Immune responses to citrullinated and homocitrullinated peptides in healthy donors are not restricted to the HLA SE shared allele and can be selected into the memory pool.

Citrullination and homocitrullination are stress induced post-translational modifications (siPTMs) which can be recognized by T cells. Peripheral blood mononuclear cells isolated from healthy donors and rheumatoid arthritis (RA) patients were stimulated with nine siPTM-peptides. CD45RA/CD45RO depletion was employed to determine if peptide-specific responses are naïve or memory. Human leucocyte antigen (HLA)-DP4 and HLA-DR4 transgenic mice were immunized with siPTM-peptides and immune responses were determined with ex vivo ELISpot assays. The majority (24 out of 25) of healthy donors showed CD4 T cell-specific proliferation to at least 1 siPTM-peptide, 19 to 2 siPTM-peptides, 14 to 3 siPTM-peptides, 9 to 4 siPTM-peptides, 6 to 5 siPTM-peptides and 4 to 6 siPTM-peptides. More donors responded to Vim28-49cit (68%) and Bip189-208cit (75%) compared with Vim415-433cit (33%). In RA patients, the presentation of citrullinated epitopes is associated with HLA-SE alleles; however, we witnessed responses in healthy donors who did not express the SE allele. The majority of responding T cells were effector memory cells with a Th1/cytotoxic phenotype. Responses to Vim28-49cit and Eno241-260cit originated in the memory pool, while the response to Vim415-433cit was naïve. In the HLA-DP4 and HLA-DR4 transgenic models, Vim28cit generated a memory response. Peptide-specific T cells were capable of Epstein-Barr virus transformed lymphoblastoid cell line recognition suggesting a link with stress due to infection. These results suggest siPTM-peptides are presented under conditions of cellular stress and inflammation and drive cytotoxic CD4 T cell responses that aid in the removal of stressed cells. The presentation of such siPTM-peptides is not restricted to HLA-SE in both humans and animal models.

A Patient-Centered Approach to Research Prioritization in Prostate Cancer.

PURPOSE: Research priorities are often set by expert clinicians and researchers. We sought to apply an established process in patient-centered research to engage survivors and their caregivers in prioritizing research topics in prostate cancer. MATERIALS AND METHODS: A prostate cancer patient survey network, formed in partnership with Us TOO and the National Alliance of State Prostate Cancer Coalitions, engaged in a series of mixed-methods studies to prioritize comparative effectiveness research questions. This was accomplished through an iterative process that included 2 survey rounds and multidisciplinary working groups. RESULTS: There were 591 and 706 survey respondents in the first and second rounds, respectively, with most having had localized prostate cancer (58.1%). Survey participants represented 45 states in the U.S. Five of the top 11 prioritized research questions related to treatment decision making and/or survivorship care. The following had the highest overall importance ratings: What is the comparative effectiveness of different 1) strategies to improve counseling regarding the side effects of prostate cancer treatment, 2) tools for decision making in localized prostate cancer and 3) sequences of treatments for metastatic prostate cancer? CONCLUSIONS: We present a unique, patient-centered list of prioritized research questions among prostate cancer patients and their caregivers. These research questions may inform funding decisions for organizations that support research, and should be considered as priorities for clinicians, researchers and institutions conducting prostate cancer research. Prostate cancer is a common disease that affects 1 in 9 men over their lifetime. Researchers usually identify questions to study without asking men with prostate cancer. We asked survivors of prostate cancer and their caregivers to help us. They identified research questions and topics that are important to them. Researchers can focus on this list of questions to help men with prostate cancer. Groups who pay for research studies can make these questions their priority.

OxVent: Design and evaluation of a rapidly-manufactured Covid-19 ventilator.

BACKGROUND: The manufacturing of any standard mechanical ventilator cannot rapidly be upscaled to several thousand units per week, largely due to supply chain limitations. The aim of this study was to design, verify and perform a pre-clinical evaluation of a mechanical ventilator based on components not required for standard ventilators, and that met the specifications provided by the Medicines and Healthcare Products Regulatory Agency (MHRA) for rapidly-manufactured ventilator systems (RMVS). METHODS: The design utilises closed-loop negative feedback control, with real-time monitoring and alarms. Using a standard test lung, we determined the difference between delivered and target tidal volume (VT) at respiratory rates between 20 and 29 breaths per minute, and the ventilator's ability to deliver consistent VT during continuous operation for >14 days (RMVS specification). Additionally, four anaesthetised domestic pigs (3 male-1 female) were studied before and after lung injury to provide evidence of the ventilator's functionality, and ability to support spontaneous breathing. FINDINGS: Continuous operation lasted 23 days, when the greatest difference between delivered and target VT was 10% at inspiratory flow rates >825 mL/s. In the pre-clinical evaluation, the VT difference was -1 (-90 to 88) mL [mean (LoA)], and positive end-expiratory pressure (PEEP) difference was -2 (-8 to 4) cmH2O. VT delivery being triggered by pressures below PEEP demonstrated spontaneous ventilation support. INTERPRETATION: The mechanical ventilator presented meets the MHRA therapy standards for RMVS and, being based on largely available components, can be manufactured at scale. FUNDING: Work supported by Wellcome/EPSRC Centre for Medical Engineering,King's Together Fund and Oxford University.

Role of distinct fibroblast lineages and immune cells in dermal repair following UV radiation-induced tissue damage.

Solar ultraviolet radiation (UVR) is a major source of skin damage, resulting in inflammation, premature ageing, and cancer. While several UVR-induced changes, including extracellular matrix reorganisation and epidermal DNA damage, have been documented, the role of different fibroblast lineages and their communication with immune cells has not been explored. We show that acute and chronic UVR exposure led to selective loss of fibroblasts from the upper dermis in human and mouse skin. Lineage tracing and in vivo live imaging revealed that repair following acute UVR is predominantly mediated by papillary fibroblast proliferation and fibroblast reorganisation occurs with minimal migration. In contrast, chronic UVR exposure led to a permanent loss of papillary fibroblasts, with expansion of fibroblast membrane protrusions partially compensating for the reduction in cell number. Although UVR strongly activated Wnt signalling in skin, stimulation of fibroblast proliferation by epidermal ß-catenin stabilisation did not enhance papillary dermis repair. Acute UVR triggered an infiltrate of neutrophils and T cell subpopulations and increased pro-inflammatory prostaglandin signalling in skin. Depletion of CD4- and CD8-positive cells resulted in increased papillary fibroblast depletion, which correlated with an increase in DNA damage, pro-inflammatory prostaglandins, and reduction in fibroblast proliferation. Conversely, topical COX-2 inhibition prevented fibroblast depletion and neutrophil infiltration after UVR. We conclude that loss of papillary fibroblasts is primarily induced by a deregulated inflammatory response, with infiltrating T cells supporting fibroblast survival upon UVR-induced environmental stress.

Fibroblast Memory in Development, Homeostasis and Disease.

Fibroblasts are the major cell population in the connective tissue of most organs, where they are essential for their structural integrity. They are best known for their role in remodelling the extracellular matrix, however more recently they have been recognised as a functionally highly diverse cell population that constantly responds and adapts to their environment. Biological memory is the process of a sustained altered cellular state and functions in response to a transient or persistent environmental stimulus. While it is well established that fibroblasts retain a memory of their anatomical location, how other environmental stimuli influence fibroblast behaviour and function is less clear. The ability of fibroblasts to respond and memorise different environmental stimuli is essential for tissue development and homeostasis and may become dysregulated in chronic disease conditions such as fibrosis and cancer. Here we summarise the four emerging key areas of fibroblast adaptation: positional, mechanical, inflammatory, and metabolic memory and highlight the underlying mechanisms and their implications in tissue homeostasis and disease.

Engineering the Human Fc Region Enables Direct Cell Killing by Cancer Glycan-Targeting Antibodies without the Need for Immune Effector Cells or Complement.

Murine IgG3 glycan-targeting mAb often induces direct cell killing in the absence of immune effector cells or complement via a proinflammatory mechanism resembling oncotic necrosis. This cancer cell killing is due to noncovalent association between Fc regions of neighboring antibodies, resulting in enhanced avidity. Human isotypes do not contain the residues underlying this cooperative binding mode; consequently, the direct cell killing of mouse IgG3 mAb is lost upon chimerization or humanization. Using the Lewisa/c/x -targeting 88mAb, we identified the murine IgG3 residues underlying the direct cell killing and increased avidity via a series of constant region shuffling and subdomain swapping approaches to create improved ("i") chimeric mAb with enhanced tumor killing in vitro and in vivo. Constant region shuffling identified a major CH3 and a minor CH2 contribution, which was further mapped to discontinuous regions among residues 286-306 and 339-378 that, when introduced in 88hIgG1, recapitulated the direct cell killing and avidity of 88mIgG3. Of greater interest was the creation of a sialyl-di-Lewisa-targeting i129G1 mAb via introduction of these selected residues into 129hIgG1, converting it into a direct cell killing mAb with enhanced avidity and significant in vivo tumor control. The human iG1 mAb, termed Avidimabs, retained effector functions, paving the way for the proinflammatory direct cell killing to promote antibody-dependent cellular cytotoxicity and complement-dependent cytotoxicity through relief of immunosuppression. Ultimately, Fc engineering of human glycan-targeting IgG1 mAb confers proinflammatory direct cell killing and enhanced avidity, an approach that could be used to improve the avidity of other mAb with therapeutic potential. SIGNIFICANCE: Fc engineering enhances avidity and direct cell killing of cancer-targeting anti-glycan antibodies to create superior clinical candidates for cancer immunotherapy.

A review of methods to measure tendon dimensions.

Tendons are soft tissues of the musculoskeletal system that are designed to facilitate joint movement. Tendons exhibit a wide range of mechanical properties matched to their functions and, as a result, have been of interest to researchers for many decades. Dimensions are an important aspect of tendon properties.Change in the dimensions of tissues is often seen as a sign of injury and degeneration, as it may suggest inflammation or general disorder of the tissue. Dimensions are also important for determining the mechanical properties and behaviours of materials, particularly the stress, strain, and elastic modulus. This makes the dimensions significant in the context of a mechanical study of degenerated tendons. Additionally, tendon dimensions are useful in planning harvesting for tendon transfer and joint reconstruction purposes.Historically, many methods have been used in an attempt to accurately measure the dimensions of soft tissue, since improper measurement can lead to large errors in the calculated properties. These methods can be categorised as destructive (by approximation), contact, and non-contact and can be considered in terms of in vivo and ex vivo.

Construction of a High-Efficiency Drug and Gene Co-Delivery System for Cancer Therapy from a pH-Sensitive Supramolecular Inclusion between Oligoethylenimine- graft-ß-cyclodextrin and Hyperbranched Polyglycerol Derivative.

Introducing genes into drug-delivery system for a combined therapy has become a promising strategy for cancer treatment. However, improving the in vivo therapy effect resulted from the high delivery efficiency, low toxicity, and good stability in the blood remains a challenge. For this purpose, the supramolecular inclusion was considered to construct a high-efficiency drug and gene co-delivery system in this work. The oligoethylenimine-conjugated ß-cyclodextrin (ß-CD-PEI600) and benzimidazole-modified four-arm-polycaprolactone-initiated hyperbranched polyglycerol (PCL-HPG-BM) were synthesized as the host and guest molecules, respectively, and then the co-delivery carrier of PCL-HPG-PEI600 was formed from the pH-mediated inclusion interaction between ß-CD and BM. PCL-HPG-PEI600 showed the improved drug (doxorubicin, DOX) and gene (MMP-9 shRNA plasmid, pMMP-9) delivery ability in vivo, and their cellular uptake and intracellular delivery were investigated. Particularly, PCL-HPG-PEI600 showed excellent pMMP-9 delivery ability with significantly higher transfection efficiency than PEI25k due to its excellent serum resistance. For the combined therapy to breast cancer MCF-7 tumor, the co-delivery system of PCL-HPG-PEI600/DOX/pMMP-9 resulted in a much better inhibition effect on MCF-7 cell proliferation and migration in vitro as well as the suppression effect on MCF-7 tumors in vivo compared to those of single DOX or pMMP-9 formulation used. Moreover, PCL-HPG-PEI600 displayed nontoxicity and excellent blood compatibility, suggesting a promising drug and gene co-delivery carrier in combined therapy to tumors.

Redox-responsive chemosensitive polyspermine delivers ursolic acid targeting to human breast tumor cells: The depletion of intracellular GSH contents arouses chemosensitizing effects.

Antitumor efficacy of ursolic acid (UA) is seriously limited due to its low hydrophilicity and needy bioavailability. To overcome these obstacles, chemosensitive polyspermine (CPSP) conjugated with UA and folic acid (FA) as a novel targeted prodrug was designed and successfully synthesized in this investigation. This prodrug not only showed high aqueous solubility, GSH-triggered degradation and good biocompatibility, but also exhibited better inhibition effect on the tumor cells proliferation in comparison with free UA. FA-CPSP-UA could down-regulate the generation of GSH and manifest excellent ability in enhancing antitumor efficacy. In addition, FA-CPSP-UA could inhibit the expression of MMP-9, which led to restricting MCF-7 cells migration. Taken together, the results indicated that FA-CPSP-UA, as a carrier, can efficiently deliver UA to folate receptor positive cancer cells and improve tumor therapy of UA by Chemosensitive effect.

Reduction-Responsive Codelivery System Based on a Metal-Organic Framework for Eliciting Potent Cellular Immune Response.

Utilizing nanoparticles to deliver subunit vaccines can be viewed as a promising strategy for enhancing the immune response, especially with regard to cellular immunity to fight against infectious viruses and malignant cancer. Nevertheless, its applications are still far from practicality because of some limitations such as high cost, non-biocompatibility, non-biodegradability, and the inefficient stimulation of cytotoxic T lymphocyte (CTL) response. In this study, we use metal-organic framework (MOF) MIL-101-Fe-NH2 nanoparticles as carriers to fabricate an innovative reduction-responsive antigen delivery system for cotransporting the antigen model ovalbumin (OVA) and an immune adjuvant, unmethylated cytosine-phosphate-guanine (CpG) oligonucleotide. In vitro cellular tests show that the MOF nanoparticles can not only greatly improve the uptake of OVA by the antigen-presenting cells but also smartly deliver both OVA and CpG into the same cell. By feat of the reductively controllable release of OVA and the promoting function of CpG, the delivery system can elicit strong cellular immunity and CTL response in mice. Moreover, the increased frequencies of effector memory T cells inspired by the delivery system indicate that it can induce a potent immune memory response. These results demonstrate that MOF nanoparticles are excellent vehicles for codelivering antigen and immune adjuvant and may find wider applications in biomedical fields.

Synthesis of Janus Au nanorods/polydivinylbenzene hybrid nanoparticles for chemo-photothermal therapy.

Chemo-photothermal therapy has attracted tremendous attention due to its synergistic effect in killing cancer cells, making it one of the most efficient therapies. Although most of the applied core-shell hybrid nanoparticles (NPs) can perform such a function, the lowering of their thermal efficiency through polymer coating and limited drug loading capacity severely limit their performance. Janus NPs with exposed metal and a polymer/silica matrix show improved chemo- and photothermal-efficiency, but have a complicated synthesis, and their loading capacity for hydrophobic drugs still needs to be optimized. Herein, we report the facile synthesis of Janus NPs comprising Au nanorods (NRs) and a hydrophobic polydivinylbenzene (PDVB) matrix. The UV-vis extinction of the Janus NPs is in the near infrared region (the region used in medicine), which makes it an ideal candidate for photothermal therapy, and the hydrophobic PDVB component is a good anticancer drug (curcumin) carrier for chemotherapy. With this combination of chemo- and photothermal-effects, a significant decrease in cell viability, migration, and invasion was realised, making the material a promising biomedical candidate for the treatment of cancer.

Biocompatible hyperbranched polyglycerol modified ß-cyclodextrin derivatives for docetaxel delivery.

The development of biocompatible vector for hydrophobic drug delivery remains a longstanding issue in cancer therapy. We design and synthesis a drug delivery system based on HPG modified ß-CD (ß-CD-HPG) by conjugating HPG branches onto ß-CD core and its structure was confirmed by NMR, FTIR, GPC and solubility. In vitro biocompatibility tests showed that HPG modification significantly improved red blood cells morphology alteration and hemolysis cause by ß-CD and ß-CD-HPG displayed cell safety apparently in a wide range of 0.01-1mg/mL. An anti-cancer drug, docetaxel, was effectively encapsulated into ß-CD-HPG which was confirmed by DSC analysis. This copolymer could form nanoparticles with small size (<200nm) and exhibited better DTX loading capacity and controlled release kinetics without initial burst release behavior compared with ß-CD. Furthermore, antitumor assay in vitro show that ß-CD-HPG/DTX effectively inhibited proliferation of human breast adenocarcinoma cells. Therefore, ß-CD-HPG/DTX exhibit great potential for cancer chemotherapy.

Injectable supramolecular hydrogel formed from α-cyclodextrin and PEGylated arginine-functionalized poly(l-lysine) dendron for sustained MMP-9 shRNA plasmid delivery.

Hydrogels have attracted much attention in cancer therapy and tissue engineering due to their sustained gene delivery ability. To obtain an injectable and high-efficiency gene delivery hydrogel, methoxypolyethylene glycol (MPEG) was used to conjugate with the arginine-functionalized poly(l-lysine) dendron (PLLD-Arg) by click reaction, and then the synthesized MPEG-PLLD-Arg interacted with α-cyclodextrin (α-CD) to form the supramolecular hydrogel by the host-guest interaction. The gelation dynamics, hydrogel strength and shear viscosity could be modulated by α-CD content in the hydrogel. MPEG-PLLD-Arg was confirmed to bind and deliver gene effectively, and its gene transfection efficiency was significantly higher than PEI-25k under its optimized condition. After gelation, MMP-9 shRNA plasmid (pMMP-9) could be encapsulated into the hydrogel matrix in situ and be released from the hydrogels sustainedly, as the release rate was dependent on α-CD content. The released MPEG-PLLD-Arg/pMMP-9 complex still showed better transfection efficiency than PEI-25k and induced sustained tumor cell apoptosis. Also, in vivo assays indicated that this pMMP-9-loaded supramolecular hydrogel could result in the sustained tumor growth inhibition meanwhile showed good biocompatibility. As an injectable, sustained and high-efficiency gene delivery system, this supramolecular hydrogel is a promising candidate for long-term gene therapy. STATEMENT OF SIGNIFICANCE: To realize the sustained gene delivery for gene therapy, a supramolecular hydrogel with high-efficiency gene delivery ability was prepared through the host-guest interaction between α-cyclodextrin and PEGylated arginine-functionalized poly(l-lysine) dendron. The obtained hydrogel was injectable and biocompatible with adjustable physicochemical property. More importantly, the hydrogel showed the high-efficiency and sustained gene transfection to our used cells, better than PEI-25k. The supramolecular hydrogel resulted in the sustained tumor growth inhibition meanwhile keep good biocompatibility. As an injectable, sustained and high-efficiency gene delivery system, this supramolecular hydrogel is a promising candidate in long-term gene therapy and tissue engineering.

A polyamidoamne dendrimer functionalized graphene oxide for DOX and MMP-9 shRNA plasmid co-delivery.

It is a promising way to treat the multi drug resistance (MDR) of tumor cells in both of drug and gene methods. A polyamidoamne dendrimer functionalized graphene oxide (GO-PAMAM) was designed, which could load doxorubicin (DOX) and MMP-9 shRNA plasmid at the same time in order to achieve effective treatment to breast cancer. GO-PAMAM has a high loading capacity to DOX and pH-controlled DOX release. Besides, it has efficient gene transfer ability, the transfection efficiency is significantly better than PEI-25k in the presence of serum, and it can significantly inhibit the expression of MMP-9 protein in MCF-7 cells. The effect of DOX and MMP-9 shRNA plasmid co-delivery was more significant than that of the single drug. Moreover, GO-PAMAM exhibited lower cytotoxicity compared to PEI-25k in CCK-8 assays, and also showed a good biocompatibility in vivo. Therefore, GO-PAMAM will have broad prospects for drug and gene co-delivery.

Star-Shaped Amphiphilic Hyperbranched Polyglycerol Conjugated with Dendritic Poly(l-lysine) for the Codelivery of Docetaxel and MMP-9 siRNA in Cancer Therapy.

The drug/gene codelivery is a promising strategy for cancer treatment. Herein, to realize the codelivery of docetaxel and MMP-9 siRNA plasmid efficiently into tumor cells, a star-shaped amphiphilic copolymer consisting of hyperbranched polyglycerol derivative (HPG-C18) and dendritic poly(l-lysine) (PLLD) was synthesized by the click reaction between azido-modified HPG-C18 and propargyl focal point PLLD. The obtained HPG-C18-PLLD could form the nanocomplexes with docetaxel and MMP-9, and the complexes showed good gene delivery ability in vitro by inducing an obvious decrease in MMP-9 protein expression in MCF-7 cells. The apoptosis assay showed that the complex could induce a more significant apoptosis to breast cancer cells than that of docetaxel or MMP-9 used alone. In vivo assay indicated that the codelivery strategy displayed a better effect on tumor inhibition. Moreover, HPG-C18-PLLD displayed lower toxicity as well as better blood compatibility compared to polyethylenimine PEI-25k, which may be the result of that HPG-C18-PLLD showed the comparative MMP-9 delivery ability in vivo compared with PEI-25k even if it showed the slight lower transfection efficiency in vitro. Therefore, HPG-C18-PLLD is a safe and effective carrier for the codelivery of drug/gene, which should be encouraged in tumor therapy.

Rotated Hough filtering for automatically distinguishing the collagen bundles in the most superficial layer of articular cartilage.

The structure of the collagen matrix in the most superficial layer of articular cartilage (AC) is particularly critical to the wear and tensile resistance of AC. Disruption of the collagen network leads to rapid wear of the articular surface, which is a major contributory factor of osteoarthritis. Interwoven fiber bundles have been observed in the most superficial layer of healthy AC under confocal microscopy, but gradually disappear with age and pathological change of AC. The image analysis techniques developed in this paper aimed to provide a quantitative description of the relationship between the presence of the fiber bundles in the lamina splendens and health status of AC. The result of this quantitative study confirmed the existence of fiber bundles in healthy AC, and the accuracy of the identified fiber bundles was up to 90%. With the development of confocal arthroscopy for imaging microstructure of AC without biopsy, the image analysis technique can aid to efficiently assess the physiological status of AC for orthopedic clinics.

Study of the collagen structure in the superficial zone and physiological state of articular cartilage using a 3D confocal imaging technique.

INTRODUCTION: The collagen structure in the superficial zone of articular cartilage is critical to the tissue's durability. Early osteoarthritis is often characterized with fissures on the articular surface. This is closely related to the disruption of the collagen network. However, the traditional histology can not offer visualization of the collagen structure in articular cartilage because it uses conventional optical microscopy that does not have insufficient imaging resolution to resolve collagen from proteoglycans in hyaline articular cartilage. This study examines the 3D collagen network of articular cartilage scored from 0 to 2 in the scoring system of International Cartilage Repair Society, and aims to develop a 3D histology for assessing early osteoarthritis. METHODS: Articular cartilage was visually classified into five physiological groups: normal cartilage, aged cartilage, cartilage with artificial and natural surface disruption, and fibrillated. The 3D collagen matrix of the cartilage was acquired using a 3D imaging technique developed previously. Traditional histology was followed to grade the physiological status of the cartilage in the scoring system of International Cartilage Repair Society. RESULTS: Normal articular cartilage contains interwoven collagen bundles near the articular surface, approximately within the lamina splendens. However, its collagen fibres in the superficial zone orient predominantly in a direction spatially oblique to the articular surface. With age and disruption of the articular surface, the interwoven collagen bundles are gradually disappeared, and obliquely oriented collagen fibres change to align predominantly in a direction spatially perpendicular to the articular surface. Disruption of the articular surface is well related to the disappearance of the interwoven collagen bundles. CONCLUSION: A 3D histology has been developed to supplement the traditional histology and study the subtle changes in the collagen network in the superficial zone during early physiological alteration of articular cartilage. The fibre confocal imaging technology used in this study has allowed developing confocal arthroscopy for in vivo studying the chondrocytes in different depth of articular cartilage. Therefore, the current study has potential to develop an in vivo 3D histology for diagnosis of early osteoarthritis.

Confocal arthroscopic assessment of osteoarthritis in situ.

PURPOSE: This study aimed to assess the ability of the laser scanning confocal arthroscope (LSCA) to evaluate cartilage microstructure, particularly in differentiating stages of human osteoarthritis (OA) as classified by the International Cartilage Repair Society (ICRS) OA grade definitions. METHODS: Ten tibial plateaus from total knee arthroplasty patients were obtained at the time of surgery. Cartilage areas were visually graded based on the ICRS classification, imaged by use of a 7-mm-diameter LSCA (488-nm excitation with 0.5% [wt/vol] fluorescein, 20-minute staining period), and then removed with underlying bone for histologic examination with H&E staining. The 2 imaging techniques were then compared for each ICRS grade to ascertain similarity between the methods and thus gauge the techniques' diagnostic resolution. Cartilage surface degeneration was readily imaged and OA severity accurately gauged by the LSCA and confirmed by histology. RESULTS: LSCA and histologic images of specimens in the late stages of OA were seen to be mutually related even though they were imaged in planes that were orthogonal to each other. Useful and comparable diagnostic resolution was obtained in all imaged specimens from subjects with various stages of OA. CONCLUSIONS: This study showed the LSCA's ability to image detailed cartilage surface morphologic features that identify grade 1 through 4 of the ICRS OA grading system. The LSCA's imaging potential was best shown by its ability to resolve the fine collagen network present under the lamina splendens. The incorporation of high-magnification confocal technology within the confines of an arthroscopic probe has proved to provide the imaging requirements necessary to perform detailed cartilage condition assessment. CLINICAL RELEVANCE: In comparison to video arthroscopy, LSCA provides increased magnification along with improved contrast and resolution.

Confocal arthroscopy-based patient-specific constitutive models of cartilaginous tissues - II: prediction of reaction force history of meniscal cartilage specimens.

The theoretical framework developed in a companion paper (Part I) is used to derive estimates of mechanical response of two meniscal cartilage specimens. The previously developed framework consisted of a constitutive model capable of incorporating confocal image-derived tissue microstructural data. In the present paper (Part II) fibre and matrix constitutive parameters are first estimated from mechanical testing of a batch of specimens similar to, but independent from those under consideration. Image analysis techniques which allow estimation of tissue microstructural parameters form confocal images are presented. The constitutive model and image-derived structural parameters are then used to predict the reaction force history of the two meniscal specimens subjected to partially confined compression. The predictions are made on the basis of the specimens' individual structural condition as assessed by confocal microscopy and involve no tuning of material parameters. Although the model does not reproduce all features of the experimental curves, as an unfitted estimate of mechanical response the prediction is quite accurate. In light of the obtained results it is judged that more general non-invasive estimation of tissue mechanical properties is possible using the developed framework.

Confocal arthroscopy-based patient-specific constitutive models of cartilaginous tissues--I: development of a microstructural model.

Current development of a laser scanning confocal arthroscope within our school will enable 3D microscopic imaging of joint tissues in vivo. Such an instrument could be useful, for example, in assessing the microstructural condition of the living tissues without physical biopsy. It is envisaged also that linked to a suitable microstructural constitutive formulation, such imaging could allow non-invasive patient-specific estimation of tissue mechanical performance. Such a procedure could have applications in surgical planning and simulation, and assessment of engineered tissue replacements, where tissue biopsy is unacceptable. In this first of two papers the development of a suitable constitutive framework for generating such estimates is reported. A microstructure-based constitutive formulation for cartilaginous tissues is presented. The model extends existing fibre composite-type models and accounts for strain-rate sensitivity of the tissue mechanical response through incorporation of a viscoelastic fibre phase. Importantly, the model is constructed so as to allow direct incorporation of structural data from confocal images. A finite element implementation of the formulation suitable for incorporation within commercial codes is also presented.