Materials-driven fibronectin assembly on nanoscale topography enhances mesenchymal stem cell adhesion, protecting cells from bacterial virulence factors and preventing biofilm formation.

Post-operative infection is a major complication in patients recovering from orthopaedic surgery. As such, there is a clinical need to develop biomaterials for use in regenerative surgery that can promote mesenchymal stem cell (MSC) osteospecific differentiation and that can prevent infection caused by biofilm-forming pathogens. Nanotopographical approaches to pathogen control are being identified, including in orthopaedic materials such as titanium and its alloys. These topographies use high aspect ratio nanospikes or nanowires to prevent bacterial adhesion but these features also significantly reduce MSC adhesion and activity. Here, we use a poly (ethyl acrylate) (PEA) polymer coating on titanium nanowires to spontaneously organise fibronectin (FN) and to deliver bone morphogenetic protein 2 (BMP2) to enhance MSC adhesion and osteospecific signalling. Using a novel MSC-Pseudomonas aeruginosa co-culture, we show that the coated nanotopographies protect MSCs from cytotoxic quorum sensing and signalling molecules, enhance MSC adhesion and osteoblast differentiation and reduce biofilm formation. We conclude that the PEA polymer-coated nanotopography can both support MSCs and prevent pathogens from adhering to a biomaterial surface, thus protecting from biofilm formation and bacterial infection, and supporting osteogenic repair.

Osteoporosis treatment rate following hip fracture in a community hospital.

Treatment rates for osteoporosis after a major osteoporotic fracture are unacceptably low. We evaluate the effectiveness of an ortho-geriatric team (OGT) in initiating pharmacologic therapy for osteoporosis post-hip fracture. The OGT was able to achieve a higher treatment rate for patients post-hip fracture in comparison to usual care provided by the primary care hospitalist. Potential reasons for delaying or not proceeding with drug therapy include patient concern regarding potential rare side effects of antiresorptive therapy including osteonecrosis of the jaw and atypical femoral fracture. These events however are rare, and in this study, only 3% of hip fractures were atypical femoral fractures. INTRODUCTION: Currently, a significant care gap for osteoporosis therapy exists post-hip fracture despite advances in pharmacologic therapy. We evaluate the effectiveness of the OGT at the Oakville Trafalgar Memorial Hospital (OTMH), Ontario, Canada, in reducing the care gap and initiating pharmacologic therapy in hip fracture patients prior to hospital discharge. We also evaluated the incidence of atypical femoral fracture (AFF) separately. METHODS: A retrospective chart review of patients 59 years and older with a hip fracture admitted to OTMH from January 1, 2016, to February 1, 2017, was conducted. The primary outcome was the proportion of hip fracture patients discharged from the hospital with appropriate treatment for their underlying osteoporosis. A sub-analysis was completed reporting the incidence of AFF among older adults. RESULTS: A total of 197 patients with a hip fracture were identified, 134/197 (68%) patients were seen by the OGT, 98/134 (73%) of these patients were started on pharmacologic therapy prior to discharge, and 120/134 (89%) of patients seen by the OGT were on treatment within 3 months of discharge following assessment in the complex osteoporosis clinic. Sixty-three patients of the 197 (63/197) (32%) of the hip fracture patients were seen by a hospitalist, and treatment rates prior to discharge were 5%. Only 6/197 patients had experienced an AFF during the study period, and all patients with an atypical femoral fracture had been on long-term bisphosphonate therapy. All of the patients with an AFF had thigh or groin pain for several weeks to months prior to the development of the atypical femoral fracture, providing an opportunity to stop therapy and possibly prevent the development of a complete AFF. CONCLUSION: The OGT was able to initiate anti-osteoporosis therapy in significantly more patients in comparison to usual care, and higher treatment rates are possible with an OGT.

Reduced neuroprotective potential of the mesenchymal stromal cell secretome with ex vivo expansion, age and progressive multiple sclerosis.

BACKGROUND: Clinical trials using ex vivo expansion of autologous mesenchymal stromal cells (MSCs) are in progress for several neurological diseases including multiple sclerosis (MS). Given that environment alters MSC function, we examined whether in vitro expansion, increasing donor age and progressive MS affect the neuroprotective properties of the MSC secretome. METHODS: Comparative analyses of neuronal survival in the presence of MSC-conditioned medium (MSCcm) isolated from control subjects (C-MSCcm) and those with MS (MS-MSCcm) were performed following (1) trophic factor withdrawal and (2) nitric oxide-induced neurotoxicity. RESULTS: Reduced neuronal survival following trophic factor withdrawal was seen in association with increasing expansion of MSCs in vitro and MSC donor age. Controlling for these factors, there was an independent, negative effect of progressive MS. In nitric oxide neurotoxicity, MSCcm-mediated neuroprotection was reduced when C-MSCcm was isolated from higher-passage MSCs and was negatively associated with increasing MSC passage number and donor age. Furthermore, the neuroprotective effect of MSCcm was lost when MSCs were isolated from patients with MS. DISCUSSION: Our findings have significant implications for MSC-based therapy in neurodegenerative conditions, particularly for autologous MSC therapy in MS. Impaired neuroprotection mediated by the MSC secretome in progressive MS may reflect reduced reparative potential of autologous MSC-based therapy in MS and it is likely that the causes must be addressed before the full potential of MSC-based therapy is realized. Additionally, we anticipate that understanding the mechanisms responsible will contribute new insights into MS pathogenesis and may also be of wider relevance to other neurodegenerative conditions.

Accumulation of cortical hyperphosphorylated neurofilaments as a marker of neurodegeneration in multiple sclerosis.

BACKGROUND: Axonal loss and grey matter neuronal injury are pathological processes that contribute to disease progression in multiple sclerosis (MS). Axon damage has been associated with changes in the phosphorylation state of neurofilaments and the presence of axonal spheroids. Perikaryal accumulation of abnormally phosphorylated neurofilament proteins has been reported in some neurodegenerative diseases. OBJECTIVES: The objective of this article is to determine whether abnormally phosphorylated neurofilament accumulates in neuronal perikarya in demyelinated MS cortex. METHODS: We used an antibody to hyperphosphorylated neurofilament-H (SMI-34) to assess the level and distribution of this antigen in paraffin sections of cerebral cortex from cases of neuropathologically confirmed MS and controls. We also examined the relationship of neurofilament phosphorylation to cortical demyelination. RESULTS: The number of SMI-34-positive neuronal somata was significantly higher in the MS cortex than the control cortex. As a proportion of the total number of neurons present (i.e. taking account of neuronal loss), the proportion of SMI-34-positive neurons was also significantly higher in the demyelinated and non-demyelinated MS cortex than the control cortex. CONCLUSIONS: MS is associated with the widespread accumulation of hyperphosphorylated neurofilament protein in neuronal somata, with the most marked accumulation in regions of cortical demyelination. This aberrant localisation of hyperphosphorylated neurofilament protein may contribute to neuronal dysfunction and degeneration in MS patients.

The PPAR-γ agonist pioglitazone protects cortical neurons from inflammatory mediators via improvement in peroxisomal function.

BACKGROUND: Inflammation is known to play a pivotal role in mediating neuronal damage and axonal injury in a variety of neurodegenerative disorders. Among the range of inflammatory mediators, nitric oxide and hydrogen peroxide are potent neurotoxic agents. Recent evidence has suggested that oligodendrocyte peroxisomes may play an important role in protecting neurons from inflammatory damage. METHODS: To assess the influence of peroxisomal activation on nitric oxide mediated neurotoxicity, we investigated the effects of the peroxisomal proliferator activated receptor (PPAR) gamma agonist, pioglitazone in primary cortical neurons that were either exposed to a nitric oxide donor or co-cultured with activated microglia. RESULTS: Pioglitazone protected neurons and axons against both nitric-oxide donor-induced and microglia-derived nitric oxide-induced toxicity. Moreover, cortical neurons treated with this compound showed a significant increase in the protein and gene expression of PPAR-gamma, which was associated with a concomitant increase in the enzymatic activity of catalase. In addition, the protection of neurons and axons against hydrogen peroxide-induced toxicity afforded by pioglitazone appeared to be dependent on catalase. CONCLUSIONS: Collectively, these observations provide evidence that modulation of PPAR-gamma activity and peroxisomal function by pioglitazone attenuates both NO and hydrogen peroxide-mediated neuronal and axonal damage suggesting a new therapeutic approach to protect against neurodegenerative changes associated with neuroinflammation.

Peroxisome proliferator-activated receptor-α agonists protect cortical neurons from inflammatory mediators and improve peroxisomal function.

Inflammation is known to cause significant neuronal damage and axonal injury in many neurological disorders. Among the range of inflammatory mediators, nitric oxide is a potent neurotoxic agent. Recent evidence has suggested that cellular peroxisomes may be important in protecting neurons from inflammatory damage. To assess the influence of peroxisomal activation on nitric oxide-mediated neurotoxicity, we investigated the effects of the peroxisomal proliferator-activated receptor (PPAR)-α agonist fenofibrate on cortical neurons exposed to a nitric oxide donor or co-cultured with activated microglia. Fenofibrate protected neurons and axons against both nitric oxide donor-induced and microglia-derived nitric oxide-induced toxicity. Moreover, cortical neurons treated with this compound showed a significant increase in gene expression of ABCD3 (the gene encoding for peroxisomal membrane protein-70), with a concomitant increase in protein levels of PPAR-α and catalase, which was associated with a functional increase in the activity of this enzyme. Collectively, these observations provide evidence that modulation of PPAR-α activity and peroxisomal function by fenofibrate attenuates nitric oxide-mediated neuronal and axonal damage, suggesting a new therapeutic approach to protect against neurodegenerative changes associated with neuroinflammation.

Human bone marrow-derived mesenchymal stem cells secrete brain-derived neurotrophic factor which promotes neuronal survival in vitro.

Bone marrow-derived mesenchymal stem cells (MSCs) are of therapeutic interest in a variety of neurological diseases. In this study, we wished to determine whether human MSCs secrete factors which protect cultured rodent cortical neurons from death by trophic factor withdrawal or nitric oxide (NO) exposure. Medium conditioned by MSCs attenuated neuronal death under these conditions, a process which was dependent on intact PI(3)kinase/Akt pathway signaling. Trophic withdrawal and NO exposure in cultured cortical neurons led to reduction in Akt signaling pathways, whereas NO administration activated p38 MAPkinase in neuronal cultures. Addition of MSC-conditioned medium significantly activated the PI3kinase/Akt pathway and in neurons exposed to NO, MSC-conditioned medium reduced p38 signaling. We show that MSCs secrete brain-derived neurotrophic factor (BDNF) and addition of anti-BDNF neutralising antibodies to MSC-conditioned medium attenuated its neuroprotective effect. Exposure of neurons to BDNF increased activation of Akt pathways and protected neurons from trophic factor withdrawal. These observations determine the mechanisms of neuroprotection offered by MSC-derived factors and suggest an important role for BDNF in neuronal protection.

Myocardial, inflammatory, and stress responses in off-pump coronary artery bypass graft surgery with thoracic epidural anesthesia.

OBJECTIVES: Epidural anesthesia has been suggested to exert a protective effect against the inflammatory and stress responses associated with surgery. The aim of this study was to evaluate the impact of thoracic epidural anesthesia on myocardial cell damage, inflammatory, and stress responses in patients undergoing off-pump coronary artery bypass graft (OPCABG) surgery. METHODS: Seventy-four patients (66 male [89%], mean age 65.2 years [SD 9.6]) undergoing OPCABG surgery were randomly assigned to receive either general anesthesia plus epidural (GAE [n = 36]) or general anesthesia only (GA [n = 38]). Troponin I, 8-isoprostane, cortisol, C3alpha, interleukin (IL)-6, IL-8, and IL-10 were measured preoperatively, at 30 minutes, and 4, 12, 24, and 48 hours postoperatively. RESULTS: Baseline characteristics were similar in the two groups. One patient died in the GAE group, but no other major postoperative complications were recorded in either group. The IL-6 and IL-8 levels were lower in the GAE group (ratio 0.83, 95% confidence interval: 0.68 to 1.02; p = 0.070) than in the GA group (ratio 0.90, 95% confidence interval: 0.78 to 1.02; p = 0.090). The difference in levels of IL-10 between the GAE and GA groups varied over time (p greater, similar 0.001). The C3alpha, troponin I, 8-isoprostane, and cortisol release was similar in the two groups throughout (p > or = 0.12). CONCLUSIONS: Thoracic epidural anesthesia does not provide any additional benefits in terms of reducing myocardial damage, inflammatory, and stress response compared with general anesthesia only in patients undergoing OPCABG surgery.