1048 In Vitro Evaluation of the Response of Human Tendon-Derived Stromal Cells to a Novel Electrospun Suture

Aim

Recurrent tears after surgical tendon repair remain common, with 40% of rotator cuff repairs failing within one year. Repair failures can be partly attributed to the use of sutures not designed for the tendon cellular niche. Synthetic electrospun materials can mechanically support the tendon while providing topographical cues that modulate the immune response to promote wound healing. Here, a novel electrospun suture made from twisted polydioxanone (PDO) polymer filaments is compared to PDS II, a PDO suture clinically utilised in tendon repair.

Method

We evaluated the ability of electrospun suture and PDS II to support the attachment and proliferation of human tendon-derived stromal cells using PrestoBlue cell viability assays and scanning electron microscopy. Suture surface chemistry was analysed using X-ray photoelectron spectroscopy (XPS). Bulk RNA-Seq interrogated the transcriptional response of primary tendon-derived stromal cells to sutures after 14 days.

Results

The electrospun suture showed increased initial cell attachment compared to PDS II. XPS revealed that both sutures had similar local surface chemistry, indicating that the tendon-like architecture of electrospun suture was responsible for the greater cell attachment. Furthermore, electrospun suture elicited a stronger transcriptional response compared with PDS II, with relative enrichment of pathways including mTorc1 signalling and depletion of epithelial-to-mesenchymal transition and extracellular matrix gene sets. Neither suture induced transcriptional upregulation of inflammatory pathways.

Conclusion

Twisted electrospun sutures show promise in improving outcomes in surgical tendon repair by allowing increased cell attachment while maintaining a tissue response indicative of cell proliferation and wound healing, without significant fibrosis.

CT angiograms for lower GI bleeding: the experience of a large UK teaching hospital

INTRODUCTION

The clinical presentation of lower gastrointestinal bleeding (LGIB) is variable in severity, cause and potential investigations. The British Society of Gastroenterology recently published LGIB guidelines, recommending CT angiography (CT-A) for haemodynamically unstable patients, defined by shock index (SI) greater than 1. The aim of this study was to assess the use and role of CT-A in diagnosing LGIB, by assessing the pickup rate of active LGIB defined by contrast extravasation or 'blush' and to determine any association between positive CT-A with various patient and clinical characteristics.

METHODS

A retrospective analysis was carried out of 4 years of LGIB admissions. Demographics, inpatient observations and use of blood products were acquired. Vital signs nearest the time of CT-A plus abnormal vital signs preceding imaging were used to calculate SI, Age SI, National Early Warning Score 2 (NEWS2) and Standardised Early Warning Score (SEWS). A consultant gastrointestinal radiologist further reviewed all consultant-reported scans.

RESULTS

In total, 930 patients were admitted with LGIB. Median age was 71 years and 51% were male; 179 (19.2%) patients received red blood cell transfusion and 93 patients (10%) underwent CT-A, who were older and were likely to be hypotensive and receive red cell transfusions. Following exclusions, 92 CT-As were included in the analysis. Nine (9.8%) were positive. Univariate analysis showed no association between positive CT-A and any scoring system. A multivariate analysis, including age and gender, showed association between both NEWS2 and SEWS scores with positive CT-A.

CONCLUSION

In our analysis of the typical LGIB population, CT-A has shown relatively low pick up rate of active bleeding. CT-A clearly has a role in the investigation of LGIB, but selection remains challenging.

CT angiograms for lower GI bleeding: the experience of a large UK teaching hospital

INTRODUCTION

The clinical presentation of lower gastrointestinal bleeding (LGIB) is variable in severity, cause and potential investigations. The British Society of Gastroenterology recently published LGIB guidelines, recommending CT angiography (CT-A) for haemodynamically unstable patients, defined by shock index (SI) greater than 1. The aim of this study was to assess the use and role of CT-A in diagnosing LGIB, by assessing the pickup rate of active LGIB defined by contrast extravasation or 'blush' and to determine any association between positive CT-A with various patient and clinical characteristics.

METHODS

A retrospective analysis was carried out of 4 years of LGIB admissions. Demographics, inpatient observations and use of blood products were acquired. Vital signs nearest the time of CT-A plus abnormal vital signs preceding imaging were used to calculate SI, Age SI, National Early Warning Score 2 (NEWS2) and Standardised Early Warning Score (SEWS). A consultant gastrointestinal radiologist further reviewed all consultant-reported scans.

RESULTS

In total, 930 patients were admitted with LGIB. Median age was 71 years and 51% were male; 179 (19.2%) patients received red blood cell transfusion and 93 patients (10%) underwent CT-A, who were older and were likely to be hypotensive and receive red cell transfusions. Following exclusions, 92 CT-As were included in the analysis. Nine (9.8%) were positive. Univariate analysis showed no association between positive CT-A and any scoring system. A multivariate analysis, including age and gender, showed association between both NEWS2 and SEWS scores with positive CT-A.

CONCLUSION

In our analysis of the typical LGIB population, CT-A has shown relatively low pick up rate of active bleeding. CT-A clearly has a role in the investigation of LGIB, but selection remains challenging.

A new tool to assess community-level evidence to inform public health decision making

Background

As public health responds to evolving challenges around the globe, it is critical to draw on community-level evidence to inform decisions on emerging needs. There are existing tools for assessing the quality of research evidence, but none that explicitly focus on quality assessment of evidence from community sources, including local health status and ever-changing community and political preferences and actions.

Methods

The National Collaborating Centre for Methods and Tools (NCCMT) in Canada has developed new tools, called Quality Assessment of Community Evidence (QACE), to help public health decision makers assess the quality of community evidence. The QACE tools were drafted through extensive review of existing frameworks, tools and measures for appraising population health and community evidence, and diverse key informants. We identified three consistent themes that became the core dimensions in these tools. By using the QACE tools, practitioners can answer the question: “Is the quality of this evidence about local context, community needs and political preferences good enough to influence decision making?”

Results

The QACE tools provide probing questions for each of three dimensions: relevant, trustworthy and equity-informed. Supplementary resources help users delve more deeply into different aspects of quality assessment. The QACE tools are intended for public health practitioners who provide and use evidence to support or make decisions about public health practice and policy, including public health practitioners, senior leaders, policy makers and funders.

Conclusions

The QACE tool is a new addition to the public health toolbox for evidence-informed decision making, providing questions to ask about evidence from community sources. By using the tool as part of a decision-making process, public health practitioners can be assured that their decisions are based on the best-available evidence for their communities.

Key messages

The new Quality Assessment of Community Evidence (QACE) tools fill the gap in assessing quality of community-level evidence for public health decision-makers. Community evidence, including local health status and needs and community and political preferences and actions, should be assessed for quality in three critical domains.

Resorbable electrospun polydioxanone fibres modify the behaviour of cells from both healthy and diseased human tendons

Chronic tendinopathy in an active and ageing population represents an increasing burden to healthcare systems. Rotator cuff tendinopathy alone accounts for approximately 70 % of all shoulder pain. Tendinopathic tissue has a disorganised extracellular matrix, altered vasculature, and infiltration of fibroblasts and inflammatory cells. This altered biology may contribute to the limited success of surgical repair strategies. Electrospun resorbable scaffolds can potentially enhance endogenous repair mechanisms by influencing the tissue microenvironment. Polydioxanone (PDO) has an established safety profile in patients. We compared the response of healthy and diseased human tendon cells to electrospun PDO fibres using live cell imaging, proliferation, flow cytometry, and gene expression studies. Within 4 h of initial contact with electrospun PDO, healthy tendon cells underwent a marked transformation; elongating along the fibres in a fibre density dependent manner. Diseased tendon cells initially responded at a slower rate, but ultimately underwent a similar morphological change. Electrospun fibres increased the proliferation rate of diseased tendon cells and increased the ratio of type I:IIIcollagenmRNA expression. Flow cytometry revealed decreased expression of CD106, a marker of mesenchymal stem cells, and increased expression of CD10 on healthy versus diseased tendon cells. PDO electrospun scaffolds further promoted CD106negCD10pos expression of healthy tendon cells. Despite their behavioural differences, both healthy and diseased human tendon cells responded to electrospun PDO fibres. This encourages further work establishing their efficacy in augmenting surgical repair of diseased tendons.

A gene expression study of normal and damaged cartilage in anteromedial gonarthrosis, a phenotype of osteoarthritis

OBJECTIVE

To identify osteoarthritis (OA) relevant genes and pathways in damaged and undamaged cartilage isolated from the knees of patients with anteromedial gonarthrosis (AMG) - a specific form of knee OA.

DESIGN

Cartilage was obtained from nine patients undergoing unicompartmental knee replacement (UKR) for AMG. AMG provides a spatial representation of OA progression; showing a reproducible and histologically validated pattern of cartilage destruction such that damaged and undamaged cartilage from within the same knee can be consistently isolated and examined. Gene expression was analysed by microarray and validated using real-time PCR.

RESULTS

Damaged and undamaged cartilage showed distinct gene expression profiles. 754 genes showed significant up- or down-regulation (non-False discovery rate (FDR) P < 0.05) with enrichment for genes involved in cell signalling, Extracellular Matrix (ECM) and inflammatory response. A number of genes previously unreported in OA showed strongly altered expression including RARRES3, ADAMTSL2 and DUSP10. Confirmation of genes previously identified as modulated in OA was also obtained e.g., SFRP3, MMP3 and IGF1.

CONCLUSIONS

This is the first study to examine a common and consistent phenotype of OA to allow direct comparison of damaged and undamaged cartilage from within the same joint compartment. We have identified specific gene expression profiles in damaged and undamaged cartilage and have determined relevant genes and pathways in OA progression. Importantly this work also highlights the necessity for phenotypic and microanatomical characterization of cartilage in future studies of OA pathogenesis and therapeutic development.

Allelic expression analysis suggests that cis-acting polymorphism of FRZB expression does not contribute to osteoarthritis susceptibility

OBJECTIVE

The FRZB gene codes for secreted frizzled-related protein 3 (sFRP3), a soluble antagonist of wnt signalling that is required for maintaining cartilage integrity. Two common single nucleotide polymorphisms (SNPs) that code for the substitution of conserved arginine residues have previously been identified in FRZB and found to be associated with osteoarthritis (OA). Functional studies revealed that the arginine substitutions lead to a loss-of-function of sFRP3 activity. We set out to assess whether cis-acting polymorphism in the regulation of FRZB expression exists, as this may be an additional mechanism through which sFRP3 activity could be modulated.

METHODS

RNA was extracted from the articular cartilage chondrocytes of 25 individuals who had undergone joint replacement for OA and who were heterozygous for one of the two FRZB SNPs. Allelic output was measured by single base extension in to the SNPs and deviations from the expected 1:1 pattern were assessed using the Mann-Whitney U test.

RESULTS

Differential allelic expression was observed in six of the 25 individuals. However, the average fold difference in allelic expression in the six was only 1.19.

CONCLUSIONS

The presence of a small degree of differential allelic expression in a low proportion (24%) of the individuals studied suggests that polymorphism in FRZB cis-acting regulatory elements can be discounted as a major factor that could influence the development of OA.

Genetic association analysis of LRCH1 as an osteoarthritis susceptibility locus

OBJECTIVE

A genetic association with knee osteoarthritis (OA) of a single nucleotide polymorphism (SNP) in intron 1 of the LRCH1 gene was recently reported in a UK Caucasian case-control sample and confirmed in a Newfoundland Caucasian sample. Our objective was to assess whether the SNP was associated with OA in our large UK Caucasian sample.

METHODS

The SNP was genotyped in 1521 cases that had undergone elective joint replacement of the hip (1098 cases), of the knee (340 cases) or of the hip and knee (83 cases) due to end-stage primary OA. The SNP was also genotyped in 736 controls of similar ages in the cases.

RESULTS

There was no significant difference (all P-values >0.05) in genotype or allele frequencies between our cases and our controls. There was also no significant difference when the cases were stratified by sex, by joint replaced or by sex combined with joint replaced.

CONCLUSION

Our data on 2257 individuals implies that the LRCH1 intron 1 SNP is not a risk factor for OA aetiology of the knee or of the hip in our UK Caucasian sample.

The influence of tumour microenvironmental factors on the efficacy of cisplatin and novel platinum(IV) complexes

The chemotherapeutic drug cisplatin is an important treatment for many types of solid tumours, in particular non-small cell lung cancer (NSCLC). Platinum(IV) complexes offer several advantages to cisplatin due to their requirement for reduction to the active platinum(II) form to elicit cytotoxicity. This should minimise non-specific effects and facilitate higher amounts of the active complexes reaching the target DNA. Hypoxia and a quiescent cell population are features of the tumour microenvironment known to lead to resistance to many chemotherapeutic agents. It is unclear how these microenvironmental factors will impact on the efficacy of novel platinum(IV) complexes. Consequently, the cytotoxicities of several platinum drugs were determined in monolayer and tumour spheroid cultures derived from NSCLC lines. Platinum(IV) reduction potential correlated well with cytotoxicity. The complex containing a chloro axial ligand demonstrated the greatest potency and the drug with the hydroxy ligand was the least effective. Although drug cytotoxicity was not enhanced under hypoxic conditions, both cisplatin and the platinum(IV) complexes retained full potency. In addition, all of the platinum drugs retained the ability to evoke apoptosis in quiescent cells. In summary, unlike many anticancer drugs, the platinum(IV) complexes retain cytotoxic potency under resistance-inducing tumour microenvironmental conditions and warrant further investigation as more selective alternatives to current platinum-based therapy for the treatment of solid tumours.

Ceftazidime or gentamicin plus benzylpenicillin in neonates less than forty-eight hours old

A clinical trial was conducted to assess the value of ceftazidime as a first-line antibiotic in a neonatal intensive care unit. Fifty-five infants less than 48 h old with suspected sepsis were randomly treated with ceftazidime or penicillin and gentamicin. A full septic screen was performed in all infants before treatment. Treatment was stopped after 48 h if cultures were sterile. A further 22 infants more than 48 h old, with clinical evidence of sepsis, were treated with ceftazidime in an open trial. Ceftazidime proved effective against all but two of the septicaemias. A group D beta-haemolytic streptococcus and a coagulase-negative staphylococcus proved resistant, but were also resistant to penicillin and gentamicin. No adverse response to ceftazidime was noted, and the incidence of later candidiasis was similar to that after other broad-spectrum antibiotic combinations. The avoidance of gentamicin assay in the ceftazidime group was an advantage in this age group.