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Schwartz G, Best TM, Chen CB, Travascio F, Jackson AR. Assessing the role of surface layer and molecular probe size in diffusion within meniscus tissue. PLoS One 2024; 19:e0301432. [PMID: 38626169 PMCID: PMC11020779 DOI: 10.1371/journal.pone.0301432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 03/15/2024] [Indexed: 04/18/2024] Open
Abstract
Diffusion within extracellular matrix is essential to deliver nutrients and larger metabolites to the avascular region of the meniscus. It is well known that both structure and composition of the meniscus vary across its regions; therefore, it is crucial to fully understand how the heterogenous meniscal architecture affects its diffusive properties. The objective of this study was to investigate the effect of meniscal region (core tissue, femoral, and tibial surface layers) and molecular weight on the diffusivity of several molecules in porcine meniscus. Tissue samples were harvested from the central area of porcine lateral menisci. Diffusivity of fluorescein (MW 332 Da) and three fluorescence-labeled dextrans (MW 3k, 40k, and 150k Da) was measured via fluorescence recovery after photobleaching. Diffusivity was affected by molecular size, decreasing as the Stokes' radius of the solute increased. There was no significant effect of meniscal region on diffusivity for fluorescein, 3k and 40k dextrans (p>0.05). However, region did significantly affect the diffusivity of 150k Dextran, with that in the tibial surface layer being larger than in the core region (p = 0.001). Our findings contribute novel knowledge concerning the transport properties of the meniscus fibrocartilage. This data can be used to advance the understanding of tissue pathophysiology and explore effective approaches for tissue restoration.
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Affiliation(s)
- Gabi Schwartz
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, United States of America
| | - Thomas M. Best
- Department of Orthopaedic Surgery, University of Miami, Miami, FL, United States of America
- UHealth Sports Medicine Institute, Coral Gables, FL, United States of America
| | - Cheng-Bang Chen
- Department of Industrial and Systems Engineering, University of Miami, Coral Gables, FL, United States of America
| | - Francesco Travascio
- Department of Orthopaedic Surgery, University of Miami, Miami, FL, United States of America
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL, United States of America
- Max Biedermann Institute for Biomechanics at Mount Sinai Medical Center, Miami Beach, FL, United States of America
| | - Alicia R. Jackson
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, United States of America
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Primrose JG, Jain L, Bolam SM, Monk AP, Munro JT, Dalbeth N, Poulsen RC. Concentration-dependent effects of leptin on osteoarthritis-associated changes in phenotype of human chondrocytes. Connect Tissue Res 2023; 64:457-468. [PMID: 37171229 DOI: 10.1080/03008207.2023.2214249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 05/10/2023] [Indexed: 05/13/2023]
Abstract
Metabolic syndrome is a risk factor for osteoarthritis. Elevated leptin levels have been implicated as a potential cause of this association. Previous studies have shown that supra-physiological leptin concentrations can induce osteoarthritis-like changes in chondrocyte phenotype. Here, we tested the effects of leptin in the concentration range found in synovial fluid on chondrocyte phenotype. Chondrocytes isolated from macroscopically normal regions of cartilage within osteoarthritic joints from patients undergoing knee arthroplasty, all with body mass index >30 kg/m2 were treated with 2-40 ng/ml leptin for 24 h. Chondrocyte phenotype marker expression was measured by RT-qPCR and western blot. The role of HES1 in mediating the effects of leptin was determined by gene knockdown using RNAi and over-expression using adenoviral-mediated gene delivery. Treatment of chondrocytes with 20 or 40 ng/ml leptin resulted in decreased SOX9 levels and decreased levels of the SOX9-target genes COL2A1 and ACAN. Levels of HES1 were lower and ADAMTS5 higher in chondrocytes treated with 20 or 40 ng/ml leptin. HES1 knockdown resulted in increased ADAMTS5 expression whereas over-expression of HES1 prevented the leptin-induced increase in ADAMTS5. An increase in MMP13 expression was only evident in chondrocytes treated with 40 ng/ml leptin and was not mediated by HES1 activity. High concentrations of leptin can cause changes in chondrocyte phenotype consistent with those seen in osteoarthritis. Synovial fluid leptin concentrations of this level are typically observed in patients with metabolic syndrome and/or women, suggesting elevated leptin levels may form part of the multifactorial network that leads to osteoarthritis development in these patients.
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Affiliation(s)
- Julia Gb Primrose
- Department of Pharmacology and Clinical Pharmacology, University of Auckland, Auckland, New Zealand
| | - Lekha Jain
- Department of Pharmacology and Clinical Pharmacology, University of Auckland, Auckland, New Zealand
| | - Scott M Bolam
- Department of Surgery, University of Auckland, Auckland, New Zealand
- Department of Medicine, University of Auckland, Auckland, New Zealand
| | - A Paul Monk
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Jacob T Munro
- Department of Surgery, University of Auckland, Auckland, New Zealand
| | - Nicola Dalbeth
- Department of Medicine, University of Auckland, Auckland, New Zealand
| | - Raewyn C Poulsen
- Department of Pharmacology and Clinical Pharmacology, University of Auckland, Auckland, New Zealand
- Department of Medicine, University of Auckland, Auckland, New Zealand
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Ren P, Chen P, Reeves RA, Buchweitz N, Niu H, Gong H, Mercuri J, Reitman CA, Yao H, Wu Y. Diffusivity of Human Cartilage Endplates in Healthy and Degenerated Intervertebral Disks. J Biomech Eng 2023; 145:071006. [PMID: 36752723 PMCID: PMC10159583 DOI: 10.1115/1.4056871] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2022] [Revised: 01/29/2023] [Accepted: 02/05/2023] [Indexed: 02/09/2023]
Abstract
The cartilage endplates (CEPs) on the superior and inferior surfaces of the intervertebral disk (IVD), are the primary nutrient transport pathways between the disk and the vertebral body. Passive diffusion is responsible for transporting small nutrient and metabolite molecules through the avascular CEPs. The baseline solute diffusivities in healthy CEPs have been previously studied, however alterations in CEP diffusion associated with IVD degeneration remain unclear. This study aimed to quantitatively compare the solute diffusion in healthy and degenerated human CEPs using a fluorescence recovery after photobleaching (FRAP) approach. Seven healthy CEPs and 22 degenerated CEPs were collected from five fresh-frozen human cadaveric spines and 17 patients undergoing spine fusion surgery, respectively. The sodium fluorescein diffusivities in CEP radial and vertical directions were measured using the FRAP method. The CEP calcification level was evaluated by measuring the average X-ray attenuation. No difference was found in solute diffusivities between radial and axial directions in healthy and degenerated CEPs. Compared to healthy CEPs, the average solute diffusivity was 44% lower in degenerated CEPs (Healthy: 29.07 μm2/s (CI: 23.96-33.62 μm2/s); degenerated: 16.32 μm2/s (CI: 13.84-18.84 μm2/s), p < 0.001). The average solute diffusivity had an inverse relationship with the degree of CEP calcification as determined by the normalized X-ray attenuation values (ß = -22.19, R2 = 0.633; p < 0.001). This study suggests that solute diffusion through the disk and vertebral body interface is significantly hindered by CEP calcification, providing clues to help further understand the mechanism of IVD degeneration.
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Affiliation(s)
- Pengling Ren
- Department of Bioengineering, Clemson University, Clemson, SC 29425; Department of Orthopaedics and Physical Medicine, Medical University of South Carolina (MUSC), Charleston, SC 29425; Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100052, China; Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Peng Chen
- Department of Bioengineering, Clemson University, Clemson, SC 29425
| | - Russell A. Reeves
- Department of Radiology, Sidney Kimmel Medical College, Thomas Jefferson University, Philadelphia, PA 19107
| | - Nathan Buchweitz
- Department of Bioengineering, Clemson University, Clemson, SC 29425
| | - Haijun Niu
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - He Gong
- Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education, School of Biological Science and Medical Engineering, Beihang University, Beijing 100191, China
| | - Jeremy Mercuri
- Department of Bioengineering, Clemson University, Clemson, SC 29425
| | - Charles A. Reitman
- Department of Orthopaedics and Physical Medicine, Medical University of South Carolina (MUSC), Charleston, SC 29425
| | - Hai Yao
- Department of Bioengineering, Clemson University, Clemson, SC 29425; Department of Orthopaedics and Physical Medicine, Medical University of South Carolina (MUSC), Charleston, SC 29425
| | - Yongren Wu
- Department of Bioengineering, Clemson University, 68 President Street, MSC501, Clemson, SC 29425; Department of Orthopaedics and Physical Medicine, Medical University of South Carolina (MUSC), Charleston, SC 29425
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Morejon A, Schwartz G, Best TM, Travascio F, Jackson AR. Effect of molecular weight and tissue layer on solute partitioning in the knee meniscus. OSTEOARTHRITIS AND CARTILAGE OPEN 2023; 5:100360. [PMID: 37122844 PMCID: PMC10133802 DOI: 10.1016/j.ocarto.2023.100360] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 04/04/2023] [Indexed: 05/02/2023] Open
Abstract
Objective Knee meniscus tissue is partly vascularized, meaning that nutrients must be transported through the extracellular matrix of the avascular portion to reach resident cells. Similarly, drugs used as therapeutic agents to treat meniscal pathologies rely on transport through the tissue. The driving force of diffusive transport is the gradient of concentration, which depends on molecular solubility. The meniscus is organized into a core region sandwiched between the tibial and femoral superficial layers. Structural differences exist across meniscal regions; therefore, regional differences in solubility are also hypothesized. Methods Samples from the core, tibial and femoral layers were obtained from 5 medial and 5 lateral porcine menisci. The partition coefficient (K) of fluorescein, 3 kDa and 40 kDa dextrans in the layers of the meniscus was measured using an equilibration experiment. The effect of meniscal compartment, layer, and solute molecular weight on K was analyzed using a three-way ANOVA. Results K ranged from a high of ∼2.9 in fluorescein to a low of ∼0.1 in 40 kDa dextran and was inversely related to the solute molecular weight across all tissue regions. Tissue layer only had a significant effect on partitioning of 40k Dex solute, which was lower in the tibial surface layer relative to the core (p = 0.032). Conclusion This study provides insight into depth-dependent partitioning in the meniscus, indicating the limiting effect of the meniscus superficial layer on solubility increases with solute molecular size. This illustrates how the surface layers could potentially reduce the effectiveness of drug delivery therapies incorporating large molecules (>40 kDa).
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Affiliation(s)
- Andy Morejon
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL, USA
| | - Gabi Schwartz
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
| | - Thomas M. Best
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
- Department of Orthopedic Surgery, University of Miami, Coral Gables, FL, USA
- UHealth Sports Medicine Institute, Coral Gables, FL, USA
| | - Francesco Travascio
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL, USA
- Department of Orthopedic Surgery, University of Miami, Coral Gables, FL, USA
- Max Biedermann Institute for Biomechanics at Mount Sinai Medical Center, Miami Beach, FL, USA
- Corresponding author. College of Engineering, University of Miami, 1251 Memorial Drive, MEB 276, Coral Gables, FL 33146, USA.
| | - Alicia R. Jackson
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL, USA
- Corresponding author. College of Engineering, University of Miami, 1251 Memorial Drive, MEA 219, Coral Gables, FL 33146 USA.
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Molecular Mechanisms of Cartilage Repair and Their Possible Clinical Uses: A Review of Recent Developments. Int J Mol Sci 2022; 23:ijms232214272. [PMID: 36430749 PMCID: PMC9697852 DOI: 10.3390/ijms232214272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 11/14/2022] [Accepted: 11/16/2022] [Indexed: 11/19/2022] Open
Abstract
Articular cartilage (AC) defects are frequent but hard to manage. Osteoarthritis (OA) is a musculoskeletal illness that afflicts between 250 and 500 million people in the world. Even though traditional OA drugs can partly alleviate pain, these drugs cannot entirely cure OA. Since cartilaginous tissue of the joints has a poor self-repair capacity and very poor proliferative ability, the healing of injured cartilaginous tissue of the joint has not been accomplished so far. Consequently, the discovery of efficacious mediations and regenerative treatments for OA is needed. This manuscript reviews the basic concepts and the recent developments on the molecular mechanisms of cartilage repair and their potential clinical applications. For this purpose, a literature exploration was carried out in PubMed for the years 2020, 2021, and 2022. On 31 October 2022 and using "cartilage repair molecular mechanisms" as keywords, 41 articles were found in 2020, 42 in 2021, and 36 in 2022. Of the total of 119 articles, 80 were excluded as they were not directly related to the title of this manuscript. Of particular note are the advances concerning the mechanisms of action of hyaluronic acid, mesenchymal stem cells (MSCs), nanotechnology, enhancer of zeste 2 polycomb repressive complex 2 subunit (EHZ2), hesperetin, high mobility group box 2 (HMGB2), α2-macroglobulin (α2M), proteoglycan 4 (Prg4)/lubricin, and peptides related to cartilage repair and treatment of OA. Despite the progress made, current science has not yet achieved a definitive solution for healing AC lesions or repairing cartilage in the case of OA. Therefore, further research into the molecular mechanisms of AC damage is needed in the coming decades.
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Schwartz G, Morejon A, Best TM, Jackson AR, Travascio F. Strain-Dependent Diffusivity of Small and Large Molecules in Meniscus. J Biomech Eng 2022; 144:111010. [PMID: 35789377 PMCID: PMC9309715 DOI: 10.1115/1.4054931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 06/28/2022] [Indexed: 11/08/2022]
Abstract
Due to lack of full vascularization, the meniscus relies on diffusion through the extracellular matrix to deliver small (e.g., nutrients) and large (e.g., proteins) to resident cells. Under normal physiological conditions, the meniscus undergoes up to 20% compressive strains. While previous studies characterized solute diffusivity in the uncompressed meniscus, to date, little is known about the diffusive transport under physiological strain levels. This information is crucial to fully understand the pathophysiology of the meniscus. The objective of this study was to investigate strain-dependent diffusive properties of the meniscus fibrocartilage. Tissue samples were harvested from the central portion of porcine medial menisci and tested via fluorescence recovery after photobleaching to measure diffusivity of fluorescein (332 Da) and 40 K Da dextran (D40K) under 0%, 10%, and 20% compressive strain. Specifically, average diffusion coefficient and anisotropic ratio, defined as the ratio of the diffusion coefficient in the direction of the tissue collagen fibers to that orthogonal, were determined. For all the experimental conditions investigated, fluorescein diffusivity was statistically faster than that of D40K. Also, for both molecules, diffusion coefficients significantly decreased, up to ∼45%, as the strain increased. In contrast, the anisotropic ratios of both molecules were similar and not affected by the strain applied to the tissue. This suggests that compressive strains used in this study did not alter the diffusive pathways in the meniscus. Our findings provide new knowledge on the transport properties of the meniscus fibrocartilage that can be leveraged to further understand tissue pathophysiology and approaches to tissue restoration.
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Affiliation(s)
- Gabi Schwartz
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL 33146
| | - Andy Morejon
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL 33146
| | - Thomas M Best
- Department of Orthopaedic Surgery, University of Miami, Miami, FL 33136; Department of Biomedical Engineering, University of Miami, Coral Gables, FL 33146;UHealth Sports Medicine Institute, Coral Gables, FL 33146
| | - Alicia R Jackson
- Department of Biomedical Engineering, University of Miami, Coral Gables, FL 33146
| | - Francesco Travascio
- Department of Mechanical and Aerospace Engineering, University of Miami, Coral Gables, FL 33146; Department of Orthopaedic Surgery, University of Miami, Miami, FL 33136; Max Biedermann Institute for Biomechanics at Mount, Sinai Medical Center, Miami Beach, FL 33140
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Salzer E, Mouser VHM, Tryfonidou MA, Ito K. A bovine nucleus pulposus explant culture model. J Orthop Res 2022; 40:2089-2102. [PMID: 34812520 PMCID: PMC9542046 DOI: 10.1002/jor.25226] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 10/18/2021] [Accepted: 11/20/2021] [Indexed: 02/04/2023]
Abstract
Low back pain is a global health problem that is frequently caused by intervertebral disc degeneration (IVDD). Sulfated glycosaminoglycans (sGAGs) give the healthy nucleus pulposus (NP) a high fixed charge density (FCD), which creates an osmotic pressure that enables the disc to withstand high compressive forces. However, during IVDD sGAG reduction in the NP compromises biomechanical function. The aim of this study was to develop an ex vivo NP explant model with reduced sGAG content and subsequently investigate biomechanical restoration via injection of proteoglycan-containing notochordal cell-derived matrix (NCM). Bovine coccygeal NP explants were cultured in a bioreactor chamber and sGAG loss was induced by chondroitinase ABC (chABC) and cultured for up to 14 days. Afterwards, diurnal loading was studied, and explant restoration was investigated via injection of NCM. Explants were analyzed via histology, biochemistry, and biomechanical testing via stress relaxation tests and height measurements. ChABC injection induced dose-dependent sGAG reduction on Day 3, however, no dosing effects were detected after 7 and 14 days. Diurnal loading reduced sGAG loss after injection of chABC. NCM did not show an instant biomechanical (equilibrium pressure) or biochemical (FCD) restoration, as the injected fixed charges leached into the medium, however, NCM stimulated proliferation and increased Alcian blue staining intensity and matrix organization. NCM has biological repair potential and biomaterial/NCM combinations, which could better entrap NCM within the NP tissue, should be investigated in future studies. Concluding, chABC induced progressive, time-, dose- and loading-dependent sGAG reduction that led to a loss of biomechanical function. Keywords biomechanics | intervertebral disc | matrix degradation | low back pain | proteoglycans.
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Affiliation(s)
- Elias Salzer
- Orthopaedic Biomechanics, Department of Biomedical EngineeringEindhoven University of TechnologyEindhovenNoord‐BrabantThe Netherlands
| | - Vivian H. M. Mouser
- Orthopaedic Biomechanics, Department of Biomedical EngineeringEindhoven University of TechnologyEindhovenNoord‐BrabantThe Netherlands
| | - Marianna A. Tryfonidou
- Department of Clinical Sciences, Faculty of Veterinary MedicineUtrecht UniversityUtrechtThe Netherlands
| | - Keita Ito
- Orthopaedic Biomechanics, Department of Biomedical EngineeringEindhoven University of TechnologyEindhovenNoord‐BrabantThe Netherlands
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Application Effect of Different Concentrations of Platelet-Rich Plasma Combined with Quadriceps Training on Cartilage Repair of Knee Osteoarthritis. JOURNAL OF HEALTHCARE ENGINEERING 2022; 2022:7878064. [PMID: 35111289 PMCID: PMC8801772 DOI: 10.1155/2022/7878064] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 11/29/2021] [Accepted: 12/09/2021] [Indexed: 12/20/2022]
Abstract
We investigated the application effect of different concentrations of platelet-rich plasma (PRP) combined with quadriceps training on cartilage repair of knee osteoarthritis. Data of 37 patients with knee osteoarthritis (KOA) treated in our hospital (November 2019–February 2021) were retrospectively analyzed and the patients were divided into low concentration group (LCG) (n = 12), medium concentration group (MCG) (n = 12), and high concentration group (HCG) (n = 13) according to the order of admission. All patients received quadriceps training. Three groups above received knee injection of PRP, and the platelet concentrations were 1000–1400 × 109/L, 1400–1800 × 109/L, and 1800–2100 × 109/L, respectively. Articular cartilage thickness of the medial and lateral femur, knee joint function scores, inflammatory factor levels, and matrix metalloproteinases (MMPs) levels were compared. After treatment, compared with the MCG and HCG, articular cartilage thickness of the medial and lateral femur of the diseased side in the LCG was obviously lower (P < 0.05). At 2 months after treatment (T3), compared with the HCG, articular cartilage thickness of the medial and lateral femur of the diseased side in the MCG was obviously higher (P < 0.05), without remarkable difference in articular cartilage thickness of the medial and lateral femur of the healthy side among three groups (P > 0.05). After treatment, compared with the LCG, knee joint function scores of the MCG and HCG were obviously better (P < 0.001). Compared with the HCG, the knee function score at T3 in the MCG was obviously better (P < 0.001). After treatment, compared with the LCG, inflammatory factor levels and levels of MMPs in the MCG and HCG were obviously lower (P < 0.05). Compared with the HCG, inflammatory factor levels and levels of MMPs at T3 in the MCG were obviously lower (P < 0.05). PRP combined with quadriceps training can accelerate cartilage repair of patients with KOA and reduce inflammatory factor levels and levels of MMPs, but the treatment effect of PRP depends on platelet concentration, with the best range of 1400–1800 × 109/L. Too high or too low platelet concentrations will affect recovery of knee function.
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Seitz AM, Osthaus F, Schwer J, Warnecke D, Faschingbauer M, Sgroi M, Ignatius A, Dürselen L. Osteoarthritis-Related Degeneration Alters the Biomechanical Properties of Human Menisci Before the Articular Cartilage. Front Bioeng Biotechnol 2021; 9:659989. [PMID: 34026741 PMCID: PMC8134692 DOI: 10.3389/fbioe.2021.659989] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Accepted: 03/24/2021] [Indexed: 12/15/2022] Open
Abstract
An exact understanding of the interplay between the articulating tissues of the knee joint in relation to the osteoarthritis (OA)-related degeneration process is of considerable interest. Therefore, the aim of the present study was to characterize the biomechanical properties of mildly and severely degenerated human knee joints, including their menisci and tibial and femoral articular cartilage (AC) surfaces. A spatial biomechanical mapping of the articulating knee joint surfaces of 12 mildly and 12 severely degenerated human cadaveric knee joints was assessed using a multiaxial mechanical testing machine. To do so, indentation stress relaxation tests were combined with thickness and water content measurements at the lateral and medial menisci and the AC of the tibial plateau and femoral condyles to calculate the instantaneous modulus (IM), relaxation modulus, relaxation percentage, maximum applied force during the indentation, and the water content. With progressing joint degeneration, we found an increase in the lateral and the medial meniscal instantaneous moduli (p < 0.02), relaxation moduli (p < 0.01), and maximum applied forces (p < 0.01), while for the underlying tibial AC, the IM (p = 0.01) and maximum applied force (p < 0.01) decreased only at the medial compartment. Degeneration had no influence on the relaxation percentage of the soft tissues. While the water content of the menisci did not change with progressing degeneration, the severely degenerated tibial AC contained more water (p < 0.04) compared to the mildly degenerated tibial cartilage. The results of this study indicate that degeneration-related (bio-)mechanical changes seem likely to be first detectable in the menisci before the articular knee joint cartilage is affected. Should these findings be further reinforced by structural and imaging analyses, the treatment and diagnostic paradigms of OA might be modified, focusing on the early detection of meniscal degeneration and its respective treatment, with the final aim to delay osteoarthritis onset.
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Affiliation(s)
- Andreas M Seitz
- Institute of Orthopedic Research and Biomechanics, Center of Trauma Research Ulm, Ulm University Medical Center, Ulm, Germany
| | - Felix Osthaus
- Institute of Orthopedic Research and Biomechanics, Center of Trauma Research Ulm, Ulm University Medical Center, Ulm, Germany
| | - Jonas Schwer
- Institute of Orthopedic Research and Biomechanics, Center of Trauma Research Ulm, Ulm University Medical Center, Ulm, Germany
| | - Daniela Warnecke
- Institute of Orthopedic Research and Biomechanics, Center of Trauma Research Ulm, Ulm University Medical Center, Ulm, Germany
| | - Martin Faschingbauer
- Department of Orthopedic Surgery, Universitäts- und Rehabilitationskliniken Ulm (RKU), Ulm University Medical Center, Ulm, Germany
| | - Mirco Sgroi
- Department of Orthopedic Surgery, Universitäts- und Rehabilitationskliniken Ulm (RKU), Ulm University Medical Center, Ulm, Germany
| | - Anita Ignatius
- Institute of Orthopedic Research and Biomechanics, Center of Trauma Research Ulm, Ulm University Medical Center, Ulm, Germany
| | - Lutz Dürselen
- Institute of Orthopedic Research and Biomechanics, Center of Trauma Research Ulm, Ulm University Medical Center, Ulm, Germany
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