Gli autori ringraziano T. Palmer e H. Basile (Stanford neurochirurgia) per la fornitura di murino NPC. Vector art nella Figura 4 è stato usato e adattato da Servier arte medica sotto Creative Commons Attribution 3.0 Unported License (https://creativecommons.org/ licenses/by/3.0/legalcode). Parte di questo lavoro è stato effettuato presso la Stanford Nano ha condiviso strutture (FNS), sostenuto dalla National Science Foundation sotto Premio ECCS-1542152. N.a.s. riconosce sostegno dal National Institute of General Medical Sciences, della National Institutes of Health (32GM 008412). C.m.m. riconosce il supporto da un NRSA NIH pre-dottorato (F31 EB020502) e il programma di studiosi di Siebel. S.C.H riconosce sostegno dal National Institutes of Health (U19 AI116484 ed EB018407 R21), National Science Foundation (DMR 1508006) e il California Institute for Regenerative Medicine (RT3-07948). Questa ricerca ha ricevuto finanziamenti dall'alleanza rigenerativa riabilitazione Research & Training (AR3T), che è sostenuta dalla Eunice Kennedy Shriver National Institute of Child Health e Human Development (NICHD), Istituto nazionale di Disordini neurologici e colpo (NINDS) e Istituto nazionale di Imaging biomedico e Bioingegneria (NIBIB) degli istituti nazionali di salute sotto Premio numero P2CHD086843. Il contenuto è di esclusiva responsabilità degli autori e non rappresentano necessariamente le opinioni del National Institutes of Health.

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	<li>Cukierman, E., Pankov, R., Stevens, D. R., Yamada, K. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Taking+Cell-Matrix+Adhesions+to+the+Third+Dimension.">Taking Cell-Matrix Adhesions to the Third Dimension.</a> Science. 294 (5547), 1708-1712 (2001).</li><li>Birgersdotter, A., Sandberg, R., Ernberg, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gene+expression+perturbation+in+vitro-A+growing+case+for+three-dimensional+(3D)+culture+systems.">Gene expression perturbation in vitro-A growing case for three-dimensional (3D) culture systems.</a> Seminars in Cancer Biology. 15 (5), 405-412 (2005).</li><li>G&#243;mez-Lech&#243;n, M. 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E., Chilkoti, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+of+recombinant+proteins+by+fusion+with+thermally-responsive+polypeptides.">Purification of recombinant proteins by fusion with thermally-responsive polypeptides.</a> Nature Biotechnology. 17 (11), 1112-1115 (1999).</li><li>Aladini, F., Araman, C., Becker, C. F. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemical+synthesis+and+characterization+of+elastin-like+polypeptides+(ELPs)+with+variable+guest+residues.">Chemical synthesis and characterization of elastin-like polypeptides (ELPs) with variable guest residues.</a> Journal of Peptide Science. 22 (5), 334-342 (2016).</li><li>McMillan, R. A., Caran, K. L., Apkarian, R. P., Conticello, V. 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Purificazione ed espressione recombinant della proteina è un potente strumento per sintetizzare biomateriali con elevata riproducibilità. A causa dell'avvento della clonazione molecolare commercializzato in gran parte, plasmidi ricombinanti personalizzati possono essere acquistati da diversi fornitori, che riduce significativamente il tempo di lavorare con materiali come ELPs. Allo stesso modo, plasmidi possono essere richiesti direttamente dal laboratorio di origine quando l'opera originale è stata sostenuta da un co...

Durante il secolo passato, coltura del tessuto bidimensionale (2D) è sviluppato in un set di strumenti integrato per lo studio della biologia fondamentale delle cellule in vitro. Inoltre, i protocolli relativamente basso costo e semplici per la coltura cellulare 2D hanno condotto alla sua adozione attraverso molte discipline biologiche e mediche. Tuttavia, ricerca passata ha dimostrato che le tradizionali piattaforme 2D possono portare a risultati che si discostano sensibilmente da quelli raccolti in vivo, causando tempo prezioso e finanziamenti sprecati per ricerca clinicamente orientata1,2, 3. Noi ed altri suppongono che questa discrepanza può essere attribuita alla mancanza di nativi biochimiche e biofisiche spunti forniti per le cellule coltivate su superfici 2D, che possono essere necessarie per la proliferazione ottimale e maturazione dei vari tipi di cellule.
Per risolvere queste limitazioni e aiuto ponte il divario tra 2D in vitro e in vivo gli studi, i ricercatori hanno sviluppato idrogel tridimensionale (3D) piattaforme per cellulari-incapsulamento1,4,5 ,6. Idrogeli sono materiali ideali per ricapitolare il microambiente endogeno della matrice extracellulare (ECM) in vivo a causa di loro proprietà meccaniche del tessuto-come e struttura gonfio d'acqua che consente il rapido trasporto di nutrienti e segnalazione fattori7,8. Inoltre, idrogeli 3D possono essere progettati per avere controllo indipendente sulle proprietà meccaniche e biochimiche dell'impalcatura. Sia matrice meccanica9,10,11,12 e ligandi cellulari-adesivo13,14,15 sono ben noti per influenzare la cella comportamento in vitro e in vivo. Così, idrogeli 3D con proprietà sintonizzabile offrono una piattaforma per studiare le relazioni causali tra cellule e loro microambiente. Criteri per una matrice di idrogel 3D ideale includono semplice, non citotossica delle cellule-incapsulamento come pure accordabilità indipendente di proprietà meccaniche fisiologicamente rilevanti e mimici di nativi cella-adesivo motivi.
Entrambi sintetico (ad es., polietilenglicole, acido polilattico, poli (acido glicolico)) e di derivazione naturale (ad es., alginato, collagene, Matrigel) idrogeli presentano vantaggi rispetto 2D in vitro piattaforme di cultura; Tuttavia, essi hanno anche notevoli lacune che limitano la loro applicabilità. Primo, molte piattaforme di derivazione naturale e sintetiche richiedono condizioni di reticolazione duro che possono essere potenzialmente tossiche per le cellule di mammiferi, che porta alla diminuzione di attuabilità delle cellule7. Inoltre, molte piattaforme sintetici mancano nativa bioattività e bisogno di essere funzionalizzate attraverso reazioni chimiche secondarie, che possono aggiungere maggiore costo e complessità16. Infine, mentre materiali di derivazione naturale contengono tipicamente intrinseche bio-attivi domini, essi sono spesso afflitti da un'elevata variabilità lotto e spesso sono limitate a formare gel relativamente debole7,17.
Ingegneria delle proteine ricombinanti presenta un unico set di strumenti per la progettazione di materiali consentendo controllo esplicito sulla sequenza della proteina e, per estensione, le potenziali proprietà meccaniche e biochimiche dell'idrogel finale dell'impalcatura18. Inoltre, sfruttando il ben nota macchine biologiche di Escherichia coli (Escherichia coli) per esprimere proteine, materiali possono essere prodotto in modo conveniente e coerente con la variabilità limitata inter - e intra-batch. La proteina elastina-come (ELP) presentata qui ha tre domini ingegnerizzati: (1) un tag T7 e His6 che consente per etichettatura tramite fluorescente contrassegnati gli anticorpi, (2) una regione 'elastin-like' che conferisce proprietà meccaniche elastiche e consente per l'industria chimica reticolazione e (3) una regione 'bio-attivi' che codifica per motivi di cella-adesivo.
Nostra regione di elastina-come si basa sulla canonica sequenza di elastina (Val-Pro-Gly-Xaa-Gly)5 dove quattro dei 'Xaa' siti dell'amminoacido isoleucina (Ile), ma potrebbero essere progettato per essere qualsiasi amminoacido ad eccezione della prolina. Questa sequenza dota ricombinante ELPs con comportamento di temperatura (LCST) soluzione critica inferiore che può essere sfruttata per post-l'espressione purificazione semplice via19,20di cicli termici. Questa proprietà LCST può essere sintonizzata per termicamente aggregato a temperature diverse modificando l'ospite 'Xaa' residuo21,22.
Qui, la posizione di 'Xaa' su una delle cinque ripetizioni elastina-come è stata sostituita con la presentazione di ammina lisina (Lys) dell'aminoacido, che è utilizzata per la reticolazione di idrogel. Il nostro lavoro precedente ha indicato non citotossica e robusto reticolazione tramite reazione con l'ammina-reattivo crosslinker tetrachis (idrossimetil) fosfonio cloruro (THPC)23. Di varie proteine contenuti e crosslinker concentrazione complessiva, siamo in grado di produrre idrogel che può essere sintonizzato per estendersi su una rigidità fisiologicamente rilevanti gamma (~0.5-50 kPa)9,23,24. Oltre alle proprietà meccaniche di tuning, cellula adesione all'interno dei risultati di idrogel dall'integrazione dei domini canonici di cella-adesivo all'interno la spina dorsale della proteina ELP. Ad esempio, l'incorporazione di estesa fibronectin-derivato 'RGDS' sequenza dell'amminoacido permette delle cellule adesione e flessibilità conformazionale, mentre le uova strapazzate, variante di 'RDGS' non vincolante limita di adesione cellula-matrice24. Modulando il rapporto di cella-adesivo non adesivo proteine come pure la concentrazione nella proteina totale, siamo in grado di produrre in modo efficace gli idrogel che abbracciano una vasta gamma di concentrazione del ligando. Resultantly, abbiamo sviluppato una piattaforma di idrogel con proprietà biochimiche e biofisiche disaccoppiate, che può essere regolato in modo indipendente per coltura ottima 3D di vari tipi cellulari.
Oltre alla matrice di rigidezza e accordabilità legante adesivo, ricombinante idrogel offrono la possibilità di profili di degrado del materiale specifico design, che è necessaria per la diffusione delle cellule, la proliferazione e la migrazione all'interno di un contesto 3D4 , 9. questo degrado è garantito dalla secrezione delle cellule delle proteasi che si rivolgono specificamente elastina-come sequenza25o estesa 'RGDS'9 . ELP idrogeli inoltre sono stati indicati per sostenere le successive analisi biochimiche che sono necessari per lo studio di attuabilità delle cellule e la funzione compreso immunocytochemistry così come estrazione di DNA/RNA/proteine per inversione quantitativa reazione a catena della polimerasi della trascrizione (qRT-PCR) e Western blot9. ELP varianti inoltre sono stati usati in un certo numero di modelli in vivo e sono noti per essere tollerato dal sistema immunitario26.
Presi insieme, ELP come una piattaforma di materiale per gli studi delle cellule-incapsulamento vanta una vasta gamma di vantaggi rispetto alle piattaforme di materiale sintetiche o di derivazione naturale, che spesso non hanno lo stesso grado di accordabilità biochimiche e biofisiche e riproducibilità. Inoltre, non citotossica un di ELP uso semplice e con un'ampia varietà di tipi cellulari (ad es., pulcino radice dorsale dei gangli14,24, progenitrici neurali murini cellule9, cellule staminali mesenchimali umane27, bovino condrociti neonatale28, human endothelial cells29,30) consente per un modello più fisiologicamente rilevante del ECM 3D endogeno rispetto alla coltura delle cellule 2D. Qui, presentiamo un protocollo per l'espressione di recombinantly-derivati, ELPs per l'uso come una piattaforma di idrogel sintonizzabile per 3D cell incapsulamento. Vi presentiamo ulteriormente la metodologia per l'etichettatura fluorescente downstream e microscopia confocale delle cellule incapsulate.

<table><tbody><tr><td>&lt;strong&gt;Elastin-Like Protein Expression and Purification&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>10 cm Petri Dishes</td><td>Thermo Fisher Scientific</td><td>FB0875713</td><td></td></tr><tr><td>70% Ethanol</td><td>RICCA Chemical</td><td>2546.70-1</td><td></td></tr><tr><td>Ammonium Sulfate</td><td>Sigma-Aldrich</td><td>A3920-500G</td><td></td></tr><tr><td>Ampicillin</td><td>Thermo Fisher Scientific</td><td>BP1760-25G</td><td></td></tr><tr><td>Bacto Agar</td><td>Thermo Fisher Scientific</td><td>9002-18-0&amp;nbsp;</td><td></td></tr><tr><td>BL21(DE3)pLysS Competent Cells</td><td>Invitrogen</td><td>C606003</td><td></td></tr><tr><td>Chloramphenicol</td><td>Amresco</td><td>0230-100G&amp;nbsp;</td><td></td></tr><tr><td>Deoxyribonuclease I from bovine pancreas</td><td>Sigma-Aldrich</td><td>DN25</td><td></td></tr><tr><td>EDTA disodium salt, dihydrate</td><td>Thermo Fisher Scientific</td><td>O2793-500</td><td></td></tr><tr><td>Glycerol</td><td>Thermo Fisher Scientific</td><td>BP229-4</td><td></td></tr><tr><td>Isopropanol</td><td>Thermo Fisher Scientific</td><td>A451-4</td><td></td></tr><tr><td>Isopropyl &amp;beta;-D-1-thiogalactopyranoside (IPTG)&amp;nbsp;</td><td>Thermo Fisher Scientific</td><td>BP1755-10G</td><td></td></tr><tr><td>Luria Broth</td><td>EMD Millipore</td><td>1.10285.5007</td><td></td></tr><tr><td>Parafilm</td><td>VWR</td><td>52858-000</td><td></td></tr><tr><td>Phenylmethanesulfonyl fluoride (PMSF)</td><td>MP Biomedicals</td><td>195381</td><td></td></tr><tr><td>Sodium Chloride</td><td>Thermo Fisher Scientific</td><td>BP358-212</td><td></td></tr><tr><td>Sodium Hydroxide</td><td>Sigma-Aldrich</td><td>S 8045-1KG</td><td></td></tr><tr><td>Syringe Filter Unit (0.22 &amp;mu;m)</td><td>Millipore</td><td>SLGP033RB</td><td></td></tr><tr><td>Terrific Broth</td><td>Millipore</td><td>71754-4</td><td></td></tr><tr><td>Tris Base</td><td>Thermo Fisher Scientific</td><td>BP152-1</td><td></td></tr><tr><td>&lt;strong&gt;Cell Encapsulation in 3D ELP Hydrogels&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>0.22 &amp;mu;m syringe filters</td><td>Millipore</td><td>SLGV004SL</td><td></td></tr><tr><td>0.5 mm thick silicone sheet</td><td>Electron Microscopy Science</td><td>70338-05</td><td></td></tr><tr><td>24-well tissue culture plates&amp;nbsp;</td><td>Corning</td><td>353047</td><td></td></tr><tr><td>Disposable Biopsy Punch (2 mm)</td><td>Integra Miltex</td><td>33-31</td><td></td></tr><tr><td>Disposable Biopsy Punch (4 mm)</td><td>Integra Miltex</td><td>33-34</td><td></td></tr><tr><td>Disposable Biopsy Punch (5 mm)</td><td>Integra Miltex</td><td>33-35</td><td></td></tr><tr><td>Dulbecco&amp;rsquo;s phosphate buffered saline (DPBS)&amp;nbsp;</td><td>Corning</td><td>21-031-CM</td><td></td></tr><tr><td>No. 1 12 mm glass coverslips</td><td>Thermo Fisher Scientific</td><td>12-545-80</td><td></td></tr><tr><td>Tetrakis(hydroxymethyl)phosphonium chloride (THPC)</td><td>Sigma-Aldrich</td><td>404861-100ML</td><td></td></tr><tr><td>0.5% Tryspin/EDTA</td><td>Thermo Fisher&amp;nbsp;</td><td>15400054</td><td></td></tr><tr><td>&lt;strong&gt;Immunocytochemistry of Cells in 3D ELP Hydrogels&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>16% (w/v) Paraformaldehyde (PFA)</td><td>Electron Microscopy Sciences</td><td>15701</td><td></td></tr><tr><td>Bovine Serum Albumin (BSA)</td><td>Roche</td><td>3116956001</td><td></td></tr><tr><td>DAPI (4&#039;,6-Diamidino-2-Phenylindole, Dihydrochloride)</td><td>Molecular Probes</td><td>D1306&amp;nbsp;</td><td></td></tr><tr><td>Donkey Serum</td><td>Lampire Biological Labs</td><td>7332100</td><td></td></tr><tr><td>Goat anti-mouse Secondary Antibody (AF488)</td><td>Molecular Probes</td><td>A-11017</td><td></td></tr><tr><td>Goat anti-rabbit Secondary Antibody (AF546)</td><td>Molecular Probes</td><td>A-11071</td><td></td></tr><tr><td>Goat Serum</td><td>Gibco</td><td>16210-072</td><td></td></tr><tr><td>Mouse Nestin Primary Antibody</td><td>BD Pharmingen</td><td>556309</td><td></td></tr><tr><td>Mouse Sox2 Primary Antibody</td><td>Cell Signaling Technology</td><td>23064S</td><td></td></tr><tr><td>Nail Polish</td><td>Electron Microscopy Sciences</td><td>72180</td><td></td></tr><tr><td>Triton X-100</td><td>Sigma-Aldrich</td><td>X100-100ML</td><td></td></tr><tr><td>Vectashield Hardset Mounting Medium&amp;nbsp;</td><td>Vector Labs</td><td>H-1400&amp;nbsp;</td><td></td></tr></tbody></table>

production of elastin-like protein hydrogels for encapsulation and immunostaining of cells in 3d

Tecniche di coltura tissutale (2D) bidimensionali sono stati essenziali per la nostra comprensione della biologia delle cellule fondamentali. Tuttavia, la mancanza di sistemi di coltura del tessuto 2D tradizionale una matrice tridimensionale (3D), risultante in un significativo scollamento tra risultati raccolti in vitro e in vivo. Per risolvere questa limitazione, i ricercatori hanno creato piattaforme di coltura del tessuto 3D idrogel che possono imitare le proprietà biochimiche e biofisiche del microambiente delle cellule in vivo . Questa ricerca ha motivato la necessità di sviluppare materiale piattaforme che supportano incapsulamento cella 3D e analisi biochimiche a valle. Ingegneria delle proteine ricombinanti offre un unico set di strumenti per disegno materiale idrogel 3D e sviluppo, consentendo il controllo specifico di sequenza della proteina e quindi, per estensione, le potenziali proprietà meccaniche e biochimiche della risultante matrice. Qui, presentiamo un protocollo per l'espressione di recombinantly-elastina-come proteina derivata (ELP), che può essere utilizzato per forma idrogel con proprietà meccaniche regolabili in modo indipendente e concentrazione del ligando delle cellule-adesivo. Presentiamo inoltre una metodologia per l'incapsulamento di cellule all'interno di ELP idrogeli e macchiatura immunofluorescente successive di embedded cellule per analisi a valle e la quantificazione.

Il ELPs utilizzata nel presente protocollo sono costituite da cinque regioni: un tag di T7, His6 tag, sito di clivaggio Enterochinasi (EK), una regione di bio-attivi e una regione di elastina-like (Figura 1). I tag T7 e His6 consentono per una facile identificazione mediante tecniche di Western blot standard. Introduzione del sito di clivaggio EK permette la rimozione enzimatica della regione tag, se necessario. La regione di bio-attivi codifica per l'estesa,...

Watch this Scientific Journal Video about Production of Elastin-like Protein Hydrogels for Encapsulation and Immunostaining of Cells in 3D at JoVE.com

Production of Elastin-like Protein Hydrogels for Encapsulation and Immunostaining of Cells in 3D

Idrogeli di ingegneria della proteina ricombinanti sono vantaggiosi per la coltura cellulare 3D poiché consentono completa accordabilità della catena polimerica e di conseguenza, il microambiente delle cellule. Qui, descriviamo il processo di purificazione della proteina ricombinante elastino-simili e la sua applicazione in incapsulamento cella 3D idrogel.

Produzione di elastina-come proteina idrogeli per incapsulamento e Immunostaining delle cellule in 3D

Two-dimensional (2D) tissue culture techniques have been essential for our understanding of fundamental cell biology. However, traditional 2D tissue ...

production-elastin-like-protein-hydrogels-for-encapsulation

Universidad de Cartagena UDEC

Research

JoVE Journal

Bioengineering

12.3K Views.  Stanford University. Idrogeli di ingegneria della proteina ricombinanti sono vantaggiosi per la coltura cellulare 3D poiché consentono completa accordabilità della catena polimerica e di conseguenza, il microambiente delle cellule. Qui, descriviamo il processo di purificazione della proteina ricombinante elastino-simili e la sua applicazione in incapsulamento cella 3D idrogel.

Video: Production of Elastin-like Protein Hydrogels for Encapsulation and Immunostaining of Cells in 3D

Easy Manipulation of Architectures in Protein-based Hydrogels for Cell Culture Applications

Hydrogels are recognized as promising materials for cell culture applications due to their ability to provide highly hydrated cell environments. The field of 3D templates is rising due to the potential resemblance of those materials to the natural extracellular matrix. Protein-based hydrogels are particularly promising because they can easily be functionalized and can achieve defined structures with adjustable physicochemical properties. However, the production of macroporous 3D templates for cell culture applications using natural materials is often limited by their weaker mechanical properties compared to those of synthetic materials. Here, different methods were evaluated to produce macroporous bovine serum albumin (BSA)-based hydrogel systems, with adjustable pore sizes in the range of 10 to 70 &#181;m in radius. Furthermore, a method to generate channels in this protein-based material that are several hundred microns long was established. The different methods to produce pores, as well as the influence of pore size on material properties such as swelling ratio, pH, temperature stability, and enzymatic degradation behavior, were analyzed. Pore sizes were investigated in the native, swollen state of the hydrogels using confocal laser scanning microscopy. The feasibility for cell culture applications was evaluated using a cell-adhesive RGD peptide modification of the protein system and two model cell lines: human breast cancer cells (A549) and adenocarcinomic human alveolar basal epithelial cells (MCF7).

Different methods to manipulate three-dimensional architecture in protein-based hydrogels are evaluated here with respect to material properties. The macroporous networks are functionalized with a cell-adhesive peptide, and their feasibility in cell culture is evaluated using two different model cell lines.

Facile manipolazione delle architetture in idrogel a base di proteine per applicazioni della coltura delle cellule

Hydrogels are recognized as promising materials for cell culture applications due to their ability to provide highly hydrated cell environments. The field ...

Ricerca

Biochimica

Generation and Recovery of &beta;-cell Spheroids From Step-growth PEG-peptide Hydrogels

Hydrogels are hydrophilic crosslinked polymers that provide a three-dimensional microenvironment with tissue-like elasticity and high permeability for culturing therapeutically relevant cells or tissues. Hydrogels prepared from poly(ethylene glycol) (PEG) derivatives are increasingly used for a variety of tissue engineering applications, in part due to their tunable and cytocompatible properties. In this protocol, we utilized thiol-ene step-growth photopolymerizations to fabricate PEG-peptide hydrogels for encapsulating pancreatic MIN6 b-cells. The gels were formed by 4-arm PEG-norbornene (PEG4NB) macromer and a chymotrypsin-sensitive peptide crosslinker (CGGYC). The hydrophilic and non-fouling nature of PEG offers a cytocompatible microenvironment for cell survival and proliferation in 3D, while the use of chymotrypsin-sensitive peptide sequence (CGGY&darr;C, arrow indicates enzyme cleavage site, while terminal cysteine residues were added for thiol-ene crosslinking) permits rapid recovery of cell constructs forming within the hydrogel. The following protocol elaborates techniques for: (1) Encapsulation of MIN6 &beta;-cells in thiol-ene hydrogels; (2) Qualitative and quantitative cell viability assays to determine cell survival and proliferation; (3) Recovery of cell spheroids using chymotrypsin-mediated gel erosion; and (4) Structural and functional analysis of the recovered spheroids.

Generation and Recovery of &#946;-cell Spheroids From Step-growth PEG-peptide Hydrogels

The following protocol provides techniques for encapsulating pancreatic &#x03B2;-cells in step-growth PEG-peptide hydrogels formed by thiol-ene photo-click reactions. This material platform not only offers a cytocompatible microenvironment for cell encapsulation, but also permits user-controlled rapid recovery of cell structures formed within the hydrogels.

Generazione e recupero dei β-cellule Spheroids dal passaggio di crescita PEG-peptide idrogel

Hydrogels are hydrophilic crosslinked polymers that provide a three-dimensional  microenvironment with tissue-like elasticity and high permeability for  ...

Bioingegneria

Preparation of Chitosan-based Injectable Hydrogels and Its Application in 3D Cell Culture

The protocol presents a facile, efficient, and versatile method to prepare chitosan-based hydrogels using dynamic imine chemistry. The hydrogel is prepared by mixing solutions of glycol chitosan with a synthesized benzaldehyde terminated polymer gelator, and hydrogels are efficiently obtained in several minutes at room temperature. By varying ratios between glycol chitosan, polymer gelator, and water contents, versatile hydrogels with different gelation times and stiffness are obtained. When damaged, the hydrogel can recover its appearances and modulus, due to the reversibility of the dynamic imine bonds as crosslinkages. This self-healable property enables the hydrogel to be injectable since it can be self-healed from squeezed pieces to an integral bulk hydrogel after the injection process. The hydrogel is also multi-responsive to many bio-active stimuli due to different equilibration statuses of the dynamic imine bonds. This hydrogel was confirmed as bio-compatible, and L929 mouse fibroblast cells were embedded following standard procedures and the cell proliferation was easily assessed by a 3D cell cultivation process. The hydrogel can offer an adjustable platform for different research where a physiological mimic of a 3D environment for cells is profited. Along with its multi-responsive, self-healable, and injectable properties, the hydrogels can potentially be applied as multiple carriers for drugs and cells in future bio-medical applications.

Here we describe a facile preparation of chitosan-based injectable hydrogels using dynamic imine chemistry. Methods to adjust the hydrogel&#8217;s mechanical strength and its application in 3D cell culture are presented.

Preparazione di idrogeli iniettabili a base di chitosano e la sua applicazione nella coltura cellulare 3D

The protocol presents a facile, efficient, and versatile method to prepare chitosan-based hydrogels using dynamic imine chemistry. The hydrogel is ...

Chimica

Cellular Encapsulation in 3D Hydrogels for Tissue Engineering 

The 3D encapsulation of cells within hydrogels represents an increasingly important and popular technique for culturing cells and towards the development of constructs for tissue engineering. This environment better mimics what cells observe in vivo, compared to standard tissue culture, due to the tissue-like properties and 3D environment. Synthetic polymeric hydrogels are water-swollen networks that can be designed to be stable or to degrade through hydrolysis or proteolysis as new tissue is deposited by encapsulated cells. A wide variety of polymers have been explored for these applications, such as poly(ethylene glycol) and hyaluronic acid. Most commonly, the polymer is functionalized with reactive groups such as methacrylates or acrylates capable of undergoing crosslinking through various mechanisms. In the past decade, much progress has been made in engineering these microenvironments - e.g., via the physical or pendant covalent incorporation of biochemical cues - to improve viability and direct cellular phenotype, including the differentiation of encapsulated stem cells (Burdick et al.).
The following methods for the 3D encapsulation of cells have been optimized in our and other laboratories to maximize cytocompatibility and minimize the number of hydrogel processing steps. In the following protocols (see Figure 1 for an illustration of the procedure), it is assumed that functionalized polymers capable of undergoing crosslinking are already in hand; excellent reviews of polymer chemistry as applied to the field of tissue engineering may be found elsewhere (Burdick et al.) and these methods are compatible with a range of polymer types. Further, the Michael-type addition (see Lutolf et al.) and light-initiated free radical (see Elisseeff et al.) mechanisms focused on here constitute only a small portion of the reported crosslinking techniques. Mixed mode crosslinking, in which a portion of reactive groups is first consumed by addition crosslinking and followed by a radical mechanism, is another commonly used and powerful paradigm for directing the phenotype of encapsulated cells (Khetan et al., Salinas et al.).

Cellular Encapsulation in 3D Hydrogels for Tissue Engineering

We present protocols for the 3-dimensional (3D) encapsulation of cells within synthetic hydrogels. The encapsulation procedure is outlined for two commonly used methods of crosslinking (michael-type addition and light-initiated free radical mechanisms), as well as a number of techniques for assessing encapsulated cell behavior.

Incapsulamento cellulare in idrogel 3D per l&#39;ingegneria tissutale

The 3D encapsulation of cells within hydrogels represents an increasingly important and popular technique for culturing cells and towards the development ...

Biologia

Preparation of 3D Collagen Gels and Microchannels for the Study of 3D Interactions In Vivo

Historically, most cellular processes have been studied in only 2 dimensions. While these studies have been informative about general cell signaling mechanisms, they neglect important cellular cues received from the structural and mechanical properties of the local microenvironment and extracellular matrix (ECM). To understand how cells interact within a physiological ECM, it is important to study them in the context of 3 dimensional assays. Cell migration, cell differentiation, and cell proliferation are only a few processes that have been shown to be impacted by local changes in the mechanical properties of a 3-dimensional ECM. Collagen I, a core fibrillar component of the ECM, is more than a simple structural element of a tissue. Under normal conditions, mechanical cues from the collagen network direct morphogenesis and maintain cellular structures. In diseased microenvironments, such as the tumor microenvironment, the collagen network is often dramatically remodeled, demonstrating altered composition, enhanced deposition and altered fiber organization. In breast cancer, the degree of fiber alignment is important, as an increase in aligned fibers perpendicular to the tumor boundary has been correlated to poorer patient prognosis1. Aligned collagen matrices result in increased dissemination of tumor cells via persistent migration2,3. The following is a simple protocol for embedding cells within a 3-dimensional, fibrillar collagen hydrogel. This protocol is readily adaptable to many platforms, and can reproducibly generate both aligned and random collagen matrices for investigation of cell migration, cell division, and other cellular processes in a tunable, 3-dimensional, physiological microenvironment.

Preparation of 3D Collagen Gels and Microchannels for the Study of 3D Interactions In Vivo

Collagen is a core component of the ECM, and provides essential cues for several cellular processes ranging from migration to differentiation and proliferation. Provided here is a protocol for embedding cells within 3D collagen hydrogels, and a more advanced technique for generating randomized or aligned collagen matrices using PDMS microchannels.

Preparazione del 3D collagene Gel e microcanali per lo studio delle interazioni 3D<em&gt; In Vivo</em

Historically, most cellular processes have been studied in only 2 dimensions.  While these studies have been informative about general cell signaling ...

Engineering Three-dimensional Epithelial Tissues Embedded within Extracellular Matrix

The architecture of branched organs such as the lungs, kidneys, and mammary glands arises through the developmental process of branching morphogenesis, which is regulated by a variety of soluble and physical signals in the microenvironment. Described here is a method created to study the process of branching morphogenesis by forming engineered three-dimensional (3D) epithelial tissues of defined shape and size that are completely embedded within an extracellular matrix (ECM). This method enables the formation of arrays of identical tissues and enables the control of a variety of environmental factors, including tissue geometry, spacing, and ECM composition. This method can also be combined with widely used techniques such as traction force microscopy (TFM) to gain more information about the interactions between cells and their surrounding ECM. The protocol can be used to investigate a variety of cell and tissue processes beyond branching morphogenesis, including cancer invasion.

This manuscript describes a soft lithography-based technique to engineer uniform arrays of three-dimensional (3D) epithelial tissues of defined geometry surrounded by extracellular matrix. This method is amenable to a wide variety of cell types and experimental contexts and allows for high-throughput screening of identical replicates.

Tessuti epiteliali Ingegneria tridimensionali integrati all&#39;interno di matrice extracellulare

The architecture of branched organs such as the lungs, kidneys, and mammary glands arises through the developmental process of branching morphogenesis, ...

Tunable Hydrogels from Pulmonary Extracellular Matrix for 3D Cell Culture

Here we present a method for establishing multiple component cell culture hydrogels for in vitro lung cell culture. Beginning with healthy en bloc lung tissue from porcine, rat, or mouse, the tissue is perfused and submerged in subsequent chemical detergents to remove the cellular debris. Histological comparison of the tissue before and after processing confirms removal of over 95% of double stranded DNA and alpha galactosidase staining suggests the majority of cellular debris is removed. After decellularization, the tissue is lyophilized and then cryomilled into a powder. The matrix powder is digested for 48 hr in an acidic pepsin digestion solution and then neutralized to form the pregel solution. Gelation of the pregel solution can be induced by incubation at 37 &#176;C and can be used immediately following neutralization or stored at 4 &#176;C for up to two weeks. Coatings can be formed using the pregel solution on a non-treated plate for cell attachment. Cells can be suspended in the pregel prior to self-assembly to achieve a 3D culture, plated on the surface of a formed gel from which the cells can migrate through the scaffold, or plated on the coatings. Alterations to the strategy presented can impact gelation temperature, strength, or protein fragment sizes. Beyond hydrogel formation, the hydrogel stiffness may be increased using genipin.

This is a method to create a 3-dimensional cell culture scaffold from pulmonary extracellular matrix. Intact lung is processed into hydrogels that can support the growth of cells in three-dimensions.

Sintonizzabile idrogel da polmonare matrice extracellulare per colture cellulari 3D

Here we present a method for establishing multiple component cell culture hydrogels for in vitro lung cell culture. Beginning with healthy en bloc lung ...

3D Microtissues for Injectable Regenerative Therapy and High-throughput Drug Screening

To upgrade traditional 2D cell culture to 3D cell culture, we have integrated microfabrication with cryogelation technology to produce macroporous microscale cryogels (microcryogels), which can be loaded with a variety of cell types to form 3D microtissues. Herein, we present the protocol to fabricate versatile 3D microtissues and their applications in regenerative therapy and drug screening. Size and shape-controllable microcryogels can be fabricated on an array chip, which can be harvested off-chip as individual cell-loaded carriers for injectable regenerative therapy or be further assembled on-chip into 3D microtissue arrays for high-throughput drug screening. Due to the high elastic nature of these microscale cryogels, the 3D microtissues exhibit great injectability for minimally invasive cell therapy by protecting cells from mechanical shear force during injection. This ensures enhanced cell survival and therapeutic effect in the mouse limb ischemia model. Meanwhile, assembly of 3D microtissue arrays in a standard 384-multi-well format facilitates the use of common laboratory facilities and equipment, enabling high-throughput drug screening on this versatile 3D cell culture platform.

This protocol describes the fabrication of elastic 3D macroporous microcryogels by integrating microfabrication with cryogelation technology. Upon loading with cells, 3D microtissues are generated, which can be readily injected in vivo to facilitate regenerative therapy or assembled into arrays for in vitro high-throughput drug screening.

Microtissues 3D per la terapia rigenerativa iniettabile e droga di High-throughput Screening

To upgrade traditional 2D cell culture to 3D cell culture, we have integrated microfabrication with cryogelation technology to produce macroporous ...

Agarose Fluid Gels Formed by Shear Processing During Gelation for Suspended 3D Bioprinting

The use of granular matrices to support parts during the bioprinting process was first reported by Bhattacharjee et al. in 2015, and since then, several approaches have been developed for the preparation and use of supporting gel beds in 3D bioprinting. This paper describes a process to manufacture microgel suspensions using agarose (known as fluid gels), wherein particle formation is governed by the application of shear during gelation. Such processing produces carefully defined microstructures, with subsequent material properties that impart distinct advantages as embedding print media, both chemically and mechanically. These include behaving as viscoelastic solid-like materials at zero shear, limiting long-range diffusion, and demonstrating the characteristic shear-thinning behavior of flocculated systems. 
On the removal of shear stress, however, fluid gels have the capacity to rapidly recover their elastic properties. This lack of hysteresis is directly linked to the defined microstructures previously alluded to; because of the processing, reactive, non-gelled polymer chains at the particle interface facilitate interparticle interactions-similar to a Velcro effect. This rapid recovery of elastic properties enables bioprinting high-resolution parts from low-viscosity biomaterials, as rapid reformation of the support bed traps the bioink in situ, maintaining its shape. Furthermore, an advantage of agarose fluid gels is the asymmetric gelling/melting transitions (gelation temperature of ~30 &#176;C and melting temperature of ~90 &#176;C). This thermal hysteresis of agarose makes it possible to print and culture the bioprinted part in situ without the supporting fluid gel melting. This protocol shows how to manufacture agarose fluid gels and demonstrates their use to support the production of a range of complex hydrogel parts within suspended-layer additive manufacture (SLAM).

Shear processing during hydrogel formation results in the production of microgel suspensions that shear-thin but rapidly restructure following the removal of shear forces. Such materials have been used as a supporting matrix for bioprinting complex, cell-laden structures. Here, methods used to manufacture the supporting bed and compatible bioinks are described.

Gel fluidi di agarosio formati dalla lavorazione a taglio durante la gelificazione per la bioprinting 3D sospesa

The use of granular matrices to support parts during the bioprinting process was first reported by Bhattacharjee et al. in 2015, and since then, several ...

Idrogel biostampati fototunable per sondare le risposte cellulari all'irrigidimento della ECM

3D Bioprinting Phototunable Hydrogels to Study Fibroblast Activation

Phototunable hydrogels can transform spatially and temporally in response to light exposure. Incorporating these types of biomaterials in cell-culture platforms and dynamically triggering changes, such as increasing microenvironmental stiffness, enables researchers to model changes in the extracellular matrix (ECM) that occur during fibrotic disease progression. Herein, a method is presented for 3D bioprinting a phototunable hydrogel biomaterial capable of two sequential polymerization reactions within a gelatin support bath. The technique of Freeform Reversible Embedding of Suspended Hydrogels (FRESH) bioprinting was adapted by adjusting the pH of the support bath to facilitate a Michael addition reaction. First, the bioink containing poly(ethylene glycol)-alpha methacrylate (PEG&#945;MA) was reacted off-stoichiometry with a cell-degradable crosslinker to form soft hydrogels. These soft hydrogels were later exposed to photoinitator and light to induce the homopolymerization of unreacted groups and stiffen the hydrogel. This protocol covers hydrogel synthesis, 3D bioprinting, photostiffening, and endpoint characterizations to assess fibroblast activation within 3D structures. The method presented here enables researchers to 3D bioprint a variety of materials that undergo pH-catalyzed polymerization reactions and could be implemented to engineer various models of tissue homeostasis, disease, and repair.

Autore in primo piano: Comprendere le malattie polmonari croniche utilizzando idrogel fototunable stampati in 3D 

This article describes how to 3D bioprint phototunable hydrogels to study extracellular matrix stiffening and fibroblast activation.

Idrogel fotoregistrabili in bioprinting 3D per studiare l'attivazione dei fibroblasti

Phototunable hydrogels can transform spatially and temporally in response to light exposure. Incorporating these types of biomaterials in cell-culture ...

Produzione di elastina-come proteina idrogeli per incapsulamento e Immunostaining delle cellule in 3D

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