Die Autoren danken, die Finanzierung von Bildungsministerium ACRF Tier 1 (RG41) bestätigen und starten Zuschuss von der Nanyang Technological University. Low und Tjin werden von der Forschung Student Scholarship (RSS) aus Nanyang Technological University, Singapur finanziert.

1. Klonierung von rekombinanten Plasmiden, die für Proteine ​​aECM <ol><li> Gestalten Sie die Aminosäuresequenz der funktionellen Domäne (zB Zellbindungsdomäne und Elastin-ähnliche Wiederholungen). Design Restriktionsstellen flankieren die Enden der funktionellen Domänen zu erleichtern Subklonierung mit freier Software nach Software-Anweisungen (zB http://biologylabs.utah.edu/jorgensen/wayned/ape/). Wählen Sie hier einmal vorkommende Restriktionsstellen, die nicht in der funktionalen Domäne vorhanden, um die Verdauung an die vorgesehenen Standorte beschränkt sind. Wählen Restriktionsstellen in der multiplen Klonierungsstelle (MCS) des Wirt-Vektor angegeben (z pET22b (+)) für Sub-Klonen. </li><li> Rückwärts übersetzen die Aminosäuresequenz in die Nukleotidsequenz mit kostenlosen Websites nach Software-Anweisungen. (ZB http://www.bioinformatics.org/sms2/rev_trans.html). Stellen Sie sicher, Codons für E. optimiert coli-Hosts. </li><li> Gen von Interesse kann purchas seined Handel als Einzelstrang-Oligonukleotiden (dh, wenn die Oligonukleotide &lt;100 Basenpaare (bp)) und durchzuführen, DNA Tempern (siehe Schritt 1.4), die Kosten zu reduzieren. Ansonsten für Gene größer als 100 bp, sie könnten durch die Handelsgesellschaften erworben werden. </li><li> DNA Annealing der Oligonukleotide <ol><li> Tempern die DNA-Oligomeren, um die gewünschte Gen-Sequenz zu erhalten. Aufzulösen DNA-Oligonukleotide in einem DNA-Oligomer-Puffer (10 mM Tris: 2-Amino-2- (hydroxymethyl) -propan-1,3-diol, pH 8,0, filtriert) zu einer Endkonzentration von 1 ug / ul. </li><li> Hinzuzufügen 4 ul jedes Oligomers zu 32 ul DNA Annealing-Puffer (10 mM Tris, 100 mM NaCl und 100 nM MgCl 2), um insgesamt 40 ul Mischung zu erzielen. </li><li> Kochen Sie ein Becherglas mit Wasser unter Verwendung einer Kochplatte und tauchen Sie die Mischung für 5 min, 95 ° C. Das Becherglas und allmählich abkühlen die gesamte in einem Styropor-Box O / N eingestellt. Die Oligomere wurden geglüht und sind bereit für die Verdauung. </li></ol></li&gt; <li> Hinzufügen der entsprechenden Restriktionsenzyme, die geglüht Oligomere (dh als Einsatz bezeichnet) und Wirt-Vektor (dh pET22b (+)) separat zu verdauen. Verwenden des folgenden Rezepts (1-2 ug DNA, 2 ul jedes Restriktionsenzym wurden 5 ul 10x Restriktionsenzym-Puffer und Wasser bis zu insgesamt 50 &amp; mgr; l Mischung) für 3-4 h bei 37 ° C. HINWEIS: Der pET22b (+) Plasmidvektor Ampicillin Antibiotika-resistente und enthält ein 6x-His-Tag am C-Terminus. Die 6x-His in pET22b (+) vorhanden tag ermöglicht es uns, His-markierten Antikörper zu verwenden, um das Zielprotein durch Western-Blot in Schritt 7 zu identifizieren. </li><li> In 6x Ladepuffer zu jedem Verdauungsgemisch. Führen Sie die Aufschlussgemische getrennt einschließlich einer DNA-Leiter auf 1,2% Agarosegelen DNA, enthaltend eine UV-fluoreszierende DNA-Farbstoff 1 h bei 100 V visualisieren die 1,2% DNA Agarosegel mit einer UV-Lichtbeleuchtung. </li><li> Schneiden Sie das Gel auf verdauten DNA-Produkte mit kommerziellen Gel Aufreinigungskits extrahieren. Elute mit dem Mindestvolumen für die Spalte, um eine minimale DNA-Konzentration von 50 bis 100 ng / &amp; mgr; l zu erreichen. </li><li> Kombinieren der das interessierende Gen sequentiell durch Ligation des DNA-Inserts verdaut (dh Elastin Wiederholungen oder Zellbindungsdomänen von DNA Glühen erhalten wird) in den Plasmidvektor unter Verwendung von T4-Ligase mit dem folgenden Rezept: (2 &amp; mgr; l Vektor, 1 ul T4-Ligase, 1,5 ul T4-Ligationspuffer, x ul Einsatz, 10,5 x ul Wasser für insgesamt 15 &amp; mgr; l Mischung). Inkubieren Sie die Ligationsmischung bei RT für 2 h. HINWEIS: molare Konzentration von Vektor einfügen sollte geändert werden, um Ligationseffizienz zu optimieren. Volumen als x im Rezept beschrieben Einsatz ist abhängig von der eluierten DNA-Konzentration von Schritt 1.7. </li><li> Thaw E. coli DH5a chemisch kompetente Zellen (oder jedes Klonen Stamm) auf Eis. Warm 2xYT Agar-Platten (Tabelle 1), enthaltend Ampicillin (25 ug / ml) auf 37 ° C. </li><li> Transformieren der Zellen unter VerwendungHitzeschock: <ol><li> Aliquot 50 ul kompetenter Zellen in saubere, vorgekühlte Mikrozentrifugenröhrchen. Pipette 5 ul (zwischen 100 pg bis 100 ng) der Ligationsmischung in die Zellen, Pipettieren vorsichtig nach oben und unten zu mischen. Lassen Sie die Mischung auf Eis für 20 min. </li><li> Eintauchen der Mikrozentrifugenröhrchen, das die Zellmischung in einem 42 ° C warmen Wasserbad für 2 Minuten und kehrte auf Eis für 2 min. Zeit der Eintauchdauer, um Hitzeschäden an den Zellen zu minimieren. </li><li> Gib 500 &amp; mgr; l SOC-Medium (Tabelle 1) in das Mikrozentrifugenröhrchen und Inkubieren bei 37 ° C unter Schütteln für 1 Stunde. </li><li> Verbreiten 50 500 ul der Zell / Ligationsmischung auf einem 2 × YT-Agar-Platte, die auf RT erwärmt worden ist, enthaltend Ampicillin (25 ug / ml) und Inkubation Platten der Oberseite nach unten bei 37 ° CO / N (12-16 h) . </li></ol></li><li> Am nächsten Tag abholen DNA Kolonien von der Agar-Platte mit saubere Pipettenspitzen. Wachsen die Kolonien in 5 ml 2YT-Medium (Tabelle1), das Ampicillin (25 ug / ml) O / N bei 37 ° CO / N (12-16 h) unter Schütteln (225 rpm). </li><li> Am folgenden Tag, mit einem Plasmid Isolation Kit, um die DNA-Plasmide für jede Kolonie nach Herstellerprotokoll aufgenommen zu extrahieren. Elution der DNA mit 50 ul Wasser. </li><li> Führen Sie einen Test verdauen mit Restriktionsenzymen mit folgender Rezeptur: (5 ul DNA, 0,2 ul jedes Restriktionsenzym, 1 ul 10x Restriktionsenzym-Puffer und füllen Sie Wasser für insgesamt 10 ul Gemisch), Inkubation für 2 Stunden bei 37 ° C zum Bildschirm für die Kolonien, die wahrscheinlich enthalten den Einsatz und laufen auf 1,2% Agarose-Gel-DNA, wie in Schritt 1.6. HINWEIS: Bei der Verdauung, eine erfolgreiche Ligation sollten die Ergebnisse in zwei Bänder, je eine für Vektor- und Insert, das auf ihre jeweiligen Molekulargewicht entspricht (Abbildung 1). </li><li> Senden Sie die wahrscheinlich Kolonien zur DNA-Sequenzierung unter Verwendung von T7-Promotor Vorwärts- und Rückwärtsprimer für kommerzielle Sequenzer. </li></ol><ol><li> Von der Sequenzierung Ergebnis, wählen Sie eine Kolonie, die erfolgreich ligiert wurde und verwenden Sie den DNA-Plasmid für die Transformation in einen E. coli Expressionswirt. </li><li> Thaw E. coli Expressionsstamm (BL21 (DE3) pLysS) auf Eis. Inzwischen warmen Agarplatten, enthaltend Ampicillin (25 ug / ml) und Chloramphenicol (34 ug / ml) auf Raumtemperatur. ANMERKUNG: Das Plasmid pLysS in Bakterien vorliegende Stamm BL21 (DE3) pLysS eine Chloramphenicol-Resistenz-Gen enthält. Die pLysS Plasmid enthält ein T7 Repressorgen, die konstitutiv exprimiert wird, um undichte Ausdruck der aECM Protein zu begrenzen. Chloramphenicol ist notwendig, um für die Bakterienzellen, die pLysS während der Kultur enthält auszuwählen. </li><li> Wiederholen Sie Schritt 1,10 bis transformierten E. zu erhalten coli-Zellen, die bereit sind, die künstliche Proteine ​​zu exprimieren sind. Wrap-Agar-Platten in Parafilm und lagern auf den Kopf in 4 6; C für bis zu einem Monat. </li></ol> 3. Bakterielle Expression des Proteins aECM <ol><li> Siehe Abbildung 2, wählen Sie eine Kolonie von der Agarplatte transformiert mit einer Pipettenspitze und Beimpfen in 10 ml sterilem Terrific Broth (TB) -Medium (Tabelle 1), die sowohl Ampicillin und Chloramphenicol-Antibiotika in einem Reagenzglas. Inkubieren Sie dieses Starterkultur bei 37 ° CO / N (12-16 h) mit 225 rpm schütteln. </li><li> 10 ml der Starterkultur in 1 l frisch und sterile TB-Medien mit den gleichen Antibiotika in einen 3 l-Erlenmeyerkolben ergänzt. Inkubieren Sie die Kultur bei 37 ° C unter Schütteln bei 225 rpm für 2-3 Stunden und beobachten Sie die optische Dichte der Kultur (OD 600) erreicht 0,6-0,8 durch Pipettieren von 1 ml der Kultur in eine leere Küvette zum Lesen. Sparen Sie 1 ml der Kultur vor der Induktion für SDS-PAGE Charakterisierung. <ol><li> Um OD 600 von der Zellkultur messen, bereiten 1 Flasche TB Medien in einer Küvettefür eine Leermessung. Getrennt davon wurde je 1 ml der Kultur aus der Kulturflasche in eine neue leere Küvette. Anschließend wird die optische Dichte der Kultur mit einem Spektrophotometer gegen die Blindprobe bei einer Absorption von 600 nm. </li><li> Speichern der Probe (für nachfolgende SDS-PAGE-Analyse) durch Übertragen der 1 ml der Kultur in ein 1,5 ml Mikrozentrifugenröhrchen, Zentrifugieren bei 12.000 × g für 2 min, und Dekantieren. </li></ol></li><li> Induzieren die Kultur mit Isopropyl β-D-1-thiogalactopyranosid (IPTG) zu einer Endkonzentration von 1 mM und Inkubation bei 37 ° C unter Schütteln bei 225 rpm für weitere 4 Std. Speichern 1 ml der Kultur am Ende der Induktion bei 4 Stunden für die SDS-PAGE-Charakterisierung. </li><li> Ernte der Zellen durch die Übertragung der Kultur in 1 l-Zentrifugenflaschen und Zentrifugieren bei 12.000 xg für 30 min bei 4 ° C. Überstand verwerfen, wiegen die Zellpellets und resuspendieren in TEN-Puffer (1 M Tris, 0,01 M EDTA, 0,1 M NaCl, pH = 8,0) bei 0,5 g / ml. </li></ol> 4. Die Lyse von Bakterienkulturen <ol><li> Frieren Sie den resuspendierten Zellkultur bei -80 ° CO / N. Auftauen der gefrorenen Zellkultur in einem Wasserbad bei RT oder auf Eis, um die Zellen zu lysieren. Zugabe von 10 ug / ml Deoxyribonuclease I (DNase I), 10 &amp; mgr; g / ml Ribonuclease A (RNase I), und 50 ug / ml Phenylmethylsulfonylfluorid (PMSF), während dem Auftauen und homogenisieren der Lösung unter langsamem Rühren. </li><li> Nachdem alle resuspendierten Zellen werden aufgetaut, passen Sie die Lösung auf pH 9,0, um das Protein Löslichkeit in Wasser 12 zu erhöhen. In 6 N NaOH tropfenweise unter Rühren auf Eis, um eine homogene Konsistenz zu erreichen. Lyse durch Ultraschall Unterbrechung für 20 Minuten auf Eis mit einem Durchmesser von 2 mm flache Spitze, 5 sec Puls. </li><li> Zentrifugieren Sie die Zell-Lösung bei 12.000 × g für 30 min bei 4 ° C. Den Überstand in ein sauberes, leere Flasche und bei 4 ° C zur Reinigung später. </li><li> Inzwischen Zellpellet wieder mit TEN-Puffer und wieder einfrieren bei -80 ° C. Bisvollständige Zelllyse, wiederholen Einfrieren / Auftauen und Beschallen Prozess bis zu dreimal. Sparen Sie 20 ul Zellysat für SDS-PAGE-Charakterisierung. </li></ol> 5. Reinigung von Proteinen mit aECM Inverse Transition Radfahren <ol><li> Kollationieren des Zelllysats aus Schritt 4.3 und damit fortfahren, die aECM Proteine ​​mittels ITC, ähnlich der für die Reinigung von Proteinen elastinbasiertem 21 verwendet zu reinigen. Zyklen bei den verschiedenen Temperaturen, die 4 ° C durchgeführt werden und 37 ° C (bezeichnet als &quot;kalt&quot; bezeichnet) Zyklen (nachfolgend als &quot;warm&quot; bezeichnet) auf. </li><li> Spalten die Zelllysat in 50 ml-Zentrifugenflaschen und Zentrifugieren bei 40.000 × g für 2 Stunden bei 4 ° C. Das Aussehen der Zellpellet sollte dunkelbraun sein und freuen flüssig. </li><li> Entfernen Sie den Überstand mit einer Pipette, um eine saubere Trennung von dem Pellet zu erhalten. Sammeln Sie den Überstand in sauberes Zentrifugenflaschen und NaCl bis zu einer Endkonzentration von 1 M (bis zu einem Maximum von 3 M). Warmdie Lösung auf 37 ° C für 2 Stunden mit Schütteln bei 225 rpm. HINWEIS: Die Zugabe von NaCl wird der Übergang des Elastin-Komponente des aECM verursachen Aggregation auszulösen. Der Überstand wird sich trüben. Wenn die Proteinkonzentration hoch genug ist, kann weißen schaumigen Protein an den Seiten des Zentrifugenflasche ersichtlich ist. </li><li> Zentrifugieren der Überstand aus Schritt 5.3 bei 40.000 × g für 2 Stunden bei 37 ° C. Den Überstand umfüllen. Crush the Pellet mit einem Metallspatel und das Pellet Bits in eiskaltem autoklaviert destilliertem Wasser (50 mg / ml) unter kräftigem Rühren O / N bei 4 ° C unter Verwendung eines magnetischen Rührstab und Teller. Das Pellet sollte vollständig aufgelöst werden. </li><li> Die Schritte 5.2 bis 5.4 für weitere drei bis fünf Mal, um eine höhere Reinheit des Proteins zu erhalten. </li><li> Nach dem letzten Reinigungszyklus, entsalzen der Proteinlösung durch Dialyse gegen destilliertes Wasser bei 4 ° C. Dialysiere Proteinlösung gegen Wasser für 2-3 Tage mit Veränderungen der Wasser alle 4h oder 8 h für O / N. Sparen Sie 20 ul des gereinigten Proteins für SDS-PAGE und lyophilisieren den Rest des gereinigten Proteins und bei -80 ° C bis zur weiteren Verwendung. </li></ol> 6. Charakterisierung von aECM Proteinen mit SDS-PAGE-Elektrophorese <ol><li> Vorbereitung eines 12% SDS-PAGE-Gel (wenn das Molekulargewicht groß ist, nutzen 8% SDS-PAGE-Gele für eine bessere Trennung). Hinzuzufügen 2x SDS-Ladepuffer zu jeder Probe, Erwärmen der Proben für 10 min bei 100 ° C einstellen und Auftragung auf das Gel 1 h lang bei 100 V, bis das Protein Leiter entsprechend dem Molekulargewicht des Proteins aECM der Mitte der erreicht Gel. </li><li> Abrufen des Gels aus dem SDS-PAGE einzurichten und fügen Coomassie Brilliant Blue-Färbung (Tabelle 2) mit einem Volumen, das Gel für 1 Stunde in einer Petrischale eintauchen. Rinse Gel in einer Entfärbelösung (Tabelle 2) für 5 min auf einer Wippe. Ändern Sie die Entfärbelösung, und weiter, um das Gel mit Schaukel bis dem Hintergrund t entfärbener gel deutlich. Proteinbanden muss deutlich sichtbar sein. </li><li> Vergleichen der Position des Zielproteins gegen das Protein Leiter um das Molekulargewicht des Zielproteins zu bestimmen. </li><li> Um die Anwesenheit des Target-Proteins weiter zu bestätigen, führen Western Blotting, wie in Schritt 7. </li></ol> 7. Charakterisierung von Proteinen mit aECM Western Blotting <ol><li> Führen Sie die Proben auf einem 12% SDS-PAGE-Gel, wie in Kapitel 6 ohne Färbung. </li><li> Geschnitten Nitrocellulosemembran auf eine Größe geringfügig größer als die SDS-PAGE-Gel. Schneiden 4 Stück Filterpapier in der gleichen Größe. </li><li> Wet einem Stück Filterpapier mit westlichen Transferpuffer (20% v / v Methanol, 25 mM Tris, 190 mM Glycin, pH 8,3), legen Sie die SDS-PAGE-Gel auf dem Filterpapier, gefolgt von einem weiteren Stück Filterpapier , dann die Nitrocellulosemembran und einem abschließenden beiden anderen Stücke von Filterpapier. Stellen Sie sicher, das ganze Set-up wird mit ausreichend westlichen Transferpuffer eingetaucht. ANMERKUNG: Das Gel und die Membran nicht in Kontakt zu diesem Zeitpunkt, wie Proteine ​​könnten an die Membran bei Kontakt zu binden. </li><li> Übertragen Sie die Proteine ​​auf der Nitrocellulosemembran, indem zwei Filterpapiere in einen westlichen halbtrockenen Transfereinheit, gefolgt von der Nitrocellulosemembran und vorsichtig die SDS-PAGE-Gel in und an der Membran, schließlich legen Sie die letzten zwei feuchtem Filterpapier auf Die SDS-PAGE-Gel. Führen Sie den westlichen Übertragung bei 45 mA, 30 min. In Puffer, wenn die Spannung höher als 30 V. HINWEIS: vorzugsweise die SDS-PAGE-Gel auf die Membran bei einem Versuch und vermeiden Verschieben des Gels unnötig auf der Membran als Proteine ​​könnten an die Membran bei Kontakt zu binden. </li><li> Abrufen und blockieren die Nitrocellulose-Membran mit Blockierungslösung (5% fettfreier Milch in PBS, pH 7,4, mit Filterpapier filtriert) für 2 h bei RT. Entsorgen Blockierungspuffer und fügen PBS spülen. HINWEIS: Wechseln Sie neue Handschuhe zu vermeiden Kontamination der Membran mit unerwünschten proteIns. </li><li> Inkubieren primären anti-His Antikörper mit Verdünnung in PBS auf 1: 1000 bei RT für 1 h unter Schütteln. Vorbereitung einer Mischung mit einem Volumen, das die gesamte Membran eintauchen könnte, beispielsweise mit Verdünnungsverhältnis 1: 1.000, fügen 1 ul Antikörper (Stammkonzentration: 1 mg / ml) zu 999 &amp; mgr; l PBS für eine 1 ml Gesamtmischung. </li><li> Spülen der Membran mit 5 ml PBST (PBS mit 0,1% Tween 20). </li><li> Inkubieren mit sekundärem Antikörper bei 1, konjugiert an Meerrettich-Peroxidase (HRP) mit Verdünnung in PBS: 5000 bei RT für 1 h unter Schütteln. Vorbereitung einer Mischung mit einem Volumen, das die gesamte Membran eintauchen könnte, beispielsweise mit Verdünnungsverhältnis 1: 5.000, fügen 1 ul Antikörper (Stammkonzentration: 1 mg / ml) bis 4,999 &amp; mgr; l PBS für eine 5 ml Gesamtmischung. </li><li> Waschen Sie die Membran mit 5 ml PBST und zweimal wiederholen. </li><li> Übernehmen Sie die Chemilumineszenzsubstrat an die Membran mit einem Volumen, um die Membran abdecken und inkubieren indem Sie die Anweisungen für das verwendete Substrat. HINWEIS: Die Empfindlichkeit der Substrat zur Proteinnachweis können variieren, empfehlen wir ein Substrat mit maximaler Empfindlichkeit für sehr niedrige Signale bei steigender Antikörperkonzentration keine Signale zu erhöhen. </li><li> Erfassen Sie die chemolumineszierende Signale unter Verwendung einer CCD-Kamera auf Basis Imager. Stellen Sie die primären und sekundären Antikörperverdünnungsverhältnis, wenn Signale schwach und nicht-spezifisch sind. Länger inkubieren in Blockierungslösung, wenn Hintergrundsignal hoch ist. </li></ol>

<ol>
	<li>Chen, Q., Liang, S., Thouas, G. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Elastomeric+biomaterials+for+tissue+engineering.">Elastomeric biomaterials for tissue engineering.</a> Prog Polym Sci. 38 (3-4), 584-671 (2013).</li><li>Groeber, F., Holeiter, M., Hampel, M., Hinderer, S., Schenke-Layland, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Skin+tissue+engineering+-+In+vivo+and+in+vitro+applications.">Skin tissue engineering - In vivo and in vitro applications.</a> Adv Drug Deliv Rev. 63 (4-5), 352-366 (2011).</li><li>Kushner, A. M., Guan, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modular+Design+in+Natural+and+Biomimetic+Soft+Materials.">Modular Design in Natural and Biomimetic Soft Materials.</a> Angewandte Chemie International Edition. 50 (39), 9026-9057 (2011).</li><li>Gagner, J. E., Kim, W., Chaikof, E. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Designing+protein-based+biomaterials+for+medical+applications.">Designing protein-based biomaterials for medical applications.</a> Acta Biomater. 10 (4), 1542-1557 (2014).</li><li>Gomes, S., Leonor, I. B., Mano, J. F., Reis, R. L., Kaplan, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Natural+and+genetically+engineered+proteins+for+tissue+engineering.">Natural and genetically engineered proteins for tissue engineering.</a> Prog Polym Sci. 37 (1), 1-17 (2012).</li><li>Werkmeister, J. A., Ramshaw, J. A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recombinant+protein+scaffolds+for+tissue+engineering.">Recombinant protein scaffolds for tissue engineering.</a> Biomedical Materials. 7 (1), 012002 (2012).</li><li>MacNeil, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biomaterials+for+tissue+engineering+of+skin.">Biomaterials for tissue engineering of skin.</a> Materials Today. 11 (5), 26-35 (2008).</li><li>Fong, E., Tirrell, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collective+Cell+Migration+on+Artificial+Extracellular+Matrix+Proteins+Containing+Full-Length+Fibronectin+Domains.">Collective Cell Migration on Artificial Extracellular Matrix Proteins Containing Full-Length Fibronectin Domains.</a> Advanced Materials. 22 (46), 5271-5275 (2010).</li><li>Ratner, B. D., Bryant, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=BIOMATERIALS:+Where+We+Have+Been+and+Where+We+are+Going.">BIOMATERIALS: Where We Have Been and Where We are Going.</a> Annual Review of Biomedical Engineering. 6 (1), 41-75 (2004).</li><li>Cai, L., Heilshorn, S. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Designing+ECM-mimetic+materials+using+protein+engineering.">Designing ECM-mimetic materials using protein engineering.</a> Acta Biomater. 10 (4), 1751-1760 (2014).</li><li>Annabi, N., 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=Elastomeric+recombinant+protein-based+biomaterials.">Elastomeric recombinant protein-based biomaterials.</a> Biochemical Engineering Journal. 77, 110-118 (2013).</li><li>Heilshorn, S. C., DiZio, K. A., Welsh, E. R., Tirrell, D. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Endothelial+cell+adhesion+to+the+fibronectin+CS5+domain+in+artificial+extracellular+matrix+proteins.">Endothelial cell adhesion to the fibronectin CS5 domain in artificial extracellular matrix proteins.</a> Biomaterials. 24 (23), 4245-4252 (2003).</li><li>Simnick, A. J., Lim, D. W., Chow, D., 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=Biomedical+and+Biotechnological+Applications+of+Elastin-Like+Polypeptides.">Biomedical and Biotechnological Applications of Elastin-Like Polypeptides.</a> Polymer Reviews. 47 (1), 121-154 (2007).</li><li>Tjin, M. S., Chua, A. W. C., Ma, D. R., Lee, S. T., Fong, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Human+Epidermal+Keratinocyte+Cell+Response+on+Integrin-Specific+Artificial+Extracellular+Matrix+Proteins.">Human Epidermal Keratinocyte Cell Response on Integrin-Specific Artificial Extracellular Matrix Proteins.</a> Macromolecular Bioscience. 14 (8), 1125-1134 (2014).</li><li>MacNeil, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Progress+and+opportunities+for+tissue-engineered+skin.">Progress and opportunities for tissue-engineered skin.</a> Nature. 445 (7130), 874-880 (2007).</li><li>Kariya, Y., 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=Differential+regulation+of+cellular+adhesion+and+migration+by+recombinant+laminin-5+forms+with+partial+deletion+or+mutation+within+the+G3+domain+of+&#945;3+chain.">Differential regulation of cellular adhesion and migration by recombinant laminin-5 forms with partial deletion or mutation within the G3 domain of &#945;3 chain.</a> J Cell Biochem. 88 (3), 506-520 (2003).</li><li>Shang, M., Koshikawa, N., Schenk, S., Quaranta, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+LG3+module+of+laminin-5+harbors+a+binding+site+for+integrin+&#945;3&#914;1+that+promotes+cell+adhesion,+spreading,+and+migration.">The LG3 module of laminin-5 harbors a binding site for integrin &#945;3&#914;1 that promotes cell adhesion, spreading, and migration.</a> J Biol Chem. 276 (35), 33045-33053 (2001).</li><li>Hassouneh, W., Christensen, T., 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=Elastin-like+polypeptides+as+a+purification+tag+for+recombinant+proteins.">Elastin-like polypeptides as a purification tag for recombinant proteins.</a> Current Protocols in Protein Science. , 6.11.1-6.11.16 (2010).</li><li>Keeley, F., Mecham, R., Keeley, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ch.+4.">Ch. 4.</a> Evolution of Extracellular Matrix.Biology of Extracellular Matrix. , 73-119 (2013).</li><li>Le, D. H. T., 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=Self-Assembly+of+Elastin-Mimetic+Double+Hydrophobic+Polypeptides.">Self-Assembly of Elastin-Mimetic Double Hydrophobic Polypeptides.</a> Biomacromolecules. 14 (4), 1028-1034 (2013).</li><li>MacEwan, S. R., Hassouneh, W., 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=Non-chromatographic+Purification+of+Recombinant+Elastin-like+Polypeptides+and+their+Fusions+with+Peptides+and+Proteins+from+Escherichia+coli.">Non-chromatographic Purification of Recombinant Elastin-like Polypeptides and their Fusions with Peptides and Proteins from Escherichia coli.</a> Journal of visualized experiments: JoVE. (88), e51583 (2014).</li><li>Meyer, D. 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=Genetically+encoded+synthesis+of+protein-based+polymers+with+precisely+specified+molecular+weight+and+sequence+by+recursive+directional+ligation:+examples+from+the+elastin-like+polypeptide+system.">Genetically encoded synthesis of protein-based polymers with precisely specified molecular weight and sequence by recursive directional ligation: examples from the elastin-like polypeptide system.</a> Biomacromolecules. 3 (2), 357-367 (2002).</li></ol>

Die Autoren erklären, dass sie keine konkurrierenden finanziellen Interessen.

Recombinant Protein-Engineering ist eine vielseitige Technik, um neue Proteinmaterialien unter Verwendung eines Bottom-up-Ansatz zu schaffen. Die Materialien auf Proteinbasis kann je nach Anwendungsfall von Interesse konstruiert werden, um mehrere Funktionalitäten aufweisen, zugeschnitten. Aufgrund der zunehmenden Fortschritt in der Klonierung und Proteinexpression Technologien ist es relativ einfach (und kostengünstiger) zu werden, um eine Vielzahl von künstlichen Proteine ​​auf eine reproduzierbare und skalierb...

For several decades, both synthetic and natural materials have been explored for use as scaffolds in tissue engineering1,2. While synthetic materials such as polymers offer excellent structural integrity and tunable mechanical properties, they often have insufficient bioactivity to promote growth and infiltration of tissues. On the other hand, natural materials such as extracellular matrix (ECM) proteins have excellent biological activity, but have limitations such as batch-to-batch variability, rapid degradation and immunogenicity issues. As such, recombinant proteins are desired, since they can be designed to mimic only the desirable properties of native proteins3,4.
Recombinant protein engineering has garnered widespread interests as a versatile platform for the design and production of novel artificial protein biopolymers. By controlling the genetic sequence, the functionalities of the artificial proteins can be tailored for a wide variety of applications5,6. In particular, artificial extracellular matrix (aECM) proteins can be tailored to have multiple functionalities for applications in tissue engineering, regeneration and wound repair2,7. More importantly, advances in cloning and purification technologies have increased scalability and reduced the cost of manufacturing recombinant proteins tremendously. It is possible to produce large quantities of recombinant proteins at low production costs which are economic for use in the clinic5. 
Artificial extracellular matrix proteins have been developed for tissue engineering applications8-11. For instance, Tirrell et al. designed a small diameter vascular graft using artificial proteins containing fibronectin CS5 sequence and elastin-like repeats (ELP-CS5). They showed that human umbilical vein endothelial cells (HUVECs) were able to adhere and grow on these materials12. Others have also incorporated short bioactive sequences taken from fibronectin, collagen, laminin, fibrinogen and vitronectin as well as structural domains that mimic elastin, spider silk and collagens to create a variety of fusion proteins10. Bulk cross-linked films made out of elastin-based aECM proteins also exhibited mechanical properties similar to that of native elastin (elastic moduli ranges between 0.3-0.6 MPa)13. Subsequently, aECM proteins containing longer fibronectin fragments were also reported to accelerate wound healing in vitro due to increased integrin binding affinities8. 
Recently, integrin-specific artificial ECM proteins have been developed by Tjin and coworkers14. Each aECM protein contains a bioactive cell-binding domain taken from ECM components of native human skin2,7,15, such as laminin-5, collagen-IV and fibronectin. For example, the integrin &#945;3&#914;1 has been shown to bind the PPFLMLLKGSTR sequence found in the laminin-5 alpha-3 chain globular domain 3 (LG3)16,17. In their report, they showed that primary human skin epidermal keratinocytes preferentially engage different integrins for binding to each of the aECM proteins, depending on the type of cell binding domain present.
The aECM proteins discussed in the work by Tjin et al. contain flanking elastin-like domains {(VPGIG)2VPGKG(VPGIG)2}8 that confer elasticity which mimics the mechanical properties of human skin. In addition, the incorporation of lysine residues within the elastin-like repeats also increases the overall protein solubility in aqueous solvents. In addition, the lysine residues also serve as crosslinking sites to facilitate the formation of crosslinked aECM films12. Inclusion of elastin-like repeats within the aECM protein sequence allow the proteins to be readily purified via Inverse Transition Cycling (ITC)14. Elastins undergo a sharp and reversible phase transition at a specific temperature known as the lower critical solution temperature (LCST) or the inverse transition temperature (Tt)18-20. Elastins and elastin-like repeats adopt hydrophilic random coil conformations below their LCST and become soluble in water, whereas above their LCST, elastins aggregate rapidly into micron-size particles. Such phase transitions are reversible and hence, can be exploited to allow elastin-based aECM proteins to be readily purified via the ITC technique21.
In this work, we report a generalized procedure to design, construct and purify artificial ECM proteins containing bioactive cell-binding domains, fused to elastin-like repeats. The process to design and clone the plasmids that encode for the amino acid sequences for the aECM proteins is described. The steps involved to purify the aECM proteins using ITC are outlined. Finally, the methods to determine the purity of the aECM proteins obtained using SDS-PAGE electrophoresis and Western Blotting are discussed.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>pET22b (+)</td>
			<td>Novagen</td>
			<td>69744</td>
			<td>T7 expression vectors with resistance to ampicillin&#160;</td>
		</tr>
		<tr>
			<td>BL21(DE3)pLysS&#160;</td>
			<td>Invitrogen</td>
			<td>C6060-03</td>
			<td>additional antibiotics - chloramphenicol</td>
		</tr>
		<tr>
			<td>Isopropyl-beta-D-thiogalactoside (IPTG)</td>
			<td>Gold Biotechnology</td>
			<td>I2481C</td>
			<td>1M stock solution with autoclaved water, make fresh prior to induction.</td>
		</tr>
		<tr>
			<td>QIAprep Spin Miniprep Kit</td>
			<td>Qiagen</td>
			<td>27106</td>
			<td>plasmid isolation kit</td>
		</tr>
		<tr>
			<td>T4 ligase</td>
			<td>New England Biolabs</td>
			<td>M0202S</td>
			<td></td>
		</tr>
		<tr>
			<td>Ampicillin</td>
			<td>Affymetrix</td>
			<td>11259</td>
			<td></td>
		</tr>
		<tr>
			<td>Chloramphenicol</td>
			<td>Affymetrix</td>
			<td>23660</td>
			<td></td>
		</tr>
		<tr>
			<td>Zymoclean&#8482; gel DNA recovery kit</td>
			<td>Zymo Research</td>
			<td>D4001</td>
			<td></td>
		</tr>
		<tr>
			<td>XL10-gold strain</td>
			<td>Agilent Technologies</td>
			<td>200315</td>
			<td></td>
		</tr>
	</tbody>
</table>

design and construction of artificial extracellular matrix (aecm) proteins from escherichia coli for skin tissue engineering

Recombinant technology is a versatile platform to create novel artificial proteins with tunable properties. For the last decade, many artificial proteins that have incorporated functional domains derived from nature (or created de novo) have been reported. In particular, artificial extracellular matrix (aECM) proteins have been developed; these aECM proteins consist of biological domains taken from fibronectin, laminins and collagens and are combined with structural domains including elastin-like repeats, silk and collagen repeats. To date, aECM proteins have been widely investigated for applications in tissue engineering and wound repair. Recently, Tjin and coworkers developed integrin-specific aECM proteins designed for promoting human skin keratinocyte attachment and propagation. In their work, the aECM proteins incorporate cell binding domains taken from fibronectin, laminin-5 and collagen IV, as well as flanking elastin-like repeats. They demonstrated that the aECM proteins developed in their work were promising candidates for use as substrates in artificial skin. Here, we outline the design and construction of such aECM proteins as well as their purification process using the thermo-responsive characteristics of elastin.

Bei der Konstruktion von Fusionsproteinen enthalten, Elastin-ähnlichen Wiederholungen, ist es wichtig, eine Gesamt Elastingehalt, groß genug Anteil des Fusionsproteins 18 aufrechtzuerhalten. Dies soll sicherstellen, dass das Fusionsproteinkonstrukt behält seine Elastin ähnlichen Eigenschaften, um die ITC zur Aufreinigung verwenden. Die aECM Proteine ​​Design und in diesem Abschnitt beschriebenen Sequenzen wurden speziell von der Arbeit von Tjin et al. 14 genommen. In diese...

Watch this Scientific Journal Video about Design and Construction of Artificial Extracellular Matrix aECM Proteins from Escherichia coli for Skin Tissue Engineering at JoVE.com

Design and Construction of Artificial Extracellular Matrix aECM Proteins from Escherichia coli for Skin Tissue Engineering

Recombinant technologies have enabled material designers to create novel artificial proteins with customized functionalities for tissue engineering applications. For example, artificial extracellular matrix proteins can be designed to incorporate structural and biological domains derived from native ECMs. Here, we describe the construction and purification of aECM proteins containing elastin-like repeats.

Planung und Bau von künstlichen extrazellulären Matrix (aECM) Proteine ​​aus<em&gt; Escherichia coli</em&gt; Zum Haut Tissue Engineering

Recombinant technology is a versatile platform to create novel artificial proteins with tunable properties. For the last decade, many artificial proteins ...

design-construction-artificial-extracellular-matrix-aecm-proteins

Research

JoVE Journal

Bioengineering

Design and Construction of Artificial Extracellular Matrix (aECM) Proteins from Escherichia coli for Skin Tissue Engineering

8.8K Aufrufe.  Nanyang Technological University. Recombinant technologies have enabled material designers to create novel artificial proteins with customized functionalities for tissue engineering applications. For example, artificial extracellular matrix proteins can be designed to incorporate structural and biological domains derived from native ECMs. Here, we describe the construction and purification of aECM proteins containing elastin-like repeats. 

Serie: Design and Construction of Artificial Extracellular Matrix aECM Proteins from Escherichia coli for Skin Tissue Engineering

Non-contact, Label-free Monitoring of Cells and Extracellular Matrix using Raman Spectroscopy

Non-destructive, non-contact and label-free technologies to monitor cell and tissue cultures are needed in the field of biomedical research.1-5 However, currently available routine methods require processing steps and alter sample integrity. Raman spectroscopy is a fast method that enables the measurement of biological samples without the need for further processing steps. This laser-based technology detects the inelastic scattering of monochromatic light.6 As every chemical vibration is assigned to a specific Raman band (wavenumber in cm-1), each biological sample features a typical spectral pattern due to their inherent biochemical composition.7-9 Within Raman spectra, the peak intensities correlate with the amount of the present molecular bonds.1 Similarities and differences of the spectral data sets can be detected by employing a multivariate analysis (e.g. principal component analysis (PCA)).10
Here, we perform Raman spectroscopy of living cells and native tissues. Cells are either seeded on glass bottom dishes or kept in suspension under normal cell culture conditions (37 &deg;C, 5% CO2) before measurement. Native tissues are dissected and stored in phosphate buffered saline (PBS) at 4 &deg;C prior measurements. Depending on our experimental set up, we then either focused on the cell nucleus or extracellular matrix (ECM) proteins such as elastin and collagen. For all studies, a minimum of 30 cells or 30 random points of interest within the ECM are measured. Data processing steps included background subtraction and normalization.

Raman spectroscopy is a suitable technique for the non-contact, label-free analysis of living cells, tissue-engineered constructs and native tissues. Source-specific spectral fingerprints can be generated and analyzed using multivariate analysis.

Berührungslose, Label-freie Überwachung von Zellen und extrazellulären Matrix mittels Raman-Spektroskopie

Non-destructive, non-contact and label-free technologies to monitor cell and tissue cultures are needed in the field of biomedical research.1-5 However, ...

Forschung

Biotechnik

Design of a Biaxial Mechanical Loading Bioreactor for Tissue Engineering

We designed a loading device that is capable of applying uniaxial or biaxial mechanical strain to a tissue engineered biocomposites fabricated for transplantation. While the device primarily functions as a bioreactor that mimics the native mechanical strains, it is also outfitted with a load cell for providing force feedback or mechanical testing of the constructs. The device subjects engineered cartilage constructs to biaxial mechanical loading with great precision of loading dose (amplitude and frequency) and is compact enough to fit inside a standard tissue culture incubator. It loads samples directly in a tissue culture plate, and multiple plate sizes are compatible with the system. The device has been designed using components manufactured for precision-guided laser applications. Bi-axial loading is accomplished by two orthogonal stages. The stages have a 50 mm travel range and are driven independently by stepper motor actuators, controlled by a closed-loop stepper motor driver that features micro-stepping capabilities, enabling step sizes of less than 50 nm. A polysulfone loading platen is coupled to the bi-axial moving platform. Movements of the stages are controlled by Thor-labs Advanced Positioning Technology (APT) software. The stepper motor driver is used with the software to adjust load parameters of frequency and amplitude of both shear and compression independently and simultaneously. Positional feedback is provided by linear optical encoders that have a bidirectional repeatability of 0.1 &mu;m and a resolution of 20 nm, translating to a positional accuracy of less than 3 &mu;m over the full 50 mm of travel. These encoders provide the necessary position feedback to the drive electronics to ensure true nanopositioning capabilities. In order to provide the force feedback to detect contact and evaluate loading responses, a precision miniature load cell is positioned between the loading platen and the moving platform. The load cell has high accuracies of 0.15% to 0.25% full scale.

We designed a novel mechanical loading bioreactor that can apply uniaxial or biaxial mechanical strain to a cartilage biocomposite prior to transplantation into an articular cartilage defect.

Entwurf eines Biaxiale Mechanische Belastung Bioreaktor für Tissue Engineering

We  designed a loading device that is capable of applying uniaxial or biaxial  mechanical strain to a tissue engineered biocomposites fabricated for  ...

Tissue Engineering: Construction of a Multicellular 3D Scaffold for the Delivery of Layered Cell Sheets

Many tissues, such as the adult human hearts, are unable to adequately regenerate after damage.2,3 Strategies in tissue engineering propose innovations to assist the body in recovery and repair. For example, TE approaches may be able to attenuate heart remodeling after myocardial infarction (MI) and possibly increase total heart function to a near normal pre-MI level.4 As with any functional tissue, successful regeneration of cardiac tissue involves the proper delivery of multiple cell types with environmental cues favoring integration and survival of the implanted cell/tissue graft. Engineered tissues should address multiple parameters including: soluble signals, cell-to-cell interactions, and matrix materials evaluated as delivery vehicles, their effects on cell survival, material strength, and facilitation of cell-to-tissue organization. Studies employing the direct injection of graft cells only ignore these essential elements.2,5,6 A tissue design combining these ingredients has yet to be developed. Here, we present an example of integrated designs using layering of patterned cell sheets with two distinct types of biological-derived materials containing the target organ cell type and endothelial cells for enhancing new vessels formation in the &#8220;tissue&#8221;. Although these studies focus on the generation of heart-like tissue, this tissue design can be applied to many organs other than heart with minimal design and material changes, and is meant to be an off-the-shelf product for regenerative therapies. The protocol contains five detailed steps. A temperature sensitive Poly(N-isopropylacrylamide) (pNIPAAM) is used to coat tissue culture dishes. Then, tissue specific cells are cultured on the surface of the coated plates/micropattern surfaces to form cell sheets with strong lateral adhesions. Thirdly, a base matrix is created for the tissue by combining porous matrix with neovascular permissive hydrogels and endothelial cells. Finally, the cell sheets are lifted from the pNIPAAM coated dishes and transferred to the base element, making the complete construct.

For creation of highly organized structures of complex tissue, one must assemble multiple material and cell types into an integrated composite. This combinatorial design incorporates organ-specific layered cell sheets with two distinct biologically-derived materials containing a strong fibrous matrix base, and endothelial cells for enhancing new vessels formation.

Tissue Engineering: Aufbau eines Multizelluläre 3D Gerüst für die Lieferung von Layered Zellschichten

Many tissues, such as the adult human hearts, are unable to adequately regenerate after damage.2,3 Strategies in tissue engineering propose innovations to ...

Generation of a Three-dimensional Full Thickness Skin Equivalent and Automated Wounding

In vitro models are a cost effective and ethical alternative to study cutaneous wound healing processes. Moreover, by using human cells, these models reflect the human wound situation better than animal models. Although two-dimensional models are widely used to investigate processes such as cellular migration and proliferation, models that are more complex are required to gain a deeper knowledge about wound healing. Besides a suitable model system, the generation of precise and reproducible wounds is crucial to ensure comparable results between different test runs. In this study, the generation of a three-dimensional full thickness skin equivalent to study wound healing is shown. The dermal part of the models is comprised of human dermal fibroblast embedded in a rat-tail collagen type I hydrogel. Following the inoculation with human epidermal keratinocytes and consequent culture at the air-liquid interface, a multilayered epidermis is formed on top of the models. To study the wound healing process, we additionally developed an automated wounding device, which generates standardized wounds in a sterile atmosphere.

The goal of this protocol is to build up a three-dimensional full thickness skin equivalent, which resembles natural skin. With a specifically constructed automated wounding device, precise and reproducible wounds can be generated under maintenance of sterility.

Erzeugung eines dreidimensionalen Vollhaut Equivalent und automatisierte Verwundung

In vitro models are a cost effective and ethical alternative to study cutaneous wound healing processes. Moreover, by using human cells, these models ...

Epithelial Cell Repopulation and Preparation of Rodent Extracellular Matrix Scaffolds for Renal Tissue Development

This protocol details the generation of acellular, yet biofunctional, renal extracellular matrix (ECM) scaffolds that are useful as small-scale model substrates for organ-scale tissue development. Sprague Dawley rat kidneys are cannulated by inserting a catheter into the renal artery and perfused with a series of low-concentration detergents (Triton X-100 and sodium dodecyl sulfate (SDS)) over 26 hr to derive intact, whole-kidney scaffolds with intact perfusable vasculature, glomeruli, and renal tubules. Following decellularization, the renal scaffold is placed inside a custom-designed perfusion bioreactor vessel, and the catheterized renal artery is connected to a perfusion circuit consisting of: a peristaltic pump; tubing; and optional probes for pH, dissolved oxygen, and pressure. After sterilizing the scaffold with peracetic acid and ethanol, and balancing the pH (7.4), the kidney scaffold is prepared for seeding via perfusion of culture medium within a large-capacity incubator maintained at 37 &#176;C and 5% CO2. Forty million renal cortical tubular epithelial (RCTE) cells are injected through the renal artery, and rapidly perfused through the scaffold under high flow (25 ml/min) and pressure (~230 mmHg) for 15 min before reducing the flow to a physiological rate (4 ml/min). RCTE cells primarily populate the tubular ECM niche within the renal cortex, proliferate, and form tubular epithelial structures over seven days of perfusion culture. A 44 &#181;M resazurin solution in culture medium is perfused through the kidney for 1 hr during medium exchanges to provide a fluorometric, redox-based metabolic assessment of cell viability and proliferation during tubulogenesis. The kidney perfusion bioreactor permits non-invasive sampling of medium for biochemical assessment, and multiple inlet ports allow alternative retrograde seeding through the renal vein or ureter. These protocols can be used to recellularize kidney scaffolds with a variety of cell types, including vascular endothelial, tubular epithelial, and stromal fibroblasts, for rapid evaluation within this system.

This protocol describes decellularization of Sprague Dawley rat kidneys by antegrade perfusion of detergents through the vasculature, producing acellular renal extracellular matrices that serve as templates for repopulation with human renal epithelial cells. Recellularization and use of the resazurin perfusion assay to monitor growth is performed within specially-designed perfusion bioreactors.

Epithelialen Zellwiederbevölkerung und Herstellung von Nagetier extrazellulären Matrix Scaffolds für Nierengewebe Entwicklung

This protocol details the generation of acellular, yet biofunctional, renal extracellular matrix (ECM) scaffolds that are useful as small-scale model ...

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.

Technik Dreidimensionale Epithelgewebe Eingebettet in extrazellulären Matrix

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

Preparation of Extracellular Matrix Protein Fibers for Brillouin Spectroscopy

Brillouin spectroscopy is an emerging technique in the biomedical field. It probes the mechanical properties of a sample through the interaction of visible light with thermally induced acoustic waves or phonons propagating at a speed of a few km/sec. Information on the elasticity and structure of the material is obtained in a nondestructive contactless manner, hence opening the way to in vivo applications and potential diagnosis of pathology. This work describes the application of Brillouin spectroscopy to the study of biomechanics in elastin and trypsin-digested type I collagen fibers of the extracellular matrix. Fibrous proteins of the extracellular matrix are the building blocks of biological tissues and investigating their mechanical and physical behavior is key to establishing structure-function relationships in normal tissues and the changes which occur in disease. The procedures of sample preparation followed by measurement of Brillouin spectra using a reflective substrate are presented together with details of the optical system and methods of spectral data analysis.

We present a protocol for the application of Brillouin light scattering spectroscopy to elastin and trypsin-purified type I collagen fibers of the extracellular matrix to extract their full elastic properties.

Herstellung von extrazellulären Matrix Proteinfasern für Brillouin-Spektroskopie

Brillouin spectroscopy is an emerging technique in the biomedical field. It probes the mechanical properties of a sample through the interaction of ...

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.

Tunable Hydrogele aus Pulmonary Extrazellulärmatrix für 3D-Zellkultur

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

Fabrication of Extracellular Matrix-derived Foams and Microcarriers as Tissue-specific Cell Culture and Delivery Platforms

Cell function is mediated by interactions with the extracellular matrix (ECM), which has complex tissue-specific composition and architecture. The focus of this article is on the methods for fabricating ECM-derived porous foams and microcarriers for use as biologically-relevant substrates in advanced 3D in vitro cell culture models or as pro-regenerative scaffolds and cell delivery systems for tissue engineering and regenerative medicine. Using decellularized tissues or purified insoluble collagen as a starting material, the techniques can be applied to synthesize a broad array of tissue-specific bioscaffolds with customizable geometries. The approach involves mechanical processing and mild enzymatic digestion to yield an ECM suspension that is used to fabricate the three-dimensional foams or microcarriers through controlled freezing and lyophilization procedures. These pure ECM-derived scaffolds are highly porous, yet stable without the need for chemical crosslinking agents or other additives that may negatively impact cell function. The scaffold properties can be tuned to some extent by varying factors such as the ECM suspension concentration, mechanical processing methods, or synthesis conditions. In general, the scaffolds are robust and easy to handle, and can be processed as tissues for most standard biological assays, providing a versatile and user-friendly 3D cell culture platform that mimics the native ECM composition. Overall, these straightforward methods for fabricating customized ECM-derived foams and microcarriers may be of interest to both biologists and biomedical engineers as tissue-specific cell-instructive platforms for in vitro and in vivo applications.

The tissue-specific extracellular matrix (ECM) is a key mediator of cell function. This article describes methods for synthesizing pure ECM-derived foams and microcarriers that are stable in culture without the need for chemical crosslinking for applications in advanced 3D in vitro cell culture models or as pro-regenerative bioscaffolds.

Die Herstellung von extrazellulären Matrix-derived Foams und Mikroträgern als gewebespezifische Zellkultur und Delivery-Plattformen

Cell function is mediated by interactions with the extracellular matrix (ECM), which has complex tissue-specific composition and architecture. The focus ...

Fabricating a Kidney Cortex Extracellular Matrix-Derived Hydrogel

Extracellular matrix (ECM) provides important biophysical and biochemical cues to maintain tissue homeostasis. Current synthetic hydrogels offer robust mechanical support for in vitro cell culture but lack the necessary protein and ligand composition to elicit physiological behavior from cells. This manuscript describes a fabrication method for a kidney cortex ECM-derived hydrogel with proper mechanical robustness and supportive biochemical composition. The hydrogel is fabricated by mechanically homogenizing and solubilizing decellularized human kidney cortex ECM. The matrix preserves native kidney cortex ECM protein ratios while also enabling gelation to physiological mechanical stiffnesses. The hydrogel serves as a substrate upon which kidney cortex-derived cells can be maintained under physiological conditions. Furthermore, the hydrogel composition can be manipulated to model a diseased environment which enables the future study of kidney diseases.

Here we present a protocol to fabricate a kidney cortex extracellular matrix-derived hydrogel to retain the native kidney extracellular matrix (ECM) structural and biochemical composition. The fabrication process and its applications are described. Finally, a perspective on using this hydrogel to support kidney-specific cellular and tissue regeneration and bioengineering is discussed.

Herstellung einer Niere Cortex extrazelluläre Matrix abgeleitet Hydrogel

Extracellular matrix (ECM) provides important biophysical and biochemical cues to maintain tissue homeostasis. Current synthetic hydrogels offer robust ...

Planung und Bau von künstlichen extrazellulären Matrix (aECM) Proteine ​​aus

Planung und Bau von künstlichen extrazellulären Matrix (aECM) Proteine aus