Kind gift of THP-1 cells from Dr. Mark Chong and assistance in microfabrication from Dr. Yuejun Kang and Dr. Nishanth V. Menon (School of Chemical and Biomedical Engineering, Nanyang Technological University) were greatly acknowledged. This project was funded by NTU-Northwestern Institute of Nanomedicine (Nanyang Technological University). H.W.H. was supported by Lee Kong Chian School of Medicine (LKCMedicine) postdoctoral fellowship.

1. Le nanoparticelle (NP) Etichettatura delle cellule staminali mesenchimali e monociti <ol><li> Le cellule staminali mesenchimali Cultura (MSC) in terreno di Dulbecco modificato Eagle (DMEM) supplementato con 10% siero fetale bovino (FBS) e antibiotici per ≥80% di confluenza prima di etichettatura. Analogamente, la cultura cellule THP-1 (ATCC) in Roswell Park Memorial Institute (RPMI) 1640 supplementato con 10% FBS ad una densità di ~ 10 6 cellule / ml. </li><li> NP carico di silice (~ 500 micron), con soluzione colorante calceina (200 micron) con agitazione durante la notte. Realizzare PLGA-calceina AM (CAM) utilizzando un protocollo descritto in precedenza. 22 <ol><li> Sciogliere CAM 250 mg e 100 mg PLGA (50:50) in cloroformio a 4 ° C. </li><li> Generare NP emulsione singoli utilizzando un omogeneizzatore ad alta velocità (13.600 xg, 60 sec) a temperatura ambiente. Si evapora il cloroformio in una cappa chimica (≥3 ore) prima della raccolta mediante centrifugazione (3.400 xg per 5 min), lavaggio (doppia distinta sacqua riempito), congelare-essiccazione e stoccaggio in -20 ° C. </li></ol></li><li> Incubare CAM-PLGA NP (1 mg) o NP di silice calceina (150 mcg) a poli-L-lisina soluzione 0,01% (PLL) a temperatura ambiente per 15 - 20 min. </li><li> Centrifugare a 3.400 xg per 5 minuti per rimuovere l&#39;eccesso PLL surnatante prima risospensione NP in 1 ml di terreno di coltura rispettivo. </li><li> Incubare le NP con le cellule (MSC o THP-1, ~ 1 - 2 x 10 6 cellule in totale) per circa 24 ore (0,1 mg · concentrazione ml -1 etichettatura). </li><li> Dissociarsi e raccogliere le cellule staminali mesenchimali aderenti etichettati con 2 ml di 0,25% tripsina (5 min, 37 ° C) e spegnere con 6 ml di DMEM. Centrifugare le cellule a (1.000 xg, 4 min) e risospendere ad una concentrazione di 10 5 - 10 6 cellule / ml per l&#39;elaborazione microfluidica. Utilizzare etichettati cellule THP-1 (10 Giugno 5-10 cellule / ml) direttamente per la purificazione microfluidica. </li></ol> 2. Preparazione dispositivo a microfluidi <ol><li> fabbricazione di dispositivi <ol><li> Realizzare il dispositivo a spirale microfluidica (500 micron (w) x 115 micron (h)) con polidimetilsilossano (PDMS) da un kit commerciale utilizzando passi litografia soft standard. 23 </li><li> Mescolare 30 g del prepolimero base e 3 g induritore accuratamente in una barca pesatura. De-gas la miscela in un essiccatore per 60 minuti per eliminare le bolle d&#39;aria. </li><li> Versare il composto PDMS sul master stampo di wafer di silicio modellata con il disegno del canale a spirale attenzione ad un&#39;altezza di ~ 5 - 10 mm. </li><li> De-gas la miscela sotto vuoto essiccatore per 60 minuti ancora per rimuovere eventuali bolle d&#39;aria. Ripetere il processo fino a quando tutte le bolle vengono eliminati. </li><li> Curare la miscela PDMS in un forno a 80 ° C per 2 ore fino a quando il PDMS è impostato. Assicurarsi che il wafer non sia inclinato durante l&#39;indurimento ad avere un&#39;altezza costante dispositivo. </li><li> Tagliare il dispositivo a spirale PDMS con un bisturi e la buccia con attenzione la lastra PDMS dallo stampo master. </li><li> Trim i bordi del dispositivo con un bisturi per assicurare superficie liscia per incollaggio. </li><li> Punzone due fori (1,5 mm) per gli ingressi e due fori (1,5 mm) per le prese sul dispositivo PDMS utilizzando una biopsia perforatore 1,5 mm. </li><li> Lavare il dispositivo con isopropanolo (IPA) per rimuovere eventuali detriti e asciugare il dispositivo in un forno a 80 ° C per 5 min. </li><li> Pulire la superficie inferiore del dispositivo PDMS (con le caratteristiche del canale) con nastro adesivo. </li><li> Pulire un lato di un vetrino (2 &quot;3&quot;) mediante nastro adesivo. </li><li> Posizionare con cura ed esporre le superfici pulite del dispositivo PDMS e vetrino nella camera di un pulitore plasma e sottoporli a vuoto per 60 sec. Successivamente, accendere il plasma potere al massimo e abbassare la pressione nella camera finché la camera diventa di colore rosa. <ol><li> Esporre le superfici a plasma ad aria per 60 sec. Il plasma crea le specie reattive sulle superfici esposte delle PDMS e vetro che consente di legame stretto quando entrano in fisicaal contatto. Spegnere l&#39;alimentazione al plasma e rilasciare la pressione dal più pulito al plasma per recuperare il vetrino dispositivo e vetro. </li></ol></li><li> Incollare il dispositivo PDMS e vetrino insieme premendo le superfici plasma esposte ermeticamente, senza far bolle sono intrappolati tra le due superfici. </li><li> Riscaldare il dispositivo accoppiato mediante una piastra fissata a 80 ° C per 2 ore per rafforzare il legame. </li></ol></li><li> Funzionamento del dispositivo <ol><li> Tagliare due pezzi di tubo (1,52 millimetri OD) di ~ 15 - 20 cm per le siringhe di aspirazione e collegare una siringa (calibro 23) su una estremità di ciascun tubo. </li><li> Tagliare due pezzi di tubo (1,52 millimetri OD) di ~ 5 - 10 cm per le prese e fissare i fori di uscita del dispositivo PDMS. </li><li> Prima di campionare esecuzione, manualmente adescare il dispositivo con una siringa contenente il 70% di etanolo fino fuoriesce dal tubo di uscita. Lasciare il sit etanolo per 30 secondi a 1 minuto per sterilizzare il dispositivo. </li><li> Caricare 30 ml di filtrato(0,2 micron pori) tampone guaina (Phosphate-Buffered Saline (PBS) con 0,1% di sieroalbumina bovina (BSA)) nella siringa 60 ml e fissare la siringa su una pompa a siringa. Impostare la pompa per le impostazioni corrette (dimensioni della siringa: 60 ml, Volume: 60.000 ml). Nota: L&#39;aggiunta di BSA PBS è ridurre al minimo vincolante cellula-cellula e vincolante tra le cellule e il dispositivo PDMS non specifico. </li><li> Carico 3 ml di cellule marcate nella siringa 3 ml e fissare la siringa su una pompa a siringa separata. Impostare la pompa per le impostazioni corrette (dimensioni della siringa: 3 ml, Volume: 3.000 ml). </li><li> Verificare che non bolle d&#39;aria intrappolate nelle siringhe per garantire un flusso stabile. Rimuovere eventuali bolle d&#39;aria estraendo delicatamente alcune gocce di liquido dall&#39;ugello. </li><li> Collegare le punte ingresso siringa e tubo per le siringhe, e inserirli nei rispettivi ingressi del dispositivo (guaina e ingresso campione). Assicurarsi che non vi siano bolle lungo il tubo. </li><li> Montare i dispositivi su un invertitoEd microscopio a contrasto di fase per l&#39;imaging in tempo reale durante il processo di selezione delle cellule. </li><li> Fissare un piccolo bicchiere di rifiuti e due provette da 15 ml in prossimità del dispositivo sul palco microscopio con adesivi. </li><li> Posizionare i tubi di scarico nel bicchiere rifiuti. </li><li> Impostare il rapporto di flusso per il campione di tampone guaina a 1:10 e iniziare a entrambe le pompe siringa per avviare il processo di smistamento Esempio (: per siringa campione e 1200 microlitri per guaina siringa 120 microlitri / min / min; velocità di flusso del canale ~ 0,38 m / sec ). </li><li> Eseguire il dispositivo per 1,5 min per il flusso si stabilizzi. Questo può essere confermato dalla presenza di cellule inerziale focalizzate vicino alla parete interna del canale in campo chiaro con contrasto di fase usando una macchina fotografica ad alta velocità (~ 5.000 - 10.000 fotogrammi al secondo (fps), il tempo di esposizione: 10-50 msec). </li><li> Posizionare i tubi di uscita in diverse provette per raccogliere gli eluenti dalla presa cellulare e uscita dei rifiuti. </li></ol></li></ol>

<ol>
	<li>Wiraja, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Aptamer+technology+for+tracking+cells'+status+&amp;+function.">Aptamer technology for tracking cells' status &amp; function.</a> Mol. Cell. Ther. 2, 33 (2014).</li><li>Yeo, D. C., Wiraja, C., Mantalaris, A., Xu, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanosensors+for+Regenerative+Medicine.">Nanosensors for Regenerative Medicine.</a> J. Biomed. Nanotech. 10, 2722-2746 (2014).</li><li>Naumova, A. V., Modo, M., Moore, A., Murry, C. E., Frank, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+imaging+in+regenerative+medicine.">Clinical imaging in regenerative medicine.</a> Nat. Biotechnol. 32, 804-818 (2014).</li><li>Soenen, S. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+toxicity+of+inorganic+nanoparticles:+Common+aspects+and+guidelines+for+improved+nanotoxicity+evaluation.">Cellular toxicity of inorganic nanoparticles: Common aspects and guidelines for improved nanotoxicity evaluation.</a> Nano Today. 6, 446-465 (2011).</li><li>Donaldson, K., Poland, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanotoxicity:+challenging+the+myth+of+nano-specific+toxicity.">Nanotoxicity: challenging the myth of nano-specific toxicity.</a> Curr. Opin. Biotechnol. 24, 724-734 (2013).</li><li>Veiseh, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Size-+and+shape-dependent+foreign+body+immune+response+to+materials+implanted+in+rodents+and+non-human+primates.">Size- and shape-dependent foreign body immune response to materials implanted in rodents and non-human primates.</a> Nat. Mater. 14, 643-651 (2015).</li><li>Jones, S. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanoparticle+clearance+is+governed+by+Th1/Th2+immunity+and+strain+background.">Nanoparticle clearance is governed by Th1/Th2 immunity and strain background.</a> J. Clin. Invest. 123, 3061-3073 (2013).</li><li>Marchi, L. F., Sesti-Costa, R., Chedraoui-Silva, S., Mantovani, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+four+methods+for+the+isolation+of+murine+blood+neutrophils+with+respect+to+the+release+of+reactive+oxygen+and+nitrogen+species+and+the+expression+of+immunological+receptors.">Comparison of four methods for the isolation of murine blood neutrophils with respect to the release of reactive oxygen and nitrogen species and the expression of immunological receptors.</a> Comp. Clin. Pathol. 23, 1469-1476 (2014).</li><li>Morton, K. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hydrodynamic+metamaterials:+Microfabricated+arrays+to+steer,+refract,+and+focus+streams+of+biomaterials.">Hydrodynamic metamaterials: Microfabricated arrays to steer, refract, and focus streams of biomaterials.</a> Proc. Natl. Acad. of Sci USA. 105, 7434-7438 (2008).</li><li>Hu, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Marker-specific+sorting+of+rare+cells+using+dielectrophoresis.">Marker-specific sorting of rare cells using dielectrophoresis.</a> Proc. Natl. Acad. of Sci USA. 102, 15757-15761 (2005).</li><li>Cummings, E. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Streaming+dielectrophoresis+for+continuous-flow+microfluidic+devices.">Streaming dielectrophoresis for continuous-flow microfluidic devices.</a> IEEE Eng. Med. Biol. Mag. 22, 75-84 (2003).</li><li>Augustsson, P., Persson, J., Ekstrom, S., Ohlin, M., Laurell, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Decomplexing+biofluids+using+microchip+based+acoustophoresis.">Decomplexing biofluids using microchip based acoustophoresis.</a> Lab Chip. 9, 810-818 (2009).</li><li>Di Carlo, D., Irimia, D., Tompkins, R. G., Toner, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+inertial+focusing,+ordering,+and+separation+of+particles+in+microchannels.">Continuous inertial focusing, ordering, and separation of particles in microchannels.</a> Proc. Natl. Acad. of Sci USA. 104, 18892-18897 (2007).</li><li>Hur, S. C., Henderson-MacLennan, N. K., McCabe, E. R. B., Di Carlo, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Deformability-based+cell+classification+and+enrichment+using+inertial+microfluidics.">Deformability-based cell classification and enrichment using inertial microfluidics.</a> Lab Chip. 11, 912-920 (2011).</li><li>Mach, A. J., Di Carlo, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Continuous+scalable+blood+filtration+device+using+inertial+microfluidics.">Continuous scalable blood filtration device using inertial microfluidics.</a> Biotechnol. Bioengin. 107, 302-311 (2010).</li><li>Gossett, D. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inertial+manipulation+and+transfer+of+microparticles+across+laminar+fluid+streams.">Inertial manipulation and transfer of microparticles across laminar fluid streams.</a> Small. 8, 2757-2764 (2012).</li><li>Amini, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Engineering+fluid+flow+using+sequenced+microstructures.">Engineering fluid flow using sequenced microstructures.</a> Nat. Commun. 4, 1826 (2013).</li><li>Sollier, E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inertial+microfluidic+programming+of+microparticle-laden+flows+for+solution+transfer+around+cells+and+particles.">Inertial microfluidic programming of microparticle-laden flows for solution transfer around cells and particles.</a> Microfluid. Nanofluid. 19, 53-65 (2015).</li><li>Lee, W. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multivariate+biophysical+markers+predictive+of+mesenchymal+stromal+cell+multipotency.">Multivariate biophysical markers predictive of mesenchymal stromal cell multipotency.</a> Proc. Natl. Acad. of Sci USA. 111, E4409-E4418 (2014).</li><li>Hou, H. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+retrieval+of+circulating+tumor+cells+using+centrifugal+forces.">Isolation and retrieval of circulating tumor cells using centrifugal forces.</a> Sci. Rep. 3, 1259 (2013).</li><li>Hou, H. W., Bhattacharyya, R. P., Hung, D. T., Han, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Direct+detection+and+drug-resistance+profiling+of+bacteremias+using+inertial+microfluidics.">Direct detection and drug-resistance profiling of bacteremias using inertial microfluidics.</a> Lab Chip. 15, 2297-2307 (2015).</li><li>Yeo, D. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interference-free+Micro/nanoparticle+Cell+Engineering+by+Use+of+High-Throughput+Microfluidic+Separation.">Interference-free Micro/nanoparticle Cell Engineering by Use of High-Throughput Microfluidic Separation.</a> ACS Appl. Mater. Inter. 7, 20855-20864 (2015).</li><li>Xia, Y., Whitesides, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Soft+Lithography.">Soft Lithography.</a> Angew. Chem. Int. Edit. 37, 550-575 (1998).</li><li>Lee, W. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-throughput+cell+cycle+synchronization+using+inertial+forces+in+spiral+microchannels.">High-throughput cell cycle synchronization using inertial forces in spiral microchannels.</a> Lab Chip. 11, 1359-1367 (2011).</li><li>Kuntaegowdanahalli, S. S., Bhagat, A. A., Kumar, G., Papautsky, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inertial+microfluidics+for+continuous+particle+separation+in+spiral+microchannels.">Inertial microfluidics for continuous particle separation in spiral microchannels.</a> Lab Chip. 9, 2973-2980 (2009).</li></ol>

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La tecnologia di purificazione delle cellule DFF qui descritta consente la separazione rapida e continua di cellule marcate in maniera elevata produttività. Questo approccio separazione è ideale per grandi volumi campione o campione di trasformazione alta concentrazione cellulare, ed è meglio di filtrazione su membrana a base convenzionale che è soggetta a intasamento dopo un uso prolungato. Analogamente, separazione magnetica affinità basata richiede ulteriori operazioni di etichettatura cellule che sono laboriosi...

Ingegneria delle cellule da agenti caricato micro / nanoparticelle (NP) è un metodo di integrazione libera e versatile semplice, genomica per migliorare la capacità bioimmagini e aumentare / integrare le sue proprietà terapeutiche nativi nella medicina rigenerativa. 1-3 modificazioni cellulari si ottengono l&#39;etichettatura del membrana plasmatica o nel citoplasma con un eccesso di concentrazione di NP agente-caricato di saturare i siti di legame. Tuttavia, un grave inconveniente di questo metodo è la quantità significative di particelle non legate rimangono in soluzione dopo i processi di etichettatura delle cellule, che possono potenzialmente confondere precisa identificazione delle cellule di particelle-ingegnerizzato o complicare risultati terapeutici. 4,5 Inoltre, l&#39;esposizione a NP contenenti trasformativa agenti (fattori di crescita, corticosteroidi, ecc) a eccessivamente alta concentrazione possono causare citotossicità e l&#39;esposizione mal possono indurre conseguenze non volute sulle cellule non bersaglio. Anche i portatori di particolato composto of materiali &quot;biocompatibili&quot; [per esempio, poli (co-glicolico acido lattico), PLGA] possono incitano potenti risposte delle cellule immunitarie in determinate condizioni pure. 6 Ciò è particolarmente rischiosa in individui con sistema immunitario compromesso (per esempio, l&#39;artrite reumatoide) che potenzialmente ritardi sistemica pallone nanoparticella. 7 Pertanto, rimozione efficiente di particelle libere prima dell&#39;introduzione delle cellule particelle-ingegnerizzato è di grande importanza per minimizzare profilo di tossicità e ridurre l&#39;esposizione alle particelle misdirected agenti caricata in vivo. Conventional centrifugazione gradiente è spesso usato per separare le cellule ingegnerizzate da particelle libere, ma è laboriosa e gestito in modalità batch. Inoltre, sforzi di taglio con esperienza da parte delle cellule durante la centrifugazione ad alta velocità ed i costituenti del mezzo gradiente di densità possono compromettere l&#39;integrità delle cellule e / o il comportamento delle cellule influenza. 8 microfluidica è un&#39;alternativa attraente con SEVtecnologie di separazione rale tra cui spostamento laterale deterministico (DLD) 9, dieletrophoresis 10,11 e acoustophoresis 12 sviluppata per le piccole particelle di separazione e le applicazioni di scambio di buffer. Tuttavia, questi metodi soffrono di bassa produttività (1-10 ml · min - 1) e sono soggetti a intasamento problemi. separazioni attivi quali i metodi dielettroforesi basati richiedono anche le differenze di fenotipi cellulari dielettroforetica intrinseche o aggiuntive misure di etichettatura delle cellule per realizzare la separazione. Un approccio più promettente coinvolge microfluidica inerziale - la migrazione laterale di particelle o cellule attraverso semplifica mettere a fuoco in posizioni distinte a causa di forze di sollevamento dominanti (F L) ad alto numero di Reynolds (Re) 13 Grazie alle sue condizioni di alta portata e la risoluzione dimensione superiore. , è stato spesso sfruttato per applicazioni di scambio di dimensioni basate su separazione delle cellule 14,15 e di buffer. 16-18 HoweveR, le prestazioni di Exchange tampone rimane povero con una soluzione di contaminante ~10-30% come le cellule separate di solito rimangono in prossimità del confine tra soluzioni originali e nuovo buffer. 16-18 Ancora più importante, la distribuzione delle dimensioni delle cellule bersaglio deve essere simile a raggiungere precisa inerziale focalizzazione e separazione dalla soluzione tampone originale che pone un problema particolare nel trattamento di tipi cellulari eterogenei dimensioni come le cellule staminali mesenchimali (MSC). 19 Abbiamo già messo a punto una nuova tecnica di smistamento delle cellule inerziale microfluidica chiamato Dean flusso Frazionamento (DFF) per isolare le cellule tumorali circolanti (CTC) 20 e batteri 21 dal sangue intero con un 2-ingresso, 2-outlet dispositivo microcanali spirale. In questo protocollo video, descriveremo il processo di cellule THP-1 di etichettatura (acuta linea cellulare monocitica leucemia umana) sospensione monociti (~ 15 micron) e MSC (10-30 micron) con calceina-lNP oaded, seguita da realizzazione e di funzionamento della spirale Microdevice DFF per recupero efficiente di cellule marcate e rimozione delle NP non legati. 22 Questa strategia unica purificazione passo consente il ripristino continuo della sospensione etichettati e cellule aderenti sospese in soluzione tampone fresco senza centrifugazione. Inoltre, si può elaborare fino a 10 milioni di cellule · ml -1, una densità cellulare suscettibili per applicazioni di medicina rigenerativa.

<table border="0" cellpadding="0" cellspacing="0" width="781">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td colspan="4" height="21" style="height:21px;width:780px;">Cell lines &#38; Media</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Mesenchymal Stem Cells (MSCs)</td>
			<td style="width:127px;">Lonza</td>
			<td style="width:119px;">PT-2501</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Dulbecco&#8217;s modified Eagle&#8217;s medium (DMEM)</td>
			<td style="width:127px;">Lonza</td>
			<td style="width:119px;">12-614F</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Fetal Bovine Serum (FBS)</td>
			<td style="width:127px;">Gibco</td>
			<td style="width:119px;">10270-106</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">THP-1 monocyte cells (THP-1)</td>
			<td style="width:127px;">ATCC</td>
			<td style="width:119px;">TIB-202</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Roswell Park Memorial Institute (RPMI) 1640 media</td>
			<td style="width:127px;">Lonza</td>
			<td style="width:119px;">12-702F</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Name</td>
			<td style="width:127px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr height="21">
			<td colspan="4" height="21" style="height:21px;width:780px;">Reagents &#38; Materials</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">0.01% poly-L-lysine (PLL)</td>
			<td style="width:127px;">Sigma-Aldrich</td>
			<td style="width:119px;">P8920</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">3 mL Syringe</td>
			<td style="width:127px;">BD</td>
			<td style="width:119px;">302113</td>
			<td>Syringe 3ml Luer-Lock</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">60 ml Syringe</td>
			<td style="width:127px;">BD</td>
			<td style="width:119px;">309653</td>
			<td>Syringe 60ml Luer-Lock</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Bovine Serum Albumin (BSA)</td>
			<td style="width:127px;">Biowest</td>
			<td style="width:119px;">P6154-100GR</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Calcein, AM (CAM)</td>
			<td style="width:127px;">Life Technologies</td>
			<td style="width:119px;">C1430</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Calcein</td>
			<td style="width:127px;">Sigma-Aldrich</td>
			<td style="width:119px;">C0875</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Isopropanol</td>
			<td style="width:127px;">Fisher Chemical</td>
			<td style="width:119px;">#P/7507/17</td>
			<td>HPLC Grade 2.5 L</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Phosphate-Buffered Saline (PBS)</td>
			<td style="width:127px;">Lonza</td>
			<td style="width:119px;">17-516Q/12</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Plain Microscope Slides</td>
			<td style="width:127px;">Fisher Scientific</td>
			<td style="width:119px;">FIS#12-550D</td>
			<td>75 X 25 X 1 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Polydimethylsiloxane (PDMS)</td>
			<td style="width:127px;">Dow Corning</td>
			<td style="width:119px;">SYLGARD&#174; 184</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Scotch tape</td>
			<td style="width:127px;">3M</td>
			<td style="width:119px;">21200702044</td>
			<td>18mm x 25m</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Silica NPs (&#8764;200 &#956;m)</td>
			<td style="width:127px;">Sigma-Aldrich</td>
			<td style="width:119px;">748161</td>
			<td>Pore size 4 nm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Syringe Tip</td>
			<td style="width:127px;">JEC Technology</td>
			<td style="width:119px;">7018302</td>
			<td style="width:167px;">23GA .013 X .25</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Trypsin-EDTA (0.25%)</td>
			<td style="width:127px;">Life Technologies</td>
			<td style="width:119px;">25200-056</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Tygon Tubing</td>
			<td style="width:127px;">Spectra-Teknik</td>
			<td style="width:119px;">06419-01</td>
			<td>.02X.06&#34; 100</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:368px;">Name</td>
			<td style="width:127px;">Company</td>
			<td style="width:119px;">Catalog Number</td>
			<td>Comments/Description</td>
		</tr>
		<tr height="21">
			<td colspan="4" height="21" style="height:21px;width:780px;">Equipment</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Biopsy punch</td>
			<td style="width:127px;">Harris Uni-Core</td>
			<td>69036-15</td>
			<td>1.50 mm</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Dessicator</td>
			<td style="width:127px;">Scienceware</td>
			<td style="width:119px;">111/4 IN OD</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">High-speed Camera</td>
			<td style="width:127px;">Phantom&#160;</td>
			<td style="width:119px;">V9.1</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Inverted phase-contrast microscope&#160;</td>
			<td style="width:127px;">Nikon</td>
			<td>Eclipse Ti</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Plasma cleaner</td>
			<td style="width:127px;">Harrick Plasma</td>
			<td style="width:119px;">PDC-002</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:368px;">Syringe Pump</td>
			<td style="width:127px;">Chemyx</td>
			<td style="width:119px;">CX Fusion 200</td>
			<td></td>
		</tr>
	</tbody>
</table>

microfluidic buffer exchange for interference-free micro/nanoparticle cell engineering

cellule Engineering con micro-ingrediente attivo-caricato / nanoparticelle (NP) sta diventando un metodo sempre più popolare per migliorare le proprietà terapeutiche nativi, abilitare l&#39;imaging bio e controllare il fenotipo delle cellule. Un problema critico ancora affrontato in modo inadeguato è il numero di particelle che rimangono non legato dopo l&#39;etichettatura delle cellule che non può essere facilmente rimosso per centrifugazione convenzionale. Questo porta ad un aumento della bio rumore delle immagini di sfondo e può impartire effetti trasformativi sulle cellule non bersaglio adiacenti. In questo protocollo, presentiamo una strategia inerziale microfluidica a base di buffer di scambio definito come Dean flusso Frazionamento (DFF) per separare in modo efficiente cellule marcate da NP liberi in un modo elevato throughput. Il Microdevice spirale sviluppato facilita raccolta continua (&gt; il recupero delle cellule del 90%) delle cellule purificate (THP-1 e MSC) sospese in nuova soluzione tampone, oltre a raggiungere&gt; 95% esaurimento di colorante fluorescente non legato o NP dye-caricato (silica o PLGA). Questo single-step, la strategia di purificazione delle cellule size-based permette un throughput di elaborazione ad alta cella (10 6 cellule / min) ed è molto utile per la purificazione delle cellule di grandi volumi di micro / cellule nanoparticelle progettato per realizzare applicazioni cliniche senza interferenze.

Dopo l&#39;etichettatura delle cellule con bio di imaging NP agente-caricato durante la notte, le cellule marcate (contenente particelle libere) vengono raccolte e purificate dal DFF spirale Microdevice per rimuovere NP liberi in un unico processo passo (Figura 1A). Il 2-ingresso, microchannel spirale 2-presa è stato progettato da un software di ingegneria e microfabbricazione usando SU-8 fotosensibile. Il wafer di silicio modellato viene quindi utilizzato come modello ...

Watch this Scientific Journal Video about Microfluidic Buffer Exchange for Interference-free Micro/Nanoparticle Cell Engineering at JoVE.com

Microfluidic Buffer Exchange for Interference-free Micro/Nanoparticle Cell Engineering

Questo protocollo descrive l&#39;uso di una strategia di scambio tampone microfluidica basata inerziale per purificare cellule ingegnerizzate micro / nanoparticelle con efficiente esaurimento delle particelle non legate.

Scambio Buffer Microfluidic per senza interferenze micro / nanoparticelle cellulare Ingegneria

Engineering cells with active-ingredient-loaded micro/nanoparticles (NPs) is becoming an increasingly popular method to enhance native therapeutic ...

microfluidic-buffer-exchange-for-interference-free-micronanoparticle

Research

JoVE Journal

Bioengineering

9.0K Views.  Nanyang Technological University.  Questo protocollo descrive l'uso di una strategia di scambio tampone microfluidica basata inerziale per purificare cellule ingegnerizzate micro / nanoparticelle con efficiente esaurimento delle particelle non legate. 

Video: Microfluidic Buffer Exchange for Interference-free Micro/Nanoparticle Cell Engineering

Site-specific Bacterial Chromosome Engineering: &#934;C31 Integrase Mediated Cassette Exchange (IMCE)

The bacterial chromosome may be used to stably maintain foreign DNA in the mega-base range1. Integration into the chromosome circumvents issues such as plasmid replication, plasmid stability, plasmid incompatibility, and plasmid copy number variance. This method uses the site-specific integrase from the Streptomyces phage (&Phi;) C312,3. The &Phi;C31 integrase catalyzes a direct recombination between two specific DNA sites: attB and attP (34 and 39 bp, respectively)4. This recombination is stable and does not revert5. A "landing pad" (LP) sequence consisting of a spectinomycin- resistance gene, aadA (SpR), and the E. coli &szlig;-glucuronidase gene (uidA) flanked by attP sites has been integrated into the chromosomes of Sinorhizobium meliloti, Ochrobactrum anthropi, and Agrobacterium tumefaciens in an intergenic region, the ampC locus, and the tetA locus, respectively. S. meliloti is used in this protocol. Mobilizable donor vectors containing attB sites flanking a stuffer red fluorescent protein (rfp) gene and an antibiotic resistance gene have also been constructed. In this example the gentamicin resistant plasmid pJH110 is used. The rfp gene6 may be replaced with a desired construct using SphI and PstI. Alternatively a synthetic construct flanked by attB sites may be sub-cloned into a mobilizable vector such as pK19mob7. The expression of the &Phi;C31 integrase gene (cloned from pHS628) is driven by the lac promoter, on a mobilizable broad host range plasmid pRK78139.
A tetraparental mating protocol is used to transfer the donor cassette into the LP strain thereby replacing the markers in the LP sequence with the donor cassette. These cells are trans-integrants. Trans-integrants are formed with a typical efficiency of 0.5%. Trans-integrants are typically found within the first 500-1,000 colonies screened by antibiotic sensitivity or blue-white screening using 5-bromo-4-chloro-3-indolyl-beta-D-glucuronic acid (X-gluc). This protocol contains the mating and selection procedures for creating and isolating trans-integrants.

A quick and efficient method to integrate foreign DNA of interest into pre-made acceptor strains, termed landing pad strains, is described. The method allows site-specific integration of a DNA cassette into the engineered landing pad locus of a given strain, through conjugation and expression of the &#934;C31 integrase.

Site-specific Ingegneria batterica Cromosoma: ΦC31 integrasi Mediated Cassette Exchange (IMCE)

The bacterial chromosome may be used to stably maintain foreign DNA in the mega-base range1. Integration into the chromosome circumvents issues such as ...

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Bioingegneria

Microfluidic Mixers for Studying Protein Folding

The process by which a protein folds into its native conformation is highly relevant to biology and human health yet still poorly understood. One reason for this is that folding takes place over a wide range of timescales, from nanoseconds to seconds or longer, depending on the protein1. Conventional stopped-flow mixers have allowed measurement of folding kinetics starting at about 1 ms. We have recently developed a microfluidic mixer that dilutes denaturant ~100-fold in ~8 &mu;s2. Unlike a stopped-flow mixer, this mixer operates in the laminar flow regime in which turbulence does not occur. The absence of turbulence allows precise numeric simulation of all flows within the mixer with excellent agreement to experiment3-4.
Laminar flow is achieved for Reynolds numbers Re &le;100. For aqueous solutions, this requires micron scale geometries. We use a hard substrate, such as silicon or fused silica, to make channels 5-10 &mu;m wide and 10 &mu;m deep (See Figure 1). The smallest dimensions, at the entrance to the mixing region, are on the order of 1 &mu;m in size. The chip is sealed with a thin glass or fused silica coverslip for optical access. Typical total linear flow rates are ~1 m/s, yielding Re~10, but the protein consumption is only ~0.5 nL/s or 1.8 &mu;L/hr. Protein concentration depends on the detection method: For tryptophan fluorescence the typical concentration is 100 &mu;M (for 1 Trp/protein) and for FRET the typical concentration is ~100 nM.
The folding process is initiated by rapid dilution of denaturant from 6 M to 0.06 M guanidine hydrochloride. The protein in high denaturant flows down a central channel and is met on either side at the mixing region by buffer without denaturant moving ~100 times faster (see Figure 2). This geometry causes rapid constriction of the protein flow into a narrow jet ~100 nm wide. Diffusion of the light denaturant molecules is very rapid, while diffusion of the heavy protein molecules is much slower, diffusing less than 1 &mu;m in 1 ms. The difference in diffusion constant of the denaturant and the protein results in rapid dilution of the denaturant from the protein stream, reducing the effective concentration of the denaturant around the protein. The protein jet flows at a constant rate down the observation channel and fluorescence of the protein during folding can be observed using a scanning confocal microscope5.

In this work we explain the fabrication and use of a microfluidic mixer capable of mixing two solutions in ~8 &mu;s. We also demonstrate the use of these mixers with spectroscopic detection using UV fluorescence and fluorescence resonance energy transfer (FRET).

Miscelatori per lo studio microfluidici Protein Folding

The process by which a protein folds into its native conformation is highly relevant to biology and human health yet still poorly understood. One reason ...

Systematic Analysis of In Vitro Cell Rolling Using a Multi-well Plate Microfluidic System

A major challenge for cell-based therapy is the inability to systemically target a large quantity of viable cells with high efficiency to tissues of interest following intravenous or intraarterial infusion. Consequently, increasing cell homing is currently studied as a strategy to improve cell therapy. Cell rolling on the vascular endothelium is an important step in the process of cell homing and can be probed in-vitro using a parallel plate flow chamber (PPFC). However, this is an extremely tedious, low throughput assay, with poorly controlled flow conditions. Instead, we used a multi-well plate microfluidic system that enables study of cellular rolling properties in a higher throughput under precisely controlled, physiologically relevant shear flow1,2. In this paper, we show how the rolling properties of HL-60 (human promyelocytic leukemia) cells on P- and E-selectin-coated surfaces as well as on cell monolayer-coated surfaces can be readily examined. To better simulate inflammatory conditions, the microfluidic channel surface was coated with endothelial cells (ECs), which were then activated with tumor necrosis factor-&#945; (TNF-&#945;), significantly increasing interactions with HL-60 cells under dynamic conditions. The enhanced throughput and integrated multi-parameter software analysis platform, that permits rapid analysis of parameters such as rolling velocities and rolling path, are important advantages for assessing cell rolling properties in-vitro. Allowing rapid and accurate analysis of engineering approaches designed to impact cell rolling and homing, this platform may help advance exogenous cell-based therapy.

Systematic Analysis of In Vitro Cell Rolling Using a Multi-well Plate Microfluidic System

This study used a multi-well plate microfluidic system, significantly increasing throughput of cell rolling studies under physiologically relevant shear flow. Given the importance of cell rolling in the multi-step cell homing cascade and the importance of cell homing following systemic delivery of exogenous populations of cells in patients, this system offers potential as a screening platform to improve cell-based therapy.

Analisi sistematica delle<em&gt; In Vitro</em&gt; Cella rotolamento Utilizzando un piatto multi-ben Sistema Microfluidic

A major challenge for cell-based therapy is the inability to systemically target a large quantity of viable cells with high efficiency to tissues of ...

Cell Squeezing as a Robust, Microfluidic Intracellular Delivery Platform

Rapid mechanical deformation of cells has emerged as a promising, vector-free method for intracellular delivery of macromolecules and nanomaterials. This technology has shown potential in addressing previously challenging applications; including, delivery to primary immune cells, cell reprogramming, carbon nanotube, and quantum dot delivery. This vector-free microfluidic platform relies on mechanical disruption of the cell membrane to facilitate cytosolic delivery of the target material. Herein, we describe the detailed method of use for these microfluidic devices including, device assembly, cell preparation, and system operation. This delivery approach requires a brief optimization of device type and operating conditions for previously unreported applications. The provided instructions are generalizable to most cell types and delivery materials as this system does not require specialized buffers or chemical modification/conjugation steps. This work also provides recommendations on how to improve device performance and trouble-shoot potential issues related to clogging, low delivery efficiencies, and cell viability.

Rapid mechanical deformation of cells has emerged as a promising, vector-free method for intracellular delivery of macromolecules and nanomaterials. This protocol provides detailed steps on how to use the system for a broad range of applications.

Spremere cellulare come un robusto, Microfluidic intracellulare Delivery Platform

Rapid mechanical deformation of cells has emerged as a promising, vector-free method for intracellular delivery of macromolecules and nanomaterials. This ...

A Microfluidic Technique to Probe Cell Deformability

Here we detail the design, fabrication, and use of a microfluidic device to evaluate the deformability of a large number of individual cells in an efficient manner. Typically, data for ~102 cells can be acquired within a 1 hr experiment. An automated image analysis program enables efficient post-experiment analysis of image data, enabling processing to be complete within a few hours. Our device geometry is unique in that cells must deform through a series of micron-scale constrictions, thereby enabling the initial deformation and time-dependent relaxation of individual cells to be assayed. The applicability of this method to human promyelocytic leukemia (HL-60) cells is demonstrated. Driving cells to deform through micron-scale constrictions using pressure-driven flow, we observe that human promyelocytic (HL-60) cells momentarily occlude the first constriction for a median time of 9.3 msec before passaging more quickly through the subsequent constrictions with a median transit time of 4.0 msec per constriction. By contrast, all-trans retinoic acid-treated (neutrophil-type) HL-60 cells occlude the first constriction for only 4.3 msec before passaging through the subsequent constrictions with a median transit time of 3.3 msec. This method can provide insight into the viscoelastic nature of cells, and ultimately reveal the molecular origins of this behavior.

We demonstrate a microfluidics-based assay to measure the timescale for cells to transit through a sequence of micron-scale constrictions.

Una tecnica Microfluidic per sondare deformabilità cellulare

Here we detail the design, fabrication, and use of a microfluidic device to evaluate the deformability of a large number of individual cells in an ...

Controlled Microfluidic Environment for Dynamic Investigation of Red Blood Cell Aggregation

Blood, as a non-Newtonian biofluid, represents the focus of numerous studies in the hemorheology field. Blood constituents include red blood cells, white blood cells and platelets that are suspended in blood plasma. Due to the abundance of the RBCs (40% to 45% of the blood volume), their behavior dictates the rheological behavior of blood especially in the microcirculation. At very low shear rates, RBCs are seen to assemble and form entities called aggregates, which causes the non-Newtonian behavior of blood. It is important to understand the conditions of the aggregates formation to comprehend the blood rheology in microcirculation. The protocol described here details the experimental procedure to determine quantitatively the RBC aggregates in microcirculation under constant shear rate, based on image processing. For this purpose, RBC-suspensions are tested and analyzed in 120 x 60 &#181;m poly-dimethyl-siloxane (PDMS) microchannels. The RBC-suspensions are entrained using a second fluid in order to obtain a linear velocity profile within the blood layer and thus achieve a wide range of constant shear rates. The shear rate is determined using a micro Particle Image Velocimetry (&#181;PIV) system, while RBC aggregates are visualized using a high speed camera. The videos captured of the RBC aggregates are analyzed using image processing techniques in order to determine the aggregate sizes based on the images intensities.

The protocol described details an experimental procedure to quantify Red Blood Cell (RBC) aggregates under a controlled and constant shear rate, based on image processing techniques. The goal of this protocol is to relate RBC aggregate sizes to the corresponding shear rate in a controlled microfluidic environment.

Ambiente controllato Microfluidic per Dynamic Indagine Globulo rosso Aggregazione

Blood, as a non-Newtonian biofluid, represents the focus of numerous studies in the hemorheology field. Blood constituents include red blood cells, white ...

Using Adhesive Patterning to Construct 3D Paper Microfluidic Devices

We demonstrate the use of patterned aerosol adhesives to construct both planar and nonplanar 3D paper microfluidic devices. By spraying an aerosol adhesive through a metal stencil, the overall amount of adhesive used in assembling paper microfluidic devices can be significantly reduced. We show on a simple 4-layer planar paper microfluidic device that the optimal adhesive application technique and device construction style depends heavily on desired performance characteristics. By moderately increasing the overall area of a device, it is possible to dramatically decrease the wicking time and increase device success rates while also reducing the amount of adhesive required to keep the device together. Such adhesive application also causes the adhesive to form semi-permanent bonds instead of permanent bonds between paper layers, enabling single-use devices to be non-destructively disassembled after use. Nonplanar 3D origami devices also benefit from the semi-permanent bonds during folding, as it reduces the likelihood that unrelated faces may accidently stick together. Like planar devices, nonplanar structures see reduced wicking times with patterned adhesive application vs uniformly applied adhesive.

We demonstrate the use of patterned aerosol adhesives to construct 3D paper microfluidic devices. This method of adhesive application forms semi-permanent bonds between layers, enabling single-use devices to be non-destructively disassembled after use and to ease folding complex nonplanar structures.

Utilizzando adesivo Patterning per costruire dispositivi microfluidici di carta 3D

We demonstrate the use of patterned aerosol adhesives to construct both planar and nonplanar 3D paper microfluidic devices. By spraying an aerosol ...

A Microfluidic Platform for High-throughput Single-cell Isolation and Culture

Studying the heterogeneity of single cells is crucial for many biological questions, but is technically difficult. Thus, there is a need for a simple, yet high-throughput, method to perform single-cell culture experiments. Here, we report a microfluidic chip-based strategy for high-efficiency single-cell isolation (~77%) and demonstrate its capability of performing long-term single-cell culture (up to 7 d) and cellular heterogeneity analysis using clonogenic assay. These applications were demonstrated with KT98 mouse neural stem cells, and A549 and MDA-MB-435 human cancer cells. High single-cell isolation efficiency and long-term culture capability are achieved by using different sizes of microwells on the top and bottom of the microfluidic channel. The small microwell array is designed for precisely isolating single-cells, and the large microwell array is used for single-cell clonal culture in the microfluidic chip. This microfluidic platform constitutes an attractive approach for single-cell culture applications, due to its flexibility of adjustable cell culture spaces for different culture strategies, without decreasing isolation efficiency.

Here, we present a protocol for isolating and culturing single cells with a microfluidic platform, which utilizes a new microwell design concept to allow for high-efficiency single cell isolation and long-term clonal culture.

Una piattaforma Microfluidic per l&#39;isolamento Single-cell high-throughput e cultura

Studying the heterogeneity of single cells is crucial for many biological questions, but is technically difficult. Thus, there is a need for a simple, yet ...

Multi-step Variable Height Photolithography for Valved Multilayer Microfluidic Devices

Microfluidic systems have enabled powerful new approaches to high-throughput biochemical and biological analysis. However, there remains a barrier to entry for non-specialists who would benefit greatly from the ability to develop their own microfluidic devices to address research questions. Particularly lacking has been the open dissemination of protocols related to photolithography, a key step in the development of a replica mold for the manufacture of polydimethylsiloxane (PDMS) devices. While the fabrication of single height silicon masters has been explored extensively in literature, fabrication steps for more complicated photolithography features necessary for many interesting device functionalities (such as feature rounding to make valve structures, multi-height single-mold patterning, or high aspect ratio definition) are often not explicitly outlined. 
Here, we provide a complete protocol for making multilayer microfluidic devices with valves and complex multi-height geometries, tunable for any application. These fabrication procedures are presented in the context of a microfluidic hydrogel bead synthesizer and demonstrate the production of droplets containing polyethylene glycol (PEG diacrylate) and a photoinitiator that can be polymerized into solid beads. This protocol and accompanying discussion provide a foundation of design principles and fabrication methods that enables development of a wide variety of microfluidic devices. The details included here should allow non-specialists to design and fabricate novel devices, thereby bringing a host of recently developed technologies to their most exciting applications in biological laboratories.

Multilayer microfluidic devices often involve the fabrication of master molds with complex geometries for functionality. This article presents a complete protocol for multi-step photolithography with valves and variable height features tunable to any application. As a demonstration, we fabricate a microfluidic droplet generator capable of producing hydrogel beads.

Multi-step altezza variabile fotolitografia per Valvolati multistrato microfluidici Devices

Microfluidic systems have enabled powerful new approaches to high-throughput biochemical and biological analysis. However, there remains a barrier to ...

Microfluidic Bioprinting for Engineering Vascularized Tissues and Organoids

Engineering vascularized tissue constructs and organoids has been historically challenging. Here we describe a novel method based on microfluidic bioprinting to generate a scaffold with multilayer interlacing hydrogel microfibers. To achieve smooth bioprinting, a core-sheath microfluidic printhead containing a composite bioink formulation extruded from the core flow and the crosslinking solution carried by the sheath flow, was designed and fitted onto the bioprinter. By blending gelatin methacryloyl (GelMA) with alginate, a polysaccharide that undergoes instantaneous ionic crosslinking in the presence of select divalent ions, followed by a secondary photocrosslinking of the GelMA component to achieve permanent stabilization, a microfibrous scaffold could be obtained using this bioprinting strategy. Importantly, the endothelial cells encapsulated inside the bioprinted microfibers can form the lumen-like structures resembling the vasculature over the course of culture for 16 days. The endothelialized microfibrous scaffold may be further used as a vascular bed to construct a vascularized tissue through subsequent seeding of the secondary cell type into the interstitial space of the microfibers. Microfluidic bioprinting provides a generalized strategy in convenient engineering of vascularized tissues at high fidelity.

We provide a generalized protocol based on a microfluidic bioprinting strategy for engineering a microfibrous vascular bed, where a secondary cell type could be further seeded into the interstitial space of this microfibrous structure to generate vascularized tissues and organoids.