Chitosan-Based Nanogels: Synthesis and Toxicity Profile for Drug Delivery to Articular Joints.

One important challenge in treating avascular-degraded cartilage is the development of new drugs for both pain management and joint preservation. Considerable efforts have been invested in developing nanosystems using biomaterials, such as chitosan, a widely used natural polymer exhibiting numerous advantages, i.e., non-toxic, biocompatible and biodegradable. However, even if chitosan is generally recognized as safe, the safety and biocompatibility of such nanomaterials must be addressed because of potential for greater interactions between nanomaterials and biological systems. Here, we developed chitosan-based nanogels as drug-delivery platforms and established an initial biological risk assessment for osteocartilaginous applications. We investigated the influence of synthesis parameters on the physicochemical characteristics of the resulting nanogels and their potential impact on the biocompatibility on all types of human osteocartilaginous cells. Monodisperse nanogels were synthesized with sizes ranging from 268 to 382 nm according to the acidic solution used (i.e., either citric or acetic acid) with overall positive charge surface. Our results demonstrated that purified chitosan-based nanogels neither affected cell proliferation nor induced nitric oxide production in vitro. However, nanogels were moderately genotoxic in a dose-dependent manner but did not significantly induce acute embryotoxicity in zebrafish embryos, up to 100 µg∙mL-1. These encouraging results hold great promise for the intra-articular delivery of drugs or diagnostic agents for joint pathologies.

Lymphocyte transformation test reveals low prevalence of true metal hypersensitivity among pre-operative total knee arthroplasty patients.

PURPOSE: The aims of this study were to determine the prevalence of metal hypersensitivity, and identify pre-operative factors which could predict susceptibility to hypersensitivity reactions among patients scheduled for primary total knee arthroplasty (TKA). The present study used a testing method consistent with the recognised biological response to metals. METHODS: A prospective cross-sectional analysis of 220 patients was conducted. All patients received a testing protocol using lymphocyte transformation test to evaluate reactivity to possible contents of orthopaedic implants. Test response is interpreted as stimulation index (SI) values. A comprehensive questionnaire was used to evaluate prior exposure. Patients were categorised according to SI values and the odds ratios (OR) were calculated as comparative effect measure for each predetermined prior exposure factor. RESULTS: The prevalence of metal sensitivity response was 28% (n = 61) among patients with susceptibility to at least one agent (SI = 2 to 4.9), and 3.2% (n = 7) among patients with true hypersensitivity (SI ≥ 5). The population-weighted prevalence, adjusted for sampling weights of symptomatic knee osteoarthritis, was SI ≥ 5 = 4.7% (95% CI 0.4-11.8%) and SI ≥ 2 = 35.2% (95% CI 24.8-48.6%). Stimulation index levels of response to materials were markedly varied with the highest being aluminium. Female sex, smoking history, cutaneous reaction to jewellery, occupational exposure, and dental procedures were among factors shown to increase the odds of having higher reactivity response to tested metals. Nevertheless, patients with well-functioning prior contralateral TKA did not appear at greater risk of having either sensitivity or susceptibility with odds ratio (OR) = 0.2 (95% CI 0.01-3.2), p: NS and OR = 0.6 (95% CI 0.3-1.2), p: NS, respectively. Prior positive patch test was neither predictor of susceptibility to hypersensitivity OR = 1.2 (95% CI 0.6-2.6) p: NS nor predictor of true hypersensitivity OR = 0.7 (95% CI 0.08-6.1), p: NS. CONCLUSION: Among patients scheduled for primary TKA with no prior clinical features of metal allergy the prevalence of true hypersensitivity to at least one metal is just over 3%. Patients are likely to encounter a material to which they have pre-existing susceptibility to hypersensitivity. With certain prior exposure factors, there was increased susceptibility to metal hypersensitivity reaction evoking an acquired condition. LEVEL OF EVIDENCE: Level II, prospective cross-sectional study.

Trajectories of Follow-up Compliance in a Fracture Liaison Service and Their Predictors: A Longitudinal Group-Based Trajectory Analysis.

INTRODUCTION/OBJECTIVES: Identification of groups of patients following similar trajectories of time-varying patient characteristics are often of considerable clinical value. This study provides an example of how the identification of trajectory groups of patients can be useful. METHODS: Using clinical and administrative data of a prospective cohort study aiming to improve the secondary prevention of osteoporosis-related fractures with a Fracture Liaison Service (FLS), trajectory groups for visit compliance over time (2-year follow-up) were predicted using group-based trajectory modeling. Predictors of trajectory groups were identified using multinomial logistic regressions. RESULTS: Among 532 participants (86% women, mean age 63 years), three trajectories were identified and interpreted as high followers, intermediate followers, and low followers. The predicted probability for group-membership was: 48.4% high followers, 28.1% intermediate followers, 23.5% low followers. A lower femoral bone mineral density and polypharmacy were predictors of being in the high followers compared to the low followers group; predictors for being in the intermediate followers group were polypharmacy and referral to a bone specialist at baseline. CONCLUSIONS: Results provided information on visit compliance patterns and predictors for the patients undergoing the intervention. This information has important implications when implementing such health services and determining their effectiveness.

Patient Healthcare Trajectory and its Impact on the Cost-Effectiveness of Fracture Liaison Services.

This study aimed to assess the cost-utility of a Fracture Liaison Service (FLS) with a systematic follow-up according to patients' follow-up compliance trajectories. The Lucky Bone™ FLS is a prospective cohort study conducted on women and men (≥40 years) with fragility fractures. Dedicated personnel of the program identified fractures, investigated, treated, and followed patients systematically over 2 years. Groups of follow-up compliance trajectories were identified, and Markov decision models were used to assess the cost-utility of each follow-up trajectory group compared to usual care. A lifetime horizon from the perspective of the healthcare payer was modeled. Costs were converted to 2018 Canadian dollars and incremental cost-utility ratios (ICURs) were measured. Costs and benefits were discounted at 1.5%. A total of 532 participants were followed in the FLS (86% women, mean age of 63 years). Three trajectories were predicted and interpreted; the high followers (HFs, 48.4%), intermediate followers (IFs, 28.1%), and low followers (LFs, 23.5%). The costs of the interventions per patient varied between $300 and $446 for 2 years, according to the follow-up trajectory. The FLS had higher investigation, treatment, and persistence rates compared to usual care. Compared to usual care, the ICURs for the HF, IF, and LF trajectory groups were $4250, $21,900, and $72,800 per quality-adjusted life year (QALY) gained, respectively ($9000 per QALY gained for the overall FLS). Sensitivity analyses showed that the HF and IF trajectory groups, as well as the entire FLS, were cost-effective in >67% of simulations with respect to usual care. In summary, these results suggest that a high-intensity FLS with a systematic 2-year follow-up can be cost-effective, especially when patients attend follow-up visits. They also highlight the importance of understanding the behaviors and factors that surround follow-up compliance over time as secondary prevention means that they are at high risk of re-fracture. © 2020 American Society for Bone and Mineral Research (ASBMR).

Performance of a Fracture Liaison Service in an Orthopaedic Setting: A Report of Key Indicators and Improvement of Longitudinal Outcomes.

BACKGROUND: Many Fracture Liaison Services (FLSs) have been successfully implemented, but very few incorporate systematic longitudinal follow-up. The objective of this study was to report on the performance of such an FLS using key performance indicators and longitudinal clinical outcomes. METHODS: An FLS was implemented in 2 outpatient orthopaedic clinics. Men and women who were ≥40 years of age and had a recent fragility fracture were recruited. Participants were evaluated, treated when appropriate, and systematically followed over a 2-year period. Clinical data including chart review and questionnaires were collected. Medical services and hospitalization claims data were retrieved from administrative databases. The primary outcomes were the following key performance indicators: the numbers of investigated and treated patients, follow-up attendance, and the incidence of subsequent fractures. Secondary outcomes were the changes in bone turnover markers and quality of life, physical capacity, and pain scores between baseline and follow-up visits. RESULTS: A total of 532 subjects with a mean age of 63.4 years were recruited; 85.7% were female. Bone mineral density results were collected for 472 subjects (88.7%) and a prescription for anti-osteoporosis medication was given to 86.6% of patients. Overall, 83.6% of patients attended at least 1 follow-up visit. The subsequent fracture incidence rate was 2.6 per 100 person-years (23 fractures). The mean level of type-I collagen C-telopeptide (CTX-1), a bone resorption marker, decreased >35%. Clinically important improvements of functional capacity scores (by 14.4% to 63.7%) and pain level (by 19.3% to 35.7%) were observed over time; however, the increase in quality-of-life scores was not clinically important (by 3% to 15.2%). CONCLUSIONS: In this FLS, the rates of investigation, treatment, and participation were >80% over a 2-year period. The subsequent fragility fracture incidence rate was <3 per 100 person-years. These results suggest that an intensive FLS model of care, with a systematic longitudinal follow-up, is effective. A randomized controlled trial is needed to support these results. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Persistence and compliance to osteoporosis therapy in a fracture liaison service: a prospective cohort study.

Persistence and compliance to osteoporosis medications aiming to prevent fragility fractures are essential for fracture prevention, but are suboptimal in the population. A Fracture Liaison Service with a systematic follow-up led to ongoing therapy and optimal drug compliance for more than half of treated patients over 2 years. PURPOSE: Fracture Liaison Services (FLS) have the potential to improve persistence and compliance to osteoporosis therapy. We aimed to assess patterns of drug use in a high-level intervention FLS. METHODS: Women and men (> 40 years) with a fragility fracture were recruited in a FLS, where osteoporosis therapy was prescribed if appropriate. Based on claims data, patients who filled their prescription in the 3-month period following baseline were selected. The 1- and 2-year persistence rates were measured using survival analysis. In non-persistent subjects, 1-year treatment re-initiation was measured. The 1- and 2-year compliance levels were measured, using the proportion of days covered (PDC > 80% = compliant). Regression analyses were performed to identify predictors of non-persistence/compliance. RESULTS: Out of 332 subjects with complete drug insurance coverage, 297 (89.5%) were prescribed osteoporosis therapy by the FLS, and 275 (92.6%) were dispensed. Two hundred sixty participants (86.9% female; mean age 65.6 years) were selected for having filled a prescription inside 3 months after baseline. The 1- and 2-year persistence rates were 66.4% and 55.6%, respectively. Treatment re-initiation was observed in 56% of non-persistent patients. PDC was > 80% in 64.2% for 1 year and 62.5% for 2 years. Older and younger age, smoking, higher spine bone mineral density, lower major FRAX risk, and missing follow-up visits were predictors of non-persistence and/or non-compliance. CONCLUSIONS: After 2 years in a high-level intervention FLS, more than half the treated participants were persistent and compliant to treatment. Comparative effectiveness studies must be undertaken to determine whether this intervention is an improvement over usual care.

Rationale, study design, and descriptive data of the Lucky Bone™ Fracture Liaison Service.

The study design of a multidisciplinary Fracture Liaison Service (2-year follow-up) aiming to optimize fragility fracture management in an outpatient setting is presented. Patient characteristics, investigation, and treatment initiation data at baseline were recorded. Results corroborate the care gap in osteoporosis management, reinforcing the need for secondary fracture prevention programs. PURPOSE: This paper describes the study design, implementation, and baseline characteristics of a multidisciplinary Fracture Liaison Service (FLS) in Quebec (Canada). METHODS: A FLS was implemented as a prospective cohort study. After identification, fracture risk was assessed and patients were started on treatment or referred, according to guidelines and risk assessment. Thereafter, patients were systematically followed over 2 years. Clinical data (fractures, bone density, blood testing (bone turnover markers), quality of life, physical disability) as well as administrative data (pharmacological, health services, hospitalization) was collected. Baseline descriptive data was analyzed and presented. RESULTS: Of 542 recruited participants, 532 underwent baseline assessment (85.7% female, mean age 63.4 years). Overall, 29.7% of participants either withdrew from the study or were lost to follow-up. Almost 27% were referred to a specialist, while > 70% received anti-osteoporosis medication prescriptions through the FLS at baseline. Mean femoral T-score was - 1.6 ± 1.0 and vertebral T-score was - 1.7 ± 1.4. Nearly 19% of subjects reported being under anti-osteoporosis medication at the time of incident fracture. Thirty-three percent of participants reported a prior fracture history, of which 29.7% reported being given anti-osteoporosis therapy. Most fracture sites were to the wrist and ankle, while < 19% were hip/femur or vertebral fractures. CONCLUSIONS: These results highlight the important care gap in fragility fracture management and reinforce the need for secondary fracture prevention programs. This prospective study will allow the evaluation of key performance indicators for outpatient clinic-based FLS, such as medication usage, by combining prospective clinical and administrative data.

Incidence of symptomatic venous thromboembolism in 2372 knee and hip replacement patients after discharge: data from a thromboprophylaxis registry in Montreal, Canada.

BACKGROUND: Low-molecular-weight heparin (LMWH) is a recommended anticoagulant for thromboprophylaxis after major orthopedic surgery. Dabigatran etexilate is an oral anticoagulant recognized as noninferior to LMWH. We aimed to assess the incidence of symptomatic venous thromboembolic events (VTEs) after discharge in patients who underwent joint replacement, using a hospital registry. PATIENTS AND METHODS: Patients who underwent total knee and hip arthroplasty between September 2011 and March 2015 were selected. Subcutaneous enoxaparin (30 mg twice daily) was given during hospitalization. At discharge, patients received either enoxaparin 30 mg twice daily/40 mg once daily or dabigatran 220 mg/150 mg once daily. Patients were seen or called at 2, 6, and 12 weeks after surgery. Outcomes were the number of VTEs, including deep venous thrombosis, pulmonary embolism, and the number of major/minor bleeding events after discharge. RESULTS: After discharge, 1468 patients were prescribed enoxaparin and 904 dabigatran (1396 total knee arthroplasty and 976 total hip arthroplasty patients). Mean age was 66±10 years, and 60% were female. The cumulative incidence of VTEs during the 12-week follow-up was 0.7%. One patient sustained a VTE during the switch window. Seven patients sustained a pulmonary embolism (0.3%). There was no statistical difference between the total knee arthroplasty and total hip arthroplasty groups. The incidence of major and minor bleeding events during follow-up was 0.3% and 30.3%, respectively. These events had a higher incidence in the dabigatran group compared to the enoxaparin group after discharge (p<0.05), but not between knee and hip replacement groups for major bleeding events. CONCLUSION: A pharmaceutical prophylaxis protocol using LMWH and dabigatran during the post-discharge period resulted in low incidences of VTE and equivalence between treatments. However, the increased number of major and minor bleeding events in patients taking dabigatran is of concern regarding the safety and needs to be evaluated using analyses adjusted for risk factors.

An overview of the role of lipid peroxidation-derived 4-hydroxynonenal in osteoarthritis.

BACKGROUND: Over the years, many theories have been proposed and examined to better explain the etiology and development of osteoarthritis (OA). The characteristics of joint destruction are one of the most important aspects in disease progression. Therefore, investigating different factors and signaling pathways involved in the alteration of extracellular matrix (ECM) turnover, and the subsequent catabolic damage to cartilage holds chief importance in understanding OA development. Among these factors, reactive oxygen species (ROS) have been at the forefront of the physiological and pathophysiological OA investigation. FINDINGS: In the last decades, research studies provided an enormous volume of data supporting the involvement of ROS in OA. Most interestingly, published data regarding the effect of exogenous antioxidant therapy in OA lack conclusive results from clinical trials to back up in vitro data. Accordingly, it is rational to suggest that there are other reactive species in OA that are not taken into account. Thus, our present review is focused on our current understanding of the involvement of lipid peroxidation-derived 4-hydroxynonenal (HNE) in OA. CONCLUSION: Our findings, like those in the literature, illustrate the central role played by HNE in the regulation of a number of factors involved in joint homeostasis. HNE could thus be considered as an attractive therapeutic target in OA.

Elucidating the Role of Protandim and 6-Gingerol in Protection Against Osteoarthritis.

Protandim and 6-gingerol, two potent nutraceuticals, have been shown to decrease free radicals production through enhancing endogenous antioxidant enzymes. In this study, we evaluated the effects of these products on the expression of different factors involved in osteoarthritis (OA) process. Human OA chondrocytes were treated with 1 ng/ml IL-1ß in the presence or absence of protandim (0-10 µg/ml) or 6-gingerol (0-10 µM). OA was induced surgically in mice by destabilization of the medial meniscus (DMM). The animals were treated weekly with an intraarticular injection of 10 µl of vehicle or protandim (10 µg/ml) for 8 weeks. Sham-operated mice served as controls. In vitro, we demonstrated that protandim and 6-gingerol preserve cell viability and mitochondrial metabolism and prevented 4-hydroxynonenal (HNE)-induced cell mortality. They activated Nrf2 transcription factor, abolished IL-1ß-induced NO, PGE2 , MMP-13, and HNE production as well as IL-ß-induced GSTA4-4 down-regulation. Nrf2 overexpression reduced IL-1ß-induced HNE and MMP-13 as well as IL-1ß-induced GSTA4-4 down-regulation. Nrf2 knockdown following siRNA transfection abolished protandim protection against oxidative stress and catabolism. The activation of MAPK and NF-κB by IL-1ß was not affected by 6-gingerol. In vivo, we observed that Nrf2 and GSTA4-4 expression was significantly lower in OA cartilage from humans and mice compared to normal controls. Interestingly, protandim administration reduced OA score in DMM mice. Altogether, our data indicate that protandim and 6-gingerol are essential in preserving cartilage and abolishing a number of factors known to be involved in OA pathogenesis. J. Cell. Biochem. 118: 1003-1013, 2017. © 2016 Wiley Periodicals, Inc.

A lateral approach defect closure technique with deep fascia flap for valgus knee TKA.

BACKGROUND: Routinely, we use a midline skin incision and lateral parapatellar approach of the knee to perform valgus knee TKA (total knee arthroplasty). It is generally very difficult to close the lateral capsular defect after valgus knee TKA, especially for severe valgus and flexion knee deformity. METHODS: We describe a new surgical technique to close the lateral capsular defect with a deep fascia flap. From 2009 to 2012, we used the new technique to close lateral capsular defects for nine valgus TKA in eight patients. The wound healing, infection, range of motion, and postoperative X-ray Laurien view were evaluated. RESULTS: According to follow-up, we found that this technique can reduce the risk of intra- and postoperative complications (exposure of knee prosthesis, larger subcutaneous hematoma, poor wound healing, and higher risk of infection) and improve clinical outcome of total knee replacement (good range of motion and patellar tracking). There is no need for lateral parapatellar capsule Z-plasty during incision or filling the distal capsular defect with fat pad or composite meniscal-capsular-fat pad. CONCLUSION: Closing lateral capsular defect with a deep fascia flap for valgus knee TKA through a lateral parapatellar approach is a new and effective surgical technique.

Periprosthetic fractures of the acetabulum during cup insertion: posterior column stability is crucial.

Periprosthetic hip fractures around acetabular components are rare with little information available to guide surgical management of these complex injuries. A retrospective review of intraoperative isolated acetabular periprosthetic fractures from three tertiary surgical units was done. A total of 32 patients were identified with 9 initially missed. Acetabular components were stable (type 1) in 11 patients with no failures; unstable (type 2) in 12 patients and treated with supplemental fixation. Non-union and displacement were correlated with absent posterior column plating. Missed fractures (type 3) had the highest reoperation rate. Anterior patterns all healed, whereas fractures with posterior column instability had a 67% failure rate. Periprosthetic acetabular fracture can heal successfully with posterior column stability. Plating is mandatory for large posterior wall fragments to achieve osteointegration.

New evidence implicating 4-hydroxynonenal in the pathogenesis of osteoarthritis in vivo.

OBJECTIVE: To demonstrate the involvement of 4-hydroxynonenal (HNE), a very reactive aldehyde derived from lipid peroxidation, in the pathogenesis of osteoarthritis (OA) in vivo. METHODS: In the first experimental protocol, OA was induced by anterior cruciate ligament transection (ACLT) of the right knees of crossbred dogs (n = 6 per group). The animals were treated with placebo or HNE-trapping carnosine (5 or 20 mg/kg/day) orally for 8 weeks. Another group of dogs was treated for 4 weeks with 20 mg/kg/day of carnosine starting 4 weeks after surgery. Sham-operated dogs served as controls. In the second experimental protocol, a pathophysiologic dose of HNE (80 nmoles/ml) or vehicle was injected weekly into the right knee joints of crossbred dogs (n = 6 per group) for 8 weeks. Articular cartilage was subjected to macroscopic, histomorphologic, and immunohistochemical analyses. Cartilage-degrading enzymes and oxidative stress-related products were assessed in synovial fluid and cartilage explants. Markers of inflammation were evaluated in synovium and synovial fluid. RESULTS: In dogs that had undergone ACLT, carnosine treatment reduced the severity and histopathology score of OA cartilage lesions and also decreased HNE-protein adducts, pentosidine, nitrosylated proteins, cartilage-degrading enzymes, and markers of inflammation. Intraarticular injection of HNE induced cartilage lesions, as assessed by macroscopic and microscopic criteria. Cartilage-degrading enzymes and markers of inflammation increased in HNE-treated dogs. CONCLUSION: This is the first in vivo study to demonstrate the pathophysiologic role of HNE in OA. That carnosine abolishes HNE production and a number of factors known to be involved in OA pathogenesis renders it a clinically valuable agent in prevention of the disease.

Sorbitol-modified hyaluronic acid reduces oxidative stress, apoptosis and mediators of inflammation and catabolism in human osteoarthritic chondrocytes.

OBJECTIVE AND DESIGN: Our study was designed to elucidate the precise molecular mechanisms by which sorbitol-modified hyaluronic acid (HA/sorbitol) exerts beneficial effects in osteoarthritis (OA). METHODS: Human OA chondrocytes were treated with increasing doses of HA/sorbitol ± anti-CD44 antibody or with sorbitol alone and thereafter with or without interleukin-1beta (IL-1ß) or hydrogen peroxide (H2O2). Signal transduction pathways and parameters related to oxidative stress, apoptosis, inflammation, and catabolism were investigated. RESULTS: HA/sorbitol prevented IL-1ß-induced oxidative stress, as measured by reactive oxygen species, p47-NADPH oxidase phosphorylation, 4-hydroxynonenal (HNE) production and HNE-metabolizing glutathione-S-transferase A4-4 expression. Moreover, HA/sorbitol stifled IL-1ß-induced metalloproteinase-13, nitric oxide (NO) and prostaglandin E2 release as well as inducible NO synthase expression. Study of the apoptosis process revealed that this gel significantly attenuated cell death, caspase-3 activation and DNA fragmentation elicited by exposure to a cytotoxic H2O2 dose. Examination of signaling pathway components disclosed that HA/sorbitol prevented IL-1ß-induced p38 mitogen-activated protein kinase and nuclear factor-kappa B activation, but not that of extracellular signal-regulated kinases 1 and 2. Interestingly, the antioxidant as well as the anti-inflammatory and anti-catabolic effects of HA/sorbitol were attributed to sorbitol and HA, respectively. CONCLUSIONS: Altogether, our findings support a beneficial effect of HA/sorbitol in OA through the restoration of redox status and reduction of apoptosis, inflammation and catabolism involved in cartilage damage.

Polymeric systems as nanodevices for siRNA delivery.

The delivery of small interfering RNAs (siRNAs) is a promising approach to silencing gene expression aimed at treating infections, cancer, neurodegenerative diseases and various other disorders. Recent progress in this area has been achieved with nanodevices possessing multiple properties and assembled with new, biodegradable, synthetic polymers and polysaccharides. Different synthetic routes and multiple strategies, such as multilayer systems and stimuliresponsive polymers, have been developed to attain high efficiencies. This review covers the most important, promising and successful approaches to improve siRNA delivery. It is a concise report on multiple strategies employed, including cell-specific delivery coupling ligands or antibodies with nanodevices to improve siRNA efficiency and specificity.

Linear polyethylenimine produced by partial acid hydrolysis of poly(2-ethyl-2-oxazoline) for DNA and siRNA delivery in vitro.

Polyethylenimines (PEIs) are the most efficient synthetic vectors for gene delivery available to date. With its high charge density and strong proton-buffering effect, PEI has an ability to condense DNA and small interfering RNA at physiologic pH. However, the polymer suffers from the disadvantage of high cellular toxicity. To reduce its cellular toxicity, we synthesized linear PEIs by partial hydrolysis of poly(2-ethyl-2-oxazoline). Three linear PEIs with different hydrolysis percentages (30%, 70%, and 96%, respectively) were produced as PEI30, PEI70, and PEI96. PEI30 and PEI96 cannot be considered as suitable transfection agents because of low transfection efficiency (PEI30) or high cellular toxicity (PEI96). PEI70 displayed very weak cell toxicity. The charge density of this polymer (PEI70) was strong enough to condense DNA and small interfering RNA at a physiologic pH of 7.4. Our results also show that PEI70 was highly efficient in DNA delivery and small interfering RNA-mediated knockdown of target genes. Thus, polymers such as PEI70 appear to be very promising vectors for gene delivery.

Polyethylenimine600-ß-cyclodextrin: a promising nanopolymer for nonviral gene delivery of primary mesenchymal stem cells.

Genetically modified mesenchymal stem cells (MSCs) have great potential in the application of regenerative medicine and molecular therapy. In the present manuscript, we introduce a nanopolymer, polyethylenimine600-ß-cyclodextrin (PEI600-ß-CyD), as an efficient polyplex-forming plasmid delivery agent with low toxicity and ideal transfection efficiency on primary MSCs. PEI600-ß-CyD causes significantly less cytotoxicity and apoptosis on MSCs than 25 kDa high-molecular-weight PEI (PEI25kDa). PEI600-ß-CyD also exhibits similar transfection efficiency as PEI25kDa on MSCs, which is higher than that of PEI600Da. Quantum dot-labeled plasmids show that PEI600-ß-CyD or PEI25kDa delivers the plasmids in a more scattered manner than PEI600Da does. Further study shows that PEI600-ß-CyD and PEI25kDa are more capable of delivering plasmids into the cell lysosome and nucleus than PEI600Da, which correlates well with the results of their transfection-efficiency assay. Moreover, among the three vectors, PEI600-ß-CyD has the most capacity of enhancing the alkaline phosphatase activity of MSCs by transfecting bone morphogenetic protein 2, 7, or special AT-rich sequence-binding protein 2. These results clearly indicate that PEI600-ß-CyD is a safe and effective candidate for the nonviral gene delivery of MSCs because of its ideal inclusion ability and proton sponge effect, and the application of this nanopolymer warrants further investigation.

Validation of an advanced practice physiotherapy model of care in an orthopaedic outpatient clinic.

BACKGROUND: In Canada, new models of orthopaedic care involving advanced practice physiotherapists (APP) are being implemented. In these new models, aimed at improving the efficiency of care for patients with musculoskeletal disorders, APPs diagnose, triage and conservatively treat patients. Formal validation of the efficiency and appropriateness of these emerging models is scarce. The purpose of this study is to assess the diagnostic agreement of an APP compared to orthopaedic surgeons as well as to assess treatment concordance, healthcare resource use, and patient satisfaction in this new model. METHODS: 120 patients presenting for an initial consult for hip or knee complaints in an outpatient orthopaedic hospital clinic in Montreal, Canada, were independently assessed by an APP and by one of three participating orthopaedic surgeons. Each health care provider independently diagnosed the patients and provided triage recommendations (conservative or surgical management). Proportion of raw agreement and Cohen's kappa were used to assess inter-rater agreement for diagnosis, triage, treatment recommendations and imaging tests ordered. Chi-Square tests were done in order to compare the type of conservative treatment recommendations made by the APP and the surgeons and Student t-tests to compare patient satisfaction between the two types of care. RESULTS: The majority of patients assessed were female (54%), mean age was 54.1 years and 91% consulted for a knee complaint. The raw agreement proportion for diagnosis was 88% and diagnostic inter-rater agreement was very high (κ=0.86; 95% CI: 0.80-0.93). The triage recommendations (conservative or surgical management) raw agreement proportion was found to be 88% and inter-rater agreement for triage recommendation was high (κ=0.77; 95% CI: 0.65-0.88). No differences were found between providers with respect to imaging tests ordered (p≥0.05). In terms of conservative treatment recommendations made, the APP gave significantly more education and prescribed more NSAIDs, joint injections, exercises and supervised physiotherapy (p<0.05). Patient satisfaction was significantly higher for APP care than for the surgeons care (p<0.05). CONCLUSION: The diagnoses and triage recommendations for patients with hip and knee disorders made by the APP were similar to the orthopaedic surgeons. These results provide evidence supporting the APP model for orthopaedic care.

Low molecular weight chitosan conjugated with folate for siRNA delivery in vitro: optimization studies.

The low transfection efficiency of chitosan is one of its drawbacks as a gene delivery carrier. Low molecular weight chitosan may help to form small-sized polymer-DNA or small interfering RNA (siRNA) complexes. Folate conjugation may improve gene transfection efficiency because of the promoted uptake of folate receptor-bearing cells. In the present study, chitosan was conjugated with folate and investigated for its efficacy as a delivery vector for siRNA in vitro. We demonstrate that the molecular weight of chitosan has a major influence on its biological and physicochemical properties, and very low molecular weight chitosan (below 10 kDa) has difficulty in forming stable complexes with siRNA. In this study, chitosan 25 kDa and 50 kDa completely absorbed siRNA and formed nanoparticles (≤220 nm) at a chitosan to siRNA weight ratio of 50:1. The introduction of a folate ligand onto chitosan decreased nanoparticle toxicity. Compared with chitosan-siRNA, folate-chitosan-siRNA nanoparticles improved gene silencing transfection efficiency. Therefore, folate-chitosan shows potential as a viable candidate vector for safe and efficient siRNA delivery.