Yazarlar lohusalık yapısı ve dott gelişmekte teknik destek Giorgio Carlini teşekkür ederiz. Yazının kapsamlı revizyon için Ornella LoBrutto. Bu sonuçlara önde gelen araştırma Avrupa Birliği&#39;nin 7. Çerçeve Programı&#39;ndan fon aldı (ICT-FET FP7 / 2007-2013, FET Genç Kaşifler düzeni) hibe anlaşması 284.772 BEYİN BOW altında (www.brainbowproject.eu).

Deneysel protokol DL 116/1992 uyarınca ve Genova (Prot Üniversitesi kurallar tarafından İtalyan Sağlık Bakanlığı tarafından Avrupa Hayvan Bakım Mevzuatı (2010/63 / EU), tarafından kabul edildi. N. 13130, Mayıs 2011). Tüm çabalar proje için hayvanların sayısını azaltmak ve onların acılarını en aza indirmek için yapılmıştır. Malzeme ve Destekler 1. Hazırlık <ol><li> CNC (Computer Numerical Control) freze makinesi vasıtasıyla PDMS (Poly-Dimetil-Siloxane) kısıtlama oluşturmak için kalıp Construct. Bu tür bir kalıp politetrafloroetilen merkezi silindir (PTFE), polikarbonat gerçekleştirilmektedir. PDMS sertleştikten sonra bu malzeme maske daha kolay bir çıkarma verir. NOT: kalıp tasarımı Bilgisayar Destekli-Tasarım (CAD) tarafından gerçekleştirilen ve daha sonra CNC Freze makinesine teslim edilmiştir. </li><li> PDMS elastomer hazırlayın. PDMS bir organik polimerdir. Bu iki eleman oluşmaktadır, Bir kürleme maddesi ve bir polimer içerir. 1:10 hacim oranında karıştırın, sertleştirici madde bir kısmı ve polimerin dokuz kısım. Bir Petri kabındaki iki bileşen koymak sallamak ve hava kabarcıklarını yok etmek için 10 dakika süreyle vakum odasında karışımı yerleştirin. PDMS 3 g bir kısıtlama için yeterlidir. </li><li> PDMS kısıtlamayı Construct. Kalıpçı içine PDMS malzemeyi yerleştirin ve 120 ° C&#39;de 30 dakika süreyle fırına koyun. PDMS kısıtlama, sırasıyla 22,0 ve 3,0 mm&#39;lik bir dış ve iç çapa ve 650 mm yüksekliğe sahip ideal bir silindir şekline sahiptir. </li><li> Kaplama bir gün önce, çiftin bir stereo mikroskop altında bir cımbız yardımıyla Mikro Elektrot Diziler (ÇÇA) aktif alana maske ve 120 ° C&#39;de fırında PDMS maskesi sterilize edin. </li><li> Konik bir cam şişede 2 saat boyunca% 70 etanol içinde ve EV döndürme (42,3 ± 1,1 um onaylı ortalama çapı 40 ± 2 um nominal çap), cam mikro-boncuklar sterilizeery 30 dakika tüm mikroboncukları ortaya çıkarmak. </li><li> Tüpten etanol çözüm çıkarın ve mikroboncukları steril su ile iki kez yıkayın. </li><li> 0,05 ug / ml poli-D-Lisin, Laminin karışık çözeltisi 24 ul (çap 3.0 mm eşittir) PDMS maske tarafından sınırlanan MEA alanının orta kısmını hale getirin. </li><li> Coat 0,05 ug / ml&#39;de yapışma proteinleri, önceden laminin ve poli-D-lisin ile mikro-mi ve stabil ve uzun süreli bir nöronal ağ elde etmek için, 37 ° C &#39;de gece boyunca inkübatör içinde bırakın. </li><li> MEA cam yüzeyinden ve cam mikro hem yapışma faktörleri çıkarın. Aspire bir pipet ile kaplama çözeltisinin yaklaşık olarak% 95 ve MEA yüzeyi üzerinde, steril su, küçük bir hacimlerinde 24μl- uygulanır. Aspire yine 95&#39;den fazla su ve% hücreleri kaplama önce 1 saat boyunca laminer kaputun altında MEA kurumaya bırakın. Not: yerine mikro-boncuk halinde, kaplama aspireçözüm ve nöronlar kaplama olacak cam yüzeyi kondisyon için, sterilize su ve bazal orta ve B27 olarak ek ikinci bir biriyle ilk yıkama yapın. Mikro-kuru izin vermeyin. Şişe içine kültür ortamı içinde süspansiyon halinde bırak. </li><li> Bunlar tek biçimli bir tabakasını oluşturan kendi kendini monte edecek ve membran deliğinden (gözenek çapı 0,4 um) olan, çok oyuklu bir plaka üzerine bir pipet -200 μl-, tedavi edilen mikro-boncuk süspansiyonu (yaklaşık 32000) aracılığıyla, dağıtın. </li><li> Orta 0.5 ml membran Her çukurun doldurun ve inkübatör koydum (T = 37.0 o C, CO 2 =% 5) nöronlar (3.2) kaplama için hazır olana kadar. </li></ol> 2. Embriyolar diseksiyonu ve Doku Ayrılma <ol><li> Normal bir ışık-karanlık program dahilinde sabit bir sıcaklıkta (22 ± 1 ° C) ve nem (% 50) Ev yetişkin dişi sıçanlar (200-250 g) (ışık-07:00-7 pm) &#39;dehayvan tesisi. Bu yiyecek sağlanması ve su serbestçe kullanılabilir. </li><li> % 3 izofluran kullanarak geliştirme 18 gün (E18) sonra hamile kadın sıçan anestezisi. Ardından, servikal dislokasyon ile hayvan kurban. </li><li> Her sıçan embriyo hippocampi çıkarın ve Ca 2+ ve Mg olmadan buz Hank dengeli tuz çözeltisi 2+ içine koyun. Günde gelişim hipokampus ve korteks dokuları 18 Çok yumuşak ve küçük parçalar halinde kesmek için gerek yoktur. Daha fazla detay 18,19 bulunabilir. </li><li> 37 ° C&#39;de 18-20 dakika boyunca DNAz% 0.05 ihtiva eden tripsin / Hank çözeltisi 0.125% olarak doku ayırmak. </li><li> Pasteur pipeti ile süpernatan çözeltisi çıkarın ve 5 dakika boyunca,% 10 fetal sığır serumu (FBS) ile orta eklenerek enzimatik sindirim durdurun. </li><li> FBS ile Ortamı çıkarın ve eki,% 1 L-glutamin, gentamisin 10 ug / ml ortam maddesi ile bir kez yıkanır. Pasteur pip ile tekrar orta kaldırmakette eki,% 1 L-glutamin, gentamisin 10 ug / ml ile bir yetiştirme ortamı küçük bir miktarı (500 ul) ile yeniden dolum ve. </li><li> Hücre süt rengi süspansiyon görünceye kadar dar bir Pasteur pipeti ile mekanik olarak doku topağı ayrıştırmaları. Bu hücre süspansiyonu santrifüj gerekli değildir. </li><li> 2,0 ml&#39;lik bir son hacim elde etmek için büyüme ortamı hücre süspansiyonuna küçük hacimli seyreltilir. Bir hemositometre odası ile elde edilen hücresel konsantrasyon güvenin. / Ml 600-700 hücreleri istenen hücre konsantrasyonunu elde etmek üzere 5: 1 ile, bu konsantrasyon seyreltilir. </li></ol> 3. Hücre Kaplama <ol><li> PDMS kısıtlaması ile tanımlanır MEA aktif alan üzerine yaklaşık 2000 hücre / mm2 yoğunluğunda plakası hücreleri, 2B nöronal ağ oluşturmak için. NOT: Her hipokampus yaklaşık 5 x 10 5 hücreler içeren, (tek bir embriyo için 1 x 10 6). 6 x 10 toplam miktar almak için 6 embriyolar teşrih6 2 ml hücre ve / ml 3000 hücre tahmini konsantrasyonu. İstenilen hücre konsantrasyonunu elde etmek ve yaklaşık 600-700 hücre / ul plaka için 5: 1 bu konsantrasyon sulandırmak. PDMS kısıtlaması tarafından sınırlanan MEA alanı yaklaşık 7,065 mm 2 ve kaplama toplam hücre sayısı ise 600 hücre / ml x 24 ul = 14.400 hücre / mm 2 &#39;2038 hücrelerin nihai yoğunluğu. </li><li> 37 ° C&#39;de nemlendirilmiş bir CO2 atmosferi (% 5) ile inkübatör içine MEA cihazları yerleştirin. </li><li> Üç boyutlu kültür yapımı için ön hazırlık aşamasını tamamlamak için yuvalı plakalarda içine yerleştirilen mikro-mono-katman yüzeyi üzerine / ml 600-700 hücreleri (yaklaşık 100,000 hücre) hücre konsantrasyonuna sahip süspansiyon 160 ul dağıtın. 37 ° C&#39;de nemlendirilmiş bir CO2 atmosferi (% 5) ile, çok kuyucuklu bir inkübatör plakaları koyun. </li></ol> 4. 3D Nöronal Şebeke İnşaatı <ol><li> 6-8 saat sonra kaplama, yaklaşık 30-40 ul&#39;lik bir hacim için ayarlanmış bir pipet kullanılarak PDMS kısıtlaması tarafından sınırlanan bölgenin içine tamamen çok dikkatli bir şekilde, çok oyuklu plakalar ile süspansiyonu (nöronlar ile mikro-) aktarın. Her aktarımdan sonra, bir altıgen kompakt yapıda kendine monte mikroboncukları izin, yaklaşık yarım dakika bekleyin. </li><li> Tüm katmanlar yatırılır ve kendiliğinden monte edildikten sonra, ortam yaklaşık 300 ul PDMS kısıtlaması tarafından sınırlanan alanın üst büyük bir düşüş ile doldurun. </li><li> Inkübatör (T = 37,0 o C, CO 2 =% 5) MEA bağlanmış 3 boyutlu yapının koyun 48 saat için takviyesi ile büyüme ortamı kültürünün bir son hacim (yaklaşık 1 mi) ilave edilmeden önce. NOT: Membran parçası (30.000) ve MEA cihazı (6000) üzerine tek bir tabaka üzerinde tanelerin sayısı ile yuvalı plakalarda boncuk sayısı göz önünde bulundurun. Elde edilen 3D yapı mi 5 tabakadan oluşurcrobeads ve hücreler. 3D nöronal ağ geometrik mükemmel olmadığı dikkate alındığında, ortaya çıkan 3D yapı 5-8 tabakadan oluşur olabilir. </li><li> Günlük kuluçkadan sonra dikkatli bir şekilde MEA halka içinde ortam (yaklaşık 900 ul) son hacim ekleyin. 4-5 hafta boyunca 37 ° C&#39;de nemlendirilmiş bir CO2 atmosferi (5%) 3D kültürleri koruyun. Haftada bir kez orta yarısı değiştirin. </li></ol> 5. Konfokal Mikroskopi Toplama <ol><li> Bir tutucu içinde mikroskop sahneye biyolojik örnekler sabitleyin. Doğru bant emisyon filtresi ve sırayla yakalamak için her resim için PMT imajı, kazanç ve ofset (-0.3%) elde etmek için hangi lazer (Argon, 496-555 nm), tarama hızı (400 Hz) olarak ayarlayın doymasını önlemek için ve sinyal gürültü oranını geliştirmek için. Sonuçlar Bölüm Şekil 4 görüntüler elde etmek için kullanılan değerler bildirir. </li><li> Z -stack dizisi, köknar edinimi içinst, üst ve numunenin alt tabakanın z pozisyonuna değerini seçin ve sonra satın alma yapmak için adım boyutunu seçin. </li></ol>

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The authors declare that they have no competing financial interests.

Bu çalışmada, 3D oluşan in vitro platformda yeni bir deneysel ağ elektrofizyoloji için ÇÇA sunulmuştur bağlanmış nöronal kültürleri mühendislik. Z -Axis boyunca nöritik büyümesine izin iskele olarak mikro kullanımı düzlemsel MEA ile entegre edilmek üzere özel olmuştur. Bu şekilde, geçerli ve güvenilir bir in vitro 3D model elde mikro sistem sonuçları ortaya çıkan elektrofizyolojik dinamiklerini 16 incelemek için. MEA kay?...

Mikro-Elektrot Diziler (ÇÇA) bağlanmış in vitro iki boyutlu (2D) sinir ağları nöronal dinamikleri ve temel bağlantı arasındaki etkileşimi incelemek için benimsenen altın standart deneysel bir model arethe. Gelişimi sırasında, nöronlar iyi görüntüler karmaşık ağların yeniden definedspatio-temporalpatternsof aktivite 1,2 (yani patlamaları, ağ patlamaları, rastgele spike aktivitesi). ÇÇA ağ düzeyinde ifade dinamiklerin ayrıntılı bir soruşturma izin birçok sitelerden (onlarca Mikroelektronlar binlerce) elektrofizyolojik etkinliğini kaydedebilirsiniz. Buna ek olarak, ayrışmış kültürlerin kullanılması mühendislik-ağları tasarım possibile yapar. Bu şekilde anlamak kolaydır kaydedilen elektrofizyolojik aktivite arasındaki fonksiyonel ilişkiler ve hücre yoğunluğu 3, modülerlik 4,5 derecesi, heterojen nöronal pop varlığı gibi ağ organizasyonu parametrelerivb ulations 6 Ancak, ayrışmış kültürlenmiş hücreler üzerindeki in vitro çalışmalar, 2D nöronal ağlar dayanmaktadır. Her yönde 7 yayılmış düzleştirilmiş olan 2 boyutlu modeli, somata ve büyüme konilerinin (i) ve akson-dentritler büyümesinin: Bu yaklaşım, in vivo (doğal olarak 3 boyutlu, 3D) sisteme göre basitleştirmeler yol açar. (ii) 2D in vitro ağlar sergi ağının 8 nöronların çoğu içeren aktivitesini patlama hakim elektrofizyolojik dinamikleri kalıplaşmış. Son zamanlarda, farklı çözüm 3D nöronal ağlar ayrışmış in vitro yapımına izin vermek için geliştirilmiştir. Ortak fikir, nöronlar 3D moda yetişebilen bir iskele oluştururken oluşur. Bu tür bir yapı iskelesi polimer jeller ve katı gözenekli matrisler 9-13 ile gerçekleştirilebilir. Polimerlerin mekanik özelliklerini istismar ederek, bu thes içinde hücrelerin gömmek mümkünneurospheres 11 3D kültürleri üniform bir blok tanımlayarak e yapıları. Bu yaklaşımın temel özelliği neurospheres 9,12 katı mekanik özelliğidir. Ancak, bu malzemelerin gözeneklilik sınırlı ve onlar matrisi içinde hücre göçü garanti etmemektedir. Bu dezavantajı aşmak için, olası bir çözüm &#39;birim&#39; modülleri matrisi dilimleme ibarettir. Ne yazık ki, parçacıkların büyüklüğü ve şekli çeşitliliği düzenli katmanlı yapılara ambalaj engel olabilir. 7&#39;de, Cullen ve arkadaşları, biyoaktif bir hücre dışı matris bazlı iskele içinde nöronlar ve / veya astrositlerin oluşan bir 3D nöronal yapı olarak tasarlanmıştır. Böyle bir mühendislik nöral doku 3D mikro-ortamlar içinde nörobiyolojik yanıtları incelemek ve işlemek için in vitro araştırmalarda izin verdi. Bu model ekstrasellüler matriks (ECM) ve / veya hidrojel iskeleleri (500-600 mikron kalınlığında) boyunca dağıtılan nöron ve glia oluşuyordu. Bu co/ mm3 5000 hücreleri - ndition, optimum hücre canlılığı (% 90&#39;dan fazla) 3.750 nihai yoğunlukta hücreler kaplanarak bulunmuştur. Böyle bir yoğunluk değeri fare beyin korteks hücre yoğunluğu yaklaşık 90,000 hücre / mm3 14, in vivo bir durumda bir, çok daha düşük olduğunu belirtmek gerekir. Bu sınırlama Pautot üstesinden gelmek ve 15 hücre yoğunluğu ve ağ bağlantı ağının gerçek zamanlı görüntüleme sağlarken in vivo koşullarında benzer şekilde kontrol edilmektedir 3B, in vitro bir sistem hayata coworkers için. Pratikte, bu yöntem kültürlü nöronlar silis mikro büyümeye edebiliyoruz ayrışmış kavramına dayanmaktadır. Bu boncuklar uyması nöronal hücre gövdeleri ve olgun büyümek uzatmak ve diğer nöronlara sinaptik kişileri tanımlamak için kendi arborizations için yeterince büyük bir büyüme yüzey sağlar. Bu yöntem, fo mono-disperse boncuk kendiliğinden düzeneği özelliklerini kullananrm 3D farklı boncuklar üzerinde nöronlar arasındaki kısıtlı bağlantısı ile farklı katmanlarda nöronların farklı alt kümelerini içeren altıgen diziler katmanlı. Bu yöntemle elde edilen hücre yoğunluğu / mm3 yaklaşık 75,000 hücre idi. Son zamanlarda, biz ÇÇA&#39;lar 16 Pautot yöntemi adapte olması: Elde edilen sonuçlar 3D elektrofizyolojik aktivite 2D ağlar tarafından ifade olandan faaliyetlerinin geniş bir repertuara sunan olduğunu göstermektedir. 3D olgun kültürler gelişmiş bir dinamik sergiler hangi ağ patlaması ve rastgele başak aktivite bir arada hem. Benzer şekilde, Tang ve arkadaşları, 17 Schomer birkaç ay in vitro primer kortikal kültür muhafaza eden bir ipek proteini bazlı gozeneklı iskeleyi fark ve tungsten elektrot ile elektrofizyolojik aktivite göstermiştir. Bu çalışmada, deneysel prosedürleri ÇÇA bağlanmış 3D nöron ağları kurmak için tarif edilecektir.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Laminin</td>
			<td>Sigma-Aldrich</td>
			<td>L2020</td>
			<td>0.05 &#181;g/ml</td>
		</tr>
		<tr>
			<td>Poly-D-lysine</td>
			<td>Sigma-Aldrich</td>
			<td>P6407</td>
			<td>0.05 &#181;g/ml</td>
		</tr>
		<tr>
			<td>Trypsin</td>
			<td>Gibco</td>
			<td>25050-014</td>
			<td align="left">0.125% diluted 1:2 in HBSS w\o CA++, MG++</td>
		</tr>
		<tr>
			<td>DNAase</td>
			<td>Sigma-Aldrich</td>
			<td>D5025</td>
			<td>0.05% diluted&#160; in Hanks solution</td>
		</tr>
		<tr>
			<td>Neurobasal</td>
			<td>Gibco Invitrogen</td>
			<td>21103049</td>
			<td>culture medium</td>
		</tr>
		<tr>
			<td>B27</td>
			<td>Gibco Invitrogen</td>
			<td>17504044</td>
			<td>2% medium supplent</td>
		</tr>
		<tr>
			<td>Fetal bovine serum (FBS)</td>
			<td>Sigma-Aldrich</td>
			<td>F-2442</td>
			<td>10%</td>
		</tr>
		<tr>
			<td>Glutamax-I&#160;</td>
			<td>Gibco</td>
			<td>35050038</td>
			<td>0.5 mM</td>
		</tr>
		<tr>
			<td>gentamicin</td>
			<td>Sigma-Aldrich</td>
			<td>G.1272</td>
			<td>5mg/liter</td>
		</tr>
		<tr>
			<td>Poly-Dimethyl-Siloxane (PDMS)</td>
			<td>Corning Sigma</td>
			<td>481939</td>
			<td>curing agent and the polymer</td>
		</tr>
		<tr>
			<td>Micro-Electrode Arrays</td>
			<td>Multi Channel Systems (MCS)</td>
			<td>60MEA200/30-Ti-pr</td>
			<td>MEA with: Electrode grid 8x8; Electrode spacing and diameter 200 and 30 &#181;m, respectively; plastic ring without thread</td>
		</tr>
		<tr>
			<td>Microbead</td>
			<td>Distrilab-Duke Scientific</td>
			<td>9040</td>
			<td>&#160;1gr Glass Part.Size Stds 40 &#181;m</td>
		</tr>
		<tr>
			<td>Transwell</td>
			<td>Costar Sigma</td>
			<td>CLS 3413</td>
			<td>multiwell plates with membrane insert (6.5 mm diameter porous 0.4 &#181;m)</td>
		</tr>
		<tr>
			<td>HBSS w\o Ca++ ,Mg++&#160;</td>
			<td>Gibco Invitrogen</td>
			<td>14175-052</td>
			<td></td>
		</tr>
		<tr>
			<td>Hanks Buffer Solution&#160;</td>
			<td>Sigma&#160;</td>
			<td>H8264</td>
			<td></td>
		</tr>
		<tr>
			<td>Teflon</td>
			<td>Sigma</td>
			<td>430935-5G</td>
			<td>polytetrafluoroethylene</td>
		</tr>
		<tr>
			<td>Rat</td>
			<td>Sprague Dawley</td>
			<td>Wistar Rat</td>
			<td></td>
		</tr>
		<tr>
			<td>Confocal Microscopy Upright</td>
			<td>Leica</td>
			<td>TCS SP5 AOBS</td>
			<td></td>
		</tr>
		<tr>
			<td>20.0x0.50 WATER objective</td>
			<td>Leica</td>
			<td>Leica HCX APO L U-V-I&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>40.0x0.80 WATER objective</td>
			<td>Leica</td>
			<td>Leica HCX APO L U-V-I&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>25.0x0.95 WATER objective</td>
			<td>Leica</td>
			<td>HCX IRAPO L</td>
			<td></td>
		</tr>
	</tbody>
</table>

interfacing 3d engineered neuronal cultures to micro-electrode arrays: an innovative in vitro experimental model

Currently, large-scale networks derived from dissociated neurons growing and developing in vitro on extracellular micro-transducer devices are the gold-standard experimental model to study basic neurophysiological mechanisms involved in the formation and maintenance of neuronal cell assemblies. However, in vitro studies have been limited to the recording of the electrophysiological activity generated by bi-dimensional (2D) neural networks. Nonetheless, given the intricate relationship between structure and dynamics, a significant improvement is necessary to investigate the formation and the developing dynamics of three-dimensional (3D) networks. In this work, a novel experimental platform in which 3D hippocampal or cortical networks are coupled to planar Micro-Electrode Arrays (MEAs) is presented. 3D networks are realized by seeding neurons in a scaffold constituted of glass microbeads (30-40 &#181;m in diameter) on which neurons are able to grow and form complex interconnected 3D assemblies. In this way, it is possible to design engineered 3D networks made up of 5-8 layers with an expected final cell density. The increasing complexity in the morphological organization of the 3D assembly induces an enhancement of the electrophysiological patterns displayed by this type of networks. Compared with the standard 2D networks, where highly stereotyped bursting activity emerges, the 3D structure alters the bursting activity in terms of duration and frequency, as well as it allows observation of more random spiking activity. In this sense, the developed 3D model more closely resembles in vivo neural networks.

. Bu deneysel prosedürde, ilgili bir rol 3D nöronal ağın büyüme için mekanik iskele tanımlayan mikro-oynanır Şekil 1A ve B Ekran mikro-boncuk düzenlemesi (40 ± 2 um nominal çap diyagramlarıdır; sertifikalı ortalama çapı düzlemde 42.3 ± 1.1 mikron). Bu tür yapıların özelliği mikroboncukları kendiliğinden kompakt altıgen geometri (Şekil 1B ve C) tanımlayan kendine monte olmasıdır. Böylece oluşturulan iskele nörit ve hüc...

Watch this Scientific Journal Video about Interfacing 3D Engineered Neuronal Cultures to Micro-Electrode Arrays: An Innovative In Vitro Experimental Model at JoVE.com

Interfacing 3D Engineered Neuronal Cultures to Micro-Electrode Arrays: An Innovative In Vitro Experimental Model

In this work, a novel experimental model in which 3D neuronal cultures are coupled to planar Micro-Electrode Arrays (MEAs) is presented. 3D networks are built by seeding neurons in a scaffold made up of glass microbeads on which neurons grow and form interconnected 3D structures.

Mikro Elektrot Diziler 3D Engineered Nöronal Kültürler Arayüz: Yenilikçi<em&gt; İn Vitro</em&gt; Deneysel Model

Currently, large-scale networks derived from dissociated neurons growing and developing in vitro on extracellular micro-transducer devices are the ...

interfacing-3d-engineered-neuronal-cultures-to-micro-electrode-arrays

Research

JoVE Journal

Neuroscience

Interfacing 3D Engineered Neuronal Cultures to Micro-Electrode Arrays: An Innovative In Vitro Experimental Model

9.9K Görüntüleme.  University of Genova. In this work, a novel experimental model in which 3D neuronal cultures are coupled to planar Micro-Electrode Arrays (MEAs) is presented. 3D networks are built by seeding neurons in a scaffold made up of glass microbeads on which neurons grow and form interconnected 3D structures.

Video: Interfacing 3D Engineered Neuronal Cultures to Micro-Electrode Arrays: An Innovative In Vitro Experimental Model

Multi-electrode Array Recordings of Neuronal Avalanches in Organotypic Cultures

The cortex is spontaneously active, even in the absence of any particular input or motor output. During development, this activity is important for the migration and differentiation of cortex cell types and the formation of neuronal connections1. In the mature animal, ongoing activity reflects the past and the present state of an animal into which sensory stimuli are seamlessly integrated to compute future actions. Thus, a clear understanding of the organization of ongoing i.e. spontaneous activity is a prerequisite to understand cortex function. 
Numerous recording techniques revealed that ongoing activity in cortex is comprised of many neurons whose individual activities transiently sum to larger events that can be detected in the local field potential (LFP) with extracellular microelectrodes, or in the electroencephalogram (EEG), the magnetoencephalogram (MEG), and the BOLD signal from functional magnetic resonance imaging (fMRI). The LFP is currently the method of choice when studying neuronal population activity with high temporal and spatial resolution at the mesoscopic scale (several thousands of neurons). At the extracellular microelectrode, locally synchronized activities of spatially neighbored neurons result in rapid deflections in the LFP up to several hundreds of microvolts. When using an array of microelectrodes, the organizations of such deflections can be conveniently monitored in space and time. 
Neuronal avalanches describe the scale-invariant spatiotemporal organization of ongoing neuronal activity in the brain2,3. They are specific to the superficial layers of cortex as established in vitro4,5, in vivo in the anesthetized rat 6, and in the awake monkey7. Importantly, both theoretical and empirical studies2,8-10 suggest that neuronal avalanches indicate an exquisitely balanced critical state dynamics of cortex that optimizes information transfer and information processing.
In order to study the mechanisms of neuronal avalanche development, maintenance, and regulation, in vitro preparations are highly beneficial, as they allow for stable recordings of avalanche activity under precisely controlled conditions. The current protocol describes how to study neuronal avalanches in vitro by taking advantage of superficial layer development in organotypic cortex cultures, i.e. slice cultures, grown on planar, integrated microelectrode arrays (MEA; see also 11-14).

A robust way to study neuronal avalanches, i.e. scale-invariant spatio-temporal activity bursts, indicative of critical state dynamics in cortex. Avalanches emerge spontaneously in developing superficial layers of cultured cortex which allows for long-term measurements of the activity with planar integrated multi-electrode arrays (MEA) under precisely controlled conditions.

Organotipik Kültürleri nöronal Çığ Çok elektrot Dizi Kayıtlar

The cortex is spontaneously active, even in the absence of any particular input or motor output.  During development, this activity is important for the ...

Nörobilim

Organotypic Slice Cultures of Embryonic Ventral Midbrain: A System to Study Dopaminergic Neuronal Development in vitro

The mouse is an excellent model organism to study mammalian brain development due to the abundance of molecular and genetic data. However, the developing mouse brain is not suitable for easy manipulation and imaging in vivo since the mouse embryo is inaccessible and opaque. Organotypic slice cultures of embryonic brains are therefore widely used to study murine brain development in vitro. Ex-vivo manipulation or the use of transgenic mice allows the modification of gene expression so that subpopulations of neuronal or glial cells can be labeled with fluorescent proteins. The behavior of labeled cells can then be observed using time-lapse imaging. Time-lapse imaging has been particularly successful for studying cell behaviors that underlie the development of the cerebral cortex at late embryonic stages 1-2. Embryonic organotypic slice culture systems in brain regions outside of the forebrain are less well established. Therefore, the wealth of time-lapse imaging data describing neuronal cell migration is restricted to the forebrain 3,4. It is still not known, whether the principles discovered for the dorsal brain hold true for ventral brain areas. In the ventral brain, neurons are organized in neuronal clusters rather than layers and they often have to undergo complicated migratory trajectories to reach their final position. The ventral midbrain is not only a good model system for ventral brain development, but also contains neuronal populations such as dopaminergic neurons that are relevant in disease processes. While the function and degeneration of dopaminergic neurons has been investigated in great detail in the adult and ageing brain, little is known about the behavior of these neurons during their differentiation and migration phase 5. We describe here the generation of slice cultures from the embryonic day (E) 12.5 mouse ventral midbrain. These slice cultures are potentially suitable for monitoring dopaminergic neuron development over several days in vitro. We highlight the critical steps in generating brain slices at these early stages of embryonic development and discuss the conditions necessary for maintaining normal development of dopaminergic neurons in vitro. We also present results from time lapse imaging experiments. In these experiments, ventral midbrain precursors (including dopaminergic precursors) and their descendants were labeled in a mosaic manner using a Cre/loxP based inducible fate mapping system 6.

Organotypic Slice Cultures of Embryonic Ventral Midbrain: A System to Study Dopaminergic Neuronal Development in vitro

A method to generate organotypic slices from the E12.5 murine embryonic midbrain is described. The organotypic slice cultures can be used to observe the behavior of dopaminergic neurons or other ventral midbrain neurons.

Embriyonik ventral orta beyin Organotipik Dilim Kültürler: dopaminerjik Nöronal Gelişim Eğitim Bir Sistem In vitro</em

The  mouse is an excellent model organism to study mammalian brain development due  to the abundance of molecular and genetic data. However, the ...

VisioTracker, an Innovative Automated Approach to Oculomotor Analysis

Investigations into the visual system development and function necessitate quantifiable behavioral models of visual performance that are easy to elicit, robust, and simple to manipulate. A suitable model has been found in the optokinetic response (OKR), a reflexive behavior present in all vertebrates due to its high selection value. The OKR involves slow stimulus-following movements of eyes alternated with rapid resetting saccades. The measurement of this behavior is easily carried out in zebrafish larvae, due to its early and stable onset (fully developed after 96 hours post fertilization (hpf)), and benefitting from the thorough knowledge about zebrafish genetics, for decades one of the favored model organisms in this field. Meanwhile the analysis of similar mechanisms in adult fish has gained importance, particularly for pharmacological and toxicological applications.
Here we describe VisioTracker, a fully automated, high-throughput system for quantitative analysis of visual performance. The system is based on research carried out in the group of Prof. Stephan Neuhauss and was re-designed by TSE Systems. It consists of an immobilizing device for small fish monitored by a high-quality video camera equipped with a high-resolution zoom lens. The fish container is surrounded by a drum screen, upon which computer-generated stimulus patterns can be projected. Eye movements are recorded and automatically analyzed by the VisioTracker software package in real time.
Data analysis enables immediate recognition of parameters such as slow and fast phase duration, movement cycle frequency, slow-phase gain, visual acuity, and contrast sensitivity.
Typical results allow for example the rapid identification of visual system mutants that show no apparent alteration in wild type morphology, or the determination of quantitative effects of pharmacological or toxic and mutagenic agents on visual system performance.

The VisioTracker is an automated system for the quantitative analysis of visual performance of larval and small adult fish based on the recording of eye movements. It features full control over visual stimulus properties and real-time analysis, enabling high-throughput research in fields such as visual system development and function, pharmacology, neural circuit studies and sensorimotor integration.

VisioTracker, Okülomotor Analizi Yenilikçi Otomatik Yaklaşım

Investigations into the visual system development and function necessitate quantifiable behavioral models of visual performance that are easy to elicit, ...

Fast Micro-iontophoresis of Glutamate and GABA: A Useful Tool to Investigate Synaptic Integration

One of the fundamental interests in neuroscience is to understand the integration of excitatory and inhibitory inputs along the very complex structure of the dendritic tree, which eventually leads to neuronal output of action potentials at the axon. The influence of diverse spatial and temporal parameters of specific synaptic input on neuronal output is currently under investigation, e.g. the distance-dependent attenuation of dendritic inputs, the location-dependent interaction of spatially segregated inputs, the influence of GABAergig inhibition on excitatory integration, linear and non-linear integration modes, and many more.
With fast micro-iontophoresis of glutamate and GABA it is possible to precisely investigate the spatial and temporal integration of glutamatergic excitation and GABAergic inhibition. Critical technical requirements are either a triggered fluorescent lamp, light-emitting diode (LED), or a two-photon scanning microscope to visualize dendritic branches without introducing significant photo-damage of the tissue. Furthermore, it is very important to have a micro-iontophoresis amplifier that allows for fast capacitance compensation of high resistance pipettes. Another crucial point is that no transmitter is involuntarily released by the pipette during the experiment.
Once established, this technique will give reliable and reproducible signals with a high neurotransmitter and location specificity. Compared to glutamate and GABA uncaging, fast iontophoresis allows using both transmitters at the same time but at very distant locations without limitation to the field of view. There are also advantages compared to focal electrical stimulation of axons: with micro-iontophoresis the location of the input site is definitely known and it is sure that only the neurotransmitter of interest is released. However it has to be considered that with micro-iontophoresis only the postsynapse is activated and presynaptic aspects of neurotransmitter release are not resolved. In this article we demonstrate how to set up micro-iontophoresis in brain slice experiments.

In this article we introduce fast micro-iontophoresis of neurotransmitters as a technique to investigate integration of postsynaptic signals with high spatial and temporal precision.

Glutamat ve GABA hızlı Micro-iyontoforez: Synaptic Entegrasyon Araştırma yararlı bir araç

One of the fundamental interests in neuroscience is to understand the integration of excitatory and inhibitory inputs along the very complex structure of ...

Sex Stratified Neuronal Cultures to Study Ischemic Cell Death Pathways

Sex differences in neuronal susceptibility to ischemic injury and neurodegenerative disease have long been observed, but the signaling mechanisms responsible for those differences remain unclear. Primary disassociated embryonic neuronal culture provides a simplified experimental model with which to investigate the neuronal cell signaling involved in cell death as a result of ischemia or disease; however, most neuronal cultures used in research today are mixed sex. Researchers can and do test the effects of sex steroid treatment in mixed sex neuronal cultures in models of neuronal injury and disease, but accumulating evidence suggests that the female brain responds to androgens, estrogens, and progesterone differently than the male brain. Furthermore, neonate male and female rodents respond differently to ischemic injury, with males experiencing greater injury following cerebral ischemia than females. Thus, mixed sex neuronal cultures might obscure and confound the experimental results; important information might be missed. For this reason, the Herson Lab at the University of Colorado School of Medicine routinely prepares sex-stratified primary disassociated embryonic neuronal cultures from both hippocampus and cortex. Embryos are sexed before harvesting of brain tissue and male and female tissue are disassociated separately, plated separately, and maintained separately. Using this method, the Herson Lab has demonstrated a male-specific role for the ion channel TRPM2 in ischemic cell death. In this manuscript, we share and discuss our protocol for sexing embryonic mice and preparing sex-stratified hippocampal primary disassociated neuron cultures. This method can be adapted to prepare sex-stratified cortical cultures and the method for embryo sexing can be used in conjunction with other protocols for any study in which sex is thought to be an important determinant of outcome.

Primary disassociated embryonic hippocampal neuronal cultures are useful for investigating the signaling mechanisms involved in neuron death. Sexing the embryos before the isolation and dissociation of the hippocampus allows the preparation of separate male and female cultures, which enables the researcher to identify and investigate sex-specific cell signaling.

İskemik Hücre Ölümü Pathways Eğitim için seks Katmanlı Nöronal Kültürleri

Sex differences in neuronal susceptibility to ischemic injury and neurodegenerative disease have long been observed, but the signaling mechanisms ...

A Procedure for Implanting Organized Arrays of Microwires for Single-unit Recordings in Awake, Behaving Animals

In vivo electrophysiological recordings in the awake, behaving animal provide a powerful method for understanding neural signaling at the single-cell level. The technique allows experimenters to examine temporally and regionally specific firing patterns in order to correlate recorded action potentials with ongoing behavior. Moreover, single-unit recordings can be combined with a plethora of other techniques in order to produce comprehensive explanations of neural function. In this article, we describe the anesthesia and preparation for microwire implantation. Subsequently, we enumerate the necessary equipment and surgical steps to accurately insert a microwire array into a target structure. Lastly, we briefly describe the equipment used to record from each individual electrode in the array. The fixed microwire arrays described are well-suited for chronic implantation and allow for longitudinal recordings of neural data in almost any behavioral preparation. We discuss tracing electrode tracks to triangulate microwire positions as well as ways to combine microwire implantation with immunohistochemical techniques in order to increase the anatomical specificity of recorded results.

Implanting organized arrays of microwires for use in single-unit electrophysiological recordings presents a number of technical challenges.&#160;Methods for performing this technique and the equipment necessary are described.&#160;Also, the beneficial use of organized microwire arrays to record from distinct neural subregions with high spatial selectivity is discussed.

Hayvanlar davranmak, Awake Tek-birim Recordings Microwires Organize Dizileri implantasyon için Usulü

In vivo electrophysiological recordings in the awake, behaving animal provide a powerful method for understanding neural signaling at the single-cell ...

Genetic Manipulation of Cerebellar Granule Neurons In Vitro and In Vivo to Study Neuronal Morphology and Migration

Developmental events in the brain including neuronal morphogenesis and migration are highly orchestrated processes. In vitro and in vivo analyses allow for an in-depth characterization to identify pathways involved in these events. Cerebellar granule neurons (CGNs) that are derived from the developing cerebellum are an ideal model system that allows for morphological analyses. Here, we describe a method of how to genetically manipulate CGNs and how to study axono- and dendritogenesis of individual neurons. With this method the effects of RNA interference, overexpression or small molecules can be compared to control neurons. In addition, the rodent cerebellar cortex is an easily accessible in vivo system owing to its predominant postnatal development. We also present an in vivo electroporation technique to genetically manipulate the developing cerebella and describe subsequent cerebellar analyses to assess neuronal morphology and migration.

Genetic Manipulation of Cerebellar Granule Neurons In Vitro and In Vivo to Study Neuronal Morphology and Migration

Neuronal morphogenesis and migration are crucial events underlying proper brain development. Here, we describe methods to genetically manipulate cultured cerebellar granule neurons and the developing cerebellum for the assessment of morphology and migratory characteristics of neurons.

Serebellar Granül Nöronlar Genetik Manipülasyon<em&gt; In Vitro</em&gt; Ve<em&gt; In Vivo</em&gt; Nöronal morfoloji ve Göç Eğitim için

Developmental events in the brain including neuronal morphogenesis and migration are highly orchestrated processes. In vitro and in vivo analyses allow ...

Neural Activity Propagation in an Unfolded Hippocampal Preparation with a Penetrating Micro-electrode Array

This protocol describes a method for preparing a new in vitro flat hippocampus preparation combined with a micro-machined array to map neural activity in the hippocampus. The transverse hippocampal slice preparation is the most common tissue preparation to study hippocampus electrophysiology. A longitudinal hippocampal slice was also developed in order to investigate longitudinal connections in the hippocampus. The intact mouse hippocampus can also be maintained in vitro because its thickness allows adequate oxygen diffusion. However, these three preparations do not provide direct access to neural propagation since some of the tissue is either missing or folded. The unfolded intact hippocampus provides both transverse and longitudinal connections in a flat configuration for direct access to the tissue to analyze the full extent of signal propagation in the hippocampus in vitro. In order to effectively monitor the neural activity from the cell layer, a custom made penetrating micro-electrode array (PMEA) was fabricated and applied to the unfolded hippocampus. The PMEA with 64 electrodes of 200 &#181;m in height could record neural activity deep inside the mouse hippocampus. The unique combination of an unfolded hippocampal preparation and the PMEA provides a new in-vitro tool to study the speed and direction of propagation of neural activity in the two-dimensional CA1-CA3 regions of the hippocampus with a high signal to noise ratio.

We have developed an in vitro unfolded hippocampus which preserves CA1-CA3 array of neurons. Combined with the penetrating micro-electrode array, neural activity can be monitored in both the longitudinal and transverse orientations. This method provides advantages over hippocampal slice preparations as the propagation in the entire hippocampus can be recorded simultaneously.

Bir Penetran Mikro-elektrot Array ile bir Kırımsız Hipokampal Hazırlık Sinir Faaliyet Yayılım

This protocol describes a method for preparing a new in vitro flat hippocampus preparation combined with a micro-machined array to map neural activity in ...

Time-dependent Increase in the Network Response to the Stimulation of Neuronal Cell Cultures on Micro-electrode Arrays

Micro-electrode arrays (MEAs) can be used to investigate drug toxicity, design paradigms for next-generation personalized medicine, and study network dynamics in neuronal cultures. In contrast with more traditional methods, such as patch-clamping, which can only record activity from a single cell, MEAs can record simultaneously from multiple sites in a network, without requiring the arduous task of placing each electrode individually. Moreover, numerous control and stimulation configurations can be easily applied within the same experimental setup, allowing for a broad range of dynamics to be explored. One of the key dynamics of interest in these in vitro studies has been the extent to which cultured networks display properties indicative of learning. Mouse neuronal cells cultured on MEAs display an increase in response following training induced by electrical stimulation. This protocol demonstrates how to culture neuronal cells on MEAs; successfully record from over 95% of the plated dishes; establish a protocol to train the networks to respond to patterns of stimulation; and sort, plot, and interpret the results from such experiments. The use of a proprietary system for stimulating and recording neuronal cultures is demonstrated. Software packages are also used to sort neuronal units. A custom-designed graphical user interface is used to visualize post-stimulus time histograms, inter-burst intervals, and burst duration, as well as to compare the cellular response to stimulation before and after a training protocol. Finally, representative results and future directions of this research effort are discussed.

Mouse neuronal cells cultured on multi-electrode arrays display an increase in response following electrical stimulation. This protocol demonstrates how to culture neurons, how to record activity, and how to establish a protocol to train the networks to respond to patterns of stimulation.

Mikro Elektrod Dizilerinde Nöronal Hücre Kültürlerinin Uyarılmasına Ağ Yanıtına Zamana Bağlı Artış

Micro-electrode arrays (MEAs) can be used to investigate drug toxicity, design paradigms for next-generation personalized medicine, and study network ...

In Vitro Wedge Slice Preparation for Mimicking In Vivo Neuronal Circuit Connectivity

In vitro slice electrophysiology techniques measure single-cell activity with precise electrical and temporal resolution. Brain slices must be relatively thin to properly visualize and access neurons for patch-clamping or imaging, and in vitro examination of brain circuitry is limited to only what is physically present in the acute slice. To maintain the benefits of in vitro slice experimentation while preserving a larger portion of presynaptic nuclei, we developed a novel slice preparation. This &#8220;wedge slice&#8221; was designed for patch-clamp electrophysiology recordings to characterize the diverse monaural, sound-driven inputs to medial olivocochlear (MOC) neurons in the brainstem. These neurons receive their primary afferent excitatory and inhibitory inputs from neurons activated by stimuli in the contralateral ear and corresponding cochlear nucleus (CN). An asymmetrical brain slice was designed which is thickest in the rostro-caudal domain at the lateral edge of one hemisphere and then thins towards the lateral edge of the opposite hemisphere. This slice contains, on the thick side, the auditory nerve root conveying information about auditory stimuli to the brain, the intrinsic CN circuitry, and both the disynaptic excitatory and trisynaptic inhibitory afferent pathways that converge on contralateral MOC neurons. Recording is performed from MOC neurons on the thin side of the slice, where they are visualized using DIC optics for typical patch-clamp experiments. Direct stimulation of the auditory nerve is performed as it enters the auditory brainstem, allowing for intrinsic CN circuit activity and synaptic plasticity to occur at synapses upstream of MOC neurons. With this technique, one can mimic in vivo circuit activation as closely as possible within the slice. This wedge slice preparation is applicable to other brain circuits where circuit analyses would benefit from preservation of upstream connectivity and long-range inputs, in combination with the technical advantages of in vitro slice physiology.

Integration of diverse synaptic inputs to neurons is best measured in a preparation that preserves all pre-synaptic nuclei for natural timing and circuit plasticity, but brain slices typically sever many connections. We developed a modified brain slice to mimic in vivo circuit activity while maintaining in vitro experimentation capability.

In Vitro Kama Dilimi In Vivo Nöronal Devre Bağlantısı Nın TaklitI Için Hazırlık

In vitro slice electrophysiology techniques measure single-cell activity with precise electrical and temporal resolution. Brain slices must be relatively ...