Silk fibroin increases the elasticity of alginate-gelatin hydrogels and regulates cardiac cell contractile function in cardiac bioinks.

Silk fibroin (SF) is a natural protein extracted fromBombyx morisilkworm thread. From its common use in the textile industry, it emerged as a biomaterial with promising biochemical and mechanical properties for applications in the field of tissue engineering and regenerative medicine. In this study, we evaluate for the first time the effects of SF on cardiac bioink formulations containing cardiac spheroids (CSs). First, we evaluate if the SF addition plays a role in the structural and elastic properties of hydrogels containing alginate (Alg) and gelatin (Gel). Then, we test the printability and durability of bioprinted SF-containing hydrogels. Finally, we evaluate whether the addition of SF controls cell viability and function of CSs in Alg-Gel hydrogels. Our findings show that the addition of 1% (w/v) SF to Alg-Gel hydrogels makes them more elastic without affecting cell viability. However, fractional shortening (FS%) of CSs in SF-Alg-Gel hydrogels increases without affecting their contraction frequency, suggesting an improvement in contractile function in the 3D cultures. Altogether, our findings support a promising pathway to bioengineer bioinks containing SF for cardiac applications, with the ability to control mechanical and cellular features in cardiac bioinks.

Recovery rate data for silicon nitride nanoparticle isolation using sodium polytungstate density gradients.

The average recovery rate of silicon nitride nanoparticles isolated from serum using the method detailed in previous article "A novel method for isolation and recovery of ceramic nanoparticles and metal wear debris from serum lubricants at ultra-low wear rate" (Lal et al., 2016) [1] was tested gravimetrically by weighing particles doped into serum before and after the isolation process. An average recovery rate of approximately 89.6% (± 7.1 SD) was achieved.

Development and optimisation data of a tissue digestion method for the isolation of orthopaedic wear particles.

The data contained within this article relate to several enzymatic tissue digestion experiments which were performed to produce an optimised protocol for the digestion of tissue samples. The digestion experiments involved a total of four different digestion protocols. The first protocol involved digestion with proteinase K, without the use of glycine. The second protocol involved digestion with proteinase K in the presence of glycine. The third protocol consisted of proteinase K digestion in the presence of glycine, with more frequent enzyme replenishment. The final protocol was similar to the third protocol but included a papain digestion stage prior to digestion with proteinase K. The data contained within this article are photographs of tissue samples which were captured at key stages of the four protocols and written descriptions based on visual observation of the tissue samples, which document the appearance of the tissue digests.

Validation of a novel particle isolation procedure using particle doped tissue samples.

A novel particle isolation method for tissue samples was developed and tested using particle-doped peri-articular tissues from ovine cadavers. This enabled sensitivity of the isolation technique to be established by doping tissue samples of 0.25 g with very low particle volumes of 2.5 µm3 per sample. Image analysis was used to verify that the method caused no changes to particle size or morphologies.

Recovery of low volumes of wear debris from rat stifle joint tissues using a novel particle isolation method.

Less than optimal particle isolation techniques have impeded analysis of orthopaedic wear debris in vivo. The purpose of this research was to develop and test an improved method for particle isolation from tissue. A volume of 0.018 mm3 of clinically relevant CoCrMo, Ti-6Al-4V or Si3N4 particles was injected into rat stifle joints for seven days of in vivo exposure. Following sacrifice, particles were located within tissues using histology. The particles were recovered by enzymatic digestion of periarticular tissue with papain and proteinase K, followed by ultracentrifugation using a sodium polytungstate density gradient. Particles were recovered from all samples, observed using SEM and the particle composition was verified using EDX, which demonstrated that all isolated particles were free from contamination. Particle size, aspect ratio and circularity were measured using image analysis software. There were no significant changes to the measured parameters of CoCrMo or Si3N4 particles before and after the recovery process (KS tests, p > 0.05). Titanium particles were too few before and after isolation to analyse statistically, though size and morphologies were similar. Overall the method demonstrated a significant improvement to current particle isolation methods from tissue in terms of sensitivity and efficacy at removal of protein, and has the potential to be used for the isolation of ultra-low wearing total joint replacement materials from periprosthetic tissues. STATEMENT OF SIGNIFICANCE: This research presents a novel method for the isolation of wear particles from tissue. Methodology outlined in this work would be a valuable resource for future researchers wishing to isolate particles from tissues, either as part of preclinical testing, or from explants from patients for diagnostic purposes. It is increasingly recognised that analysis of wear particles is critical to evaluating the safety of an orthopaedic device.

Patient-reported quality of life outcomes following treatment for oral cancer.

Patient-reported quality of life (QoL) outcomes have the potential to assist clinicians in providing individually tailored treatment decisions. QoL assessments were collected prospectively for 168 consecutive patients treated for oral cancer between 1 January 2010 and 31 December 2014 using the University of Washington Quality of Life Questionnaire. Patients were followed up for 18 months post-treatment. Sub-group analyses were performed using paired t-tests and analysis of variance (ANOVA) to compare the effects of adjunctive chemoradiotherapy, type of bone resection, and methods of soft and hard tissue flap reconstruction. The greatest statistically significant reduction in QoL for all oral cavity sub-sites was found following the treatment of floor of mouth tumours (-18.9%, P=0.018). Laser excision for matched patient cohorts resulted in improved resultant QoL compared to other excision techniques (P=0.0002). No significant difference in QoL was found when radial forearm and anterolateral thigh flaps were matched, or when fibula and scapula flaps were matched. These findings support the use of laser excision and the avoidance of postoperative radiotherapy if curative intent and survival outcomes are maintained.

Ultrahigh molecular weight polyethylene/graphene oxide nanocomposites: Wear characterization and biological response to wear particles.

In the field of total joint replacements, polymer nanocomposites are being investigated as alternatives to ultrahigh molecular weight polyethylene (UHMWPE) for acetabular cup bearings. The objective of this study was to investigate the wear performance and biocompatibility of UHMWPE/graphene oxide (GO) nanocomposites. This study revealed that low concentrations of GO nanoparticles (0.5 wt %) do not significantly alter the wear performance of UHMWPE. In contrast, the addition of higher concentrations (2 wt %) led to a significant reduction in wear. In terms of biocompatibility, UHMWPE/GO wear particles did not show any adverse effects on L929 fibroblast and PBMNC viability at any of the concentrations tested over time. Moreover, the addition of GO to a UHMWPE matrix did not significantly affect the inflammatory response to wear particles. Further work is required to optimize the manufacturing processes to improve the mechanical properties of the nanocomposites and additional biocompatibility testing should be performed to understand the potential clinical application of these materials. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 183-190, 2018.

Adult Co-morbidity Evaluation 27 scores of head and neck cancer patients using touch-screen technology: patient satisfaction and clinical verification.

OBJECTIVES: This study aimed to assess head and neck cancer patient satisfaction with the use of a touch-screen computer patient-completed questionnaire for assessing Adult Co-morbidity Evaluation 27 co-morbidity scores prior to treatment, along with its clinical reliability. METHODS: A total of 96 head and neck cancer patients were included in the audit. An accurate Adult Co-morbidity Evaluation 27 co-morbidity score was achieved via patient-completed questionnaire assessment for 97 per cent of participants. RESULTS: In all, 96 per cent of patients found the use of a touch-screen computer acceptable and would be willing to use one again, and 62 per cent would be willing to do so without help. Patients were more likely to be willing to use the computer again without help if they were aged 65 years or younger (χ2 test; p = 0.0054) or had a performance status of 0 or 1 (χ2 test; p = 0.00034). CONCLUSION: Use of a touch-screen computer is an acceptable approach for assessing Adult Co-morbidity Evaluation 27 scores at pre-treatment assessment in a multidisciplinary joint surgical-oncology clinic.

A novel method for isolation and recovery of ceramic nanoparticles and metal wear debris from serum lubricants at ultra-low wear rates.

UNLABELLED: Ceramics have been used to deliver significant improvements in the wear properties of orthopaedic bearing materials, which has made it challenging to isolate wear debris from simulator lubricants. Ceramics such as silicon nitride, as well as ceramic-like surface coatings on metal substrates have been explored as potential alternatives to conventional implant materials. Current isolation methods were designed for isolating conventional metal, UHMWPE and ceramic wear debris. In this paper, we describe a methodology for isolation and recovery of ceramic or ceramic-like coating particles and metal wear particles from serum lubricants under ultra-low and low wear performance. Enzymatic digestion was used to digest the serum proteins and sodium polytungstate was used as a novel density gradient medium to isolate particles from proteins and other contaminants by ultracentrifugation. This method demonstrated over 80% recovery of particles and did not alter the size or morphology of ceramic and metal particles during the isolation process. STATEMENT OF SIGNIFICANCE: Improvements in resistance to wear and mechanical damage of the articulating surfaces have a large influence on longevity and reliability of joint replacement devices. Modern ceramics have demonstrated ultra-low wear rates for hard-on-hard total hip replacements. Generation of very low concentrations of wear debris in simulator lubricants has made it challenging to isolate the particles for characterisation and further analysis. We have introduced a novel method to isolate ceramic and metal particles from serum-based lubricants using enzymatic digestion and novel sodium polytungstate gradients. This is the first study to demonstrate the recovery of ceramic and metal particles from serum lubricants at lowest detectable in vitro wear rates reported in literature.

Health-related quality of life after maxillectomy: obturator rehabilitation compared with flap reconstruction.

Health-related quality of life (QoL) reported by patients has the potential to improve care after ablative surgery of the midface, as existing treatment algorithms still generally revolve around outcomes assessed traditionally only by clinicians. Decisions in particular relate to reconstruction with a flap compared with rehabilitation with an obturator, the need for adjuvant treatment, and morbidity related to the size of the defect. We prospectively collected health-related QoL assessments for 39 consecutive patients treated by maxillectomy between 01 January 2010 and 31 December 2014 using the University of Washington Quality of Life Questionnaire, and who had a mean (SD) duration of follow-up of 14 (4). We made sub-group analyses using paired t tests and analysis of variance (ANOVA) to compare reconstruction with a flap with rehabilitation with obturators, size of the vertical defect, and whether adjuvant treatment with radiotherapy or chemoradiotherapy adversely affected it. Overall there was a significant decrease in health-related QoL after treatment compared with before (p<0.001), but there was no significant difference in the effects of any of the paired reconstructive and rehabilitation treatments on it. Obturators remain an important option for rehabilitation in selected patients in addition to reconstruction with a flap. We found that neither increasing the size of the vertical defect (in an attempt to ensure clear margins) nor the use of postoperative radiotherapy seemed to have any adverse effect on QoL. More patients are required before we can conclude that the potential survival benefits of such measures may outweigh any adverse effects.

Health-related quality of life after treatment for neoplasia of the major salivary glands: a pilot study.

Treatment of malignancy of the salivary glands risks damage to the cranial nerves, and clinicians' traditional view has been that this will result in adverse effects on physical function and subsequent health-related quality of life (QoL). Preservation of nerves has been advocated to lessen this impact, but we know of no evidence that sacrifice of the facial nerve has any effect on subsequent QoL. We collected data prospectively before and after operation for all malignancies of the major salivary glands treated over five years using two health-related QoL questionnaires: the University of Washington Quality of Life Questionnaire and the Patient Concerns Inventory. Fifteen of17 eligible patients fulfilled the inclusion criteria by having assessments completed both before and after operation. Scores for QoL after treatment of cancer of the submandibular gland dropped at six months, but had resolved to more than 80% of the pretreatment score by a year, with the exception of the domains taste and saliva. The four patients who had weakness of the facial nerve after treatment had appreciable reductions in the physical function components of the QoL domains, but no significant reduction in the social-emotional domains. Use of the Patient Concerns Inventory enables tailoring of services towards those clinicians who a patient feels are potentially most likely to help alleviate factors that have an adverse effect on QoL. Sacrifice of the facial nerve in malignant parotid gland disease results in a considerable reduction in functional health-related QoL scores. Methods to ensure clearance of the tumour while limiting the effects on facial nerve function should always be considered.

Non-destructive monitoring of viability in an ex vivo organ culture model of osteochondral tissue.

Organ culture is an increasingly important tool in research, with advantages over monolayer cell culture due to the inherent natural environment of tissues. Successful organ cultures must retain cell viability. The aim of this study was to produce viable and non-viable osteochondral organ cultures, to assess the accumulation of soluble markers in the conditioned medium for predicting tissue viability. Porcine femoral osteochondral plugs were cultured for 20 days, with the addition of Triton X-100 on day 6 (to induce necrosis), camptothecin (to induce apoptosis) or no toxic additives. Tissue viability was assessed by the tissue destructive XTT (2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxyanilide tetrazolium salt) assay method and LIVE/DEAD® staining of the cartilage at days 0, 6 and 20. Tissue structure was assessed by histological evaluation using haematoxylin & eosin and safranin O. Conditioned medium was assessed every 3-4 days for glucose depletion, and levels of lactate dehydrogenase (LDH), alkaline phosphatase (AP), glycosaminoglycans (GAGs), and matrix metalloproteinase (MMP)-2 and MMP-9. Necrotic cultures immediately showed a reduction in glucose consumption, and an immediate increase in LDH, GAG, MMP-2 and MMP-9 levels. Apoptotic cultures showed a delayed reduction in glucose consumption and delayed increase in LDH, a small rise in MMP-2 and MMP-9, but no significant effect on GAGs released into the conditioned medium. The data showed that tissue viability could be monitored by assessing the conditioned medium for the aforementioned markers, negating the need for tissue destructive assays. Physiologically relevant whole- or part-joint organ culture models, necessary for research and pre-clinical assessment of therapies, could be monitored this way, reducing the need to sacrifice tissues to determine viability, and hence reducing the sample numbers necessary.

Wear and biological effects of a semi-constrained total disc replacement subject to modified ISO standard test conditions.

Development of pre-clinical testing methodologies is an important goal for improving prediction of artificial replacement joint performance and for guiding future device design. Total disc replacement wear and the potential for osteolysis is a growing concern, therefore a parametric study on the effects on wear of altered kinematics and loading was undertaken. A standard ISO testing protocol was modified in order to study the wear behaviour of lumbar total disc replacements when subject to low cross shear input kinematics, reduced axial loading and smaller flexion-extension magnitude. Volumetric wear, bearing surface topography, and wear debris biological reactivity were assessed. The ISO standard results were expected, however, the very low cross shear test produced a level of wear approximately two orders of magnitude higher than that reported for zero cross shear motions on UHMWPE bearings. When the osteolytic potential of the wear particles was calculated, all total disc replacement simulations had lower predicted osteolytic potential compared to total hip replacements, as a consequence of the generally lower wear rates found.

Analysis of wear, wear particles, and reduced inflammatory potential of vitamin E ultrahigh-molecular-weight polyethylene for use in total joint replacement.

Vitamin E (VE) has been added to ultrahigh-molecular-weight polyethylene (UHMWPE) acetabular cups and tibial trays primarily to reduce oxidative damage to the polymer. The aim of this study was to investigate the relative wear rates of UHMWPE-containing VE compared with virgin UHMWPE. The ability of VE to reduce the amount of inflammatory cytokines produced from stimulated peripheral blood mononuclear cells (PBMNCs) was also investigated. Stimulation was achieved by exposure of PBMNCs to either lipoplysaccharide (LPS) or VE-containing UHMWPE (VE-UHMWPE). In the present study, results showed that the wear rates of UHMWPE with or without VE were not significantly different. Particles generated by UHMWPE with and without VE were not significantly different in size distribution. The production of osteolytic mediators, tumor necrosis factor-alpha, interleukin 1ß (IL-ß), IL-6, and IL-8 were significantly reduced in (PBMNCs) stimulated with either LPS + VE compared with LPS or VE-UHMWPE particles compared to virgin UHMWPE particles. This trend was also observed when VE was added as a liquid to UHMWPE wear particle-stimulated PBMNCs. The exact mechanism of how VE affects the release of inflammatory mediators from particle-stimulated macrophages is not yet understood. It is likely to involve the anti-inflammatory and/or antioxidant effects of VE.

In vitro analysis of the cytotoxic and anti-inflammatory effects of antioxidant compounds used as additives in ultra high-molecular weight polyethylene in total joint replacement components.

Ultra high-molecular weight polyethylene (UHMWPE) remains the most commonly used material in modern joint replacement prostheses. However, UHMWPE wear particles, formed as the bearing articulates, are one of the main factors leading to joint replacement failure via the induction of osteolysis and subsequent aseptic loosening. Previous studies have shown that the addition of antioxidants such as vitamin E to UHMWPE can improve wear resistance of the polymer and reduce oxidative fatigue. However, little is known regarding the biological consequences of such antioxidant chemicals. This study investigated the cytotoxic and anti-inflammatory effects of a variety of antioxidant compounds currently being tested experimentally for use in hip and knee prostheses, including nitroxides, hindered phenols, and lanthanides on U937 human histocyte cells and human peripheral blood mononuclear cells (PBMNCs) in vitro. After addition of the compounds, cell viability was determined by dose response cytotoxicity studies. Anti-inflammatory effects were determined by quantitation of TNF-α release in lipopolysaccharide (LPS)-stimulated cells. This study has shown that many of these compounds were cytotoxic to U937 cells and PBMNCs, at relatively low concentrations (micromolar), specifically the hindered phenol 3,5-di-tert-butyl-4-hydroxyhydrocinnamate (HPAO1), and the nitroxide 2,2,6,6-Tetramethylpiperidine 1-oxyl (TEMPO). Lanthanides were only cytotoxic at very high concentrations and were well tolerated by the cells at lower concentrations. Cytotoxic compounds also showed reduced anti-inflammatory effects, particularly in PBMNCs. Careful consideration should therefore be given to the use of any of these compounds as potential additives to UHMWPE.

Wear and creep of highly crosslinked polyethylene against cobalt chrome and ceramic femoral heads.

The wear and creep characteristics of highly crosslinked ultrahigh-molecular-weight polyethylene (UHMWPE) articulating against large-diameter (36mm) ceramic and cobalt chrome femoral heads have been investigated in a physiological anatomical hip joint simulator for 10 million cycles. The crosslinked UHMWPE/ceramic combination showed higher volume deformation due to creep plus wear during the first 2 million cycles, and a steady-state wear rate 40 per cent lower than that of the crosslinked UHMWPE/cobalt chrome combination. Wear particles were isolated and characterized from the hip simulator lubricants. The wear particles were similar in size and morphology for both head materials. The particle isolation methodology used could not detect a statistically significant difference between the particles produced by the cobalt chrome and alumina ceramic femoral heads.

The effect of anterior-posterior shear load on the wear of ProDisc-L TDR.

The current wear-testing standard (ISO18192-1) for total disc replacement (TDR) requires only four degrees of freedom (DOF) inputs: axial load, flexion-extension, lateral bending and axial rotation. The study aim was to assess the effect of an additional DOF, anterior-posterior (AP) shear on the wear of the ProDisc-L TDR. A 5DOF simulator was used to test ProDisc-L implants under 4DOF and 5DOF conditions. The 4DOF conditions were defined by ISO18192-1 whilst the 5DOF used ISO18192-1 conditions with the addition of an AP load of +175 and -140 N (anterior and posterior, respectively), extrapolated from in vivo data. The implants were mounted such that the polyethylene insert could be removed for gravimetric measurements. Tests were run using bovine serum (15 g/l protein concentration) as a lubricant for five million cycles (MC), with measurements repeated every 1 MC. The mean wear rate in the 4DOF test was 12.7 +/- 2.1 mg/MC compared to 11.6 +/- 1.2 mg/MC in the 5DOF test. There were marked differences in the wear scars between 4DOF and 5DOF simulations. With 4DOF, wear scars were centralised on the dome of the insert, whilst 5DOF scars were larger, breaching the anterior rim of the dome causing deformation at the edge. The 4DOF wear test showed similar gravimetric wear rates to previously published ISO-tested TDRs. The addition of AP load was found to have no significant effect on the overall wear rate. However, there were pronounced differences in the respective wear scars, which highlights the need for more research in order to understand the factors that influence wear of TDR.

Identification of nanometre-sized ultra-high molecular weight polyethylene wear particles in samples retrieved in vivo.

Nanometre-sized particles of ultra-high molecular weight polyethylene have been identified in the lubricants retrieved from hip simulators. Tissue samples were taken from seven failed Charnley total hip replacements, digested using strong alkali and analysed using high-resolution field emission gun-scanning electron microscopy to determine whether nanometre-sized particles of polyethylene debris were generated in vivo. A randomised method of analysis was used to quantify and characterise all the polyethylene particles isolated. We isolated nanometre-sized particles from the retrieved tissue samples. The smallest identified was 30 nm and the majority were in the 0.1 microm to 0.99 microm size range. Particles in the 1.0 microm to 9.99 microm size range represented the highest proportion of the wear volume of the tissue samples, with 35% to 98% of the total wear volume comprised of particles of this size. The number of nanometre-sized particles isolated from the tissues accounted for only a small proportion of the total wear volume. Further work is required to assess the biological response to nanometre-sized polyethylene particles.

Wear and biological activity of highly crosslinked polyethylene in the hip under low serum protein concentrations.

Crosslinked ultra-high molecular weight polyethylene (UHMWPE) has been developed and introduced into clinical practice in order to reduce wear in the hip. Zero wear of highly crosslinked UHMWPE in vitro has been reported by some groups using lubricants with high concentrations of serum proteins in hip simulators. In contrast, some clinical studies have reported finite wear rates. The aim of this study was to compare the wear rates, wear surfaces, and wear debris produced by UHMWPE with different levels of crosslinking in a hip joint simulator, with lower, more physiologically relevant concentrations of protein in the lubricant. The UHMWPEs were tested in the Leeds ProSim hip joint simulator against cobalt-chromium (CoCr) femoral heads. The wear particles were isolated and imaged using a field emission gun scanning electron microscope (FEGSEM) at high resolution. The highly crosslinked UHMWPEs had significantly lower wear volumes than the non-crosslinked UHMWPEs. No significant difference was found in the percentage number and percentage volume of the particles in different size ranges from any of the materials. They had similar values of specific biological activity. The functional biological activity (FBA), which takes into account the wear volume and specific biological activity, showed that the highly crosslinked UHMWPEs had lower FBAs due to their lower wear volume.

Isolation and characterization of UHMWPE wear particles down to ten nanometers in size from in vitro hip and knee joint simulators.

There is currently considerable interest in the wear debris and osteolytic potential of different types of bearings used in total joint replacements. The biological activity of the wear debris is dependent on the size and volume of the particles produced. Wear volume also plays an important role in the functional biological activity of a joint replacement. In vitro studies have shown that crosslinking of ultra high molecular weight polyethylene (UHMWPE) acetabular cups and tibial trays produces a reduction in wear volume, and crosslinking has now been introduced clinically for both types of prostheses. Previous studies have identified both micron and submicron-sized polyethylene wear particles. The aim of this study was to characterize the wear and wear particles generated from moderately crosslinked GUR 1,020 GVF UHMWPE acetabular cups and tibial trays in hip and knee joint wear simulators down to 10 nanometers in size. The wear rates of the two prosthesis types were very similar at 25.6 +/- 5.3 mm(3) per million cycles for the hip prostheses and 22.75 +/- 5.95 mm(3) per million cycles for the knee prostheses. Nanometer-sized wear particles were isolated and characterized from both hip and knee simulator lubricants for the first time. Significantly higher numbers (p < 0.05) of particles in the nanometer (<0.1 microm) size range were produced by the hip prostheses compared to the knee prostheses. The knee prostheses produced larger particles, with the mode of particle size in the 0.1-1.0 microm size range, compared to <0.1 microm size range for the hip prostheses. In addition, the knee prostheses produced a greater volumetric concentration of wear particles in the 1.0-10 microm size range, and consequently lower specific biological activity and functional biological activity indices. These results indicated that the knee prostheses had a lower osteolytic potential compared to the hip prostheses.