The effects of TGF-β1 and IGF-I on the biomechanics and cytoskeleton of single chondrocytes

SummaryObjectiveAscertaining how mechanical forces and growth factors mediate normal and pathologic processes in single chondrocytes can aid in developing strategies for the repair and replacement of articular cartilage destroyed by injury or disease. This study examined effects of transforming growth factor-β1 (TGF-β1) and insulin-like growth factor-I (IGF-I) on the biomechanics and cytoskeleton of single zonal chondrocytes.MethodSuperficial and middle/deep bovine articular chondrocytes were seeded on tissue culture treated plastic for 3 and 18h and treated with TGF-β1 (5ng/mL), IGF-I (100ng/mL), or a combination of TGF-β1 (5ng/mL)+IGF-I (100ng/mL). Single chondrocytes from all treatments were individually studied using viscoelastic creep testing and stained with rhodamine phalloidin for the F-actin cytoskeleton. Lastly, real-time RT-PCR was performed for β-actin.ResultsCreep testing demonstrated that all growth factor treatments stiffened cells. Image analysis of rhodamine phalloidin stained chondrocytes showed that cells from all growth factor groups had significantly higher fluorescence than controls, mirroring creep testing results. Growth factors altered cell morphology, since chondrocytes exposed to growth factors remained more rounded, exhibited greater cell heights, and were less spread. Finally, real-time RT-PCR revealed no significant effect of growth factor exposure on β-actin mRNA abundance. However, β-actin expression varied zonally, suggesting that this gene would be unsuitable as a PCR housekeeping gene.ConclusionsThese results indicate that TGF-β1 and IGF-I increase F-actin levels in single chondrocytes leading to stiffening of cells; however, there does not appear to be direct transcriptional regulation of unpolymerized β-actin. This suggests that the observed response is most likely due to signaling cross-talk between growth factor receptors and integrin/focal adhesion complexes

Comparison of mechanical debridement and radiofrequency energy for chondroplasty in an in vivo equine model of partial thickness cartilage injury

SummaryObjectiveThe purpose of this study was to develop a long-term model of cartilage injury that could be used to compare the effects of radiofrequency energy (RFE) and mechanical debridement as a treatment.MethodsPartial thickness fibrillation of patellar cartilage was created in 16 mature ponies. Three months after the initial surgery all injured patellae were randomly selected to receive one of the four treatments (n=8/treatment): (1) control, (2) mechanical debridement with a motorized shaver, (3) TAC-CII RFE probe, and (4) CoVac 50 RFE probe. The ponies were euthanized 22 months after treatment. Macroscopic appearance of the cartilage surface was scored, vital cell staining was used to determine chondrocyte viability and light microscopy was used to grade the morphometric changes within the cartilage. Mechanical properties (aggregate modulus, Poisson's ratio and permeability) also were determined and compared to normal uninjured cartilage.ResultsThere were no differences in the cartilage surface scores among the treatment groups and control samples (P>0.05). The maximum depth of cell death and the percentage of dead area in control and mechanical debridement groups were significantly less than those in both RFE groups. There were no significant differences in maximum depth and the percentage of dead area between the two RFE treatment groups. Histologic scores demonstrated better cartilage morphology for the control and mechanical debridement groups than those of RFE groups. However, even with full thickness chondrocyte death, the matrix in the RFE treated sections was still retained and the mechanical properties of the treated cartilage did not differ from the mechanical debridement group.ConclusionRFE caused greater chondrocyte death and more severe morphological changes compared to untreated degenerative cartilage and mechanical debridement in this model

Is tissue engineering of the TMJ disc a feasible process?

Temporomandibular joint (TMJ) disorders are common and difficult to remedy. Tissue engineering is one alternative that seeks to improve TMJ sugical treatment options. Tissue engineering aims to replace diseased or injured tissue with biologically engineered constructs. These constructs should reproduce native function and limit an immune response. To achieve tissue engineering success, it is important to first understand the tissue's cellular, biochemical and mechanical properties in order to create validation and design criteria. Reviewd herein are the known properties of the TMJ disc and initial attempts toward TMJ disc tissue engineering. Important aspects of tissue engineering are scaffold selection, cell source, biochemical factors, and mechanical stimuli

Characterization of Degenerative Changes in the Temporomandibular Joint of the Bengal Tiger (Panthera tigris tigris) and Siberian Tiger (Panthera tigris altaica)

The articulation of the temporomandibular joint (TMJ) is composed of the temporal bone dorsally, the mandibular condyle ventrally and a fibrous articular disc. The TMJ disc plays an essential role in distributing load between the two articular surfaces. Degeneration of the disc in the presence of joint pathology has been shown in man; however, TMJ pathology has not been documented previously in tigers (Panthera tigris). The mandibular condyle and TMJ disc of a Bengal tiger (P. tigris tigris) and a Siberian tiger (P. tigris altaica) were evaluated grossly and the TMJ disc was characterized biochemically and mechanically. Characterization of the TMJ disc verified region- and direction-dependent biochemical and mechanical properties, reflective of the functional demands on the joint. Degenerative joint disease was observed in both cases and this was more severe in the Siberian tiger. Simultaneous evaluation of joint pathology, biochemical composition and mechanical properties of the TMJ disc revealed a loss in functional properties (tensile anisotropy) of the disc as joint pathology advanced from moderate to severe. TMJ degeneration may compromise the ability of the animal to eat and thrive and may be a factor contributing to the endangered status of these species

Cartilage immunoprivilege depends on donor source and lesion location

The ability to repair damaged cartilage is a major goal of musculoskeletal tissue engineering. Allogeneic (same species, different individual) or xenogeneic (different species) sources can provide an attractive source of chondrocytes for cartilage tissue engineering, since autologous (same individual) cells are scarce. Immune rejection of non-autologous hyaline articular cartilage has seldom been considered due to the popular notion of “cartilage immunoprivilege.” The objective of this study was to determine the suitability of allogeneic and xenogeneic engineered neocartilage tissue for cartilage repair. To address this, scaffold-free tissue engineered articular cartilage of syngeneic (same genetic background), allogeneic, and xenogeneic origin were implanted into two different locations of the rabbit knee (n=3 per group/location). Xenogeneic engineered cartilage and control xenogeneic chondral explants provoked profound innate inflammatory and adaptive cellular responses, regardless of transplant location. Cytological quantification of immune cells showed that, while allogeneic neocartilage elicited an immune response in the patella, negligible responses were observed when implanted into the trochlea; instead the responses were comparable to microfracture-treated empty defect controls. Allogeneic neocartilage survived within the trochlea implant site and demonstrated graft integration into the underlying bone. In conclusion, the knee joint cartilage does not represent an immune privileged site, strongly rejecting xenogeneic but not allogeneic chondrocytes in a location-dependent fashion. This difference in location-dependent survival of allogeneic tissue may be associated with proximity to the synovium

Histograms of Complete Blood Counts in Dogs: Maximizing Diagnostic Information

Histograms, which are an integral part of the automated complete blood count, are now available through most of the automatic hematology analyzers used in veterinary clinical practice. Data concerning the size and number of blood cells are graphically presented in histograms, and their variations are also illustrated. Important information that is not apparent from numerical results are sometimes provided by histograms. Histograms are also referred to as frequency distribution curves and are essentially graphs resulting from the placement of the sizes of cells on the x-axis and the number of cells on the y-axis. Typically, automated analyzers provide histograms for each class of blood cells, that is, for erythrocytes, leukocytes, and platelets. Thus, when the erythrocyte histogram shows asymmetry with a right shift, it means the size of the erythrocytes is greater than normal (macrocytosis); when it presents a left shift, the size of the erythrocytes is less than normal (microcytosis). When two peaks are found in the curve, two populations of erythrocytes coexist, as in the case of a blood transfusion or therapeutic response. In the leukocyte histogram, three peaks are found: the closest to the y-axis (left) corresponds to the lymphocytes, the middle to the monocytes, and the right to the polymorphonuclear cells (neutrophils, eosinophils, and basophils). Finally, in platelet histogram, asymmetry with a right shift suggests the presence of giant platelets or schistocytes. Although the histogram is not recommended as a stand-alone test, it allows the practitioner to observe abnormalities in the distribution curve that correspond to abnormalities in the size or number of cells, and to quickly make diagnostic or therapeutic decisions that are particularly important in emergencies. © 2018 Elsevier Inc

Chondroitinase ABC Treatment Results in Greater Tensile Properties of Self-Assembled Tissue-Engineered Articular Cartilage

Collagen content and tensile properties of engineered articular cartilage have remained inferior to glycosaminoglycan (GAG) content and compressive properties. Based on a cartilage explant study showing greater tensile properties after chondroitinase ABC (C-ABC) treatment, C-ABC as a strategy for cartilage tissue engineering was investigated. A scaffold-less approach was employed, wherein chondrocytes were seeded into non-adherent agarose molds. C-ABC was used to deplete GAG from constructs 2 weeks after initiating culture, followed by 2 weeks culture post-treatment. Staining for GAG and type I, II, and VI collagen and transmission electron microscopy were performed. Additionally, quantitative total collagen, type I and II collagen, and sulfated GAG content were measured, and compressive and tensile mechanical properties were evaluated. At 4 wks, C-ABC treated construct ultimate tensile strength and tensile modulus increased 121% and 80% compared to untreated controls, reaching 0.5 and 1.3 MPa, respectively. These increases were accompanied by increased type II collagen concentration, without type I collagen. As GAG returned, compressive stiffness of C-ABC treated constructs recovered to be greater than 2 wk controls. C-ABC represents a novel method for engineering functional articular cartilage by departing from conventional anabolic approaches. These results may be applicable to other GAG-producing tissues functioning in a tensile capacity, such as the musculoskeletal fibrocartilages

In-depth bioinformatic study of the cadherin 5 interactome in patients with thoracic aortic aneurysm unveils 8 novel biomarkers

OBJECTIVES: Thoracic aortic aneurysm (TAA) is characterized by the dilation of the aorta and is associated with poor prognosis if not diagnosed and treated early. In this context, the identification of biomarkers regarding the TAA diagnosis, monitoring and prognosis is crucial. The purpose of the current study was to investigate the differential gene expression profile of the cadherin 5 (CDH5 or VE-Cadherin) gene network in patients with TAA, to propose novel biomarkers. METHODS: In silico techniques were used to construct the interactome of the CDH5 network, identify the differentially expressed genes (DEGs) in TAA as compared to healthy controls, and uncover the related molecular functions and the regulating miRNAs. RESULTS: Transcriptomic data of one microarray dataset were included, incorporating 43 TAA and 43 control samples. Eight DEGs were identified; 7 were up-regulated and 1 was down-regulated. A molecular signature of 8 genes (CDH5; Calcitonin Receptor-Like Receptor-CALCRL; Activin A Receptor-Like Type 1-ACVRL1, Tryptophanyl-TRNA Synthetase 1-WARS; Junction Plakoglobin-JUP, Protein Tyrosine Phosphatase Receptor Type J-PTPRJ, Purinergic Receptor P2X 4-P2RX4, Kinase Insert Domain Receptor-KDR) were identified as biomarkers associated with TAA. PTPRJ was associated with excellent discrimination and calibration in predicting TAA presentation. Positive correlations were reported regarding the expression of CDH5-CALCRL, CDH5-ACVRL1, CDH5-WARS and CDH5-PTPRJ. Finally, gene set enrichment analysis indicated the molecular functions and miRNA families (hsa-miR-296-5p, hsa-miR-6836-5p, hsa-miR-6132, hsa-miR-27a-5p and hsa-miR-6773-5p) relevant to the 8 biomarkers. CONCLUSIONS: These outcomes propose an 8-gene molecular panel associated with TAA. © 2021 The Author(s). Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved

How can cardiothoracic and vascular medical devices stay in the market?

Surgeons, as the consumers, must engage in commercial activity regarding medical devices since it directly has impacts on surgical practice and patient outcomes. Unique features defy traditional economic convention in this specific market partly because consumers do not usually pay directly. Greater involvement with commercial activity means better post-market surveillance of medical devices which leads to improved patient safety. The medical device industry has exhibited astonishing levels of growth and profitability reaching $398 billion on a global scale with new product development focusing on unmet clinical need. The industry has rapidly emerged within the context of an ageing population and a global surge in healthcare spending. But the market remains fragmented. The split of consumer, purchaser and payer leads to clinical need driving demand for new product development. This demand contributes to potentially large profit margins mainly contained by regulatory burden and liability issues. Demographic trends, prevalence of diseases and a huge capacity to absorb technology have sustained near unparalleled growth. To stay in the market, incremental development over the short term is essentially aided by responsiveness to demand. Disruptive product development is now more likely to come from multinational companies, in an increasingly expensive, regulated industry. Understanding healthcare organization can help explain the highly complex process of diffusion of innovations in healthcare that include medical devices. The time has come for surgeons to become actively involved with all aspects of the medical device life cycle including commercial activity and post-market surveillance. This is vital for improving patient care and ensuring patient safety