Plasma fibrinogen and risk of vascular recurrence after ischaemic stroke: An individual participant and summary-level data meta-analysis of 11 prospective studies

INTRODUCTION

Inflammation is an emerging target for secondary prevention after stroke and randomised trials of anti-inflammatory therapies are ongoing. Fibrinogen, a putative pro-inflammatory marker, is associated with first stroke, but its association with major adverse cardiovascular events (MACE) after stroke is unclear.

MATERIALS AND METHODS

We did a systematic review investigating the association between fibrinogen and post-stroke vascular recurrence. Authors were invited to provide individual-participant data (IPD) and where available we did within-study multivariable analyses with adjustment for cardiovascular risk factors and medications. Adjusted summary-level data was extracted from published reports from studies that did not provide IPD. We pooled risk ratios (RR) by random-effects meta-analysis by comparing supra-median with sub-median fibrinogen levels and performed pre-specified subgroup analysis according to timing of phlebotomy after the index event.

RESULTS

Eleven studies were included (14,002 patients, 42,800 follow-up years), of which seven provided IPD. Fibrinogen was associated with recurrent MACE on unadjusted (RR 1.35, 95% CI 1.17-1.57, supra-median vs sub-median) and adjusted models (RR 1.21, 95% CI 1.06-1.38). Fibrinogen was associated with recurrent stroke on univariate analysis (RR 1.19, 95% CI 1.03-1.39), but not after adjustment (RR 1.11, 95% CI 0.94-1.31). The association with recurrent MACE was consistently observed in patients with post-acute (⩾14 days) fibrinogen measures (RR 1.29, 95% CI 1.16-1.45), but not in those with early phlebotomy (<14 days) (RR 0.98, 95% CI 0.82-1.18) (Pinteraction = 0.01). Similar associations were observed for recurrent stroke.

DISCUSSION AND CONCLUSION

Fibrinogen was independently associated with recurrence after stroke, but the association was modified by timing of phlebotomy. Fibrinogen measurements might be useful to identify patients who are more likely to derive benefit from anti-inflammatory therapies after stroke.

C-Reactive Protein, Interleukin-6, and Vascular Recurrence According to Stroke Subtype: An Individual Participant Data Meta-Analysis

BACKGROUND AND OBJECTIVES

Anti-inflammatory therapies reduce major adverse cardiovascular events (MACE) in coronary artery disease but remain unproven after stroke. Establishing the subtype-specific association between inflammatory markers and recurrence risk is essential for optimal selection of patients in randomized trials (RCTs) of anti-inflammatory therapies for secondary stroke prevention.

METHODS

Using individual participant data (IPD) identified from a systematic review, we analyzed the association between high-sensitivity C-reactive protein, interleukin-6 (IL-6), and vascular recurrence after ischemic stroke or transient ischemic attack. The prespecified coprimary end points were (1) any recurrent MACE (first major coronary event, recurrent stroke, or vascular death) and (2) any recurrent stroke (ischemic, hemorrhagic, or unspecified) after sample measurement. Analyses were performed stratified by stroke mechanism, per quarter and per biomarker unit increase after loge transformation. We then did study-level meta-analysis with comparable published studies not providing IPD. Preferred Reporting Items for Systematic Review and Meta-Analyses IPD guidelines were followed.

RESULTS

IPD was obtained from 10 studies (8,420 patients). After adjustment for vascular risk factors and statins/antithrombotic therapy, IL-6 was associated with recurrent MACE in stroke caused by large artery atherosclerosis (LAA) (risk ratio [RR] 2.30, 95% CI 1.21-4.36, p = 0.01), stroke of undetermined cause (UND) (RR 1.78, 1.19-2.66, p = 0.005), and small vessel occlusion (SVO) (RR 1.71, 0.99-2.96, p = 0.053) (quarter 4 [Q4] vs quarter 1 [Q1]). No association was observed for stroke due to cardioembolism or other determined cause. Similar results were seen for recurrent stroke and when analyzed per loge unit increase for MACE (LAA, RR 1.26 [1.06-1.50], p = 0.009; SVO, RR 1.22 [1.01-1.47], p = 0.04; UND, RR 1.18 [1.04-1.34], p = 0.01). High-sensitivity CRP was associated with recurrent MACE in UND stroke only (Q4 vs Q1 RR 1.45 [1.04-2.03], p = 0.03). Findings were consistent on study-level meta-analysis of the IPD results with 2 other comparable studies (20,136 patients).

DISCUSSION

Our data provide new evidence for the selection of patients in future RCTs of anti-inflammatory therapy in stroke due to large artery atherosclerosis, small vessel occlusion, and undetermined etiology according to inflammatory marker profile.

C-Reactive Protein, Interleukin-6, and Vascular Recurrence After Stroke: An Individual Participant Data Meta-Analysis

BACKGROUND

Anti-inflammatory therapies reduce recurrent vascular events in coronary disease. Existing studies have reported highly conflicting findings for the association of blood inflammatory markers with vascular recurrence after stroke leading to uncertainty about the potential of anti-inflammatory therapies after stroke and no consensus about the utility of measurement of inflammatory markers in current guidelines.

METHODS

We investigated the association between hsCRP (high-sensitivity C-reactive protein), IL-6 (interluekin-6), and recurrent major adverse cardiovascular events (MACE), and stroke from individual participant data from 8420 patients with ischemic stroke/transient ischemic attack from 10 prospective studies. We did within-study multivariable regression analyses and then combined adjusted risk ratio (RR) by random-effects meta-analysis.

RESULTS

During 18 920 person-years of follow-up, 1407 (16.7% [95% CI, 15.9-17.5]) patients had MACE and 1191 (14.1% [95% CI, 13.4-14.9]) patients had recurrent stroke. On bivariate analysis, baseline IL-6 was associated with MACE (RR, 1.26 [95% CI, 1.10-1.43]) and recurrent stroke (RR, 1.18 [95% CI, 1.05-1.32]), per unit increase log_eIL-6. Similar associations were observed for hsCRP (MACE RR, 1.19 [95% CI, 1.09-1.29]; recurrent stroke RR, 1.12 [95% CI, 1.04-1.21], per unit increase log_ehsCRP). After adjustment for vascular risk factors and treatment, independent associations remained with MACE (IL-6, RR, 1.12 [95% CI, 1.04-1.21]; hsCRP, RR, 1.09 [95% CI, 1.04-1.15]) and recurrent stroke (IL-6, RR, 1.09 [95% CI, 1.00-1.19]; hsCRP, RR, 1.05 [95% CI, 1.00-1.11]). Comparing the top with the bottom quarters (Q4 versus Q1), IL-6 (RR, 1.35 [95% CI, 1.09-1.67]) and hsCRP (RR, 1.31 [95% CI, 1.07-1.61]) were associated with MACE after adjustment. Similar results were observed for recurrent stroke for IL-6 (RR, 1.33 [95% CI, 1.08-1.65]) but not hsCRP (RR, 1.16 [95% CI, 0.93-1.43]).

CONCLUSIONS

Blood markers of inflammation were independently associated with vascular recurrence after stroke, strengthening the rationale for randomized trials of anti-inflammatory therapies for secondary prevention after ischemic stroke/TIA.

Risk of New-Diagnosed Atrial Fibrillation After Transient Ischemic Attack

Background

Transient ischemic attack (TIA) provides a unique opportunity to optimize secondary preventive treatments to avoid subsequent ischemic stroke (SIS). Although atrial fibrillation (AF) is the leading cause of cardioembolism in IS and anticoagulation prevents stroke recurrence (SR), limited data exists about the risk of new-diagnosed AF (NDAF) after TIA and the consequences of the diagnostic delay. The aim of our study was to determine this risk in a cohort of TIA patients with long-term follow-up.

Methods

We carried out a prospective cohort study of 723 consecutive TIA patients from January 2006 to June 2010. Median follow-up was 6.5 (5.0–9.6) years. In a subgroup of 204 (28.2%) consecutive patients, a panel of biomarkers was assessed during the first 24 h of the onset of symptoms. Multivariate analyses were performed to find out the associated factors of NDAF. Kaplan-Meier analysis was also performed to analyzed risk of SIS.

Results

NDAF was indentified in 116 (16.0%) patients: 42 (36.2%) during admission, 18 (15.5%) within first year, 29 (25%) between one and five years and 27 (23.3%) beyond 5 years. NDAF was associated with sex (female) [hazard ratio (HR) 1.61 (95% CI, 1.07- 2.41)], age [[HR 1.05 (95% CI, 1.03–1.07)], previous ischemic heart disease (IHD) [HR 1.84, (95% CI 1.15–2.97)] and cortical DWI pattern [HR 2.81 (95% CI, 1.87–4.21)]. In the Kaplan-Meier analysis, NT-proBNP ≥ 218.2 pg/ml (log-rank test P < 0.001) was associated with significant risk of NDAF during the first 5 years of follow-up. Patients with NDAF after admission and before 5 years of follow-up had the highest risk of SIS (P = 0.002).

Conclusion

The risk of NDAF after TIA is clinically relevant. We identified clinical and neuroimaging factors of NDAF. In addition, NT-proBNP was related to NDAF. Our results can be used to evaluate the benefit of long-term cardiac monitoring in selected patients.

The influence of organisational management on door-to-needle times for fibrinolytic treatment

INTRODUCTION

Door-to-needle time (DNT) has been established as the main indicator in code stroke protocols. According to the 2018 guidelines of the American Heart Association/American Stroke Association, DNT should be less than 45minuts; therefore, effective and revised pre-admission and in-hospital protocols are required.

METHOD

We analysed organisational changes made between 2011 and 2019 and their influence on DNT and the clinical progression of patients treated with fibrinolysis. We collected data from our centre, stored and monitored under the Master Plan for Cerebrovascular Disease of the regional government of Catalonia. Among other measures, we analysed the differences between years and differences derived from the implementation of the Helsinki model.

RESULTS

The study included 447 patients, and we observed significant differences in DNT between different years. Pre-hospital code stroke activation, recorded in 315 cases (70.5%), reduced DNT by a median of 14minutes. However, the linear regression model only showed an inversely proportional relationship between the adoption of the Helsinki code stroke model and DNT (beta coefficient, -0.42; P<.001). The removal of vascular neurologists after the adoption of the Helsinki model increased DNT and the 90-day mortality rate.

CONCLUSION

DNT is influenced by the organisational model. In our sample, the application of the Helsinki model, the role of the lead vascular neurologist, and notification of code stroke by pre-hospital emergency services are key factors for the reduction of DNT and the clinical improvement of the patient.

Prevalence and Predictors of Cerebral Microangiopathy Determined by Pulsatility Index in an Asymptomatic Population From the ILERVAS Project

Background: Little is known about the prevalence of cerebral microangiopathy (CM), which is related to cognitive impairment, in an asymptomatic population. Pulsatility index (PI) is an easily measurable parameter of cerebral vascular resistance in transcranial duplex of the middle cerebral artery (MCA) study. We aimed to determine the prevalence of CM measured by PI of MCA in low to moderate vascular risk subjects. Methods: We included 3,721 subjects between 45 and 70 years without previous history of vascular disease or diabetes mellitus and with at least one other vascular risk factor from the cross-sectional study ILERVAS (Lleida, Spain). Patients underwent transcranial duplex to determine MCA-PI. Possible CM was defined by MCA-PI >1.1. Carotid and femoral arteries ultrasound registration was done to determine the presence, the number, and the area of atheromatous plaques. Body mass index (BMI), pulse pressure (PP) and laboratory data were also recorded. Results: 439 (11.8%) subjects were excluded due to the low quality of transcranial duplex images. Median age was 57 [IQR 52, 62] years. Possible CM was found in 424 (12.9%) subjects. CM patients had higher prevalence of plaques than non-CM (77.4 vs. 66.4%, p < 0.001). PI showed a positive linear correlation with the number of territories with plaques (r = 0.130, p < 0.001), and the total plaque area (r = 0.082, p < 0.001). The predictors of possible CM were the age, male gender, and PP. Conclusions: In low-to-moderate vascular risk asymptomatic population, the proportion of abnormal brain microvascular bed determined by MCA-PI is not negligible. The planned 10-year follow-up will describe the clinical relevance of these findings.

A Less Frequent Etiology of Limb Shaking Syndrome: A Severe Middle Cerebral Artery Stenosis

BACKGROUND

Limb Shaking Syndrome (LSS) is usually associated with internal carotid occlusion. There are few reported-cases in context of middle cerebral artery stenosis.

METHODS

We presented LSS in a patient with middle cerebral artery stenosis disease.

RESULTS

The patient was a 62-year-old man, smoker, with high blood pressure who suffered left hemifacial and limbs myoclonus. He was initially diagnosed with focal seizures and he started antiepileptic treatment. However, he repeated the episodes. The electroencephalogram showed no abnormalities, and a vascular study with ultrasounds and angio-MRI evidenced severe middle cerebral stenosis. Finally, a diagnosis of Limb Shaking Syndrome was established and he started antiplatelet and high dose lipid-lowering treatment.

CONCLUSION

Not all abnormal movements are due to epileptic seizures. When we evaluate a patient with vascular risk factors it is important to perform a complete vascular study to discard not only critical carotid stenosis but also intracranial disease.

Sex-Related Differences in Clinical Features, Neuroimaging, and Long-Term Prognosis After Transient Ischemic Attack

Differences in sex in the incidence, presentation, and outcome of events after ischemic stroke have been studied in depth. In contrast, only limited data are available after transient ischemic attack (TIA). We aim to assess sex-related differences in the presentation, cause, neuroimaging features, and predictors of long-term prognosis in patients with TIA.

The influence of organisational management on door-to-needle times for fibrinolytic treatment

INTRODUCTION

Door-to-needle time (DNT) has been established as the main indicator in code stroke protocols. According to the 2018 guidelines of the American Heart Association/American Stroke Association, DNT should be less than 45minutes; therefore, effective and revised pre-admission and in-hospital protocols are required.

METHOD

We analysed organisational changes made between 2011 and 2019 and their influence on DNT and the clinical progression of patients treated with fibrinolysis. We collected data from our centre, stored and monitored under the Master Plan for Cerebrovascular Disease of the regional government of Catalonia. Among other measures, we analysed the differences between years and differences derived from the implementation of the Helsinki model.

RESULTS

The study included 447 patients, and we observed significant differences in DNT between different years. Pre-hospital code stroke activation, recorded in 315 cases (70.5%), reduced DNT by a median of 14minutes. However, the linear regression model only showed an inversely proportional relationship between the adoption of the Helsinki code stroke model and DNT (beta coefficient, -0.42; P<.001). The removal of vascular neurologists after the adoption of the Helsinki model increased DNT and the 90-day mortality rate.

CONCLUSION

DNT is influenced by the organisational model. In our sample, the application of the Helsinki model, the role of the lead vascular neurologist, and notification of code stroke by pre-hospital emergency services are key factors for the reduction of DNT and the clinical improvement of the patient.

REMOTE Ischemic Perconditioning Among Acute Ischemic Stroke Patients in Catalonia: REMOTE-CAT PROJECT

Rationale: Remote ischemic perconditioning during cerebral ischemia (RIPerC) refers to the application of brief episodes of transient limb ischemia commonly to a limb, it represents a new safe, simple and low-cost paradigm in neuroprotection.

Aim and/or Hypothesis: To evaluate the effects of RIPerC on acute ischemic stroke (AIS) patients, applied in the ambulance, to improve functional outcomes compared with standard of care.

Sample Size Estimates: A sample size of 286 patients in each arm achieves 80% power to detect treatment differences of 14% in the outcome, using a two-sided binomial test at significance level of 0.05, assuming that 40% of the control patients will experience good outcome and an initial misdiagnosis rate of 29%.

Methods and Design: We aim to conduct a multicentre study of pre-hospital RIPerC application in AIS patients. A total of 572 adult patients diagnosed of suspected clinical stroke within 8 h of symptom onset and clinical deficit >0 according to prehospital rapid arterial occlusion evaluation (RACE) scale score will be randomized, in blocks of size 4, to RIPerC or sham. Patients will be stratified by RACE score scale. RIPerC will be started in the ambulance before hospital admission and continued in the hospital if necessary. It will consist of five cycles of electronic tourniquet inflation and deflation (5 min each). The cuff pressure for RIPerC will be 200 mmHg during inflation. Sham will only simulate vibration of the device.

Study Outcome(s): The primary outcome will be the difference in the proportion of patients with good outcomes as defined by a mRS score of 2 or less at 90 days. Secondary outcomes to be monitored will include early neurological improvement rate, treatment related serious adverse event rates, size of the infarct volume, symptomatic intracranial hemorrhage, metabolomic and lipidomic response to RIPerC and Neuropsychological evaluation at 90 days.

Discussion: Neuroprotective therapies could not only increase the benefits of available reperfusion therapies among AIS patients but also provide an option for patients who are not candidates for these treatments. REMOTE-CAT will investigate the clinical benefit of RIC as a new neuroprotective strategy in AIS.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT03375762.

Parálisis idiopática del nervio hipogloso. Descripción de un caso

Introducción: La parálisis del nervio hipogloso es una mononeuropatía poco fre-cuente. Las etiologías más habituales son la tumoral, la traumática, la isquémica cere-bral y la iatrogénica, Descripción: Presentamos el caso de un paciente con neuropa-tía idiopática del nervio hipogloso, en el que por edad, la presencia de factores de riesgo vascular, la microangiopaía cerebral y la evolución nos lleva a discutir acerca de la posibilidad de que se trate de una mononeuropatía isquémica o diabética como etiología del déficit. Discusión: En estudios publicados de parálisis idiopáticas del nervio hipogloso la edad de presentación se sitúa entre los 20 y 45 años y tienen una evolución y recuperación favorable, atribuyéndole un mecanismo fisiopatológico similar al de la paralisis de Bell. En nuestro caso la exploración física y las pruebas complementarias realizadas no mostraron etiología del déficit, encontrándonos ante un nuevo caso de parálisis idiopática del nervio hipogloso. Sin embargo por la edad del paciente, la presencia de múltiples factores de riesgo vascular, la microangiopía cerebral y la persistencia de la sintomatología nos hace plantear la existencia de un mecanismo local, isquémico o diabético, como causa de la mononeuropatía presen-tada y pensar que nos podemos encontrar ante un mecanismo fisiopatológico similar al producido en otras mononeuropatías, como la del III o VI par craneal. Conclusión: Presentamos una parálisis del nervio hipogloso idiopática, que por las característi-cas de nuestro paciente nos hace pensar y discuti una posible etiología isquémica o diabética del déficit.

Etiología de la parálisis del nervio hipogloso. Revisión sistemática

Introducción y objetivo: La parálisis del nervio hipogloso es una entidad poco frecuente, caracterizada por alteración del habla y problemas para tragar. En este estudio realizamos una revisión de las etiologías de dicho déficit.Método: Realizamos una búsqueda en pubmed, seleccionando aquellos artículos en los cuales se mencione la etiología de la parálisis del nervio hipogloso. Resultados: Dos son los estudios con gran número de pacientes. En primero de ellos, publicado en 1996 con 100 pacientes, la etiología más frecuente es la tumoral, seguida de los traumatismos y las lesiones isquémicas. En el segundo de ellos, del 2016, con 245 pacientes incluidos, la etiología principal es la iatrogénica postoperatoria, seguida de la tumoral y la idiopática.Discusión: Son pocos los estudios que recogen un número importante de pacientes con parálisis del nervio hipogloso. Los primeros datan de la década de los 90, en los cuales la principal etiología era la tumoral. En el último estudio, publicado en 2016, la primera causa es la iatrogénica postquirúrgica, seguida de la neoplásica y la idiopática. Con 20 años de diferencia entre los dos principales estudios existe un cambio en la etiología. El aumento de los casos postquirúrgicos puede ser debido a un aumento en el número de intervenciones, siendo a su vez más largas y agresivas, resultando llamativo, y de difícil explicación, el creciente número de casos etiquetados como idiopáticos.Conclusiones: La etiología de la parálisis del nervio hipogloso ha cambiado a lo largo de las décadas. En el siglo XX la principal etiología era la tumoral. En el siglo XXI la etiología principal es la iatrogénica postquirúrgica, encontrándose en segundo lugar la tumoral y en tercero la idiopática. Con la inclusión de 345 pacientes de los dos grandes artículos en la revisión sistemática podemos concluir que la primera causa de parálisis es la tumoral, seguida de la iatrogénica y la idiopática.

Induced neuroprotection by remote ischemic perconditioning as a new paradigm in ischemic stroke at the acute phase, a systematic review

BACKGROUND

Remote ischemic conditioning during cerebral ischemia (remote ischemic perconditioning, RIPerC) refers to the application of several cycles of brief ischemia and reperfusion (I/R) commonly to a limb, and it represents a new paradigm in neuroprotection with multiple mechanisms of action in ischemic stroke (IS) patients during acute phase. Some clinical trials just finished, and a few others are still ongoing; gather the current knowledge and pull it down to influence the present and future studies was the goal of this paper.

METHODS

A systematic review of published research papers and/or registered clinical trials since 2000 was performed.

RESULTS

Nineteen studies were identified and only four studies were completed. All of them have demonstrated that RIPerC is safe, feasible and well tolerated in IS patients. However, a high heterogeneity of clinical trial characteristics was observed: five (26.3%) randomized clinical trials (RCTs) included only thrombolytic-treated patients, three (15.8%) RCTs only thrombectomy-treated patients, and five (26.3%) RCTs required radiological confirmation of IS. Temporal inclusion criteria vary from 4 h to 48 h. Most of the clinical trials used 4 cycles of RIPerC in the upper non-affected limb. Interestingly, only three (16.7%) RCTs applied RIPerC during the transportation in the ambulance. Neuroimaging outputs were the main endpoints when endovascular therapy was applied; functional outcome is also the main endpoint in large-medium size studies.

CONCLUSIONS

This review summarizes the completed and ongoing clinical trials on RIPerC in IS patients, where RIPerC has been used alone or in combination with recanalization therapies. Ongoing clinical trials will provide new information on the best RIPerC intervention strategy and potentially improve the functional outcome of IS patients; definition of new RIPerC strategies would ideally aim at enhancing tissue preservation, promoting neurological recovery, and stratify patients to improve treatment feasibility.

WEBINO syndrome (wall-eyed bilateral internuclear ophthalmoplegia) secondary to ischemic stroke, about a case

WEBINO (wall-eyed bilateral internuclear ophthalmoplegia) syndrome is characterized by bilateral adduction impairment, nystagmus of the abducting eye, and primary gaze exotropia. We present the case of a 68 year-old man who was initially attended in emergency department with sudden onset diplopia. Neurological exploration revealed WEBINO and gait ataxia. Relevant medical history included liver transplantation and subsequent tacrolimus prescription. Complementary exams revealed ischemic lesion in mesencephalic tegmentum, involving medial longitudinal fasciculus and pretectal area. WEBINO syndrome is unfrequent. Among its etiologies, ischemic and demyelinating are the most frequent. In our case, iatrogenic etiology was also considered. Clinical recognition of this syndrome is required to perform adequate exams in order to reach diagnosis.

Abstract WP101: Remote Ischemic Perconditioning Among Acute Ischemic Stroke Patients in Catalonia: Remote-Cat Project

Rationale: Remote ischemic perconditioning (RIPerC), consisting of brief episodes of transient limb ischemia, represents a new paradigm in neuroprotection with interesting results in ischemic heart disease patients.

Aim: We aim to conduct a multicentre study of pre-hospital RIPerC application in acute ischemic stroke (AIS) patients.Sample size estimates: To detect a treatment difference of 14% in the outcome, 286 patients will be included for 5% significance and 80% power.

Methods: A total of 572 adult patients diagnosed of suspected clinical stroke within 8 hours of symptom onset and clinical deficit >0 according to prehospital RACE scale will be randomized, in blocks of size 4, to RIC or sham. Patients will be stratified by RACE score scale. RIC will be started in the ambulance before hospital admission. RIPerC will consist of five cycles of electronic tourniquet inflation and deflation (5 min each). Study outcomes: The primary outcome will be the difference in clinical benefit measured by the modified Rankin Scale (mRS) score <3 at 90 days. Secondary outcomes to be monitored will include early neurological improvement rate, treatment related serious adverse event rates, size of the infarct volume, symptomatic intracranial hemorrhage, and metabolomic and lipidomic response to RIPerC.

Discussion: Neuroprotective therapies could not only increase the benefits of available reperfusion therapies among AIS patients but also provide an option for patients who are not candidates for these treatments. REMOTE-CAT will investigate the clinical benefit of RIC as a new neuroprotective strategy in AIS. Clinicaltrials.gov number: NCT03375762. Status: Active

Variably protease-sensitive prionopathy presenting within ALS/FTD spectrum

We report clinico‐pathological features of a 65‐year‐old woman and a 56‐year‐old man with a 5‐year clinical history who had clinical and neuropathological characteristics of upper and lower motor neuron disease consistent with amyotrophic lateral sclerosis, and a frontotemporal atrophy pattern in case 2 without TDP‐43 pathology. Instead, spongiform change and pathological prion protein deposits were observed in several brain regions. No prion protein gene mutations were found. Western blot analysis showed a five‐band profile compatible with variably protease‐sensitive prionopathy. We conclude that this disease can display prolonged disease duration and clinico‐pathological features within the ALS/FTLD spectrum.

Improved Chondrogenic Capacity of Collagen Hydrogel-Expanded Chondrocytes: In Vitro and in Vivo Analyses

BACKGROUND

The use of autologous chondrocytes in cartilage repair is limited because of loss of the cartilage phenotype during expansion. The mechanosensing capacity of chondrocytes suggests evaluating the use of soft substrates for in vitro expansion. Our aim was to test the expansion of chondrocytes on collagen hydrogels to improve their capacity for chondrogenesis after a number of passages.

METHODS

Rat cartilage cells were expanded on collagen hydrogels and on plastic, and the preservation of their chondrogenic capacity was tested both in vitro and in vivo. The expression of relevant markers during expansion on each surface was measured by real-time PCR (polymerase chain reaction). Expanded cells were then implanted in focal lesions in the medial femoral condyle of healthy sheep, and the newly formed tissue was analyzed by histomorphometry.

RESULTS

Compared with cells cultured on plastic, cells cultured on hydrogels had better maintenance of the expression of the Sox9, Col2 (type-II collagen), FGFR3, and Alk-5 genes and decreased expression of Alk-1 and BMP-2. Pellets also showed increased expression of the cartilage marker genes aggrecan, Sox9, and Col2, and decreased expression of Col1 and Col10 (type-I and type-X collagen). ELISA (enzyme-linked immunosorbent assay) also showed a higher ratio of type-II to type-I collagen in pellets formed from cells expanded on hydrogels. When sheep chondrocytes were expanded and implanted in cartilage lesions in the femoral condyle of healthy sheep, hydrogel-expanded cells produced histologically better tissue compared with plastic-expanded cells.

CONCLUSIONS

The expansion of chondrocytes on collagen hydrogels yielded cells with an improved chondrogenic capacity compared with cells expanded on plastic.

CLINICAL RELEVANCE

The study results favor the use of hydrogel-expanded cells over the traditional plastic-expanded cells for autologous chondrocyte implantation.

Response of sheep chondrocytes to changes in substrate stiffness from 2 to 20 Pa: effect of cell passaging

AIM

The influence of culture substrate stiffness (in the kPa range) on chondrocyte behavior has been described. Here we describe the response to variations in substrate stiffness in a soft range (2-20 Pa), as it may play a role in understanding cartilage physiopathology.

METHODS

We developed a system for cell culture in substrates with different elastic moduli using collagen hydrogels and evaluated chondrocytes after 2, 4, and 7 days in monolayer and three-dimensional (3D) cultures. Experiments were performed in normoxia and hypoxia in order to describe the effect of a low oxygen environment on chondrocytes. Finally, we also evaluated if dedifferentiated cells preserve the capacity for mechanosensing.

RESULTS

Chondrocytes showed less proliferating activity when cultured in monolayer in the more compliant substrates. Expression of the cartilage markers Aggrecan (Acan), type II collagen (Col2a1), and Sox9 was upregulated in the less stiff gels (both in monolayer and in 3D culture). Stiffer gels induced an organization of the actin cytoskeleton that correlated with the loss of a chondrocyte phenotype. When cells were cultured in hypoxia, we observed changes in the cellular response that were mediated by HIF-1α. Results in 3D hypoxia cultures were opposite to those found in normoxia, but remained unchanged in monolayer hypoxic experiments. Similar results were found for dedifferentiated cells.

CONCLUSIONS

Chondrocytes respond differently according to the stiffness of the substrate. This response depends greatly on the oxygen environment and on whether the chondrocyte is embedded or grown onto the hydrogel, since mechanosensing capacity was not lost with cell expansion.

Identification of signalling pathways triggered by changes in the mechanical environment in rat chondrocytes

AIM

The aim of this work was to determine the pathways implicated in the mechanosensing of chondrocytes.

METHODS

Rat chondrocytes were cultured in collagen hydrogels of different stiffness (2-20 Pa) in normoxia and hypoxia, in monolayer and embedded inside hydrogels. First, chondrocyte were cultured on hydrogels in the presence of antibodies to block integrins. Second, custom RT-PCR array plates and western blot were used to detect changes in expression of genes implicated in downstream signalling pathways.

RESULTS

The results allowed us to demonstrate the mechanosensing of chondrocytes for changes in stiffness in the range of Pascals. We also identified Non-Muscle Myosin II (NMMII) and integrins α1, β1 and β3 as participants in the mechanosensing, since their blockade inhibits the sensing of the stiffness, and they are up-regulated in the process. RT-PCR arrays and western blot detected up-regulation of Paxillin, RhoA, Fos, Jun and Sox9. We detected no expression of Src in the monolayer cultures, but we found a role for this protein in 3D. The expression of HIF-1α was not modified under normoxia but was found to participate under hypoxia. Focal Adhesion Kinase (FAK), showed a direct relationship with the expression of Aggrecan in hypoxia and an inverse one in normoxia. Finally, immunofluorescence analysis located the expression of factors AP-1, Sox-9 and HIF-1α inside the cell nuclei and RhoA, Src, Paxillin and FAK close to the cytoplasmic membrane.

CONCLUSIONS

We determined here some of the genes that are up-regulated during the process of chondrocyte mechanosensing.