フロリダ大学から種子助成 - 大学医学部は感謝して承諾されます。 NIH / NIGMS R25 GM061347：科学的な強化のための研究イニシアティブ（MBRを-RISE）フェローシップ - 大学院（マヌエル·サリナス）は生物医学研究プログラムの少数の機会を通じてサポートされていました。フロリダ国際大学の通じウォレスH.コールター財団、バイオメディカル技術部からの​​財政支援にも感謝して承諾されます。カマウ桟橋、マラキSuttle、ケンドール·アームストロングとアブラハムアルフォンソ：最後に、著者は、実験的なプロセスの様々な段階の間に彼らの支援のため、次の学生に感謝します。

1。準備<ol><li>トライリーフレットバルブ形状を収容するためにアセンブリを設計し、製造する。これは、少なくとも弁尖縫合糸での弁ホルダとパルス複写システムにアセンブリを固定するためにバルブホルダと周囲の付属品を収容するチューブを含むであろう。我々のケースでは、我々はViVitroラボ社（ビク​​トリア、BC）から入手できる市販のパルス複写システムを利用した。バルブホルダの設計と同様に前後アセンブリの構成は、図1に示されている。 </li><li>ループ全体は使用前にプライミングする必要があります。これには2つのステップが含まれます。ⅰ）使用前に任意の劣化チューブの交換及びii）ループに接続されている機器のキャリブレーション、すなわちポンプが使用されている、フロープローブを含む石鹸液と水を使用して、全体のループシステムの洗浄、および圧力変換器（一般的に心房、大動脈と心室の位置で測定）。キャリブレーションは、initをすることができますially 1％生理食塩水を用いて行うことが、血液アナロググリセリン溶液を使用する前に繰り返されるべきである。 </li></ol> 2。ネイティブ大動脈弁の解剖<ol><li> USDA公認の虐殺家（機関動物実験委員会（IACUC）の承認が必要になることがあります）から、そのまま大動脈で4新鮮な豚の心を得る。我々のケースでは、我々の解剖プロトコルはフロリダ国際大学（：11から020プロトコル承認番号）でのIACUCによって承認された。脱イオン水で心をすすぎ、流体力学的試験所に氷の上に生理食塩水（PBS）溶液及び輸送をバッファリングされた1％の抗生物質/抗真菌剤、滅菌リン酸で満たされた容器に入れてください。 </li><li>解剖鍋に心を置き、慎重に心膜を取り除く。腹側が手前になるように心を置きます。視覚的に検査し、心臓の4室を特定し、無傷の大動脈に大動脈弓を見つけます。 </li><li> TWに心を分離oは約0.75アニュラス下時に水平に横断することによって半分に、大動脈と左心室の間の接合部、すなわち 。慎重にまだ左心室組織セグメントに接続されているそのまま大動脈を分離。 </li><li>全く損傷や石灰化の兆候がないことを保証する大動脈ルートにある大動脈弁、上行大動脈と下弁輪との間の領域を調べます。 </li><li>アニュラス上で〜1で大動脈を分割し、大動脈弁（ 図2a）を分離するアニュラス下左心室組織セグメントを分離する。 </li></ol> 3。ポリマーとネイティブバルブ縫合プロセス<ol><li>各バルブのベースは、ポストホルダーのベースと揃うように、バルブホルダーの内側心臓弁を配置します。ペーパークリップで一時的に各ポストでの場所でバルブを固定しますが、交連または尖を損傷しないように注意してください。 </li><li>で縫合糸を挿入針。外側から針が簡単に下から引っ張られる可能性があることなどの内部に、最初の穴から針を通過させることによってバルブホルダーの底に縫合始まる。ルーピングファッションでは、バルブホルダーの支柱の上に垂直弁を縫合開始。 </li><li>ホルダーとホルダーポストの先端の周りに追加の縫合糸との安全の円周に沿って縫合（図2b）の進捗。バルブが完全に3ポストに、バルブホルダ（ 図2dおよび2eの ）の周囲で縫合糸を用いて固定されているときにクリップ（ 図2c）を除去することができる。 </li></ol> 4。流体力学的評価注：実際のプロトコルが使用されている特定のパルス複写システムに応じて変化するであろう。すべての情報はここにViVitroパルスデュプリケータソフト仕様（ViVitroラボ社、バンクーバー、BC）使用caontained。 <ol><li>バイリーフレットVALVE <ol><li> 70拍/分にパルス複写システムの心拍数を設定します。 </li><li> （ViVitroシステムの場合にはS35波形がすべての流体力学的試験のために選択した）ポンプを駆動するためのフロー波形を選択する。実験で使用される特定の波形は、リムら （2001）17によって示されている。 </li><li>アンプとピストンポンプの電源をオンにします。 15分間ウォームアップ。 </li><li>大動脈の位置に置き、双リーフレットバルブ（ 図2F）。 </li><li>漏れが発生する可能性があり、デバイスのすべての接合にスミア真空グリース。 </li><li>心房コンパートメントにグリセリン/生理食塩液を注ぐ。 35％/ 0.7 Lグリセリン、65％/食塩水1.3 L：拍複写システムはと液体の2 L上で実行されることに注意してください。食塩水9 mg / mlの（重量/体積）の濃度で脱イオン水によく溶解し、共通の塩を用いて調製される。 </li><li>大動脈の位置に配置されたフロートランスデューサをオンにします。 </li><li>番目のキャリブレーション電子ポンプ。 </li><li>圧力トランスデューサ続いフロートランスデューサ校正に進みます。同様にポンプには、単純に、キャリブレーションタブの下にそれぞれの流量と圧力のためViVitestソフトウェア（ViVitroラボ株式会社）によって与えられた指示に従ってください。 </li><li>キャリブレーションが完了すると、流体が大動脈コンパートメントをいっぱいになるまで、低回転でポンプを起動します。漏れがないかチェックします。必要に応じて追加の真空グリースを使用してください。 </li><li> 2ストップコック（大動脈と心室トランスデューサ）の位置を開くために回します。 </li><li>ストローク量が80ミリリットル/ビートに達するまで、ポンプの回転数を増やします。 </li><li>流れが安定するまで、システムが10分間実行することを許可します。フロー安定化は、画面​​に表示された流量と圧力の波形を観察することにより確認することができる。サイクル間に低なしバリエーションは、システム安定の良い指標である。 </li><li> ViVitestソフトウェアでモードを取得する]を選択します</li><li> 10サイクルを収集]をクリックします。 </li><li>分析モードから、Cテーブルの上になめて、ファイルを保存します。またViVitestで写真スナップオプションを使用して、波形の画像を保存します。 </li></ol></li><li>ネイティブおよびポリマーバルブ<ol><li> 3.1.3双方向リーフレットバルブ命令から - ポリマーと動物のバルブについては、同じ手順3.1.1に従ってください。 </li><li>カスタムメイドのアセンブリからガラス管内部に縫合バルブとバルブホルダーを置きます。上部と下部の部分とサンドイッチ管と横ネジとナットで、所定の位置に固定します。 </li><li>大動脈室とオリジナルの大動脈弁ホルダー間のアセンブリを配置します。 </li><li> 3.1.16双方向リーフレットバルブ命令から - ステップ3.1.5に進みます。 </li></ol></li></ol> 5。後処理<ol><li>流量と圧力波形<ol><li>平均波形を回収し、 すなわち動脈圧（AP）、心室圧（VP）、および流量（Q）毎に収集されたデータ。 </li><li>バルブの各グループ（ポリマー、ブタnについてative大動脈弁と双方向リーフレット）、同じプロットに対応するAP、VPとQ対時間の関係をプロットします。 </li><li> APの場合は、通常、ネイティブ大動脈弁18、および検証の目的のために文献から双方向リーフレット人工弁19プロットを重ねる。 </li></ol></li><li>流体力学的評価指標<ol><li>試験した各バルブについては、以下の流体力学的なメトリックを計算する必要があります。）順流圧力降下と最大transvalvular圧（TVP）、b）の大動脈根が大動脈順流、クロージング、漏れ平方根（RMS）前方の流量、C）を意味と総逆流量、d）のバルブエンドオリフィス面積（EOA）、e）のtransaortic順流、クロージング、漏洩、総エネルギー損失。 <ol><li>順流の圧力降下はTVP測定値から計算され、3時間間隔、Pに分類することができます。順流とHとの間隔：間隔0 TVPで始まり、0流れで終わる0 TVP、Fから始まり、終わる間隔。最大TVPはmAです大動脈と心室圧の測定値からバルブ全体で記録ximum圧力勾配。 </li><li> RMSフォワード流量（Q 実効値 ） は次のように前方流量の大きさを定量化するための有用な指標を提供する。 <img alt="式（1）" fo:src="/files/ftp_upload/50335/50335eq1highres.jpg" src="/files/ftp_upload/50335/50335eq1.jpg" /> &#39;N&#39;は、 &#39;Q I&#39;を集めた時点の合計数であるために、収集した瞬時流量測定は&#39;i&#39;です。 </li><li>前方の大動脈、閉会と漏れボリュームはフォワード、次の時間間隔に基づいて計算されます：順方向の流れの最後にバルブを通る順方向の流れの先頭（T O）、（T 1）;クロージング：T 1からインスタンスまでバルブ閉鎖（T 2）の、リーク電流：T 2からの心周期（T 3）の終わりまで。合計逆流量は単にCLOSの合計ですり、漏れボリューム。 </li><li>血プロパティに基づいてEOAは20として、これらの各期間中の平均TVPから3時間間隔、P、FとHのために計算することができます： <img alt="式（1）" fo:src="/files/ftp_upload/50335/50335eq2highres.jpg" src="/files/ftp_upload/50335/50335eq2.jpg" /></li><li>エネルギー損失は、次の21のように定義されます。 <img alt="式（1）" fo:src="/files/ftp_upload/50335/50335eq3highres.jpg" src="/files/ftp_upload/50335/50335eq3.jpg" /></li></ol></li></ol></li></ol>

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著者らは、開示することは何もありません。

本研究では、ポリマーとネイティブブタ弁のその流体力学的試験を行うことができるように、三尖弁の形状を収容するために、市販の複写拍動部を変更することの有用性を実証した。具体的に我々の場合には、修正されたシステムはViVitro左心とViViTestデータ収集システム（ViVitroシステムズ、ビクトリア、BC、カナダ）を介して制御全身シミュレータシステム（ 図1a）であった。?...

心臓弁膜症は、多くの場合、退行性弁石灰化1、リウマチ熱2、心内膜炎3,4または先天性先天性欠損症に起因する。バルブの損傷は狭窄および/または逆流弁逸脱を引き起こし、外科的に修復することはできません、発生した場合、ネイティブバルブは通常、人工弁に置き換えられます。現在利用可能なオプションは、機械弁（ケージボールバルブ、傾斜ディスク弁、 等 ）、同種移植、およびバイオ人工弁（ブタおよびウシバルブ）が含まれています。機械弁は、多くの場合、それらの耐久性に基づいて若い患者には推奨されていますが患者は5血栓性合併症を防ぐために、抗凝固療法に残るために必要です。同種移植片および生物人工弁は、血液薄く治療を避けるために有効な選択肢であったが、これらのバルブは、線維症リスクが高い、石灰化、変性、および弁の故障6に至る免疫原性合併症を有する。組織工学バルブが新たな技術7-9として調査が、はるかにはまだ明らかにされるように残っています。代替的耐久性、生体適合性、補綴弁は心臓弁膜症患者の生活の質を向上させるために必要とされる。再び、この弁の設計は、心臓弁疾患10と選択された患者の治療を変換するための可能性を示す塞栓アプローチで、経バルブ技術において使用されるプロテーゼを置き換えることができる。 現在の基準で述べたように、成功した心臓弁の代用には、次の性能特性を持っている必要があります &quot;1）許容小さな平均圧力差ドロップフロー前進ができ、2）許容小さな逆流と逆流を防ぐ、3）塞栓に抵抗する、4）抵抗溶血; 5）血栓形成に抵抗; 6）生体適合性であり、7）生体内診断技術に互換性があり、8）目標に成果と植込み型です人口; 9）一度配置固定されたまま、10）許​​容ノイズ·レベルを持っている、11）再現可能​​な機能を持って、12）は、ジェネリッククラスと一致して、合理的な寿命のためにその機能を維持し、13）合理的な棚のためにその機能と無菌性を維持する移植前の生活。 &quot;11。既存弁プロテーゼの欠点のいくつかは、潜在的にポリマー弁によって克服することができる。生体適合性ポリマーは、生体安定性、加水分解防止剤、抗酸化、などの有利な機械的特性に基づいて上位候補と考えられてきた高強度、粘弾性、特に、弾性ポリマーは、ネイティブ弁のダイナミクスに似た材料変形を提供することができる。エラストマーは、軟組織特性を模倣するように調整することができ、それらは生体トレラントであり、それが結合に耐えることができる利用可能な唯一の人工材料であってもよいin vivoで 、流体誘発性、曲げおよび引張応力は、まだ、健康に似た方法で移動ネイティブ弁運動。また、エラストマーは容易に格納され、様々なサイズで大量生産することができ、費用対効果の高いデバイスであると予想される、構造繊維強化材で補強することができる。 三尖弁を組み立てるための高分子材料の使用の概念は新しいものではなく、限られたバルブの耐久性のために、主に放棄された過去50年間12、上のいくつかの研究調査の対象となってきた。しかし、小説の製造方法13,14の出現で、高分子材料15,16と経カテーテルバルブ技術を有するポリマーバルブ代替の潜在シームレスな統合の強化は、最近になって潜在的にポリマーバルブの開発に新たな関心と活動があった現在市販バルブに実行可能な代案。この観点から、流体力学的機能を評価するためにこれらのバルブのテストを可能にするプロトコルが最初のステップである評価プロセスにおいて、まだ市販のパルスシミュレータシステムは、一般的に三尖弁の設計に対応するために装備してくると市販の心臓弁（ 例えば傾斜ディスク、バイリーフレット人工心臓弁）を挿入するための環状の間隔が含まれていません。第二に、ポリマー弁は、その流体力学だけ相対コンテキストで評価することができる新たな技術である。天然の心臓弁の圧力および流量データが利用可能であっても、そのように考慮するための高分子バルブを評価するために使用されるのと同じ脈動シミュレータを用いて、ヒトバルブ生物学的に類似しているネイティブ大動脈ブタ弁のテストを実施することが重要であるシステムに依存するかもしれない測定の違い。したがって、本研究の目的は、市販のパルスシミュレータは三尖弁構造に対応するために、体系相対CONTにおけるポリマーバルブ流体力学的指標を評価するためにアセンブリを取り付けることができるかを実証することであった機械的およびネイティブブタ心臓弁の対応と比較してEXT。この例では、予めフロリダ13大学で開発された新規な三尖弁シリコーンポリマーは、ポリマー弁群を含んでいた。

<table border="1">
	<tbody>
		<tr>
			<td>Name of Reagent/Material</td>
			<td>Company</td>
			<td>Catalog Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Pump</td>
			<td>ViVitro Labs</td>
			<td></td>
			<td><a href="http://vivitrolabs.com/products/superpump/" target="_blank">http://vivitrolabs.com/products/superpump/</a></td>
		</tr>
		<tr>
			<td>Flow Meter and Probe</td>
			<td>Carolina Medical</td>
			<td>Model 501D</td>
			<td><a href="http://www.carolinamedicalelectronics.com/documents/FM501.pdf" target="_blank">http://www.carolinamedicalelectronics.com/documents/FM501.pdf</a></td>
		</tr>
		<tr>
			<td>Pressure Transducer</td>
			<td>ViVitro Labs</td>
			<td>HCM018</td>
			<td></td>
		</tr>
		<tr>
			<td>ViVitro Pressure Measuring Assembly</td>
			<td>ViVitro Labs</td>
			<td>6186</td>
			<td></td>
		</tr>
		<tr>
			<td>Valve holder</td>
			<td>WB Engineering</td>
			<td></td>
			<td>Designed by Florida International University. Manufactured by WB Engineering</td>
		</tr>
		<tr>
			<td>Pulse Duplicator</td>
			<td>ViVitro Labs</td>
			<td>PD2010</td>
			<td><a href="http://vivitrolabs.com/wp-content/uploads/Pulse-Duplicator-Accessories1.pdf" target="_blank">http://vivitrolabs.com/wp-content/uploads/Pulse-Duplicator-Accessories1.pdf</a></td>
		</tr>
		<tr>
			<td>Pulse Duplicator Data Acquisition and Control System, including ViViTest Software</td>
			<td>ViVitro Labs</td>
			<td>PDA2010</td>
			<td><a href="http://vivitrolabs.com/products/software-daq" target="_blank">http://vivitrolabs.com/products/software-daq</a></td>
		</tr>
		<tr>
			<td>Porcine Hearts and Native Aortic Valves</td>
			<td>Mary&#39;s Ranch Inc</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Bi-leaflet Mechanical Valves</td>
			<td>Saint Jude Medical</td>
			<td></td>
			<td><a href="http://www.sjm.com/" target="_blank">http://www.sjm.com/</a></td>
		</tr>
		<tr>
			<td>High Vacuum Grease</td>
			<td>Dow Corning Corporation</td>
			<td></td>
			<td><a href="http://www1.dowcorning.com/DataFiles/090007b281afed0e.pdf" target="_blank">http://www1.dowcorning.com/DataFiles/090007b281afed0e.pdf</a></td>
		</tr>
		<tr>
			<td>Glycerin</td>
			<td>McMaster-Carr</td>
			<td>3190K293</td>
			<td>99% Natural 5 gal</td>
		</tr>
		<tr>
			<td>Phosphate Buffered Saline (PBS)</td>
			<td>Fisher Scientific</td>
			<td>MT21031CV</td>
			<td>100 ml/heart</td>
		</tr>
		<tr>
			<td>Antimycotic/Antibiotic Solution</td>
			<td>Fisher Scientific</td>
			<td>SV3007901</td>
			<td>1 ml in 100 ml of PBS/heart; 20 ml for ViVitro System</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma-Aldrich</td>
			<td>S3014-500G</td>
			<td>9 g/L of deionized water</td>
		</tr>
		<tr>
			<td>Deionized Water</td>
			<td>EMD Millipore Chemicals</td>
			<td></td>
			<td>Millipore Deionized Purification System. 1.3 L for ViVitro System, 200 ml for heart valve dissection process</td>
		</tr>
	</tbody>
</table>

protocol for relative hydrodynamic assessment of tri-leaflet polymer valves

現在利用可能な人工弁、異種移植、および同種移植の制限はトライリーフレットポリマーバルブ補綴物の分野における開発の最近の復活を促した。しかしながら、ポリマー弁流体力学的機能の初期評価のためのプロトコルの識別は、設計プロセスの初期段階で非常に重要である。 インビトロパルス複写システムにおける伝統的な可撓三尖材料を収容するように構成されていない、加えて、ポリマー弁機能の評価は、同一の試験条件下でネイティブおよび人工心臓弁に対する文脈でなされる必要があるというように異なるからの測定値のばらつき器具を回避することができる。そこで、私の流体力学的評価を実施）ネイティブ（N = 4、直径、D = 20ミリメートルを意味する）、ii）の双方向リーフレットメカニカル（N = 2、D = 23㎜）及びiii）ポリマーバルブ（N = 5、市販のパルス複写システム（ViVitroラボの使用を介したD = 22㎜）トライリーフレットバルブジオメトリに対応するために変更された株式会社、ビクトリア、BC）。フロリダ大学で開発された三尖弁は、シリコーンポリマーバルブ基を含んでいた。水、グリセリン35:65の比率の混合物は、血液の物理的特性を模倣するために使用された。圧力が心室と大動脈の位置に記録しながら瞬時流量は、左心室と大動脈単位の界面で測定した。双リーフレット及び文献から自然弁データは、流量及び圧力測定値を検証するために使用した。次の流体力学的指標が報告された：順流圧力降下は、大動脈二乗フォワード流量、大動脈閉塞、漏れや逆流量、transaortic閉鎖、リーク、及び全エネルギー損失を意味する。代表的な結果は、3つの弁グループから流体力学的メトリックが正常に市販のパルス複写システムとsubsequentlに特注のアセンブリを組み込むことによって得られることが示されたyは、客観的にポリマーバルブ設計の機能的な側面についての洞察を提供することを比較した。

代表的な流量と圧力波形は図3、図4および図5に示されている。プロットされた各グループのテストバルブのサンプルサイズで平均化され、nはそれぞれ= 5,4、およびポリマー、ネイティブブタと双方向リーフレットグループの2バルブ、。平均流体力学的メトリックおよびこれらのサンプルサイズの平均値の標準誤差を表1に示す。 <p class="jove_content" fo:kee...

Watch this Scientific Journal Video about Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves at JoVE.com

Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves

ポリマーバルブの開発に関心がリニューアルしました。ここでは、目的は、三尖形状を収容するために、近同一の条件下で収集されたネイティブおよび人工弁データと比較して、ポリマー弁流体力学的データを提示するためのプロトコルを定義するために商業的なパルスデュプリケータを変更することの実現可能性を実証することである。

トライリーフレットポリマーバルブの相対的な流体力学的評価のためのプロトコル

Limitations of currently available prosthetic valves, xenografts, and homografts have prompted a recent resurgence of developments in the area of ...

protocol-for-relative-hydrodynamic-assessment-tri-leaflet-polymer

Research

JoVE Journal

Bioengineering

13.7K ビュー.  Florida International University. ポリマーバルブの開発に関心がリニューアルしました。ここでは、目的は、三尖形状を収容するために、近同一の条件下で収集されたネイティブおよび人工弁データと比較して、ポリマー弁流体力学的データを提示するためのプロトコルを定義するために商業的なパルスデュプリケータを変更することの実現可能性を実証することである。

ビデオ: Protocol for Relative Hydrodynamic Assessment of Tri-leaflet Polymer Valves

A Microfluidic-based Hydrodynamic Trap for Single Particles

The ability to confine and manipulate single particles in free solution is a key enabling technology for fundamental and applied science. Methods for particle trapping based on optical, magnetic, electrokinetic, and acoustic techniques have led to major advancements in physics and biology ranging from the molecular to cellular level. In this article, we introduce a new microfluidic-based technique for particle trapping and manipulation based solely on hydrodynamic fluid flow. Using this method, we demonstrate trapping of micro- and nano-scale particles in aqueous solutions for long time scales. The hydrodynamic trap consists of an integrated microfluidic device with a cross-slot channel geometry where two opposing laminar streams converge, thereby generating a planar extensional flow with a fluid stagnation point (zero-velocity point). In this device, particles are confined at the trap center by active control of the flow field to maintain particle position at the fluid stagnation point. In this manner, particles are effectively trapped in free solution using a feedback control algorithm implemented with a custom-built LabVIEW code. The control algorithm consists of image acquisition for a particle in the microfluidic device, followed by particle tracking, determination of particle centroid position, and active adjustment of fluid flow by regulating the pressure applied to an on-chip pneumatic valve using a pressure regulator. In this way, the on-chip dynamic metering valve functions to regulate the relative flow rates in the outlet channels, thereby enabling fine-scale control of stagnation point position and particle trapping. The microfluidic-based hydrodynamic trap exhibits several advantages as a method for particle trapping. Hydrodynamic trapping is possible for any arbitrary particle without specific requirements on the physical or chemical properties of the trapped object. In addition, hydrodynamic trapping enables confinement of a "single" target object in concentrated or crowded particle suspensions, which is difficult using alternative force field-based trapping methods. The hydrodynamic trap is user-friendly, straightforward to implement and may be added to existing microfluidic devices to facilitate trapping and long-time analysis of particles. Overall, the hydrodynamic trap is a new platform for confinement, micromanipulation, and observation of particles without surface immobilization and eliminates the need for potentially perturbative optical, magnetic, and electric fields in the free-solution trapping of small particles.

In this article, we present a microfluidic-based method for particle confinement based on hydrodynamic flow. We demonstrate stable particle trapping at a fluid stagnation point using a feedback control mechanism, thereby enabling confinement and micromanipulation of arbitrary particles in an integrated microdevice.

単一粒子のためのマイクロ流体ベースの流体力学的トラップ

The ability to confine and manipulate single particles in free solution is a key enabling technology for fundamental and applied science.  Methods for ...

生物工学

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic valve leaflets are composed of interstitial cells suspended within an extracellular matrix (ECM) and are lined with an endothelial cell monolayer. The valve withstands a harsh, dynamic environment and is constantly exposed to shear, flexion, tension, and compression. Research has shown calcific lesions in diseased valves occur in areas of high mechanical stress as a result of endothelial disruption or interstitial matrix damage1-3. Hence, it is not surprising that epidemiological studies have shown high blood pressure to be a leading risk factor in the onset of aortic valve disease4. 
The only treatment option currently available for valve disease is surgical replacement of the diseased valve with a bioprosthetic or mechanical valve5. Improved understanding of valve biology in response to physical stresses would help elucidate the mechanisms of valve pathogenesis. In turn, this could help in the development of non-invasive therapies such as pharmaceutical intervention or prevention. Several bioreactors have been previously developed to study the mechanobiology of native or engineered heart valves6-9. Pulsatile bioreactors have also been developed to study a range of tissues including cartilage10, bone11 and bladder12. The aim of this work was to develop a cyclic pressure system that could be used to elucidate the biological response of aortic valve leaflets to increased pressure loads. 
The system consisted of an acrylic chamber in which to place samples and produce cyclic pressure, viton diaphragm solenoid valves to control the timing of the pressure cycle, and a computer to control electrical devices. The pressure was monitored using a pressure transducer, and the signal was conditioned using a load cell conditioner. A LabVIEW program regulated the pressure using an analog device to pump compressed air into the system at the appropriate rate. The system mimicked the dynamic transvalvular pressure levels associated with the aortic valve; a saw tooth wave produced a gradual increase in pressure, typical of the transvalvular pressure gradient that is present across the valve during diastole, followed by a sharp pressure drop depicting valve opening in systole. The LabVIEW program allowed users to control the magnitude and frequency of cyclic pressure. The system was able to subject tissue samples to physiological and pathological pressure conditions. This device can be used to increase our understanding of how heart valves respond to changes in the local mechanical environment.

Design of a Cyclic Pressure Bioreactor for the Ex Vivo Study of Aortic Heart Valves

A cyclic pressure bioreactor capable of subjecting heart valve tissue to physiological and pathological pressure conditions has been designed. A LabVIEW program allows users to control pressure magnitude, amplitude and frequency. This device can be used to study the mechanobiology of heart valve tissue or isolated cells.

のための周期的圧力のバイオリアクターの設計生体外で</em大動脈心臓弁の>研究

The aortic valve, located between the left ventricle and the aorta, allows for unidirectional blood flow, preventing backflow into the ventricle. Aortic ...

A Chitosan Based, Laser Activated Thin Film Surgical Adhesive, 'SurgiLux': Preparation and Demonstration

Sutures are a 4,000 year old technology that remain the 'gold-standard' for wound closure by virtue of their repair strength (~100 KPa). However, sutures can act as a nidus for infection and in many procedures are unable to effect wound repair or interfere with functional tissue regeneration.1 Surgical glues and adhesives, such as those based on fibrin and cyanoacrylates, have been developed as alternatives to sutures for the repair of such wounds. However, current commercial adhesives also have significant disadvantages, ranging from viral and prion transfer and a lack of repair strength as with the fibrin glues, to tissue toxicity and a lack of biocompatibility for the cyanoacrylate based adhesives. Furthermore, currently available surgical adhesives tend to be gel-based and can have extended curing times which limit their application.2 Similarly, the use of UV lasers to facilitate cross-linking mechanisms in protein-based or albumin 'solders' can lead to DNA damage while laser tissue welding (LTW) predisposes thermal damage to tissues.3 Despite their disadvantages, adhesives and LTW have captured approximately 30% of the wound closure market reported to be in excess of US $5 billion per annum, a significant testament to the need for sutureless technology.4
In the pursuit of sutureless technology we have utilized chitosan as a biomaterial for the development of a flexible, thin film, laser-activated surgical adhesive termed 'SurgiLux'. This novel bioadhesive uses a unique combination of biomaterials and photonics that are FDA approved and successfully used in a variety of biomedical applications and products. SurgiLux overcomes all the disadvantages associated with sutures and current surgical adhesives (see Table 1).
In this presentation we report the relatively simple protocol for the fabrication of SurgiLux and demonstrate its laser activation and tissue weld strength. SurgiLux films adhere to collagenous tissue without chemical modification such as cross-linking and through irradiation using a comparatively low-powered (120 mW) infrared laser instead of UV light. Chitosan films have a natural but weak adhesive attraction to collagen (~3 KPa), laser activation of the chitosan based SurgiLux films emphasizes the strength of this adhesion through polymer chain interactions as a consequence of transient thermal expansion.5 Without this 'activation' process, SurgiLux films are readily removed.6-9 SurgiLux has been tested both in vitro and in vivo on a variety of tissues including nerve, intestine, dura mater and cornea. In all cases it demonstrated good biocompatibility and negligible thermal damage as a consequence of irradiation.6-10

A Chitosan Based, Laser Activated Thin Film Surgical Adhesive, &#039;SurgiLux&#039;: Preparation and Demonstration

The fabrication of a novel, flexible thin film surgical adhesive from FDA approved ingredients, chitosan and indocyanine green is described. Bonding of this adhesive to collagenous tissue through a simple activation process with a low-powered infra-red laser is demonstrated.

キトサンベース、レーザー活性薄膜外科用接着剤、 &#39;SurgiLux&#39;：準備とデモ

Sutures are a 4,000 year old technology that remain the 'gold-standard' for wound closure by virtue of their repair strength (~100 KPa). However, sutures ...

Polymer Microarrays for High Throughput Discovery of Biomaterials

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a combinatorial library of materials to be screened in a parallel, high throughput format1. Herein is described the formation and characterization of a polymer microarray using an on-chip photopolymerization technique 2. This involves mixing monomers at varied ratios to produce a library of monomer solutions, transferring the solution to a glass slide format using a robotic printing device and curing with UV irradiation. This format is readily amenable to many biological assays, including stem cell attachment and proliferation, cell sorting and low bacterial adhesion, allowing the ready identification of 'hit' materials that fulfill a specific biological criterion3-5. Furthermore, the use of high throughput surface characterization (HTSC) allows the biological performance to be correlated with physio-chemical properties, hence elucidating the biological-material interaction6. HTSC makes use of water contact angle (WCA) measurements, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). In particular, ToF-SIMS provides a chemically rich analysis of the sample that can be used to correlate the cell response with a molecular moiety. In some cases, the biological performance can be predicted from the ToF-SIMS spectra, demonstrating the chemical dependence of a biological-material interaction, and informing the development of hit materials5,3.

A description of the formation of a polymer microarray using an on-chip photopolymerization technique. The high throughput surface characterization using atomic force microscopy, water contact angle measurements, X-ray photoelectron spectroscopy and time of flight secondary ion mass spectrometry and a cell attachment assay is also described.

バイオマテリアルのハイスループット検出用高分子マイクロアレイ

The discovery of novel biomaterials that are optimized for a specific biological application is readily achieved using polymer microarrays, which allows a ...

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, each offering its own advantages and shortcomings5,6. Most prominently, due to the microscale device dimensions, a high modulus is required to facilitate implantation into living tissue. Conversely, the stiffness of the device should match the surrounding tissue to minimize induced local strain7-9. Therefore, we recently developed a new class of bio-inspired materials to meet these requirements by responding to environmental stimuli with a change in mechanical properties10-14. Specifically, our poly(vinyl acetate)-based nanocomposite (PVAc-NC) displays a reduction in stiffness when exposed to water and elevated temperatures (e.g. body temperature). Unfortunately, few methods exist to quantify the stiffness of materials in vivo15, and mechanical testing outside of the physiological environment often requires large samples inappropriate for implantation. Further, stimuli-responsive materials may quickly recover their initial stiffness after explantation. Therefore, we have developed a method by which the mechanical properties of implanted microsamples can be measured ex vivo, with simulated physiological conditions maintained using moisture and temperature control13,16,17. 
To this end, a custom microtensile tester was designed to accommodate microscale samples13,17 with widely-varying Young's moduli (range of 10 MPa to 5 GPa). As our interests are in the application of PVAc-NC as a biologically-adaptable neural probe substrate, a tool capable of mechanical characterization of samples at the microscale was necessary. This tool was adapted to provide humidity and temperature control, which minimized sample drying and cooling17. As a result, the mechanical characteristics of the explanted sample closely reflect those of the sample just prior to explantation.
The overall goal of this method is to quantitatively assess the in vivo mechanical properties, specifically the Young's modulus, of stimuli-responsive, mechanically-adaptive polymer-based materials. This is accomplished by first establishing the environmental conditions that will minimize a change in sample mechanical properties after explantation without contributing to a reduction in stiffness independent of that resulting from implantation. Samples are then prepared for implantation, handling, and testing (Figure 1A). Each sample is implanted into the cerebral cortex of rats, which is represented here as an explanted rat brain, for a specified duration (Figure 1B). At this point, the sample is explanted and immediately loaded into the microtensile tester, and then subjected to tensile testing (Figure 1C). Subsequent data analysis provides insight into the mechanical behavior of these innovative materials in the environment of the cerebral cortex.

Environmentally-controlled Microtensile Testing of Mechanically-adaptive Polymer Nanocomposites for ex vivo Characterization

A method is discussed by which the in vivo mechanical behavior of stimuli-responsive materials is monitored as a function of time. Samples are tested ex vivo using a microtensile tester with environmental controls to simulate the physiological environment. This work further promotes understanding the in vivo behavior of our material.

機械的に適応型ポリマーナノコンポジットの環境制御のMicrotensileテスト<em&gt; ex vivoで</em&gt;キャラ

Implantable microdevices are gaining significant attention for several biomedical applications1-4. Such devices have been made from a range of materials, ...

Intra-lymph Node Injection of Biodegradable Polymer Particles

Generation of adaptive immune response relies on efficient drainage or trafficking of antigen to lymph nodes for processing and presentation of these foreign molecules to T and B lymphocytes. Lymph nodes have thus become critical targets for new vaccines and immunotherapies. A recent strategy for targeting these tissues is direct lymph node injection of soluble vaccine components, and clinical trials involving this technique have been promising. Several biomaterial strategies have also been investigated to improve lymph node targeting, for example, tuning particle size for optimal drainage of biomaterial vaccine particles. In this paper we present a new method that combines direct lymph node injection with biodegradable polymer particles that can be laden with antigen, adjuvant, or other vaccine components. In this method polymeric microparticles or nanoparticles are synthesized by a modified double emulsion protocol incorporating lipid stabilizers. Particle properties (e.g.&#160;size, cargo loading) are confirmed by laser diffraction and fluorescent microscopy, respectively. Mouse lymph nodes are then identified by peripheral injection of a nontoxic tracer dye that allows visualization of the target injection site and subsequent deposition of polymer particles in lymph nodes. This technique allows direct control over the doses and combinations of biomaterials and vaccine components delivered to lymph nodes and could be harnessed in the development of new biomaterial-based vaccines.

Lymph nodes are the immunological tissues that orchestrate immune response and are a critical target for vaccines. Biomaterials have been employed to better target lymph nodes and to control delivery of antigens or adjuvants. This paper describes a technique combining these ideas to inject biocompatible polymer particles into lymph nodes.

生分解性高分子粒子のリンパ節内注入

Generation of adaptive immune response relies on efficient drainage or trafficking of antigen to lymph nodes for processing and presentation of these ...

Manufacturing Of Robust Natural Fiber Preforms Utilizing Bacterial Cellulose as Binder

A novel method of manufacturing rigid and robust natural fiber preforms is presented here. This method is based on a papermaking process, whereby loose and short sisal fibers are dispersed into a water suspension containing bacterial cellulose. The fiber and nanocellulose suspension is then filtered (using vacuum or gravity) and the wet filter cake pressed to squeeze out any excess water, followed by a drying step. This will result in the hornification of the bacterial cellulose network, holding the loose natural fibers together.
Our method is specially suited for the manufacturing of rigid and robust preforms of hydrophilic fibers. The porous and hydrophilic nature of such fibers results in significant water uptake, drawing in the bacterial cellulose dispersed in the suspension. The bacterial cellulose will then be filtered against the surface of these fibers, forming a bacterial cellulose coating. When the loose fiber-bacterial cellulose suspension is filtered and dried, the adjacent bacterial cellulose forms a network and hornified to hold the otherwise loose fibers together.
The introduction of bacterial cellulose into the preform resulted in a significant increase of the mechanical properties of the fiber preforms. This can be attributed to the high stiffness and strength of the bacterial cellulose network. With this preform, renewable high performance hierarchical composites can also be manufactured by using conventional composite production methods, such as resin film infusion (RFI) or resin transfer molding (RTM). Here, we also describe the manufacturing of renewable hierarchical composites using double bag vacuum assisted resin infusion.

We present a novel method of manufacturing rigid and robust short natural fiber preforms using a papermaking process. Bacterial cellulose acts simultaneously as the binder for the loose fibers and provides rigidity to the fiber preforms. These preforms can be infused with a resin to produce truly green hierarchical composites.

バインダーとしてのバクテリアセルロースを利用堅牢な天然繊維プリフォームの製造

A novel method of manufacturing rigid and robust natural fiber preforms is presented here. This method is based on a papermaking process, whereby loose ...

Culturing Mouse Cardiac Valves in the Miniature Tissue Culture System

Heart valve disease is a major burden in the Western world and no effective treatment is available. This is mainly due to a lack of knowledge of the molecular, cellular and mechanical mechanisms underlying the maintenance and/or loss of the valvular structure. 
Current models used to study valvular biology include in vitro cultures of valvular endothelial and interstitial cells. Although, in vitro culturing models provide both cellular and molecular mechanisms, the mechanisms involved in the 3D-organization of the valve remain unclear. While in vivo models have provided insight into the molecular mechanisms underlying valvular development, insight into adult valvular biology is still elusive. 
In order to be able to study the regulation of the valvular 3D-organization on tissue, cellular and molecular levels, we have developed the Miniature Tissue Culture System. In this ex vivo flow model the mitral or the aortic valve is cultured in its natural position in the heart. The natural configuration and composition of the leaflet are maintained allowing the most natural response of the valvular cells to stimuli. The valves remain viable and are responsive to changing environmental conditions. This MTCS may provide advantages on studying questions including but not limited to, how does the 3D organization affect valvular biology, what factors affect 3D organization of the valve, and which network of signaling pathways regulates the 3D organization of the valve.

Here, we present an ex vivo flow model in which murine cardiac valves can be cultured allowing the study of the biology of the valve.

ミニチュア組織培養系でマウス心臓弁の培養

Heart valve disease is a major burden in the Western world and no effective treatment is available. This is mainly due to a lack of knowledge of the ...

Film Extrusion of Crambe abyssinica/Wheat Gluten Blends

Crambe abyssinica is a plant with potential for use in industrial (non-food) plant oil production. The side stream from this oil production is a high-protein crambe meal that has limited value, as it is not fit for food or feed use. However, it contains proteins that could potentially make it a suitable raw material for higher-value products. The purpose of this study was to find methods of making this side stream into extruded films, showing that products with a higher value can be produced. The study mainly considered the development of material compositions and methods of preparing and extruding the material. Wheat gluten was added as a supportive protein matrix material, together with glycerol as a plasticizer and urea as a denaturant. The extrudate was evaluated with respect to mechanical (tensile testing) and oxygen barrier properties, and the extrudate structure was revealed visually and by scanning electron microscopy. A denser, more homogeneous material had a lower oxygen transmission rate, higher strength, and higher extensibility. The most homogeneous films were made at an extruder die temperature of 125-130 &#176;C. It is shown here that a film can be extruded with promising mechanical and oxygen barrier properties, the latter especially after a final compression molding step.

Film Extrusion of Crambe abyssinica/Wheat Gluten Blends

The side stream from plant oil production of Crambe abyssinica has limited value. The purpose of this study was to find methods for extruding materials based on this side stream, demonstrating that products with a higher value can be produced. The extrudates were found to have promising properties.

のフィルム押出<em&gt;ハマナabyssinica</em&gt; /小麦グルテンブレンド

Crambe abyssinica is a plant with potential for use in industrial (non-food) plant oil production. The side stream from this oil production is a ...

Synthesis of Functionalized 10-nm Polymer-coated Gold Particles for Endothelium Targeting and Drug Delivery

Gold nanoparticles (AuNPs) have been used extensively in medical research due to their size, biocompatibility, and modifiable surface. Specific targeting and drug delivery are some of the applications of these AuNPs, but endothelial extracellular matrices&#39; defensive properties hamper particle uptake. To address this issue, we describe a synthesis method for ultrasmall gold nanoparticles to improve vascular delivery, with customizable functional groups and polymer lengths for further adjustments. The protocol yields 2.5 nm AuNPs that are capped with tetrakis(hydroxymethyl)phosphonium chloride (THPC). The replacement of THPC with hetero-functional polyethylene glycol (PEG) on the surface of the AuNP increases the hydrodynamic radius to 10.5 nm while providing various functional groups on the surface. The last part of the protocol includes an optional addition of a fluorophore to allow the AuNPs to be visualized under fluorescence to track nanoparticle uptake. Dialysis and lyophilization were used to purify and isolate the AuNPs. These fluorescent nanoparticles can be visualized in both in vitro and in vivo experiments due to the biocompatible PEG coating and fluorescent probes. Additionally, the size range of these nanoparticles render them an ideal candidate for probing the glycocalyx without disrupting normal vasculature function, which may lead to improved delivery and therapeutics.

We describe a method of synthesizing biocompatible 10-nm gold nanoparticles, functionalized by coating poly-ethylene glycol onto the surface. These particles can be used in vitro and in vivo for delivering therapeutics to nanoscale cellular and extracellular spaces that are difficult to access with conventional nanoparticle sizes.

粒子の合成機能 10 nm ポリマー コーティング金対象化、血管内皮細胞とドラッグデリバリー

Gold nanoparticles (AuNPs) have been used extensively in medical research due to their size, biocompatibility, and modifiable surface. Specific targeting ...