Techniques for Processing Eyes Implanted with a Retinal Prosthesis for Localized Histopathological Analysis: Part 2 Epiretinal Implants with Retinal Tacks

Retinal prostheses for the treatment of certain forms of blindness are gaining traction in clinical trials around the world with commercial devices ...

Bionics Institute

The University of Melbourne

The function of the ventral nucleus of the lateral lemniscus (VNLL), a secondary processing site within the auditory brain stem, is unclear. It is known to be a major source of inhibition to the inferior colliculus (IC). It is also thought to play a role in coding the temporal aspects of sound, such as onsets and the periodic components of complex stimuli. In vivo intracellular recordings from VNLL neurons (n = 56) in urethane anesthetized rats revealed the presence of large-amplitude, short-duration, onset inhibition in a subset of neurons (14.3%). This inhibition occurred before the first action potential (AP) elicited by noise or tone bursts, was broadly tuned to tonal frequency and was shown to delay the first AP. Our data suggest it is a result of an intrinsic circuit activated by the octopus cell pathway originating in the contralateral cochlear nucleus; this pathway is known to convey exquisitely timed and broadly tuned onset information. This powerful inhibition within the VNLL appears to control the timing of this structure's inhibitory output to higher centers, which has important auditory processing outcomes. The circuit also provides a pathway for fast, broadly tuned, onset inhibition to the IC.

Powerful, onset inhibition in the ventral nucleus of the lateral lemniscus.

La fonction du noyau ventral de la lemnisque lat&eacute;ral (VNLL), un site de traitement secondaire dans le tronc c&eacute;r&eacute;bral auditif, n&#39;est pas claire. Il est connu pour &ecirc;tre une source majeure d&#39;inhibition pour le colliculus inf&eacute;rieur (IC). On pense aussi &agrave; jouer un r&ocirc;le dans le codage les aspects temporels du son, tels que les seuils et les composantes p&eacute;riodiques des stimuli complexes. Des enregistrements intracellulaires in vivo des neurones VNLL (n = 56) en ur&eacute;thane rats anesth&eacute;si&eacute;s a r&eacute;v&eacute;l&eacute; la pr&eacute;sence d&#39;inhibition de grande amplitude, de courte dur&eacute;e, apparition dans un sous-ensemble de neurones (14,3 %). Cette inhibition est survenu avant le premier potentiel d&#39;action (PA) induites par les rafales de bruit ou de la tonalit&eacute;, &eacute;tait largement r&eacute;gl&eacute; &agrave; fr&eacute;quence tonale et a &eacute;t&eacute; montr&eacute; pour retarder la premi&egrave;re AP. Nos donn&eacute;es sugg&egrave;rent que c&#39;est le r&eacute;sultat d&#39;un circuit intrins&egrave;que activ&eacute; par la voie de cellule de poulpe originaire du noyau cochl&eacute;aire controlat&eacute;ral ; cette voie est connue pour transmettre des informations d&#39;apparition exquise chronom&eacute;tr&eacute; et largement &agrave; l&#39;&eacute;coute. Cette inhibition puissante au sein de la VNLL semble contr&ocirc;ler le moment de sortie inhibitrice de la structure aux centres sup&eacute;rieurs, qui a des r&eacute;sultats de traitement auditif important. Le circuit fournit &eacute;galement une voie pour l&#39;inhibition de l&#39;apparition rapide, largement &agrave; l&#39;&eacute;coute, l&#39;IC.

Puissant, inhibition d&#39;apparition dans le noyau ventral de la lemnisque lat&eacute;ral.

La funzione del nucleo ventrale del lemnisco laterale (VNLL), un sito di elaborazione secondaria all&#39;interno del tronco cerebrale uditivo, non &egrave; chiara. &Egrave; noto per essere una fonte importante di inibizione per il collicolo inferiore (IC). Si &egrave; anche pensato di giocare un ruolo nella codificazione degli aspetti temporali del suono, come ad esempio le esacerbazioni e i componenti periodici degli stimoli complessi. Registrazioni intracellulari in vivo da neuroni VNLL (n = 56) in uretano ratti anestetizzati ha rivelato la presenza di inibizione di grande ampiezza, di breve durata, l&#39;esordio in un sottoinsieme dei neuroni (14,3%). Questa inibizione si &egrave; verificato prima il primo potenziale d&#39;azione (AP) ha suscitato da scoppi di rumore o tono, ampiamente &egrave; stato sintonizzato frequenza tonale ed &egrave; stato indicato per ritardare il primo AP. I nostri dati suggeriscono che &egrave; il risultato di un circuito intrinseco attivato da via cella del polpo originari del nucleo coclea controlaterale; Questo percorso &egrave; conosciuto per trasmettere informazioni di insorgenza squisitamente temporizzata e ampiamente sintonizzati. Questa potente inibizione all&#39;interno il VNLL sembra controllare i tempi di output inibitorio ai centri superiori, di questa struttura che dispone di elaborazione uditiva importanti risultati. Il circuito fornisce anche un percorso per l&#39;inibizione ad esordio rapido, ampiamente sintonizzati, per l&#39;IC.

Potente, inibizione di esordio nel nucleo ventrale del lemnisco laterale.

The function of the ventral and intermediate nuclei of the lateral lemniscus (VNLL and INLL), collectively termed ventral complex of the lateral lemniscus (VCLL), is unclear. Several studies have suggested that it plays a role in coding the temporal aspects of sound. In our study, a sample (n = 161) of intracellular responses to dichotically presented noise or tone bursts was collected from the VCLL of urethane-anesthetized rats in vivo. Intracellular recordings revealed six distinct response types to tones, distinguished by their synaptic and membrane characteristics as well as firing pattern. Three of these response types were correlated with distinct cellular morphologies revealed by intracellular injection of neurobiotin. 3D reconstructions of recorded neurons within the VCLL showed the spatial distribution of various response properties, including response type, laterality, characteristic frequency (CF), and binaural influences. Cells that responded to monaural (55%) or binaural (45%) stimulation were distributed throughout the VCLL. Almost all VCLL units were responsive to contralateral stimulation (97%). Most neurons were excited by contralateral stimulation (83%), many exclusively (43%), and some in conjunction with ipsilateral inhibition (28%) or excitation (12%). The INLL contained mostly binaural neurons (65%), typically with ipsilateral inhibition and contralateral excitation. These results indicate that the VCLL is not a monaural structure and there is a dorsal-ventral segregation of binaural and monaural cells. 3D reconstructions of intracellular CFs did not reveal the presence of any tonotopic arrangement within the VCLL. Presumably, the proposed timing role of this structure does not require a systematic representation of tonal frequency.

Intracellular responses and morphology of rat ventral complex of the lateral lemniscus neurons in vivo.

La fonction des noyaux ventrales et interm&eacute;diaires de la lemnisque lat&eacute;ral (VNLL et INLL), collectivement appel&eacute;e complexe ventrale de la lemnisque lat&eacute;ral (VCLL), n&#39;est pas claire. Plusieurs &eacute;tudes ont sugg&eacute;r&eacute; qu&#39;elle joue un r&ocirc;le dans le codage les aspects temporels du son. Dans notre &eacute;tude, un &eacute;chantillon (n = 161) des r&eacute;ponses intracellulaires au bruit de dichotically pr&eacute;sent&eacute; ou ton rafales ont &eacute;t&eacute; pr&eacute;lev&eacute;s le VCLL de rats anesth&eacute;si&eacute;s &agrave; l&#39;ur&eacute;thane in vivo. Des enregistrements intracellulaires ont r&eacute;v&eacute;l&eacute; six types de r&eacute;ponses distinctes aux tons, distingu&eacute;s par leur caract&eacute;ristiques synaptiques et membrane comme motif de mise &agrave; feu. Trois de ces types de r&eacute;ponses sont en corr&eacute;lation avec les morphologies cellulaires distincts r&eacute;v&eacute;l&eacute;s par injection intracellulaire de neurobiotin. Reconstructions 3D des neurones enregistr&eacute;s au sein de la VCLL a montr&eacute; la r&eacute;partition spatiale des diff&eacute;rentes propri&eacute;t&eacute;s de r&eacute;ponse, y compris le type de r&eacute;ponse, lat&eacute;ralit&eacute;, fr&eacute;quence caract&eacute;ristique (CF) et influences binaural. Les cellules qui ont r&eacute;pondu au mono (55 %) ou la stimulation binaurale (45 %) ont &eacute;t&eacute; distribu&eacute;s tout au long de la VCLL. Presque toutes les unit&eacute;s VCLL r&eacute;pondaient &agrave; une stimulation controlat&eacute;rale (97 %). La plupart des neurones ont &eacute;t&eacute; excit&eacute;s par la stimulation controlat&eacute;rale (83 %), beaucoup exclusivement (43 %) et certains avec inhibition ipsilat&eacute;rale (28 %) ou d&#39;excitation (12 %). L&#39;INLL contenait surtout des neurones binaural (65 %), g&eacute;n&eacute;ralement avec inhibition homolat&eacute;rale et controlat&eacute;rale d&#39;excitation. Ces r&eacute;sultats indiquent que la VCLL n&#39;est pas une structure mono et il y a une s&eacute;gr&eacute;gation dorsale-ventral de cellules binaural et monophoniques. Reconstructions 3D intracellulaire pi3/s n&#39;a pas r&eacute;v&eacute;l&eacute; la pr&eacute;sence de n&#39;importe quel arrangement de tonotopique dans le VCLL. Sans doute, le r&ocirc;le du moment propos&eacute; de cette structure ne n&eacute;cessite pas une repr&eacute;sentation syst&eacute;matique de fr&eacute;quence tonale.

R&eacute;ponses intracellulaires et morphologie du complexe ventrale de rat des neurones lemnisque lat&eacute;ral in vivo.

La funzione dei nuclei ventrale e intermedi il lemnisco laterale (VNLL e INLL), collettivamente chiamata ventrale complesso del lemnisco laterale (VCLL), &egrave; chiaro. Diversi studi hanno suggerito che esso gioca un ruolo nella codificazione degli aspetti temporali del suono. Nel nostro studio, un campione (n = 161) di risposte intracellulari presentati dichotically rumore o tono scoppia &egrave; stato raccolto da VCLL di ratti anestetizzati uretano in vivo. Registrazioni intracellulari rivelarono sei tipi distinti di risposta ai toni, distinti da loro caratteristiche sinaptiche e membrana cos&igrave; come modello di infornamento. Tre di questi tipi di risposta sono stati correlati con morfologie cellulari distinte rivelate da iniezione intracellulare di neurobiotin. Ricostruzioni 3D di neuroni registrati all&#39;interno del VCLL ha mostrato la distribuzione spaziale delle varie propriet&agrave; di risposta, tra cui il tipo di risposta, lateralit&agrave;, frequenza caratteristica (CF) e influenze binaurale. Le cellule che hanno risposto al mono (55%) o la stimolazione binaurale (45%) sono state distribuite in tutto il VCLL. Quasi tutte le unit&agrave; di VCLL erano sensibli a reagire alla stimolazione controlaterale (97%). La maggior parte dei neuroni sono stati eccitati dalla stimolazione controlaterale (83%), molti esclusivamente (43%) e alcuni in collaborazione con inibizione omolaterale (28%) o eccitazione (12%). Il INLL conteneva principalmente binaurali neuroni (65%), tipicamente con inibizione omolaterale e controlaterale di eccitazione. Questi risultati indicano che il VCLL non &egrave; una struttura mono e c&#39;&egrave; una segregazione dorsale-ventrale di binaurale e monaurale cellule. Ricostruzioni 3D di CFs intracellulare non hanno rivelato la presenza di qualsiasi disposizione tonotopico all&#39;interno del VCLL. Presumibilmente, il ruolo proposto tempi di questa struttura non richiede una rappresentazione sistematica di frequenza tonale.

Risposte intracellulari e la morfologia del complesso ventrale ratto dei neuroni lemnisco laterale in vivo.

In vivo host responses to an electrode-like array of aligned carbon nanotubes (ACNTs) embedded within a biopolymer sheet are reported. This biocompatibility study assesses the suitability of immobilized carbon nanotubes for bionic devices. Inflammatory responses and foreign-body histiocytic reactions are not substantially elevated when compared to negative controls following 12 weeks implantation. A fibrous capsule isolates the implanted ACNTs from the surrounding muscle tissue. Filamentous nanotube fragments are engulfed by macrophages, and globular debris is incorporated into the fibrous capsule with no further reaction. Scattered leukocytes are observed, adherent to the ACNT surface. These data indicate that there is a minimal local foreign-body response to immobilized ACNTs, that detached fragments are phagocytosed into an inert material, and that ACNTs do not attract high levels of surface fouling. Collectively, these results suggest that immobilized nanotube structures should be considered for further investigation as bionic components.

Biocompatibility of immobilized aligned carbon nanotubes.

H6te in vivo dans un tableau de type &eacute;lectrode de nanotubes de carbone align&eacute;s (ACNTs) incorpor&eacute;s dans une feuille de biopolym&egrave;res est signal&eacute;s. Cette &eacute;tude de biocompatibilit&eacute; &eacute;value l&#39;ad&eacute;quation des nanotubes de carbone immobilis&eacute; pour dispositifs bioniques. Les r&eacute;ponses inflammatoires et r&eacute;actions histiocytaires de corps &eacute;trangers ne sont pas sensiblement &eacute;lev&eacute;es par rapport &agrave; la valeur du contr&ocirc;le n&eacute;gatif apr&egrave;s implantation de 12 semaines. Une capsule fibreuse isole les ACNTs implant&eacute;s des tissus musculaires environnantes. Des fragments de nanotube filamenteux sont cern&eacute;s par les macrophages, et d&eacute;bris globulaire est incorpor&eacute; dans la capsule fibreuse avec aucune autre r&eacute;action. Leucocytes &eacute;pars sont observ&eacute;es, adh&eacute;rent &agrave; la surface ACNT. Ces donn&eacute;es indiquent qu&#39;il y a une r&eacute;ponse de corps &eacute;trangers locale minime &agrave; ACNTs immobilis&eacute;es, que des fragments d&eacute;tach&eacute;s sont phagocyt&eacute;es dans un mat&eacute;riau inerte, et que ACNTs n&#39;attirent pas les niveaux &eacute;lev&eacute;s du colmatage de surface. Collectivement, ces r&eacute;sultats sugg&egrave;rent que les structures de nanotube immobilis&eacute;e devraient &ecirc;tre consid&eacute;r&eacute;s pour compl&eacute;ment d&#39;enqu&ecirc;te en tant que composants bioniques.

Biocompatibilit&eacute; des nanotubes de carbone align&eacute;s immobilis&eacute;e.

Risposte in vivo ospite alla matrice come elettrodo di nanotubi di carbonio allineati (ACNTs) incorporati all&#39;interno di un foglio di biopolimero sono segnalate. Questo studio di biocompatibilit&agrave; valuta l&#39;idoneit&agrave; dei nanotubi di carbonio immobilizzato per dispositivi bionici. Corpo estraneo Istiocitario reazioni e risposte infiammatorie non sono sostanzialmente elevati rispetto ai controlli negativi dopo l&#39;impianto di 12 settimane. Una capsula fibrosa consente di isolare il ACNTs impiantati dal tessuto muscolare circostante. Frammenti di nanotubi filamentose sono travolto dai macrofagi, e detriti globulare sono incorporato nella capsula fibrosa con alcuna ulteriore reazione. Si osservano leucociti sparsi, aderente alla superficie ACNT. Questi dati indicano che c&#39;&egrave; un minima locale corpo estraneo risposta a ACNTs immobilizzato, che distaccate frammenti sono phagocytosed in un materiale inerte, e che ACNTs non attirare alti livelli di incrostazione superficiale. Collettivamente, questi risultati suggeriscono che strutture nanotubo immobilizzato devono essere considerati per ulteriori indagini come componenti bionici.

Biocompatibilit&agrave; dei nanotubi di carbonio immobilizzato allineati.

Electronic retinal implants for the blind are already a market reality. A world wide effort is underway to find the technology that offers the best combination of performance and safety for potential patients. Our approach is to construct an epi-retinally targeted device entirely encapsulated in diamond to maximise longevity and biocompatibility. The stimulating array of our device comprises a monolith of electrically insulating diamond with thousands of hermetic, microscale nitrogen doped ultra-nanocrystalline diamond (N-UNCD) feedthroughs. Here we seek to establish whether the conducting diamond feedthroughs of the array can be used as stimulating electrodes without further modification with a more traditional neural stimulation material. Efficacious stimulation of retinal ganglion cells was established using single N-UNCD microelectrodes in contact with perfused, explanted, rat retina. Evoked rat retinal ganglion cell action potentials were recorded by patch clamp recording from single ganglion cells, adjacent to the N-UNCD stimulating electrode. Separately, excellent electrochemical stability of N-UNCD was established by prolonged pulsing in phosphate buffered saline at increasing charge density up to the measured charge injection limit for the material.

Electrical stimulation of retinal ganglion cells with diamond and the development of an all diamond retinal prosthesis.

Les implants r&eacute;tiniens &eacute;lectroniques pour les aveugles sont d&eacute;j&agrave; une r&eacute;alit&eacute; du march&eacute;. Un effort dans le monde entier est en cours pour trouver la technologie qui offre la meilleure combinaison de performance et de s&eacute;curit&eacute; pour les patients potentiels. Notre approche consiste &agrave; construire un dispositif epi-retinally cibl&eacute; enti&egrave;rement encapsul&eacute; en diamant pour maximiser la long&eacute;vit&eacute; et biocompatibilit&eacute;. Le tableau stimulant de notre dispositif comprend un monolithe &eacute;lectriquement isolant diamant avec des milliers d&#39;herm&eacute;tique, azote microscale dop&eacute; travers&eacute;es de diamant (N-CNUD) ultra-nanocristallins. Ici, nous cherchons &agrave; &eacute;tablir si les conducteur travers&eacute;es de diamant du tableau peuvent &ecirc;tre utilis&eacute;es comme stimulant des &eacute;lectrodes sans autre modification avec un mat&eacute;riau plus traditionnel de la neurostimulation. Une stimulation efficace des cellules ganglionnaires r&eacute;tiniennes a &eacute;t&eacute; cr&eacute;&eacute;e &agrave; l&#39;aide de micro&eacute;lectrodes unique de N-CNUD au contact de la r&eacute;tine de rat perfus&eacute;, explant&eacute;s. Potentiels d&#39;action du cellules ganglionnaires r&eacute;tiniennes rat &eacute;voqu&eacute;s ont &eacute;t&eacute; enregistr&eacute;es par patch clamp, enregistrement &agrave; partir de cellules de ganglion unique, adjacents &agrave; l&#39;&eacute;lectrode de stimulation N-CNUD. S&eacute;par&eacute;ment, excellente stabilit&eacute; &eacute;lectrochimique de N-CNUD a &eacute;t&eacute; cr&eacute;&eacute;e par une impulsion prolong&eacute;e dans une solution saline tamponn&eacute;e au phosphate &agrave; accro&icirc;tre la densit&eacute; de charge maximale de charge mesur&eacute;e injection pour le mat&eacute;riel.

Stimulation &eacute;lectrique des cellules ganglionnaires r&eacute;tiniennes avec diamant et le d&eacute;veloppement d&#39;une toutes les proth&egrave;ses r&eacute;tiniennes de diamant.

Impianti elettronici della retina per i non vedenti sono gi&agrave; una realt&agrave; di mercato. Uno sforzo di tutto il mondo &egrave; in corso per trovare la tecnologia che offre la migliore combinazione di prestazioni e sicurezza per i pazienti potenziali. Il nostro approccio &egrave; quello di costruire un dispositivo epi-retinally mirato interamente incapsulato in diamante per massimizzare la longevit&agrave; e biocompatibilit&agrave;. La matrice stimolante del nostro dispositivo &egrave; costituito da un monolito di elettricamente isolante diamante con migliaia di ermetico, Microscala azoto drogato ultra-nanocristallino passacavi diamante (N-CNUD). Qui cerchiamo di stabilire se i conduttore passacavi diamante della matrice possono essere utilizzati come stimolante elettrodi senza ulteriori modifiche con un materiale pi&ugrave; tradizionale: stimolazione neurale. Efficacia stimolazione delle cellule gangliari della retina &egrave; stata stabilita usando singoli microelettrodi N-CNUD a contatto con la retina perfusi, espiantato, ratto. Ratto evocati gangliari della retina cellule potenziali d&#39;azione sono stati registrati da patch clamp registrazione da cellule gangliari singolo, adiacente all&#39;elettrodo stimolante N-CNUD. Separatamente, eccellente stabilit&agrave; elettrochimica di N-CNUD &egrave; stata fondata da prolungata pulsare in soluzione salina tamponata con fosfato ad aumentare la densit&agrave; di carica fino al limite di iniezione di carica misurata per il materiale.

Stimolazione elettrica delle cellule gangliari della retina con diamante e lo sviluppo di un tutte le protesi retiniche di diamante.

In mammals, the sensory hair cells and auditory neurons do not spontaneously regenerate and their loss results in permanent hearing impairment. Stem cell therapy is one emerging strategy that is being investigated to overcome the loss of sensory cells after hearing loss. To successfully replace auditory neurons, stem cell-derived neurons must be electrically active, capable of organized outgrowth of processes, and of making functional connections with appropriate tissues. We have developed an in vitro assay to test these parameters using cocultures of developing cochlear explants together with neural progenitors derived from human embryonic stem cells (hESCs). We found that these neural progenitors are electrically active and extend their neurites toward the sensory hair cells in cochlear explants. Importantly, this neurite extension was found to be significantly greater when neural progenitors were predifferentiated toward a neural crest-like lineage. When grown in coculture with hair cells only (denervated cochlear explants), stem cell-derived processes were capable of locating and growing along the hair cell rows in an en passant-like manner. Many presynaptic terminals (synapsin 1-positive) were observed between hair cells and stem cell-derived processes in vitro. These results suggest that differentiated hESC-derived neural progenitors may be useful for developing therapies directed at auditory nerve replacement, including complementing emerging hair cell regeneration therapies.

An in vitro model of developmental synaptogenesis using cocultures of human neural progenitors and cochlear explants.

Chez les mammif&egrave;res, les cellules sensorielles de cheveux et neurones auditifs ne r&eacute;g&eacute;n&egrave;rent pas spontan&eacute;ment et leur perte se traduit par une d&eacute;ficience auditive permanente. Th&eacute;rapie de cellules souches est une nouvelle strat&eacute;gie qui est &agrave; l&#39;&eacute;tude pour surmonter la perte de cellules sensorielles apr&egrave;s la perte d&#39;audition. Pour remplacer avec succ&egrave;s les neurones auditifs, cellules souches d&eacute;riv&eacute;es de neurones doivent &ecirc;tre &eacute;lectriquement actives, capables d&#39;excroissance organis&eacute; des processus et d&#39;&eacute;tablir des liens fonctionnels avec des tissus appropri&eacute;s. Nous avons d&eacute;velopp&eacute; un test in vitro pour tester ces param&egrave;tres &agrave; l&#39;aide des cocultures de mettre au point des explants cochl&eacute;aires ainsi que des prog&eacute;niteurs neurones d&eacute;riv&eacute;s des cellules souches embryonnaires humaines (CSEh). Nous avons constat&eacute; que ces cellules souches neurales sont &eacute;lectriquement actifs et &eacute;tendent leur neurites vers les cellules cili&eacute;es sensorielles des explants de cochl&eacute;aire. Ce qui est important, cette extension de neurites s&#39;est av&eacute;r&eacute;e pour &ecirc;tre significativement sup&eacute;rieure lorsque les cellules souches neurales ont &eacute;t&eacute; predifferentiated vers une lign&eacute;e de cr&ecirc;te neurale-comme. Lorsqu&#39;il est cultiv&eacute; en coculture avec des cellules cili&eacute;es seul (explants cochl&eacute;aire d&eacute;nerv&eacute;), processus de cellules souches d&eacute;riv&eacute;es ont &eacute;t&eacute; capables de localiser et qui poussent sur les rang&eacute;es de cellules cili&eacute;es de mani&egrave;re semblable au fr. Nombreuses terminaisons pr&eacute;synaptiques (synapsine 1-positive) ont &eacute;t&eacute; observ&eacute;es entre les cellules cili&eacute;es et des cellules souches d&eacute;riv&eacute;es de processus in vitro. Ces r&eacute;sultats sugg&egrave;rent que diff&eacute;renci&eacute;es des prog&eacute;niteurs neurones d&eacute;riv&eacute;es de CSEh peuvent &ecirc;tre utiles pour le d&eacute;veloppement de th&eacute;rapies r&eacute;alis&eacute;s lors du remplacement du nerf auditif, y compris le compl&eacute;ment des nouvelles th&eacute;rapies de r&eacute;g&eacute;n&eacute;ration de cellules cili&eacute;es.

Un mod&egrave;le in vitro de la synaptog&eacute;n&egrave;se du d&eacute;veloppement &agrave; l&#39;aide des cocultures des prog&eacute;niteurs neurones humaines et cochl&eacute;aire des explants.

Nei mammiferi, non rigenerare spontaneamente le cellule ciliate sensoriali e neuroni uditivi e loro perdita provoca sordit&agrave; permanente. Terapia della cellula formativa &egrave; una strategia emergente che si sta analizzando per superare la perdita di cellule sensoriali dopo la perdita dell&#39;udito. Per sostituire con successo neuroni uditivi, neuroni cellule staminali derivate devono essere elettricamente attiva, capace di escrescenza organizzata dei processi e di effettuare i collegamenti funzionali con tessuti appropriati. Abbiamo sviluppato un test in vitro per testare questi parametri utilizzando cocultures di sviluppare cocleare espianti insieme ai progenitori neurali derivate da cellule staminali embrionali umane (hESC). Abbiamo scoperto che questi progenitori neurali sono elettricamente attivi ed estendono i loro neuriti verso le cellule ciliate sensoriali in espianti cocleare. Soprattutto, questa estensione dei neuriti &egrave; stata trovata per essere significativamente maggiore quando progenitori neurali erano predifferentiated verso un lignaggio come cresta neurale. Quando coltivate in coculture con cellule ciliate solo (Denervato cocleare espianti), cellule staminali derivate processi erano in grado di localizzare e crescono lungo le righe delle cellule dei capelli in maniera en passant-like. Molti terminali presinaptiche (synapsin 1-positivo) sono stati osservati tra cellule ciliate e cellule staminali derivate processi in vitro. Questi risultati suggeriscono che la differenziata progenitori neurali hESC-derivato possono essere utile per lo sviluppo di terapie dirette al nervo uditivo sostituzione, tra cui integrando emergenti terapie di rigenerazione delle cellule dei capelli.

Un modello in vitro di pervasivi dello sviluppo mediante cocultures di progenitori neurali umane e cocleare explants.

PURPOSE: The safety of chronic implantation of a retinal prosthesis in the suprachoroidal space has not been established. This study aimed to determine the safety of a wide-field suprachoroidal electrode array following chronic implantation using histopathological techniques and electroretinography. METHODS: A platinum electrode array in a wide silicone substrate was implanted unilaterally in the suprachoroidal space in cats (n = 7). The lead and connector were tunneled out of the orbit and positioned subcutaneously. Post-surgical recovery was assessed using fundus photography and electroretinography (ERG). Following 3 months of passive implantation, the animals were terminated and the eyes assessed for the pathological response to implantation. RESULTS: The implant was mechanically stable in the suprachoroidal space during the course of the study. The implanted eye showed a transient increase in ERG response amplitude at 2 weeks which returned to normal by 3 months. Pigmentary changes were observed at the distal end of the implant, near the optic disc. Histopathological assessment revealed a largely intact retina and a thin fibrous capsule around the suprachoroidal implant cavity. The foreign body response was minimal with sporadic presence of macrophages and no active inflammation. All implanted eyes were negative for bacterial or fungal infections. A mid-grade granuloma and thick fibrous build-up surrounded the extraocular cable. Scleral closure was maintained in 6 of 7 eyes. There were no staphylomas or choroidal incarceration. CONCLUSIONS: A wide-field retinal prosthesis was stable and well tolerated during long-term suprachoroidal implantation in a cat model. The surgical approach was reproducible and overall safe.

A wide-field suprachoroidal retinal prosthesis is stable and well tolerated following chronic implantation.

BUT : L&#39;innocuit&eacute; d&#39;implantation chronique d&#39;un implant r&eacute;tinien en l&#39;espace de suprachoroidal n&#39;a pas &eacute;t&eacute; &eacute;tablie. Cette &eacute;tude visait &agrave; d&eacute;terminer l&#39;innocuit&eacute; d&#39;un tableau d&#39;&eacute;lectrode suprachoroidal grand champ apr&egrave;s l&#39;implantation chronique &agrave; l&#39;aide d&#39;&eacute;lectror&eacute;tinographie et techniques histopathologiques. M&eacute;thodes : Un tableau d&#39;&eacute;lectrode de platine dans un substrat de silicone large a &eacute;t&eacute; unilat&eacute;ralement implant&eacute; dans l&#39;espace suprachoroidal chez le chat (n = 7). Le plomb et le connecteur &eacute;taient hors de l&#39;orbite en tunnel et plac&eacute;s sous la peau. R&eacute;cup&eacute;ration post-op&eacute;ratoire a &eacute;t&eacute; &eacute;valu&eacute;e &agrave; l&#39;aide de la photographie du fond de &oelig;il et &eacute;lectror&eacute;tinographie (ERG). Apr&egrave;s 3 mois d&#39;implantation passive, les animaux ont &eacute;t&eacute; r&eacute;sili&eacute;s et les yeux &eacute;valu&eacute; pour la r&eacute;ponse pathologique &agrave; la nidation. R&Eacute;SULTATS : L&#39;implant a &eacute;t&eacute; m&eacute;caniquement stable dans l&#39;espace suprachoroidal au cours de l&#39;&eacute;tude. L&#39;oeil implant&eacute; a montr&eacute; une augmentation transitoire dans l&#39;ERG r&eacute;ponse en amplitude &agrave; 2 semaines, ce qui revient &agrave; la normale de 3 mois. Changements pigmentaires ont &eacute;t&eacute; observ&eacute;es &agrave; l&#39;extr&eacute;mit&eacute; distale de l&#39;implant, pr&egrave;s du disque optique. &Eacute;valuation histopathologique a r&eacute;v&eacute;l&eacute; une r&eacute;tine en grande partie intacte et une mince capsule fibreuse autour de la cavit&eacute; d&#39;implant de suprachoroidal. La r&eacute;action au corps &eacute;tranger &eacute;tait minime avec une pr&eacute;sence sporadique des macrophages et aucune inflammation active. Tous les yeux implant&eacute;s &eacute;taient n&eacute;gatifs pour des infections bact&eacute;riennes ou fongiques. Un granulome mi-cat&eacute;gorie et accumulation fibreuse &eacute;paisse entour&eacute; le c&acirc;ble extra-oculaires. Fermeture scl&eacute;rale persistait dans 6 des 7 yeux. Il n&#39;y a aucun staphylomas ou incarc&eacute;ration choro&iuml;dienne. CONCLUSIONS : Une proth&egrave;se de r&eacute;tine grand-angulaire est stable et bien tol&eacute;r&eacute; pendant l&#39;implantation de suprachoroidal &agrave; long terme dans un mod&egrave;le de chat. L&#39;approche chirurgicale a &eacute;t&eacute; globalement s&ucirc;re et reproductible.

Une proth&egrave;se de r&eacute;tine suprachoroidal grand champ est stable et bien tol&eacute;r&eacute; apr&egrave;s l&#39;implantation chronique.

SCOPO: La sicurezza del cronico dell&#39;impianto di una protesi della retina nello spazio suprachoroidal non &egrave; stata stabilita. Questo studio finalizzato a determinare la sicurezza di una matrice di elettrodo wide-field suprachoroidal seguendo l&#39;impianto cronico utilizzando tecniche istopatologiche ed elettroretinografia. Metodi: Un array di elettrodo di platino in un substrato di vasta in silicone &egrave; stato impiantato unilateralmente nello spazio suprachoroidal in gatti (n = 7). Il cavo e connettore erano tunneled fuori l&#39;orbita e posizionati sotto la cute. Recupero post-operatorio &egrave; stata valutata utilizzando la fotografia del fundus ed elettroretinografia (ERG). Dopo 3 mesi di impianto passivo, gli animali sono stati terminati e gli occhi valutata per la risposta patologica per l&#39;impianto. RISULTATI: L&#39;impianto era meccanicamente stabile nello spazio suprachoroidal durante il corso di studio. L&#39;occhio impiantato ha mostrato un aumento transitorio ERG ampiezza di risposta a 2 settimane che torn&ograve; normale di 3 mesi. L&#39;estremit&agrave; distale dell&#39;impianto, vicino il disco ottico sono state osservate alterazioni della pigmentazione. Valutazione istopatologica ha rivelato una retina in gran parte intatto e una sottile capsula fibrosa intorno alla cavit&agrave; dell&#39;impianto suprachoroidal. La risposta da corpo estraneo &egrave; stato minima con sporadica presenza di macrofagi e nessuna infiammazione attiva. Tutti gli occhi impiantati erano negativi per le infezioni fungine o batteriche. Un granuloma contraffatto e accumulo fibroso denso circondato il cavo extraoculari. Chiusura sclerale &egrave; stato mantenuto in 6 di 7 occhi. C&#39;erano staphylomas o incarcerazione della coroide. CONCLUSIONI: Una protesi retiniche wide-field era stabile e ben tollerati durante l&#39;impianto di suprachoroidal a lungo termine in un modello di gatto. L&#39;approccio chirurgico &egrave; stato nel complesso sicuro e riproducibile.

Una protesi retiniche suprachoroidal wide-field &egrave; stabile e ben tollerato in seguito l&#39;impianto cronico.

After more than 40 years of research, visual prostheses are moving from the laboratory into the clinic. These devices are designed to provide prosthetic vision to the blind by stimulating localized neural populations in one of the retinotopically organized structures of the visual pathway - typically the retina or visual cortex. The long gestation of this research reflects the many significant technical challenges encountered including surgical access, mechanical stability, hardware miniaturization, hermetic encapsulation, high-density electrode arrays, and signal processing. This review provides an introduction to the pathophysiology of blindness; an overview of existing visual prostheses, their advantages and drawbacks; the perceptual effects evoked by electrical stimulation; as well as the role played by plasticity and training in clinical outcomes.

Visual prostheses for the blind.

Current surgical techniques for retinal prosthetic implantation require long and complicated surgery, which can increase the risk of complications and adverse outcomes.

Development of a surgical procedure for implantation of a prototype suprachoroidal retinal prosthesis.

To assess the safety and efficacy of chronic electrical stimulation of the retina with a suprachoroidal visual prosthesis.

Chronic electrical stimulation with a suprachoroidal retinal prosthesis: a preclinical safety and efficacy study.

We have previously shown that neonatal deafness of 7-13 months duration leads to loss of cochleotopy in the primary auditory cortex (AI) that can be reversed by cochlear implant use. Here we describe the effects of a similar duration of deafness and cochlear implant use on temporal processing. Specifically, we compared the temporal resolution of neurons in AI of young adult normal-hearing cats that were acutely deafened and implanted immediately prior to recording with that in three groups of neonatally deafened cats. One group of neonatally deafened cats received no chronic stimulation. The other two groups received up to 8 months of either low- or high-rate (50 or 500 pulses per second per electrode, respectively) stimulation from a clinical cochlear implant, initiated at 10 weeks of age. Deafness of 7-13 months duration had no effect on the duration of post-onset response suppression, latency, latency jitter, or the stimulus repetition rate at which units responded maximally (best repetition rate), but resulted in a statistically significant reduction in the ability of units to respond to every stimulus in a train (maximum following rate). None of the temporal response characteristics of the low-rate group differed from those in acutely deafened controls. In contrast, high-rate stimulation had diverse effects: it resulted in decreased suppression duration, longer latency and greater jitter relative to all other groups, and an increase in best repetition rate and cut-off rate relative to acutely deafened controls. The minimal effects of moderate-duration deafness on temporal processing in the present study are in contrast to its previously-reported pronounced effects on cochleotopy. Much longer periods of deafness have been reported to result in significant changes in temporal processing, in accord with the fact that duration of deafness is a major factor influencing outcome in human cochlear implantees.

Effects of deafness and cochlear implant use on temporal response characteristics in cat primary auditory cortex.

The research goal is to develop a wide-field retinal stimulating array for prosthetic vision. This study aimed at evaluating the efficacy of a suprachoroidal electrode array in evoking visual cortex activity after long term implantation.

Cortical activation following chronic passive implantation of a wide-field suprachoroidal retinal prosthesis.

Platinum (Pt) is the most commonly used metal for stimulating electrodes. This study aims to determine the amount of charge that can be delivered without causing irreversible electrochemical reactions (charge injection capacity; Qinj) of Pt macroelectrodes (geometric surface area > 0.001 cm²) in vitro and in vivo using voltage transient measurements. Pt macroelectrodes were stimulated with biphasic charge-balanced cathodic-first constant-current pulses in phosphate buffered saline. Potential excursions were measured (vs. Ag/AgCl electrode) and used to determine Qinj. The in vitro Qinj were compared to those measured in vivo following: acute and chronic implantation close to the retina; chronic intra-cochlear implantation; and acute subdural implantation, in the cat. Qinj increased with pulse width from 35 to 54 μC/cm² for respective pulse widths of 100 to 3200 μs per phase in vitro. Qinj was significantly less in vivo. There was no significant difference in Qinj between acutely (3.84 to 16.6 μC/cm² with pulse widths of 100 to 3200 μs) and chronically (6.99 to 15.8 μC/cm² with pulse widths of 200 to 3200 μs) implanted suprachoroidal electrodes. Intra-cochlear Qinj was not different to suprachoroidal Qinj while subdural Qinj was significantly less than the suprachoroidal Qinj (p < 0.05). These results have important implications in providing guidelines on Qinj for the safe use of Pt stimulating macroelectrodes and question the relevance of measuring Qinj in vivo using voltage transients.

<i>In vivo</i> and <i>in vitro</i> Comparison of the Charge Injection Capacity of Platinum Macro Electrodes.

Retinal visual prostheses ("bionic eyes") have the potential to restore vision to blind or profoundly vision-impaired patients. The medical bionic technology used to design, manufacture and implant such prostheses is still in its relative infancy, with various technologies and surgical approaches being evaluated. We hypothesised that a suprachoroidal implant location (between the sclera and choroid of the eye) would provide significant surgical and safety benefits for patients, allowing them to maintain preoperative residual vision as well as gaining prosthetic vision input from the device. This report details the first-in-human Phase 1 trial to investigate the use of retinal implants in the suprachoroidal space in three human subjects with end-stage retinitis pigmentosa. The success of the suprachoroidal surgical approach and its associated safety benefits, coupled with twelve-month post-operative efficacy data, holds promise for the field of vision restoration.

First-in-human trial of a novel suprachoroidal retinal prosthesis.

Recently, there has been interest in investigating diamond as a material for use in biomedical implants. Diamond can be rendered electrically conducting by doping with boron or nitrogen. This has led to inclusion of boron doped and nitrogen included diamond elements as electrodes and/or feedthroughs for medical implants. As these conductive device elements are not encapsulated, there is a need to establish their clinical safety for use in implants. This article compares the biocompatibility of electrically conducting boron doped diamond (BDD) and nitrogen included diamond films and electrically insulating poly crystalline diamond films against a silicone negative control and a BDD sample treated with stannous octoate as a positive control. Samples were surgically implanted into the back muscle of a guinea pig for a period of 4-15 weeks, excised and the implant site sectioned and submitted for histological analysis. All forms of diamond exhibited a similar or lower thickness of fibrotic tissue encapsulating compared to the silicone negative control samples. All forms of diamond exhibited similar or lower levels of acute, chronic inflammatory, and foreign body responses compared to the silicone negative control indicating that the materials are well tolerated in vivo. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2015.

David A.X. Nayagam

Bionics Institute

Techniques for Processing Eyes Implanted with a Retinal Prosthesis for Localized Histopathological Analysis: Part 2 Epiretinal Implants with Retinal Tacks