Displaying publications 81 - 100 of 167 in total

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  1. Fulltext The effect of water extracts of Euphorbia hirta on cartilage degeneration in arthritic rats
    Lee KH, Chen YS, Judson JP, Chakravarthi S, Sim YM, Er HM
    Malays J Pathol, 2008 Dec;30(2):95-102.
    PMID: 19291918 MyJurnal
    The effect of water extracts of Euphorbia hirta on the histological features and expressions of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) in the rat articular cartilage was investigated. Arthritis was induced in rats using Freund's Complete Adjuvant containing heat-killed M. tuberculosis, and treated with water extracts of E. hirta. Paraffin tissue sections of the arthritic joints were evaluated. The extent of cartilage degeneration was found to be greatest in rats treated with the highest dosage of E. hirta, followed by rats in the untreated group. Rats treated with the intermediary and low dosages of Euphorbia hirta showed improved histology. MMP-13 levels were found to be decreased with decreasing dosages of E. hirta. TIMP-1 levels were found to increase with decreasing dosages of E. hirta. MMP-3 levels fluctuated without any appreciable pattern. Low dosages of E. hirta seem to be beneficial in reducing cartilage degeneration in cases of arthritis.
    Matched MeSH terms: Cartilage Diseases/etiology; Cartilage Diseases/pathology*
  2. Effectiveness of concurrent procedures during high tibial osteotomy for medial compartment osteoarthritis: a systematic review and meta-analysis
    Lee OS, Ahn S, Ahn JH, Teo SH, Lee YS
    Arch Orthop Trauma Surg, 2018 Feb;138(2):227-236.
    PMID: 29143167 DOI: 10.1007/s00402-017-2826-4
    INTRODUCTION: The purpose of this systematic review and meta-analysis was to evaluate the efficacy of concurrent cartilage procedures during high tibial osteotomy (HTO) for medial compartment osteoarthritis (OA) by comparing the outcomes of studies that directly compared the use of HTO plus concurrent cartilage procedures versus HTO alone.

    MATERIALS AND METHODS: Results that are possible to be compared in more than two articles were presented as forest plots. A 95% confidence interval was calculated for each effect size, and we calculated the I 2 statistic, which presents the percentage of total variation attributable to the heterogeneity among studies. The random effects model was used to calculate the effect size.

    RESULTS: Seven articles were included to the final analysis. Case groups were composed of HTO without concurrent procedures and control groups were composed of HTO with concurrent procedures such as marrow stimulation procedure, mesenchymal stem cell transplantation, and injection. The case group showed a higher hospital for special surgery score and mean difference was 4.10 [I 2 80.8%, 95% confidence interval (CI) - 9.02 to 4.82]. Mean difference of the mechanical femorotibial angle in five studies was 0.08° (I 2 0%, 95% CI - 0.26 to 0.43). However, improved arthroscopic, histologic, and MRI results were reported in the control group.

    CONCLUSION: Our analysis support that concurrent procedures during HTO for medial compartment OA have little beneficial effect regarding clinical and radiological outcomes. However, they might have some beneficial effects in terms of arthroscopic, histologic, and MRI findings even though the quality of healed cartilage is not good as that of original cartilage. Therefore, until now, concurrent procedures for medial compartment OA have been considered optional. Nevertheless, no conclusions can be drawn for younger patients with focal cartilage defects and concomitant varus deformity. This question needs to be addressed separately.

    Matched MeSH terms: Cartilage/physiology; Cartilage/surgery
  3. Supermacroporous poly(vinyl alcohol)-carboxylmethyl chitosan-poly(ethylene glycol) scaffold: an in vitro and in vivo pre-assessments for cartilage tissue engineering
    Lee SY, Wee AS, Lim CK, Abbas AA, Selvaratnam L, Merican AM, et al.
    J Mater Sci Mater Med, 2013 Jun;24(6):1561-70.
    PMID: 23512151 DOI: 10.1007/s10856-013-4907-4
    This study aims to pre-assess the in vitro and in vivo biocompatibility of poly(vinyl alcohol)-carboxylmethyl-chitosan-poly(ethylene glycol) (PCP) scaffold. PCP was lyophilised to create supermacroporous structures. 3-(4, 5-dimethyl-thiazol-2yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and immunohistochemistry (IHC) were used to evaluate the effectiveness of PCP scaffolds for chondrocytes attachment and proliferation. The ultrastructural was assessed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Extracellular matrix (ECM) formation was evaluated using collagen type-II staining, glycosaminoglycan (GAG) and collagen assays. Histological analysis was conducted on 3-week implanted Sprague-Dawley rats. The MTT, IHC, SEM and TEM analyses confirm that PCP scaffolds promoted cell attachment and proliferation in vitro. The chondrocyte-PCP constructs secreted GAG and collagen type-II, both increased significantly from day-14 to day-28 (P 
    Matched MeSH terms: Cartilage/cytology; Cartilage/growth & development*
  4. Fulltext Feasibility of Human Platelet Lysate as an Alternative to Foetal Bovine Serum for In Vitro Expansion of Chondrocytes
    Liau LL, Hassan MNFB, Tang YL, Ng MH, Law JX
    Int J Mol Sci, 2021 Jan 28;22(3).
    PMID: 33525349 DOI: 10.3390/ijms22031269
    Osteoarthritis (OA) is a degenerative joint disease that affects a lot of people worldwide. Current treatment for OA mainly focuses on halting or slowing down the disease progress and to improve the patient's quality of life and functionality. Autologous chondrocyte implantation (ACI) is a new treatment modality with the potential to promote regeneration of worn cartilage. Traditionally, foetal bovine serum (FBS) is used to expand the chondrocytes. However, the use of FBS is not ideal for the expansion of cells mean for clinical applications as it possesses the risk of animal pathogen transmission and animal protein transfer to host. Human platelet lysate (HPL) appears to be a suitable alternative to FBS as it is rich in biological factors that enhance cell proliferation. Thus far, HPL has been found to be superior in promoting chondrocyte proliferation compared to FBS. However, both HPL and FBS cannot prevent chondrocyte dedifferentiation. Discrepant results have been reported for the maintenance of chondrocyte redifferentiation potential by HPL. These differences are likely due to the diversity in the HPL preparation methods. In the future, more studies on HPL need to be performed to develop a standardized technique which is capable of producing HPL that can maintain the chondrocyte redifferentiation potential reproducibly. This review discusses the in vitro expansion of chondrocytes with FBS and HPL, focusing on its capability to promote the proliferation and maintain the chondrogenic characteristics of chondrocytes.
    Matched MeSH terms: Cartilage/metabolism; Cartilage/pathology
  5. Tough Supramolecular Polymer Networks with Extreme Stretchability and Fast Room-Temperature Self-Healing
    Liu J, Tan CSY, Yu Z, Li N, Abell C, Scherman OA
    Adv Mater, 2017 Jun;29(22).
    PMID: 28370560 DOI: 10.1002/adma.201605325
    Recent progress on highly tough and stretchable polymer networks has highlighted the potential of wearable electronic devices and structural biomaterials such as cartilage. For some given applications, a combination of desirable mechanical properties including stiffness, strength, toughness, damping, fatigue resistance, and self-healing ability is required. However, integrating such a rigorous set of requirements imposes substantial complexity and difficulty in the design and fabrication of these polymer networks, and has rarely been realized. Here, we describe the construction of supramolecular polymer networks through an in situ copolymerization of acrylamide and functional monomers, which are dynamically complexed with the host molecule cucurbit[8]uril (CB[8]). High molecular weight, thus sufficient chain entanglement, combined with a small-amount dynamic CB[8]-mediated non-covalent crosslinking (2.5 mol%), yields extremely stretchable and tough supramolecular polymer networks, exhibiting remarkable self-healing capability at room temperature. These supramolecular polymer networks can be stretched more than 100× their original length and are able to lift objects 2000× their weight. The reversible association/dissociation of the host-guest complexes bestows the networks with remarkable energy dissipation capability, but also facile complete self-healing at room temperature. In addition to their outstanding mechanical properties, the networks are ionically conductive and transparent. The CB[8]-based supramolecular networks are synthetically accessible in large scale and exhibit outstanding mechanical properties. They could readily lead to the promising use as wearable and self-healable electronic devices, sensors and structural biomaterials.
    Matched MeSH terms: Cartilage
  6. Fulltext Current Update of Collagen Nanomaterials-Fabrication, Characterisation and Its Applications: A Review
    Lo S, Fauzi MB
    Pharmaceutics, 2021 Feb 28;13(3).
    PMID: 33670973 DOI: 10.3390/pharmaceutics13030316
    Tissue engineering technology is a promising alternative approach for improvement in health management. Biomaterials play a major role, acting as a provisional bioscaffold for tissue repair and regeneration. Collagen a widely studied natural component largely present in the extracellular matrix (ECM) of the human body. It provides mechanical stability with suitable elasticity and strength to various tissues, including skin, bone, tendon, cornea and others. Even though exogenous collagen is commonly used in bioscaffolds, largely in the medical and pharmaceutical fields, nano collagen is a relatively new material involved in nanotechnology with a plethora of unexplored potential. Nano collagen is a form of collagen reduced to a nanoparticulate size, which has its advantages over the common three-dimensional (3D) collagen design, primarily due to its nano-size contributing to a higher surface area-to-volume ratio, aiding in withstanding large loads with minimal tension. It can be produced through different approaches including the electrospinning technique to produce nano collagen fibres resembling natural ECM. Nano collagen can be applied in various medical fields involving bioscaffold insertion or fillers for wound healing improvement; skin, bone, vascular grafting, nerve tissue and articular cartilage regeneration as well as aiding in drug delivery and incorporation for cosmetic purposes.
    Matched MeSH terms: Cartilage, Articular
  7. Fulltext Neonatal post-intubation subglottic stenosis
    Loi HDK, Parhr AS, Subramaniam SK, Choo KE, Ng HP
    Med J Malaysia, 2004 Mar;59(1):126-8.
    PMID: 15535351
    Acquired subglottic stenosis is a compication or neonatal endotracheal intubation. Although it is rare, it contributes significantly to the morbidity and physical well being of post extubated neonates. A 20-day old neonate, ventilated for meconium aspiration syndrome and persistent fetal circulation, presented with marked stridor and respiratory embarrassment. A stenosed subglottic area was found on rigid bronchoscopy. Anterior cricoid split was performed to relieve the obstruction. He is asymptomatic post operatively.
    Matched MeSH terms: Cricoid Cartilage/surgery*
  8. The usage of living cartilage homografts in pre-prosthetic surgery
    Loke LT
    Dent J Malaysia Singapore, 1969 Oct;9(2):34-44.
    PMID: 4906531
    Matched MeSH terms: Cartilage/transplantation
  9. Vernonia amygdalina inhibited osteoarthritis development by anti-inflammatory and anticollagenase pathways in cartilage explant and osteoarthritis-induced rat model
    Madzuki IN, Lau SF, Abdullah R, Mohd Ishak NI, Mohamed S
    Phytother Res, 2019 Jul;33(7):1784-1793.
    PMID: 31033070 DOI: 10.1002/ptr.6366
    Vernonia amygdalina (VA) is a medicinal tropical herb for diabetes and malaria and believed to be beneficial for joint pains. The antiosteorthritis effects of VA leaf in cartilage explant assays and on postmenopausal osteoarthritis (OA) rat model were investigated. The VA reduced the proteoglycan and nitric oxide release from the cartilage explants with interleukin 1β (IL-1β) stimulation. For the preclinical investigation, ovariectomized (OVX) female rats were grouped (n = 8) into nontreated OA, OA + diclofenac (5 mg/kg), OA + VA extract (150 and 300 mg/kg), and healthy sham control. Monosodium iodoacetate was injected into the knee joints to accelerate OA development. After 8 weeks, the macroscopic, microscopic, and histological images showed that the OA rats treated with VA 300 mg/kg and diclofenac had significantly reduced cartilage erosions and osteophytes unlike the control OA rats. The extract significantly down-regulated the inflammatory prostaglandin E2, nuclear factor κβ, IL-1β, ADAMTS-5, collagen type 10α1, and caspase3 in the OVX-OA rats. It up-regulated the anti-inflammatory IL-10 and collagen type 2α1 mRNA expressions, besides reducing serum collagenases (MMP-3 and MMP-13) and collagen type II degradation biomarker (CTX-II) levels in these rats. The VA (containing various caffeoyl-quinic acids, flavanone-O-rutinoside, luteolin, apigenin derivative and vernonioside D) suppressed inflammation, pain, collagenases as well as cartilage degradation, and improved cartilage matrix synthesis to prevent OA.
    Matched MeSH terms: Cartilage
  10. Does cartilage ERα overexpression correlate with osteoarthritic chondrosenescence? Indications from Labisia pumila OA mitigation
    Madzuki IN, Lau SF, Mohamad Shalan NAA, Mohd Ishak NI, Mohamed S
    J Biosci, 2019 Sep;44(4).
    PMID: 31502578
    Chondrosenescence (chondrocyte senescence) and subchondral bone deterioration in osteoarthritic rats were analyzed after treatment with the estrogenic herb Labisia pumila (LP) or diclofenac. Osteoarthritis (OA) was induced in bilaterally ovariectomized (OVX) rats by injecting mono-iodoacetate into the right knee joints. Rats were grouped (n = 8) into nontreated OVX+OA control, OVX+OA + diclofenac (5 mg/kg) (positive control), OVX+OA + LP leaf extract (150 and 300 mg/kg) and healthy sham control. After 8 weeks' treatment, their conditions were evaluated via serum biomarkers, knee joint histology, bone histomorphometry, protein and mRNA expressions. The LP significantly reduced cartilage erosion, femur bone surface alteration, bone loss and porosity and increased trabecular bone thickness better than diclofenac and the non-treated OA. The cartilage catabolic markers' (matrix metalloproteinase (MMP)-13, RUNX2, COL10a, ERa, CASP3 and HIF-2 alpha) mRNA expressions were down-regulated and serum bone formation marker, PINP, was increased by LP in a dose-dependent manner. The LP (containing myricetin and gallic acid) showed protection against chondrosenescence, chondrocyte death, hypoxia-induced cartilage catabolism and subchondral bone deterioration. The bone and cartilage protective effects were by suppressing proteases (collagen break-down), bone resorption and upregulating subchondral bone restoration. The cartilage ER alpha over-expression showed a strong positive correlation with MMP-13, COL10 alpha1, histological, micro-computed tomography evidence for cartilage degradation and chondrosenescence.
    Matched MeSH terms: Cartilage/drug effects; Cartilage/metabolism
  11. Fulltext Tracheal cartilaginous sleeve in Pfeiffer syndrome: lesson learnt from its rarity
    Mahmud N, Abdul Latif H, Mohd Zaki F, Goh BS
    BMJ Case Rep, 2021 Apr 02;14(4).
    PMID: 33811090 DOI: 10.1136/bcr-2020-236888
    Pfeiffer syndrome is a rare inherited craniofacial disorder. Upper airway obstruction is common among patients with Pfeiffer syndrome due to craniosynostosis. They may also present with lower respiratory tract obstruction due to a rare congenital airway malformation called tracheal cartilaginous sleeve (TCS). We report the case of a patient with Pfeiffer syndrome who presented with recurrent bronchopneumonia, discovered incidentally to have TCS via direct visualisation during tracheostomy. Relevant literature for this rare clinical condition are reviewed and discussed. Clinicians should be aware of TCS when encountering patients with craniosynostosis who present with recurrent lower respiratory tract infections. Careful and meticulous investigations should be performed to look for TCS, especially in patients with craniosynostosis.
    Matched MeSH terms: Cartilage
  12. Fulltext Mesenchymal stromal cells for cartilage repair in osteoarthritis
    Mamidi MK, Das AK, Zakaria Z, Bhonde R
    Osteoarthritis Cartilage, 2016 Aug;24(8):1307-16.
    PMID: 26973328 DOI: 10.1016/j.joca.2016.03.003
    Treatment for articular cartilage damage is quite challenging as it shows limited repair and regeneration following injury. Non-operative and classical surgical techniques are inefficient in restoring normal anatomy and function of cartilage in osteoarthritis (OA). Thus, investigating new and effective strategies for OA are necessary to establish feasible therapeutic solutions. The emergence of the new discipline of regenerative medicine, having cell-based therapy as its primary focus, may enable us to achieve repair and restore the damaged articular cartilage. This review describes progress and development of employing mesenchymal stromal cell (MSC)-based therapy as a promising alternative for OA treatment. The objective of this review is to first, discuss how in vitro MSC chondrogenic differentiation mimics in vivo embryonic cartilage development, secondly, to describe various chondrogenic differentiation strategies followed by pre-clinical and clinical studies demonstrating their feasibility and efficacy. However, several challenges need to be tackled before this research can be translated to the clinics. In particular, better understanding of the post-transplanted cell behaviour and learning to enhance their potency in the disease microenvironment is essential. Final objective is to underscore the importance of isolation, storage, cell shipment, route of administration, optimum dosage and control batch to batch variations to realise the full potential of MSCs in OA clinical trials.
    Matched MeSH terms: Cartilage, Articular
  13. Nanoreinforced Hydrogels for Tissue Engineering: Biomaterials that are Compatible with Load-Bearing and Electroactive Tissues
    Mehrali M, Thakur A, Pennisi CP, Talebian S, Arpanaei A, Nikkhah M, et al.
    Adv Mater, 2017 Feb;29(8).
    PMID: 27966826 DOI: 10.1002/adma.201603612
    Given their highly porous nature and excellent water retention, hydrogel-based biomaterials can mimic critical properties of the native cellular environment. However, their potential to emulate the electromechanical milieu of native tissues or conform well with the curved topology of human organs needs to be further explored to address a broad range of physiological demands of the body. In this regard, the incorporation of nanomaterials within hydrogels has shown great promise, as a simple one-step approach, to generate multifunctional scaffolds with previously unattainable biological, mechanical, and electrical properties. Here, recent advances in the fabrication and application of nanocomposite hydrogels in tissue engineering applications are described, with specific attention toward skeletal and electroactive tissues, such as cardiac, nerve, bone, cartilage, and skeletal muscle. Additionally, some potential uses of nanoreinforced hydrogels within the emerging disciplines of cyborganics, bionics, and soft biorobotics are highlighted.
    Matched MeSH terms: Cartilage
  14. Fulltext An in vitro investigation to understand the synergistic role of MMPs-1 and 9 on articular cartilage biomechanical properties
    Mixon A, Savage A, Bahar-Moni AS, Adouni M, Faisal T
    Sci Rep, 2021 07 13;11(1):14409.
    PMID: 34257325 DOI: 10.1038/s41598-021-93744-1
    Matrix metalloproteinases (MMPs) play a crucial role in enzymatically digesting cartilage extracellular matrix (ECM) components, resulting in degraded cartilage with altered mechanical loading capacity. Overexpression of MMPs is often caused by trauma, physiologic conditions and by disease. To understand the synergistic impact MMPs have on cartilage biomechanical properties, MMPs from two subfamilies: collagenase (MMP-1) and gelatinase (MMP-9) were investigated in this study. Three different ratios of MMP-1 (c) and MMP-9 (g), c1:g1, c3:g1 and c1:g3 were considered to develop a degradation model. Thirty samples, harvested from bovine femoral condyles, were treated in groups of 10 with one concentration of enzyme mixture. Each sample was tested in a healthy state prior to introducing degradative enzymes to establish a baseline. Samples were subjected to indentation loading up to 20% bulk strain. Both control and treated samples were mechanically and histologically assessed to determine the impact of degradation. Young's modulus and peak load of the tissue under indentation were compared between the control and degraded cartilage explants. Cartilage degraded with the c3:g1 enzyme concentration resulted in maximum 33% reduction in stiffness and peak load compared to the other two concentrations. The abundance of collagenase is more responsible for cartilage degradation and reduced mechanical integrity.
    Matched MeSH terms: Cartilage, Articular*
  15. Fulltext Otitis externa complicated with chloramphenicol ear drops-induced perichondritis
    Mohamad I, Johan K, Hashim H, Nik Othman N
    Malays Fam Physician, 2014;9(1):28-9.
    PMID: 25606295 MyJurnal
    Otitis externa is a common condition of the ear. It is manifested as narrowing of the lumen owing to the edematous swelling of the ear canal lining. Perichondritis may occur independently or as a complication of the otitis externa. We report a case of perichondritis after using a topical ear drop. Changing the medication provides immediate resolution of the condition.
    Matched MeSH terms: Cartilage Diseases
  16. Fulltext An overview of bone cells and their regulating factors of differentiation
    Mohamed AM
    Malays J Med Sci, 2008 Jan;15(1):4-12.
    PMID: 22589609 MyJurnal
    Bone is a specialised connective tissue and together with cartilage forms the strong and rigid endoskeleton. These tissues serve three main functions: scaffold for muscle attachment for locomotion, protection for vital organs and soft tissues and reservoir of ions for the entire organism especially calcium and phosphate. One of the most unique and important properties of bone is its ability to constantly undergo remodelling even after growth and modelling of the skeleton have been completed. Remodelling processes enable the bone to respond and adapt to changing functional situations. Bone is composed of various types of cells and collagenous extracellular organic matrix, which is predominantly type I collagen (85-95%) called osteoid that becomes mineralised by the deposition of calcium hydroxyapatite. The non-collagenous constituents are composed of proteins and proteoglycans, which are specific to bone and the dental hard connective tissues. Maintenance of appropriate bone mass depends upon the precise balance of bone formation and bone resorption which is facilitated by the ability of osteoblastic cells to regulate the rate of both differentiation and activity of osteoclasts as well as to form new bone. An overview of genetics and molecular mechanisms that involved in the differentiation of osteoblast and osteoclast is discussed.
    Matched MeSH terms: Cartilage
  17. Recent advances in the use of animal-sourced gelatine as natural polymers for food, cosmetics and pharmaceutical applications
    Mohd Shakrie Palan Abdullah, Mohamed Ibrahim Noordin, Syed Ibrahim Mohd Ismail, Nur Murnisa Mustapha, Malina Jasamai, Ahmad Fuad Shamsuddin, et al.
    Sains Malaysiana, 2018;47:323-336.
    Gelatine is used as an excipient for various pharmaceutical dosage forms, such as capsule shells (both hard and soft),
    tablets, suspensions, emulsions and injections (e.g. plasma expanders). It is also broadly used in various industries
    such as food and cosmetics. Gelatine is a biopolymer obtained from discarded or unused materials of bovine, porcine,
    ovine, poultry and marine industrial farms. The discarded materials can be the skin, tendons, cartilages, bones and
    connective tissues. Gelatine sourced from animals is relatively easy and inexpensive to produce. The potential needs of
    gelatine cannot be overemphasised. Rising demands, health concerns and religious issues have heightened the need for
    alternative sources of gelatine. This review presents the various industrial uses of gelatine and the latest developments
    in producing gelatine from various sources.
    Matched MeSH terms: Cartilage
  18. The transcript level of interleukin-6 in the cartilage of idiopathic osteoarthritis of knee
    Moktar NM, Yusof HM, Yahaya NH, Muhamad R, Das S
    Clin Ter, 2010;161(1):25-8.
    PMID: 20393674
    AIMS: The mRNA level for interleukin-6 (IL-6) is an important marker of osteoarthritis (OA). The present study aimed to investigate the level of IL-6 mRNA in the cartilage of OA knee while comparing it to the normal cartilage obtained from the same patient.
    MATERIALS AND METHODS: A total of 21 patients who underwent total knee replacement were recruited for this study. Sectioning of the destructive cartilage was performed in the medial part of the proximal tibiofemoral cartilage. The unaffected lateral part of the knee in the same patient, served as a control. The mRNA level for IL-6 was assessed using LightCycler 2.0 quantitative real-time polymerase chain reaction (qRT-PCR). actin mRNA was used as an endogenous control.
    RESULTS: Twelve out of 21 patients (57.1%) exhibited up regulation of IL-6 mRNA in the OA cartilage as compared to the normal cartilage. The rest of the patients (42.9%) showed down regulation of IL-6 mRNA. The statistical analysis showed there was insignificant level of IL-6 mRNA in the OA (1.91 +/- 0.45) as compared to the normal cartilage (1.13 +/- 0.44) (p > 0.05). The inter-individual variation in the level of IL-6 mRNA in the cartilage of idiopathic knee was in accordance with previous findings.
    CONCLUSIONS: These observations suggest IL-6 could also act as a catabolic agent in some patients or its expression might be influenced by other cytokines.
    Study site: Pusat Perubatan Universiti Kebangsaan Malaysia (PPUKM), Kuala Lumpur, Malaysia
    Matched MeSH terms: Cartilage, Articular/metabolism*; Cartilage, Articular/pathology
  19. Extracellular matrix integrity affects the mechanical behaviour of in-situ chondrocytes under compression
    Moo EK, Han SK, Federico S, Sibole SC, Jinha A, Abu Osman NA, et al.
    J Biomech, 2014 Mar 21;47(5):1004-13.
    PMID: 24480705 DOI: 10.1016/j.jbiomech.2014.01.003
    Cartilage lesions change the microenvironment of cells and may accelerate cartilage degradation through catabolic responses from chondrocytes. In this study, we investigated the effects of structural integrity of the extracellular matrix (ECM) on chondrocytes by comparing the mechanics of cells surrounded by an intact ECM with cells close to a cartilage lesion using experimental and numerical methods. Experimentally, 15% nominal compression was applied to bovine cartilage tissues using a light-transmissible compression system. Target cells in the intact ECM and near lesions were imaged by dual-photon microscopy. Changes in cell morphology (N(cell)=32 for both ECM conditions) were quantified. A two-scale (tissue level and cell level) Finite Element (FE) model was also developed. A 15% nominal compression was applied to a non-linear, biphasic tissue model with the corresponding cell level models studied at different radial locations from the centre of the sample in the transient phase and at steady state. We studied the Green-Lagrange strains in the tissue and cells. Experimental and theoretical results indicated that cells near lesions deform less axially than chondrocytes in the intact ECM at steady state. However, cells near lesions experienced large tensile strains in the principal height direction, which are likely associated with non-uniform tissue radial bulging. Previous experiments showed that tensile strains of high magnitude cause an up-regulation of digestive enzyme gene expressions. Therefore, we propose that cartilage degradation near tissue lesions may be due to the large tensile strains in the principal height direction applied to cells, thus leading to an up-regulation of catabolic factors.
    Matched MeSH terms: Cartilage, Articular/injuries*; Cartilage, Articular/physiology
  20. Dual photon excitation microscopy and image threshold segmentation in live cell imaging during compression testing
    Moo EK, Abusara Z, Abu Osman NA, Pingguan-Murphy B, Herzog W
    J Biomech, 2013 Aug 9;46(12):2024-31.
    PMID: 23849134 DOI: 10.1016/j.jbiomech.2013.06.007
    Morphological studies of live connective tissue cells are imperative to helping understand cellular responses to mechanical stimuli. However, photobleaching is a constant problem to accurate and reliable live cell fluorescent imaging, and various image thresholding methods have been adopted to account for photobleaching effects. Previous studies showed that dual photon excitation (DPE) techniques are superior over conventional one photon excitation (OPE) confocal techniques in minimizing photobleaching. In this study, we investigated the effects of photobleaching resulting from OPE and DPE on morphology of in situ articular cartilage chondrocytes across repeat laser exposures. Additionally, we compared the effectiveness of three commonly-used image thresholding methods in accounting for photobleaching effects, with and without tissue loading through compression. In general, photobleaching leads to an apparent volume reduction for subsequent image scans. Performing seven consecutive scans of chondrocytes in unloaded cartilage, we found that the apparent cell volume loss caused by DPE microscopy is much smaller than that observed using OPE microscopy. Applying scan-specific image thresholds did not prevent the photobleaching-induced volume loss, and volume reductions were non-uniform over the seven repeat scans. During cartilage loading through compression, cell fluorescence increased and, depending on the thresholding method used, led to different volume changes. Therefore, different conclusions on cell volume changes may be drawn during tissue compression, depending on the image thresholding methods used. In conclusion, our findings confirm that photobleaching directly affects cell morphology measurements, and that DPE causes less photobleaching artifacts than OPE for uncompressed cells. When cells are compressed during tissue loading, a complicated interplay between photobleaching effects and compression-induced fluorescence increase may lead to interpretations in cell responses to mechanical stimuli that depend on the microscopic approach and the thresholding methods used and may result in contradictory interpretations.
    Matched MeSH terms: Cartilage, Articular/cytology; Cartilage, Articular/metabolism*
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