC induces significant degeneration in sheep lumbar IVDs and the potential for using this model in evaluating biomaterials for IVD repair, regeneration, or fusion. [ABSTRACT FROM AUTHOR]

Synovial fluid is dynamic in vivo with biological components changing in ratio and size depending on the health of the joint space, making it difficult to model in vitro. Previous efforts to develop synthetic synovial fluid have typically focused on single organic‐tribological interactions with implant surfaces, thus ignoring interplay between multiple solution components. Using a Taguchi orthogonal array, we were able to isolate the individual effects of five independent synovial fluid composition variables: ratios of (1) hyaluronic acid to phospholipids (HA:PL) and (2) albumin to globulin (A:G), and concentrations of (3) hydrogen peroxide (H2O2), (4) cobalt (Co2+) and (5) chromium (Cr3+) ions on macrophage viability and reduced glutathione production, local solution pH and the comprehensive CoCrMo alloy electrochemical response. While no single synovial fluid variable significantly affected the collective response, HA:PL ratio resulted in the largest impact factor (Δ) on 12 of the 13 measured responses with significant effects (p <.05) on the average macrophage survival rate and electrochemical capacitive state of the CoCrMo surface. Cluster analysis separated significant responses from all trials into three groups, corresponding to healthy, mild, or severely inflamed fluids, respectively; with the healthy synovial fluid composition having mid‐range HA:PL ratios with no Co2+ ions, and the severely inflamed fluids consisting of low and high HA:PL ratios with H2O2 and Co2+ ions. By utilizing the Taguchi approach in combination with cluster analysis, we were able to advance our knowledge of complex multivariate synthetic synovial fluids influence on macrophage and electrochemical behavior at the cell‐solution‐metal interface. [ABSTRACT FROM AUTHOR]