Spontaneous reperfusion enhances succinate concentration in peripheral blood from stemi patients but its levels does not correlate with myocardial infarct size or area at risk

Cardiovascular biology; Diagnostic markers; Prognostic markersBiología cardiovascular; Marcadores de diagnóstico; Marcadores pronósticosBiologia cardiovascular; Marcadors diagnòstics; Marcadors pronòsticsSuccinate is enhanced during initial reperfusion in blood from the coronary sinus in ST-segment elevation myocardial infarction (STEMI) patients and in pigs submitted to transient coronary occlusion. Succinate levels might have a prognostic value, as they may correlate with edema volume or myocardial infarct size. However, blood from the coronary sinus is not routinely obtained in the CathLab. As succinate might be also increased in peripheral blood, we aimed to investigate whether peripheral plasma concentrations of succinate and other metabolites obtained during coronary revascularization correlate with edema volume or infarct size in STEMI patients. Plasma samples were obtained from peripheral blood within the first 10 min of revascularization in 102 STEMI patients included in the COMBAT-MI trial (initial TIMI 1) and from 9 additional patients with restituted coronary blood flow (TIMI 2). Metabolite concentrations were analyzed by 1H-NMR. Succinate concentration averaged 0.069 ± 0.0073 mmol/L in patients with TIMI flow ≤ 1 and was significantly increased in those with TIMI 2 at admission (0.141 ± 0.058 mmol/L, p < 0.05). However, regression analysis did not detect any significant correlation between most metabolite concentrations and infarct size, extent of edema or other cardiac magnetic resonance (CMR) variables. In conclusion, spontaneous reperfusion in TIMI 2 patients associates with enhanced succinate levels in peripheral blood, suggesting that succinate release increases overtime following reperfusion. However, early plasma levels of succinate and other metabolites obtained from peripheral blood does not correlate with the degree of irreversible injury or area at risk in STEMI patients, and cannot be considered as predictors of CMR variables. Trial registration: Registered at www.clinicaltrials.gov (NCT02404376) on 31/03/2015. EudraCT number: 2015-001000-58.This work was supported by the Spanish Ministry of Economy and Competitiveness, Instituto de Salud Carlos III (Grants PI17/01397 and CIBERCV) and the Spanish Society of Cardiology (Proyectos de la FEC para Investigación Básica en Cardiología 2018, Sociedad Española de Cardiología), and was cofinanced by the European Regional Development Fund (ERDF-FEDER, a way to build Europe). Antonio Rodríguez-Sinovas has a consolidated Miguel Servet contract

Biocompatibility and functionality of graphene-based neural interfaces

Les neuropròtesis tenen com a objectiu restaurar les pèrdues funcionals després d'una amputació o de lesions neurals greus. Dins d'una neuropròtesi perifèrica, la interfície entre el nervi i la màquina està destinada a enregistrar senyals neurals i estimular poblacions de fibres nervioses, constituint una interfície bidireccional amb alta selectivitat i eficiència. No obstant això, encara són necessàries millores addicionals en la funcionalitat per aconseguir capacitats semblants a les fisiològiques per interactuar elèctricament amb el teixit nerviós. En aquesta tesi s'aborden dos problemes principals que actualment desafien el potencial ús de les neuropròtesis. En primer lloc, la capacitat de la interfície per interactuar amb el teixit nerviós depèn de les seves capacitats elèctriques. Són necessaris materials conductors amb propietats millorades, que incloguin una baixa impedància i una alta capacitat d'injecció de càrrega, per augmentar la selectivitat i durabilitat de la interfície. En segon lloc, després de la implantació de qualsevol dispositiu estrany en el cos, s'inicien una sèrie de processos immunològics coneguts col·lectivament com a reacció de cos estrany (FBR, per les seves sigles en anglès). Aquest procés té com a objectiu destruir o aïllar l'implant de la resta de l'organisme. En conseqüència, la funcionalitat d'un dispositiu dissenyat per interactuar amb els teixits on ha estat implantat es veu compromesa. Per millorar la funcionalitat, s'ha estudiat una nova generació d'interfícies neuronals que reemplaça els elèctrodes metàl·lics amb grafè dissenyat. Aquest nou dispositiu està basat en òxid de grafè reduït i modificat, anomenat EGNITE (Engineered Graphene for Neural Interface). La biocompatibilitat d'EGNITE es va validar in vitro i in vivo. La viabilitat cel·lular en cultiu no es va veure afectada per la presència d'EGNITE. Les proves funcionals i histològiques d'animals implantats amb els dispositius intraneurals que contenien EGNITE van mostrar resultats semblants a altres interfícies intraneurals, sense evidències de dany nerviós o degeneració axonal. Pel que fa a la funcionalitat, els centres actius d'EGNITE en els dispositius van ser capaços d'estimular i registrar selectivament diferents subconjunts d'axons en el nervi ciàtic de les rates. El llindar per a l'activació neuromuscular va ser menor en comparació amb els elèctrodes metàl·lics de mida més gran utilitzats en estudis anteriors. El registre de senyals sensorials amb bona discriminació va ser possible gràcies a la baixa relació senyal-soroll dels elèctrodes d'EGNITE. Per augmentar l'estabilitat crònica de les interfícies neuronals, es va estudiar la metformina com a nou tractament per modular la FBR en implants intraneurals. La metformina va reduir la formació de la càpsula al voltant de la interfície. A més, la combinació de dexametasona i metformina va demostrar ser la teràpia més òptima per reduir tant la reacció inflamatòria primerenca com la reacció fibròtica tardana. En resum, el material basat en grafè EGNITE és adequat per a la integració amb una neuropròtesi, millorant la funcionalitat en comparació amb els elèctrodes metàl·lics. A més, s'ha demostrat que la metformina va disminuir la FBR. També s'ha destacat que les teràpies combinades, que actuen en diferents fases de la FBR, poden ser l'estratègia més òptima per millorar l'estabilitat crònica i la funcionalitat de les interfícies neurals.Las neuroprótesis tienen como objetivo restaurar las funciones perdidas después de una amputación o tras lesiones neurales graves. Dentro de una neuroprótesis periférica, la interfaz entre el nervio y la máquina está destinada a registrar señales neurales y estimular poblaciones de fibras nerviosas, constituyendo una interfaz bidireccional con alta selectividad y eficiencia. Sin embargo, todavía se necesitan mejoras adicionales en la funcionalidad para alcanzar capacidades similares a las naturales para interactuar eléctricamente con el tejido nervioso. En esta tesis se abordan dos problemas principales que actualmente desafían el potencial uso de las neuroprótesis. En primer lugar, la capacidad de la interfaz para interactuar con el tejido nervioso depende de sus capacidades eléctricas. Se requieren materiales conductores con propiedades mejoradas, que incluyan una baja impedancia y una alta capacidad de inyección de carga, para aumentar la selectividad y durabilidad de la interfaz. En segundo lugar, después de la implantación de cualquier dispositivo extraño en el cuerpo, se inician una serie de procesos inmunológicos conocidos colectivamente como reacción de cuerpo extraño (FBR). Este proceso tiene como objetivo destruir o aislar el implante del resto del organismo. En consecuencia, la funcionalidad de un dispositivo diseñado para interactuar con los tejidos en los que ha sido implantado se ve comprometida. Para mejorar la funcionalidad, se ha estudiado una nueva generación de interfaces neurales que reemplaza los electrodos metálicos con grafeno diseñado. Este nuevo dispositivo está basado en óxido de grafeno reducido y modificado, llamado EGNITE (Engineered Graphene for Neural Interface). La biocompatibilidad de EGNITE fue validada in vitro e in vivo. La viabilidad celular en cultivo no se vio afectada por la presencia de EGNITE. Las pruebas funcionales e histológicas de animales implantados con dispositivos intraneurales que contenían EGNITE mostraron resultados similares a otras interfaces intraneurales, sin evidencia de daño nervioso o degeneración axonal. En cuanto a la funcionalidad, los centros activos de EGNITE en los dispoitivos fueron capaces de estimular y registrar selectivamente diferentes subconjuntos de axones en el nervio ciático de las ratas. El umbral para la activación neuromuscular fue menor en comparación con electrodos metálicos de mayor tamaño utilizados en estudios anteriores. El registro de señales sensoriales con buena discriminación fue posible debido a la baja relación señal-ruido de los electrodos de EGNITE. Para aumentar la estabilidad crónica de las interfaces neurales, se estudió la metformina como un nuevo tratamiento para modular la FBR a implantes intraneurales. La metformina redujo la formación de la cápsula alrededor de la interfaz. Además, la combinación de dexametasona y metformina demostró ser la terapia más óptima para reducir tanto la reacción inflamatoria temprana como la reacción fibrosa tardía. En resumen, el material basado en grafeno EGNITE es adecuado para la integración con una neuroprótesis, mejorando la funcionalidad en comparación con los electrodos metálicos. Además, se ha demostrado que la metformina disminuyó la FBR. También se ha enfatizado que las terapias combinadas, que actúan en diferentes fases de la FBR, pueden ser la estrategia más óptima para mejorar la estabilidad crónica y la funcionalidad de las interfaces neurales.Neuroprostheses aim to restore the lost functions after limb amputation or severe neural injuries. Within a peripheral neuroprosthesis, the interface between nerve and machine is intended to record neural signals and stimulate populations of nerve fibers, constituting a bidirectional interface with high selectivity and efficiency. However, further improvements in functionality are still needed to reach natural-like capabilities to electrically interact with the nervous tissue. In this thesis, two main issues that currently challenge the potential use of neuroprostheses are addressed. Firstly, the ability of the interface to interact with the nervous tissue depends on its electrical capabilities. Conductive materials with enhanced properties, including low impedance and high charge injection capacity are required, for increasing selectivity and durability of the interface. Secondly, after the implantation of any foreign device into the body, a series of immune processes known collectively as the foreign body reaction (FBR) are initiated. This process aims to destroy or isolate the implant from the rest of the organism. Consequently, the functionality of a device designed to interact with the tissues in which it has been implanted is compromised. To improve functionality, a new generation of neural interfaces that replaces metal electrodes with engineered graphene has been tested. This new device is based on modified reduced-graphene oxide, named EGNITE (Engineered Graphene for Neural Interface). The biocompatibility of EGNITE was validated in vitro and in vivo. Cellular viability in culture was not affected by the presence of EGNITE. Functional and histological tests of animals implanted with intraneural devices containing EGNITE showed similar outcomes to other intraneural interfaces, without evidence of nerve damage or axonal degeneration. Regarding functionality, electrodes made of EGNITE in the conductive contacts were able to selectively stimulate and record different subsets of axons in the sciatic nerve of rats. The threshold for neuromuscular activation was lower than with larger-sized metal electrodes used in previous studies. Recording of sensory signals with good discrimination was possible due to the low signal-to-noise ratio (SNR) of the EGNITE electrodes. To increase the chronic stability of neural interfaces, metformin was studied as a novel treatment to modulate the FBR to intraneural implants. Metformin reduced the capsule formation around the interface. Additionally, the combination of dexamethasone and metformin proved to be the most optimal therapy to reduce both early inflammatory reaction and late fibrotic reaction. In summary, the graphene-based material (GBM) EGNITE is suitable for integration with a neuroprosthesis, improving functionality compared to metallic electrodes. Furthermore, it has been demonstrated that metformin decreased the FBR. It has also been emphasized that combined therapies targeting different phases of the FBR may be the most optimal strategy for improving the chronic stability and functionality of neural interfaces

Un innovador dispositiu low-cost per a les lesions greus del sistema nerviós perifèric

Recuperar la funcionalitat motora i la sensibilitat d'un membre després de sofrir una lesió greu requereix la implantació d'una pròtesi o conducte nerviós, i d'un dispositiu electrònic (interfície nerviosa perifèrica) que connecti el nervi amb el múscul. Investigadors de l'Institut de Neurociències de la UAB, en col·laboració amb l'Escola Superior de Sant'Anna (Pisa), han desenvolupat un innovador dispositiu (Regenerative Cuff Electrode, RnCE) que integra les dues funcionalitats i que, en models animals ha mostrat bons resultats. El mètode de fabricació permet modificar fàcilment el disseny del dispositiu ajustant-lo a diferents situacions. A més, els costos i el temps de manufacturació són reduïts.Recuperar la funcionalidad motora y la sensibilidad de un miembro tras sufrir una lesión grave requiere la implantación de una prótesis o conducto nervioso, y de un dispositivo electrónico (interfaz nerviosa periférica) que conecte el nervio con el músculo. Investigadores del Instituto de Neurociencias de la UAB, en colaboración con la Escuela Superior de Sant'Anna (Pisa), han desarrollado un innovador dispositivo (Regenerative Cuff Electrode, RnCE) que integra las dos funcionalidades y que, en modelos animales ha mostrado buenos resultados. El método de fabricación permite modificar fácilmente el diseño del dispositivo ajustándolo a diferentes situaciones. Además, los costes y el tiempo de manufacturación son reducidos.Recovering the motor functionality and sensation of a limb after suffering a serious injury requires the implantation of a prosthesis or nerve conduit, and of an electronic device (peripheral nerve interface) that connects the nerve to the muscle. Researchers from the UAB Institute of Neurosciences, in collaboration with the Sant'Anna School in Pisa, Italy, have developed an innovative device (Regenerative Cuff Electrode, RnCE) that integrates both functionalities and that has shown good results in animal models. The manufacturing method allows the design of the device to be easily modified by adjusting it to different situations. In addition, manufacturing costs and time are reduce

Assessment of focused ultrasound stimulation to induce peripheral nerve activity and potential damage in vivo

IntroductionPeripheral neuroprostheses are aimed to restore loss of sensory and motor functions by interfacing axons in the peripheral nerves. Most common interfaces in neuroprostheses are electrodes that establish electrical connection with peripheral axons. However, some challenges arise related to long-term functionality, durability, and body response. Recently, focused ultrasound stimulation (FUS) has emerged as a non-invasive approach to modulate the nervous system. However, it is controversial whether FUS can induce axon depolarization.MethodsWe have assessed FUS applied in vivo to the rat peripheral nerve, with two objectives: first, to test whether FUS activates peripheral nerves under different stimulation conditions, and second, to evaluate if FUS inflicts damage to the nerve. FUS was delivered with three ultrasound transducers (Sonic Concept H115, H107, and H102) covering the largest set of parameters examined for FUS of peripheral nerves so far.ResultsWe did not obtain reliable evoked action potentials in either nerves or muscles, under any FUS condition applied, neither over the skin nor directly to the nerve exposed. Additional experiments ex vivo and in vivo on mice, confirmed this conclusion. When FUS stimulation was applied directly to the exposed sciatic nerve, neuromuscular function decreased significantly, and recovered one week later, except for FUS at 0.25 MHz. Histologically, degenerating nerve fibers were observed, with a tendency to be higher with the lower FUS frequency.DiscussionPast reports on the ability of ultrasound to stimulate the peripheral nerve are controversial. After testing a wide range of FUS conditions, we conclude that it is not a reliable and safe method for stimulating the peripheral nerve. Special consideration should be taken, especially when low-frequency FUS is applied, as it may lead to nerve damage

Image_1_Assessment of focused ultrasound stimulation to induce peripheral nerve activity and potential damage in vivo.PNG

IntroductionPeripheral neuroprostheses are aimed to restore loss of sensory and motor functions by interfacing axons in the peripheral nerves. Most common interfaces in neuroprostheses are electrodes that establish electrical connection with peripheral axons. However, some challenges arise related to long-term functionality, durability, and body response. Recently, focused ultrasound stimulation (FUS) has emerged as a non-invasive approach to modulate the nervous system. However, it is controversial whether FUS can induce axon depolarization.MethodsWe have assessed FUS applied in vivo to the rat peripheral nerve, with two objectives: first, to test whether FUS activates peripheral nerves under different stimulation conditions, and second, to evaluate if FUS inflicts damage to the nerve. FUS was delivered with three ultrasound transducers (Sonic Concept H115, H107, and H102) covering the largest set of parameters examined for FUS of peripheral nerves so far.ResultsWe did not obtain reliable evoked action potentials in either nerves or muscles, under any FUS condition applied, neither over the skin nor directly to the nerve exposed. Additional experiments ex vivo and in vivo on mice, confirmed this conclusion. When FUS stimulation was applied directly to the exposed sciatic nerve, neuromuscular function decreased significantly, and recovered one week later, except for FUS at 0.25 MHz. Histologically, degenerating nerve fibers were observed, with a tendency to be higher with the lower FUS frequency.DiscussionPast reports on the ability of ultrasound to stimulate the peripheral nerve are controversial. After testing a wide range of FUS conditions, we conclude that it is not a reliable and safe method for stimulating the peripheral nerve. Special consideration should be taken, especially when low-frequency FUS is applied, as it may lead to nerve damage.</p

Image_2_Assessment of focused ultrasound stimulation to induce peripheral nerve activity and potential damage in vivo.TIF

IntroductionPeripheral neuroprostheses are aimed to restore loss of sensory and motor functions by interfacing axons in the peripheral nerves. Most common interfaces in neuroprostheses are electrodes that establish electrical connection with peripheral axons. However, some challenges arise related to long-term functionality, durability, and body response. Recently, focused ultrasound stimulation (FUS) has emerged as a non-invasive approach to modulate the nervous system. However, it is controversial whether FUS can induce axon depolarization.MethodsWe have assessed FUS applied in vivo to the rat peripheral nerve, with two objectives: first, to test whether FUS activates peripheral nerves under different stimulation conditions, and second, to evaluate if FUS inflicts damage to the nerve. FUS was delivered with three ultrasound transducers (Sonic Concept H115, H107, and H102) covering the largest set of parameters examined for FUS of peripheral nerves so far.ResultsWe did not obtain reliable evoked action potentials in either nerves or muscles, under any FUS condition applied, neither over the skin nor directly to the nerve exposed. Additional experiments ex vivo and in vivo on mice, confirmed this conclusion. When FUS stimulation was applied directly to the exposed sciatic nerve, neuromuscular function decreased significantly, and recovered one week later, except for FUS at 0.25 MHz. Histologically, degenerating nerve fibers were observed, with a tendency to be higher with the lower FUS frequency.DiscussionPast reports on the ability of ultrasound to stimulate the peripheral nerve are controversial. After testing a wide range of FUS conditions, we conclude that it is not a reliable and safe method for stimulating the peripheral nerve. Special consideration should be taken, especially when low-frequency FUS is applied, as it may lead to nerve damage.</p

Image_4_Assessment of focused ultrasound stimulation to induce peripheral nerve activity and potential damage in vivo.TIF

IntroductionPeripheral neuroprostheses are aimed to restore loss of sensory and motor functions by interfacing axons in the peripheral nerves. Most common interfaces in neuroprostheses are electrodes that establish electrical connection with peripheral axons. However, some challenges arise related to long-term functionality, durability, and body response. Recently, focused ultrasound stimulation (FUS) has emerged as a non-invasive approach to modulate the nervous system. However, it is controversial whether FUS can induce axon depolarization.MethodsWe have assessed FUS applied in vivo to the rat peripheral nerve, with two objectives: first, to test whether FUS activates peripheral nerves under different stimulation conditions, and second, to evaluate if FUS inflicts damage to the nerve. FUS was delivered with three ultrasound transducers (Sonic Concept H115, H107, and H102) covering the largest set of parameters examined for FUS of peripheral nerves so far.ResultsWe did not obtain reliable evoked action potentials in either nerves or muscles, under any FUS condition applied, neither over the skin nor directly to the nerve exposed. Additional experiments ex vivo and in vivo on mice, confirmed this conclusion. When FUS stimulation was applied directly to the exposed sciatic nerve, neuromuscular function decreased significantly, and recovered one week later, except for FUS at 0.25 MHz. Histologically, degenerating nerve fibers were observed, with a tendency to be higher with the lower FUS frequency.DiscussionPast reports on the ability of ultrasound to stimulate the peripheral nerve are controversial. After testing a wide range of FUS conditions, we conclude that it is not a reliable and safe method for stimulating the peripheral nerve. Special consideration should be taken, especially when low-frequency FUS is applied, as it may lead to nerve damage.</p

Table_1_Assessment of focused ultrasound stimulation to induce peripheral nerve activity and potential damage in vivo.docx

IntroductionPeripheral neuroprostheses are aimed to restore loss of sensory and motor functions by interfacing axons in the peripheral nerves. Most common interfaces in neuroprostheses are electrodes that establish electrical connection with peripheral axons. However, some challenges arise related to long-term functionality, durability, and body response. Recently, focused ultrasound stimulation (FUS) has emerged as a non-invasive approach to modulate the nervous system. However, it is controversial whether FUS can induce axon depolarization.MethodsWe have assessed FUS applied in vivo to the rat peripheral nerve, with two objectives: first, to test whether FUS activates peripheral nerves under different stimulation conditions, and second, to evaluate if FUS inflicts damage to the nerve. FUS was delivered with three ultrasound transducers (Sonic Concept H115, H107, and H102) covering the largest set of parameters examined for FUS of peripheral nerves so far.ResultsWe did not obtain reliable evoked action potentials in either nerves or muscles, under any FUS condition applied, neither over the skin nor directly to the nerve exposed. Additional experiments ex vivo and in vivo on mice, confirmed this conclusion. When FUS stimulation was applied directly to the exposed sciatic nerve, neuromuscular function decreased significantly, and recovered one week later, except for FUS at 0.25 MHz. Histologically, degenerating nerve fibers were observed, with a tendency to be higher with the lower FUS frequency.DiscussionPast reports on the ability of ultrasound to stimulate the peripheral nerve are controversial. After testing a wide range of FUS conditions, we conclude that it is not a reliable and safe method for stimulating the peripheral nerve. Special consideration should be taken, especially when low-frequency FUS is applied, as it may lead to nerve damage.</p

Image_3_Assessment of focused ultrasound stimulation to induce peripheral nerve activity and potential damage in vivo.TIF

IntroductionPeripheral neuroprostheses are aimed to restore loss of sensory and motor functions by interfacing axons in the peripheral nerves. Most common interfaces in neuroprostheses are electrodes that establish electrical connection with peripheral axons. However, some challenges arise related to long-term functionality, durability, and body response. Recently, focused ultrasound stimulation (FUS) has emerged as a non-invasive approach to modulate the nervous system. However, it is controversial whether FUS can induce axon depolarization.MethodsWe have assessed FUS applied in vivo to the rat peripheral nerve, with two objectives: first, to test whether FUS activates peripheral nerves under different stimulation conditions, and second, to evaluate if FUS inflicts damage to the nerve. FUS was delivered with three ultrasound transducers (Sonic Concept H115, H107, and H102) covering the largest set of parameters examined for FUS of peripheral nerves so far.ResultsWe did not obtain reliable evoked action potentials in either nerves or muscles, under any FUS condition applied, neither over the skin nor directly to the nerve exposed. Additional experiments ex vivo and in vivo on mice, confirmed this conclusion. When FUS stimulation was applied directly to the exposed sciatic nerve, neuromuscular function decreased significantly, and recovered one week later, except for FUS at 0.25 MHz. Histologically, degenerating nerve fibers were observed, with a tendency to be higher with the lower FUS frequency.DiscussionPast reports on the ability of ultrasound to stimulate the peripheral nerve are controversial. After testing a wide range of FUS conditions, we conclude that it is not a reliable and safe method for stimulating the peripheral nerve. Special consideration should be taken, especially when low-frequency FUS is applied, as it may lead to nerve damage.</p

Nanoporous graphene-based thin-film microelectrodes for in vivo high-resolution neural recording and stimulation

One of the critical factors determining the performance of neural interfaces is the electrode material used to establish electrical communication with the neural tissue, which needs to meet strict electrical, electrochemical, mechanical, biological and microfabrication compatibility requirements. This work presents a nanoporous graphene-based thin-film technology and its engineering to form flexible neural interfaces. The developed technology allows the fabrication of small microelectrodes (25 µm diameter) while achieving low impedance (∼25 kΩ) and high charge injection (3–5 mC cm−2). In vivo brain recording performance assessed in rodents reveals high-fidelity recordings (signal-to-noise ratio &gt;10 dB for local field potentials), while stimulation performance assessed with an intrafascicular implant demonstrates low current thresholds (&lt;100 µA) and high selectivity (&gt;0.8) for activating subsets of axons within the rat sciatic nerve innervating tibialis anterior and plantar interosseous muscles. Furthermore, the tissue biocompatibility of the devices was validated by chronic epicortical (12 week) and intraneural (8 week) implantation. This work describes a graphene-based thin-film microelectrode technology and demonstrates its potential for high-precision and high-resolution neural interfacing