The authors would like to acknowledge Stanford Department of Orthopaedic Surgery and Stanford Coulter Translational Seed Grant for funding. J.H.L. would like to thank National Science Foundation Graduate Fellowship and DARE Doctoral Fellowship for support.

すべての実験は、スタンフォード大学の人間の被験者のガイドラインに沿って行われ、治験審査委員会のプロトコルを承認しました。 1.関節軟骨細胞の単離<ol><li>人工膝関節全置換術の際に廃棄された組織から軟骨を取得し、以前に説明したように8解剖。 </li><li>視覚滑らかな表面のための軟骨サンプルの内側または外側大腿骨顆を選択して、軟骨下骨に影響を与えることなく、4〜5ミリメ​​ートルの軟骨生検を除去するためにメスを介して軟骨の表面に切り込みを入れます。 </li><li>精製されたコラゲナーゼでO / N処理と組織の酵素解離によって細胞外マトリックスから軟骨細胞を分離します。 37℃での軟骨細胞の増殖培地にコラゲナーゼII（125 U / ml）およびコラゲナーゼIV（160 U / ml）を1：1の比を使用してください。 </li><li>翌日、70を介して分離した細胞を含む消化された組織をフィルタリングミリメートル孔径ナイロンメッシュ。 5分間600×gでDMEM / F12と遠心の20mlで2回洗浄します。 </li><li>プレート10％ウシ胎児血清（FBS）、25 / mlのアスコルビン酸、2mM L-グルタミン、抗菌剤を補充したDMEM / F12中に再懸濁以下、1×10 6細胞 / 60mm培養ディッシュの密度で単離された軟骨細胞（100 U / mlペニシリン、100μg/ mlのストレプトマイシン、および0.25 / mlのファンギゾン）。プレートを37℃で維持し、生体模倣ヒドロゲルでカプセル化の前に、高密度の単層としての一次軟骨細胞培養を維持します。 </li></ol> 2.バイオミメティックハイドロゲルの作製注：この方法は、DPBS中で、ポリ（エチレングリコールジアクリレート）（PEGDA、MW 5,000グラム/モル）、コンドロイチン硫酸 - メタクリレート（CS-MA）を含有する生体模倣ヒドロゲルの合成を可能にします。光開始剤の添加は、光活性化架橋を可能にします。最終のヒドロゲル組成物は、7％の重さが含まれW / V CS-MAの3％、および重量/体積の光開始剤の0.05％、PEGDAの（w / v）のT /体積。 <ol><li>メタクリレート基でCSポリマーを官能することにより、CS-MAを合成します。 <ol><li> MESの1.952グラムおよび脱イオン水200ml中のNaClの5.84グラム（DIH 2 O）を溶解させて緩衝50mMの2-モルホリノエタンスルホン酸（MES）の溶液及び0.5 M塩化ナトリウム（食塩）を準備します。緩衝液中のコンドロイチン硫酸ナトリウム塩を5g溶解します。 </li><li> （：EDC = 1：2 NHSのモル比）を0.532グラム（4.62ミリモル）のN-ヒドロキシスクシンイミド（NHS）および1.771グラム（9.24ミリモル）の1-エチル-3-（3-ジメチルアミノプロピル） - カルボジイミド塩酸塩（EDC）を加えます5分間溶液と、撹拌。 </li><li>溶液を24時間、室温で反応を維持する（2：1：EDC：NHS AEMA = 1のモル比）0.765グラム（4.62ミリモル）の2-アミノエチルメタクリレート（AEMA）を加えます。 </li><li>透析チューブ（12-14 kDaのMWCO）を使用して、4日間脱イオン水（DIH 2 O）に対する透析により混合物を精製します。 </li><li> Pをフィルタリング0.22μmのフィルターを通してurified解決し、デシケーター、真空O / Nでの溶液を含むオープンチューブを配置します。すべてのチューブは、光から保護されていることを確認します。光と湿気から保護-20℃で溶解したポリマーを保管してください。 </li></ol></li></ol> 3.細胞のカプセル化<ol><li> （セルを含んだ3Dハイドロゲルを打ち抜くための）PCRフィルムと円筒形ロッドをオートクレーブUV光の下で組織培養フードで0.2μmのフィルタ処理70％エタノールに浸漬して、カスタムメイドの円筒状のゲル型を滅菌します。 </li><li>漏れを防止するために、気泡や隙間なくオートクレーブPCR膜とゲル型の底部を密封します。無菌の150mmプレートに保管してください。 </li><li>前生体模倣ヒドロゲル中の細胞カプセル化する日は、コラゲナーゼIIおよびコラゲナーゼIV溶液中のO / N処理と高密度軟骨細胞単層を解離します。軟骨細胞の増殖培地に各コラゲナーゼIIおよびコラゲナーゼVI mlの160 U / 125 U / mlで使用37℃。 </li><li> 50 mlチューブに取り、5％重量/容積、ポリ（エチレングリコールジアクリレート）（PEGDA、MW = 5,000グラム/モル）（w / v）の3％重量/体積コンドロイチン硫酸 - メタクリレート（CS-MA）を追加し、そしてDPBS中のV光開始剤/ wの0.05％。溶液を混合し、それを脇に保つためにボルテックスチューブ。光からチューブを保護します。 </li><li> 50mlのファルコンチューブに解離した細胞を回収し、5分間460×gでカウントし、遠心します。吸引物は、すべてのセルチューブからメディア及び15×10 6細胞/ mlの密度で細胞を再懸濁するために上記混合ゲル材料を追加します。気泡の形成を回避しながら、徹底的に30回にそれを混ぜます。 </li><li>ピペット72カスタムメイドの円筒状のゲル型に細胞ヒドロゲル懸濁液又は単独のヒドロゲルのμL、5分間3ミリワット/ m 2のUV光（波長365nm）への暴露によりゲル化を誘導します。無細胞内容のいくつかのヒドロゲル溶液を準備します。将来の生化学的および機械的試験のための陰性対照として、これらの構築物を使用してください。 Measu紫外線強度計でUV光の強度を再。強度を調整するには、UV光源とゲル中のヒドロゲル足場の間の距離を変更します。 注：ヒドロゲルは、CSが含まれているため、無細胞の寄与は細胞のGAGのみを表現するために、細胞を含んだヒドロゲルの生化学GAG含有量から差し引かれます。 </li><li>オフイージーピール用のフィルムをカットするメスを使用して、慎重に取り外し。円筒状の棒の助けを借りて、未重合ゲルとゆるい細胞を洗い流し、無菌DPBS 5mlで6ウェルプレートにゲルを押し出します。 </li><li>培養物を各ウェルに軟骨細胞増殖培地1.5 mlを含有する24ウェルプレート中の細胞を含んだハイドロゲル。ウェルに洗浄ヒドロゲルを転送するために使い捨てへらを使用してください。 </li><li>生存性/細胞毒性キットを使ってライブ死んで染色後24時間カプセル化することによって、細胞の生存率を評価します。文化新鮮な軟骨細胞GROへの変更3-6週間のセルを含んだヒドロゲルおよび空のヒドロゲル2日ごとに解析のために回収する前にメディアWTH。 </li></ol> 4. RNA抽出および遺伝子発現解析<ol><li>慎重にメディアを吸引し、細胞を含んだだけでなく、空の制御ヒドロゲルに滅菌PBS 1Xを置きます。 </li><li>無菌のへらの助けを借りて、きれいな1.5mlのエッペンドルフチュー​​ブに各ヒドロゲルを転送し、各チューブにトライ試薬の250μlを添加します。 RNAを単離するために、メーカーの指示に従ってください。 </li><li>各サンプルからのRNAの単離および定量化の使用後は、それを1μgと高容量cDNAを逆転写キットを用いてcDNAに逆転写を行います。 </li><li>定量的PCRのために興味のある遺伝子の発現の検査のためのTaqMan遺伝子発現アレイを使用しています。 GAPDHの内部遺伝子発現レベルを正規化します。 </li><li> PCR条件のために10に続くウラシルDNAグリコシラーゼを用いた以前のアンプリコンを、不活性化するために50℃で2分間のインキュベーションを含みます60; 95℃でのインキュベーションminのTaqポリメラーゼを活性化します。その後、95℃で15秒間からなる40サイクルのPCRを行い、60℃で1分間。 </li></ol> 5.生化学分析<ol><li>各セルヒドロゲルの構築のためのDNAと以下のように硫酸化グリコサミノグリカン（sGAG）の生産を定量化します。 </li><li>慎重にメディアを吸引し、細胞を含んだだけでなく、空の制御ヒドロゲルに滅菌PBS 1Xを置きます。空のチューブを計量し、ティッシュペーパーの上にブロッティングした後、内部にヒドロゲルを入れて、ヒドロゲルの重量または湿重量を記録します。 </li><li>酵素消化のために別々の1.5mlのエッペンドルフチュー​​ブ中で-20℃で各ハイドロゲルを凍結し、後で（GAG用）（DNA用）ピコグリーンアッセイおよびジメチルメチレンブルーアッセイを実行するために、消化産物の一部を使用しています。 </li><li>ヒドロゲルの酵素消化のためpapainase溶液を調製します。 <ol><li>まずナトリウムphosphatの7.1グラムを計量することによりPBEバッファを用意Eの二塩基性（ の Na 2 HPO 4）、エチレンジアミン四酢酸二ナトリウム塩（EDTA-2ナトリウム）を1.6g。 、のdH 2 O 500mlに溶解し、pHを6.5に調整し、0.22 mmのフィルターを介して精製した溶液を濾過します。 </li><li> PBEバッファー20ml中のL-システインの0.035グラムを溶解します。溶液および滅菌パパイン酵素を100μlをフィルタリングします。 </li></ol></li><li>準備ができてアッセイを実施する場合には、-20°Cからチューブを取り、凍結されたヒドロゲルに準備パパイン溶液を300μlを添加します。乳鉢と乳棒を用いてゲルを粉砕し、モータ乳棒でよく混ぜます。 </li><li>追加のパパイン溶液で500μlにボリュームを持参してください。対照ゲルと同じ手順を実行します。 16時間3,9、60℃でインキュベートします。消化されたヒドロゲルを含む溶液は、従って、DNAおよびGAGの定量のために使用することができます。標準以下の製造業者のPRとしてラムダファージDNAとのピコグリーンアッセイを用いてDNA含量を測定otocol。 </li><li> 1,9-ジメチルメチレンブルー（DMMB）標準10としてサメのコンドロイチン硫酸と色素結合アッセイを使用して硫酸化GAG含有量を定量化します。対応湿重量のために、GAGの量を分割することにより、GAGの内容を決定します。 </li></ol> 6.機械的試験<ol><li> 10 Nロードセルを取り付けたインストロン5944試験システムを用いて、一軸圧縮試験を行います。 <ol><li> インビトロ培養の希望日後、細胞ヒドロゲル足場および無細胞制御ハイドロゲルの圧縮試験を行います。 </li><li> RTでPBS浴中で標本を水没し、負荷条件の下で軟骨組織が ​​経験する生理学的な歪みは10〜20％であると報告されているので、15％の最大ひずみ11,12に1％のひずみ/秒の速度で圧縮します13,14。 </li></ol></li><li>三次多項式を用いたひずみ曲線と曲線フィット対ストレスを作成します。 COMPRを決定15％の歪み値でカーブフィット式から能格接線係数。 </li></ol>

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H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bonding+and+fusion+of+meniscus+fibrocartilage+using+a+novel+chondroitin+sulfate+bone+marrow+tissue+adhesive.">Bonding and fusion of meniscus fibrocartilage using a novel chondroitin sulfate bone marrow tissue adhesive.</a> Tissue engineering. Part A. 19, 1843-1851 (2013).</li></ol>

The authors have nothing to disclose.

このプロトコールで報告されたように、3Dヒドロゲルは、通常、単層培養物15で遭遇する線維軟骨細胞への細胞脱分化の過程を回避し、培養中の軟骨細胞表現型を維持することができます。また、chondrocytes-ヒドロゲル構築物の長期培養は、年齢や疾患に関連する本質的な細胞機能を維持し、良好な環境を明らかにしました。 3次元生体模倣ヒドロゲルの使用は、いくつかの利点を有します。まず、コンドロイチン硫酸（CS）、関節軟骨に見出される主要なコンポーネントを含めることは、コンドロイチナーゼを分泌することによってヒドロゲルマトリックスを分解し、新たに合成された軟骨細胞外マトリックス5、16を敷設するために細胞を可能にします。また、CSが示されています関節炎の関節における抗炎症特性を有すること。生体模倣ヒドロゲルはまた、軟骨修復における細胞送達のための足場材料として用いることができ、化学的に修飾することができますより良い組織生体材料統合17,18を容易にします 。 PEG-CSのヒドロゲルの使用は、長期的な軟骨細胞の文化や生化学的および機械的特性を評価することができます。ここでは、このプラットフォームは、軟骨工学のための最適な細胞タイプを定義するために、分化した軟骨細胞のさまざまなソースの比較分析のために有用であることができる方法を示しています。興味深いことに、ヒドロゲルにカプセル化された軟骨細胞は、それらの固有の能力に応じて生存したままと増殖します。 図2に示すように、ヒドロゲル組成物は、実際には、健康な若年成人軟骨細胞の増殖を支持する。グリコサミノグリカン（GAGによって評価機能細胞外マトリックスの沈着によって示されるように記述さヒドロゲルの組成及び構造はまた、軟骨組織の形成を促進します）定量。 追加の利点は、軟骨細胞ハイドロゲル構造物であります新たに形成された軟骨組織の機械的特性について評価することができます。一軸圧縮試験は、比較のために無細胞ヒドロゲル上で実行されるべきであることに注意してください。ヒドロゲルは、実際には、CSによる部分の剛性に固有の剛性を有します。負荷条件下で軟骨組織が ​​経験する生理学的な歪みが10~20であることが報告されているので（歪み率1％/ sで）5〜20％の一軸圧縮歪みが軟骨組織11,12の機械的試験に適用することができます％13,14。機械的試験への細胞を含んだし、無細胞ヒドロゲルの両方の応答は、培養エンドポイントで評価しました。私たちは、OA軟骨細胞を含む構築物の低い剛性とは対照的に、成人および若年性の軟骨細胞を含む構築物の同等の剛性を観察し、上記の例では。細胞 - ヒドロゲル構造体の機械的特性は、機能的特性の評価を可能にします細胞成熟性の詳細な分析を与えるに形成された組織。 結論として、軟骨組織を生成するために、別の軟骨細胞集団の可能性を研究するための3次元生体模倣ヒドロゲルの使用は、広く適用することができます。ここで説明したin vitro試験のほかに、細胞を含んだ構成物のin vivoでの移植は生理的な文脈で細胞成熟と再生可能性を研究するために想定することができます。追加の生体模倣因子とヒドロゲルプラットフォームのさらなる修飾はまた、軟骨細胞の増殖および成熟を最適化するように想定することができます。

With its limited self-repair potential, human articular cartilage undergoes frequent irreversible damages. Extensive efforts are currently focused on the development of efficient cell-based approaches for treatment of articular cartilage injuries. The success of these cell-based therapies is highly dependent on the selection of an optimal cell source and the maintenance of its regenerative potential. Chondrocytes are a common cell source for cartilage repair, but they are limited in supply and can de-differentiate during in vitro expansion in 2D monolayer culture thereby limiting their generation of hyaline cartilage 1. 
The aim of this protocol is to establish a 3-dimensional hydrogel platform for an in vitro comparative study of human chondrocytes from different ages and disease state. Unlike conventional two-dimensional (2D) culture, three-dimensional (3D) hydrogels allow chondrocytes to maintain their morphology and phenotype and provides a physiologically relevant environment enabling chondrocytes to produce cartilage tissue 2,3. In addition to providing a 3D physical structure for chondrocyte culture, hydrogels mimic the function of native cartilage extracellular matrix (ECM). Specifically, the inclusion of chondroitin sulfate methacrylate provides a potential reservoir for secreted paracrine factors 4 and enables cell-mediated degradation and matrix turnover 5. Although many 3D hydrogel culture systems have been utilized widely in various studies including agarose and alginate gels, we have used a biomimetic 3D culture system that has some distinct advantages for chondrocyte culture. Chondroitin sulfate (CS) is an abundant component in articular cartilage and the PEG-CS hydrogels have been shown to maintain and even enhance chondrogenic phenotype and facilitate cell-mediated matrix degradation and turnover 2,5. In addition, the mechanical properties of the hydrogel scaffold can be easily modulated by changing concentration of PEG and hence can be utilized to further enhance the regeneration potential of chondrocytes or a related cell type 6,7. PEG/CSMA is also biocompatible and hence has the potential for a direct clinical application in cartilage defects for example. The limitation for this system is its complexity and the use of photopolymerization that can potentially affect cell viability as compared to simpler systems like agarose, however the advantages for the chondrocyte culture outweigh the potential limitations.
The 3D hydrogel culture is compatible with conventional assay for evaluation of cell phenotype (gene expression, protein immunostaining) and functional outcome (quantification of cartilage matrix production, mechanical testing). This favorable 3D environment was tested to compare the tissue regeneration potential of human chondrocytes from three different aged populations in long-term 3D cultures. 
The outcomes were evaluated via both phenotypic and functional assays. Juvenile, adult and OA chondrocytes showed differential responses in the 3D biomimetic hydrogel culture. After 3 and 6 weeks, chondrogenic gene expression was upregulated in juvenile and adult chondrocytes but was downregulated in OA chondrocytes. Deposition of cartilage tissue components including aggrecan, type II collagen, and glycosaminoglycan (GAG) was high for juvenile and adult chondrocytes but not for OA chondrocytes. The compressive moduli of the resulting cartilage constructs also exhibited similar trends. In conclusion, both juvenile and adult chondrocytes exhibited chondrogenic and cartilage matrix disposition up to 6 weeks of 3D culture in hydrogels. In contrast, osteoarthritic chondrocytes revealed a loss of cartilage phenotype and minimal ability to generate robust cartilage.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>juvenile chondrocytes (Clonetics&#8482; Normal Human Chondrocyte Cell System )</td>
			<td>Lonza</td>
			<td>CC-2550</td>
			<td></td>
		</tr>
		<tr>
			<td>adult chondrocytes (Clonetics&#8482; Normal Human Chondrocyte Cell System)</td>
			<td>Lonza</td>
			<td>CC-2550</td>
			<td></td>
		</tr>
		<tr>
			<td>poly(ethylene glycol diacrylate)</td>
			<td>Laysan Bio</td>
			<td>ACRL-PEG-ACRL-1000-1g</td>
			<td></td>
		</tr>
		<tr>
			<td>2-morpholinoethanesulfonic acid</td>
			<td>Sigma</td>
			<td>M5287</td>
			<td></td>
		</tr>
		<tr>
			<td>photoinitiator</td>
			<td>Irgacure&#160;</td>
			<td align="right">2959</td>
			<td></td>
		</tr>
		<tr>
			<td>sodium chloride&#160;</td>
			<td>Sigma</td>
			<td>S9888</td>
			<td></td>
		</tr>
		<tr>
			<td>chondroitin sulfate sodium salt&#160;</td>
			<td>Sigma</td>
			<td>C9819</td>
			<td></td>
		</tr>
		<tr>
			<td>N-hydroxysuccinimide&#160;</td>
			<td>Sigma</td>
			<td align="right">130672</td>
			<td></td>
		</tr>
		<tr>
			<td>1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride</td>
			<td>Sigma</td>
			<td>E1769</td>
			<td></td>
		</tr>
		<tr>
			<td>2-aminoethyl methacrylate</td>
			<td>Sigma</td>
			<td align="right">516155</td>
			<td></td>
		</tr>
		<tr>
			<td>dialysis tubing</td>
			<td>Spectrum Laboratories&#160;</td>
			<td align="right">132700</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagenase 2</td>
			<td>Worthington Biochemical&#160;</td>
			<td>LS004177</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagenase 4</td>
			<td>Worthington Biochemical&#160;</td>
			<td>LS004189</td>
			<td></td>
		</tr>
		<tr>
			<td>DMEM/F12 media</td>
			<td>HyClone, Thermo Scientific&#160;</td>
			<td>SH3002301&#160;</td>
			<td></td>
		</tr>
		<tr>
			<td>live/dead assay</td>
			<td>Life Technologies</td>
			<td><a href="https://www.lifetechnologies.com/order/catalog/product/L3224">L3224</a></td>
			<td></td>
		</tr>
		<tr>
			<td>Tri reagent</td>
			<td>Life Technologies</td>
			<td>AM9738</td>
			<td></td>
		</tr>
		<tr>
			<td>Quant-iT&#8482; PicoGreen&#174; dsDNA Assay Kit</td>
			<td>Invitrogen</td>
			<td><a href="https://www.lifetechnologies.com/order/catalog/product/P11496">P11496</a></td>
			<td></td>
		</tr>
		<tr>
			<td>Sodium phosphate dibasic&#160;</td>
			<td>Sigma</td>
			<td>S3264</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethylenediaminetetraacetic acid disodium salt&#160;</td>
			<td>Sigma</td>
			<td>E5134</td>
			<td></td>
		</tr>
		<tr>
			<td>L-Cysteine</td>
			<td>Sigma</td>
			<td>C1276</td>
			<td></td>
		</tr>
		<tr>
			<td>1,9-dimethylmethylene blue&#160;</td>
			<td>Sigma</td>
			<td align="right">341088</td>
			<td></td>
		</tr>
		<tr>
			<td></td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Instruments</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>UV light equipment - XX-15LW Bench Lamp, 365nm</td>
			<td>UVP</td>
			<td>95-0042-07</td>
			<td></td>
		</tr>
		<tr>
			<td>Instron 5944 testing system&#160;</td>
			<td>Instron Corporation</td>
			<td>E5940</td>
			<td></td>
		</tr>
	</tbody>
</table>

3d hydrogel scaffolds for articular chondrocyte culture and cartilage generation

Human articular cartilage is highly susceptible to damage and has limited self-repair and regeneration potential. Cell-based strategies to engineer cartilage tissue offer a promising solution to repair articular cartilage. To select the optimal cell source for tissue repair, it is important to develop an appropriate culture platform to systematically examine the biological and biomechanical differences in the tissue-engineered cartilage by different cell sources. Here we applied a three-dimensional (3D) biomimetic hydrogel culture platform to systematically examine cartilage regeneration potential of juvenile, adult, and osteoarthritic (OA) chondrocytes. The 3D biomimetic hydrogel consisted of synthetic component poly(ethylene glycol) and bioactive component chondroitin sulfate, which provides a physiologically relevant microenvironment for in vitro culture of chondrocytes. In addition, the scaffold may be potentially used for cell delivery for cartilage repair in vivo. Cartilage tissue engineered in the scaffold can be evaluated using quantitative gene expression, immunofluorescence staining, biochemical assays, and mechanical testing. Utilizing these outcomes, we were able to characterize the differential regenerative potential of chondrocytes of varying age, both at the gene expression level and in the biochemical and biomechanical properties of the engineered cartilage tissue. The 3D culture model could be applied to investigate the molecular and functional differences among chondrocytes and progenitor cells from different stages of normal or aberrant development.

PEGおよびCS部分を含有する生理活性ヒドロゲル（ 図1）は、ヒト関節軟骨細胞2,3,5,7の文化と成熟のための理想的なプラットフォームを表します。異なる年齢および疾患状態の軟骨細胞は記載された方法を用いて培養し、それらの表現型、遺伝子発現、生成、軟骨組織の生化学的および機械的特性のために分析することができます。三軟骨細胞サンプル、若年6ヶ月、adult- 34年と74年osteoarthritic-は、3Dバイオミメティックハイドロゲルで培養3週間後に回収しました。遺伝子発現は、正常な軟骨細胞の分析、若年および成人の両方が、軟骨細胞遺伝子COL2A1およびCOL6A1の発現の増加を示しました。 COL6A1（ 図2）の発現を維持し、良好なバイオミメティック環境で培養されているにもかかわらず、軟骨形成表現型の損失を示しながら逆に、病気の軟骨細胞は、COL2A1の劇的な減少を示しました。 CS-PEGヒドロゲルはまた、軟骨細胞、増殖PEGおよびCSの既存のマトリックスを消化し、その細胞周囲および細胞外マトリックスを堆積させる、成熟した軟骨組織の主要な構成要素のための動的な環境として働きます。これらの能力を考えると、 インビトロ培養の3週間後の軟骨細胞の拡大は、ピコグリーン色素とDNAを定量することによって推定することができます。細胞の三つのグループの比較分析は、OA軟骨細胞は、培養の1日目に比べて劇的な減少を示しながら、少年と成人の集団の細胞密度が変化しなかったことを示しています。 DNA含量の損失はまた、長期培養（ 図3）の間の可能な細胞死を示唆している他のOA軟骨細胞のためではなく、観察されました。分泌されたマトリックスは、培養の3週間後に終点段階でDMMB色素結合アッセイにより硫酸化GAG含有量として定量化しました。 GAG含量はrecorとしてヒドロゲルの湿重量によって正規化されますDED酵素消化および無細胞の貢献の前に減算されます。 図4に示すように、軟骨は、3Dヒドロゲルにおける培養の3週間GAGの同様の有意な量の堆積します。 物理的な足場の存在は、一軸圧縮試験の2,3を通じてサンプルの生体力学的特性を評価することができます。無細胞ヒドロゲルは、圧縮弾性率の低下を受けている間、細胞を含んだ構築物は、培養3週間後（ 図4）の後に、圧縮弾性率を維持しました。表現型は、ここで説明する生化学的および生体力学的分析は、エンジニアリング軟骨のための異なった軟骨細胞集団の可能性を評価し、理解するのに有用です。 <img alt="図1" src="/files/ftp_upload/53085/53085fig1.jpg" /> 図3Dの軟骨細胞CUL 1. PEG-CS生体模倣ヒドロゲルチャー。軟骨細胞は、ポリ（エチレングリコールジアクリレート）（PEGDA）およびコンドロイチン硫酸-メタクリレート（CS-MA）を含む混合物中に再懸濁し、カスタムメイドの円筒ゲルモールド内に鋳造されています。 UV露光した後、ゲルを型から収集され、細胞の生存率がライブ死んで染色後24時間カプセル化することによって評価される固化。 <a href="https://www.jove.com/files/ftp_upload/53085/53085fig1large.jpg" target="_blank">この図の拡大版をご覧になるにはこちらをクリックしてください。</a> <img alt="図2" src="/files/ftp_upload/53085/53085fig2.jpg" /> 3Dバイオミメティックハイドロゲルで培養したヒト軟骨細胞における軟骨形成の遺伝子の発現を図2。少年、成人およびOA軟骨細胞による軟骨マーカーCOL2A1とCOL6A1の定量的遺伝子発現3Dバイオミメティックハイドロゲルで培養3週間後。値は、1日目誤差Bでの遺伝子の発現レベルに正規化されていますARSは、平均±SDを表します。 P、両側スチューデントt検定によって決定される* &lt;0.05。 Smeriglio らから変更された。2 <a href="https://www.jove.com/files/ftp_upload/53085/53085fig2large.jpg" target="_blank">この図の拡大版をご覧になるにはこちらをクリックしてください。</a> <img alt="図3" src="/files/ftp_upload/53085/53085fig3.jpg" /> 3Dバイオミメティックハイドロゲルで培養したヒト軟骨細胞における図3のDNA含有量。3Dバイオミメティックハイドロゲルで培養3週間後、少年、成人およびOA軟骨細胞におけるピコグリーンアッセイによるDNA定量。値は、1日目にDNAレベルに正規化されている<a href="https://www.jove.com/files/ftp_upload/53085/53085fig3large.jpg" target="_blank">。この図の拡大版をご覧になるにはこちらをクリックしてください。</a> <img alt="図4" src="/files/ftp_upload/53085/53085fig4.jpg" /> &lt;BR /&gt; 図4のGAG含有量測定と1日目と3次元バイオミメティックハイドロゲルで培養3週間後のヒト軟骨細胞の一軸圧縮試験を行った。1日目とで培養3週間後の軟骨細胞におけるDMMBアッセイによって（A）のGAG定量3Dバイオミメティックハイドロゲル。値は重量（WW）を濡らすように正規化され、μgの/ gと表現した。1日目と3次元バイオミメティックハイドロゲルで培養3週間後の無細胞と細胞を含んだヒドロゲルの（B）圧縮弾性率（kPaで）。 <a href="https://www.jove.com/files/ftp_upload/53085/53085fig4large.jpg" target="_blank">ご覧になるにはこちらをクリックしてくださいこの図の拡大版。</a>

Watch this Scientific Journal Video about 3D Hydrogel Scaffolds for Articular Chondrocyte Culture and Cartilage Generation at JoVE.com

3D Hydrogel Scaffolds for Articular Chondrocyte Culture and Cartilage Generation

Cartilage repair represents an unmet medical challenge and cell-based approaches to engineer human articular cartilage are a promising solution. Here, we describe three-dimensional (3D) biomimetic hydrogels as an ideal tool for the expansion and maturation of human articular chondrocytes.

関節軟骨細胞培養軟骨の生成のための3Dハイドロゲルの足場

Human articular cartilage is highly susceptible to damage and has limited self-repair and regeneration potential. Cell-based strategies to engineer ...

3d-hydrogel-scaffolds-for-articular-chondrocyte-culture-cartilage

Research

JoVE Journal

Bioengineering

19.8K ビュー.  Stanford University. Cartilage repair represents an unmet medical challenge and cell-based approaches to engineer human articular cartilage are a promising solution. Here, we describe three-dimensional (3D) biomimetic hydrogels as an ideal tool for the expansion and maturation of human articular chondrocytes. 

ビデオ: 3D Hydrogel Scaffolds for Articular Chondrocyte Culture and Cartilage Generation

A Simple Hanging Drop Cell Culture Protocol for Generation of 3D Spheroids

Studies of cell-cell cohesion and cell-substratum adhesion have historically been performed on monolayer cultures adherent to rigid substrates. Cells within a tissue, however, are typically encased within a closely packed tissue mass in which cells establish intimate connections with many near-neighbors and with extracellular matrix components. Accordingly, the chemical milieu and physical forces experienced by cells within a 3D tissue are fundamentally different than those experienced by cells grown in monolayer culture. This has been shown to markedly impact cellular morphology and signaling. Several methods have been devised to generate 3D cell cultures including encapsulation of cells in collagen gels1or in biomaterial scaffolds2. Such methods, while useful, do not recapitulate the intimate direct cell-cell adhesion architecture found in normal tissues. Rather, they more closely approximate culture systems in which single cells are loosely dispersed within a 3D meshwork of ECM products. Here, we describe a simple method in which cells are placed in hanging drop culture and incubated under physiological conditions until they form true 3D spheroids in which cells are in direct contact with each other and with extracellular matrix components. The method requires no specialized equipment and can be adapted to include addition of any biological agent in very small quantities that may be of interest in elucidating effects on cell-cell or cell-ECM interaction. The method can also be used to co-culture two (or more) different cell populations so as to elucidate the role of cell-cell or cell-ECM interactions in specifying spatial relationships between cells. Cell-cell cohesion and cell-ECM adhesion are the cornerstones of studies of embryonic development, tumor-stromal cell interaction in malignant invasion, wound healing, and for applications to tissue engineering. This simple method will provide a means of generating tissue-like cellular aggregates for measurement of biomechanical properties or for molecular and biochemical analysis in a physiologically relevant model.

We describe a simple, rapid method of generating 3D tissue-like spheroids and their potential application to quantify differences in cell-cell interactions.

3D楕円体の生成のための簡単​​なハンギングドロップ細胞培養プロトコル

Studies of cell-cell cohesion and cell-substratum adhesion have historically been performed on monolayer cultures adherent to rigid substrates. Cells ...

生物工学

Preparation of 3D Fibrin Scaffolds for Stem Cell Culture Applications

Stem cells are found in naturally occurring 3D microenvironments in vivo, which are often referred to as the stem cell niche 1. Culturing stem cells inside of 3D biomaterial scaffolds provides a way to accurately mimic these microenvironments, providing an advantage over traditional 2D culture methods using polystyrene as well as a method for engineering replacement tissues 2. While 2D tissue culture polystrene has been used for the majority of cell culture experiments, 3D biomaterial scaffolds can more closely replicate the microenvironments found in vivo by enabling more accurate establishment of cell polarity in the environment and possessing biochemical and mechanical properties similar to soft tissue.3 A variety of naturally derived and synthetic biomaterial scaffolds have been investigated as 3D environments for supporting stem cell growth. While synthetic scaffolds can be synthesized to have a greater range of mechanical and chemical properties and often have greater reproducibility, natural biomaterials are often composed of proteins and polysaccharides found in the extracelluar matrix and as a result contain binding sites for cell adhesion and readily support cell culture. Fibrin scaffolds, produced by polymerizing the protein fibrinogen obtained from plasma, have been widely investigated for a variety of tissue engineering applications both in vitro and in vivo 4. Such scaffolds can be modified using a variety of methods to incorporate controlled release systems for delivering therapeutic factors 5. Previous work has shown that such scaffolds can be used to successfully culture embryonic stem cells and this scaffold-based culture system can be used to screen the effects of various growth factors on the differentiation of the stem cells seeded inside 6,7.
 This protocol details the process of polymerizing fibrin scaffolds from fibrinogen solutions using the enzymatic activity of thrombin. The process takes 2 days to complete, including an overnight dialysis step for the fibrinogen solution to remove citrates that inhibit polymerization. These detailed methods rely on fibrinogen concentrations determined to be optimal for embryonic and induced pluripotent stem cell culture. Other groups have further investigated fibrin scaffolds for a wide range of cell types and applications - demonstrating the versatility of this approach 8-12.

This work details the preparation of 3D fibrin scaffolds for culturing and differentiating plutipotent stem cells. Such scaffolds can be used to screen the effects of various biological compounds on stem cell behavior as well as modified to contain drug delivery systems.

幹細胞培養アプリケーションのための3Dフィブリン足場の調製

Stem cells are found in naturally occurring 3D microenvironments in vivo, which are often referred to as the stem cell niche 1. Culturing stem cells ...

Self-reporting Scaffolds for 3-Dimensional Cell Culture

Culturing cells in 3D on appropriate scaffolds is thought to better mimic the in vivo microenvironment and increase cell-cell interactions. The resulting 3D cellular construct can often be more relevant to studying the molecular events and cell-cell interactions than similar experiments studied in 2D. To create effective 3D cultures with high cell viability throughout the scaffold the culture conditions such as oxygen and pH need to be carefully controlled as gradients in analyte concentration can exist throughout the 3D construct. Here we describe the methods of preparing biocompatible pH responsive sol-gel nanosensors and their incorporation into poly(lactic-co-glycolic acid) (PLGA) electrospun scaffolds along with their subsequent preparation for the culture of mammalian cells. The pH responsive scaffolds can be used as tools to determine microenvironmental pH within a 3D cellular construct. Furthermore, we detail the delivery of pH responsive nanosensors to the intracellular environment of mammalian cells whose growth was supported by electrospun PLGA scaffolds. The cytoplasmic location of the pH responsive nanosensors can be utilized to monitor intracellular pH (pHi) during ongoing experimentation.

Biocompatible pH responsive sol-gel nanosensors can be incorporated into poly(lactic-co-glycolic acid) (PLGA) electrospun scaffolds. The produced self-reporting scaffolds can be used for in&#160;situ monitoring of microenvironmental conditions whilst culturing cells upon the scaffold. This is beneficial as the 3D cellular construct can be monitored in real-time without disturbing the experiment.

3次元細胞培養のための自己申告足場

Culturing cells in 3D on appropriate scaffolds is thought to better mimic the in vivo microenvironment and increase cell-cell interactions. The resulting ...

Generation of ESC-derived Mouse Airway Epithelial Cells Using Decellularized Lung Scaffolds

Lung lineage differentiation requires integration of complex environmental cues that include growth factor signaling, cell-cell interactions and cell-matrix interactions. Due to this complexity, recapitulation of lung development in vitro to promote differentiation of stem cells to lung epithelial cells has been challenging. In this protocol, decellularized lung scaffolds are used to mimic the 3-dimensional environment of the lung and generate stem cell-derived airway epithelial cells. Mouse embryonic stem cell are first differentiated to the endoderm lineage using an embryoid body (EB) culture method with activin A. Endoderm cells are then seeded onto decellularized scaffolds and cultured at air-liquid interface for up to 21 days. This technique promotes differentiation of seeded cells to functional airway epithelial cells (ciliated cells, club cells, and basal cells) without additional growth factor supplementation. This culture setup is defined, serum-free, inexpensive, and reproducible. Although there is limited contamination from non-lung endoderm lineages in culture, this protocol only generates airway epithelial populations and does not give rise to alveolar epithelial cells. Airway epithelia generated with this protocol can be used to study cell-matrix interactions during lung organogenesis and for disease modeling or drug-discovery platforms of airway-related pathologies such as cystic fibrosis.

This protocol efficiently directs mouse embryonic stem cell-derived definitive endoderm to mature airway epithelial cells. This differentiation technique uses 3-dimensional decellularized lung scaffolds to direct lung lineage specification, in a defined, serum-free culture setting.

脱細胞肺足場を使用してESC由来のマウス気道上皮細胞の生成

Lung lineage differentiation requires integration of complex environmental cues that include growth factor signaling, cell-cell interactions and ...

An Experimental and Finite Element Protocol to Investigate the Transport of Neutral and Charged Solutes across Articular Cartilage

Osteoarthritis (OA) is a debilitating disease that is associated with degeneration of articular cartilage and subchondral bone. Degeneration of articular cartilage impairs its load-bearing function substantially as it experiences tremendous chemical degradation, i.e. proteoglycan loss and collagen fibril disruption. One promising way to investigate chemical damage mechanisms during OA is to expose the cartilage specimens to an external solute and monitor the diffusion of the molecules. The degree of cartilage damage (i.e. concentration and configuration of essential macromolecules) is associated with collisional energy loss of external solutes while moving across articular cartilage creates different diffusion characteristics compared to healthy cartilage. In this study, we introduce a protocol, which consists of several steps and is based on previously developed experimental micro-Computed Tomography (micro-CT) and finite element modeling. The transport of charged and uncharged iodinated molecules is first recorded using micro-CT, which is followed by applying biphasic-solute and multiphasic finite element models to obtain diffusion coefficients and fixed charge densities across cartilage zones.

We propose a protocol to investigate the transport of charged and uncharged molecules across articular cartilage with the aid of recently developed experimental and numerical methods.

実験および有限要素議定書は、関節軟骨全体で中性および荷電溶質の輸送を調査します

Osteoarthritis (OA) is a debilitating disease that is associated with degeneration of articular cartilage and subchondral bone. Degeneration of articular ...

3D Magnetic Stem Cell Aggregation and Bioreactor Maturation for Cartilage Regeneration

Cartilage engineering remains a challenge due to the difficulties in creating an in vitro functional implant similar to the native tissue. An approach recently explored for the development of autologous replacements involves the differentiation of stem cells into chondrocytes. To initiate this chondrogenesis, a degree of compaction of the stem cells is required; hence, we demonstrated the feasibility of magnetically condensing cells, both within thick scaffolds and scaffold-free, using miniaturized magnetic field sources as cell attractors. This magnetic approach was also used to guide aggregate fusion and to build scaffold-free, organized, three-dimensional (3D) tissues several millimeters in size. In addition to having an enhanced size, the tissue formed by magnetic-driven fusion presented a significant increase in the expression of collagen II, and a similar trend was observed for aggrecan expression. As the native cartilage was subjected to forces that influenced its 3D structure, dynamic maturation was also performed. A bioreactor that provides mechanical stimuli was used to culture the magnetically seeded scaffolds over a 21-day period. Bioreactor maturation largely improved chondrogenesis into the cellularized scaffolds; the extracellular matrix obtained under these conditions was rich in collagen II and aggrecan. This work outlines the innovative potential of magnetic condensation of labeled stem cells and dynamic maturation in a bioreactor for improved chondrogenic differentiation, both scaffold-free and within polysaccharide scaffolds.

Chondrogenesis from stem cells requires fine tuning the culture conditions. Here, we present a magnetic approach for condensing cells, an essential step to initiate chondrogenesis. In addition, we show that dynamic maturation in a bioreactor applies mechanical stimulation to the cellular constructs and enhances cartilaginous extracellular matrix production.

軟骨再生のための3次元磁気幹細胞凝集およびバイオリアクター成熟

Cartilage engineering remains a challenge due to the difficulties in creating an in vitro functional implant similar to the native tissue. An approach ...

Bioprinting of Cartilage and Skin Tissue Analogs Utilizing a Novel Passive Mixing Unit Technique for Bioink Precellularization

Bioprinting is a powerful technique for the rapid and reproducible fabrication of constructs for tissue engineering applications. In this study, both cartilage and skin analogs were fabricated after bioink pre-cellularization utilizing a novel passive mixing unit technique. This technique was developed with the aim to simplify the steps involved in the mixing of a cell suspension into a highly viscous bioink. The resolution of filaments deposited through bioprinting necessitates the assurance of uniformity in cell distribution prior to printing to avoid the deposition of regions without cells or retention of large cell clumps that can clog the needle. We demonstrate the ability to rapidly blend a cell suspension with a bioink prior to bioprinting of both cartilage and skin analogs. Both tissue analogs could be cultured for up to 4 weeks. Histological analysis demonstrated both cell viability and deposition of tissue specific extracellular matrix (ECM) markers such as glycosaminoglycans (GAGs) and collagen I respectively.

Cartilage and skin analogs were bioprinted using a nanocellulose-alginate based bioink. The bioinks were cellularized prior to printing via a single step passive mixing unit. The constructs were demonstrated to be uniformly cellularized, have high viability, and exhibit favorable markers of differentiation.

軟骨と皮膚組織類縁ミキシング ユニット Bioink Precellularization の小説のパッシブ バイオプリンティング

Bioprinting is a powerful technique for the rapid and reproducible fabrication of constructs for tissue engineering applications. In this study, both ...

Real-time Visualization and Analysis of Chondrocyte Injury Due to Mechanical Loading in Fully Intact Murine Cartilage Explants

Homeostasis of articular cartilage depends on the viability of resident cells (chondrocytes). Unfortunately, mechanical trauma can induce widespread chondrocyte death, potentially leading to irreversible breakdown of the joint and the onset of osteoarthritis. Additionally, maintenance of chondrocyte viability is important in osteochondral graft procedures for optimal surgical outcomes. We present a method to assess the spatial extent of cell injury/death on the articular surface of intact murine synovial joints after application of controlled mechanical loads or impacts. This method can be used in comparative studies to investigate the effects of different mechanical loading regimens, different environmental conditions or genetic manipulations, as well as different stages of cartilage degeneration on short- and/or long-term vulnerability of in situ articular chondrocytes. The goal of the protocol introduced in the manuscript is to assess the spatial extent of cell injury/death on the articular surface of murine synovial joints. Importantly, this method enables testing on fully intact cartilage without compromising native boundary conditions. Moreover, it allows for real-time visualization of vitally stained articular chondrocytes and single image-based analysis of cell injury induced by application of controlled static and impact loading regimens. Our representative results demonstrate that in healthy cartilage explants, the spatial extent of cell injury depends sensitively on load magnitude and impact intensity. Our method can be easily adapted to investigate the effects of different mechanical loading regimens, different environmental conditions or different genetic manipulations on the mechanical vulnerability of in situ articular chondrocytes.

We present a method to assess the spatial extent of cell injury/death on the articular surface of intact murine joints after application of controlled mechanical loads or impacts. This method can be used to investigate how osteoarthritis, genetic factors and/or different loading regimens affect the vulnerability of in situ chondrocytes.

リアルタイム可視化と完全にそのままマウス軟骨外植片の機械的荷重により軟骨損傷の解析

Homeostasis of articular cartilage depends on the viability of resident cells (chondrocytes). Unfortunately, mechanical trauma can induce widespread ...

Fabrication of Decellularized Cartilage-derived Matrix Scaffolds

Osteochondral defects lack sufficient intrinsic repair capacity to regenerate functionally sound bone and cartilage tissue. To this extent, cartilage research has focused on the development of regenerative scaffolds. This article describes the development of scaffolds that are completely derived from natural cartilage extracellular matrix, coming from an equine donor. Potential applications of the scaffolds include producing allografts for cartilage repair, serving as a scaffold for osteochondral tissue engineering, and providing in vitro models to study tissue formation. By decellularizing the tissue, the donor cells are removed, but many of the natural bioactive cues are thought to be retained. The main advantage of using such a natural scaffold in comparison to a synthetically produced scaffold is that no further functionalization of polymers is required to drive osteochondral tissue regeneration. The cartilage-derived matrix scaffolds can be used for bone and cartilage tissue regeneration in both in vivo and in vitro settings.

Decellularized cartilage-derived scaffolds can be used as a scaffold to guide cartilage repair and as a means to regenerate osteochondral tissue. This paper describes the decellularization process in detail and provides suggestions to use these scaffolds in in vitro settings.

脱軟骨由来のマトリックス足場の作製

Osteochondral defects lack sufficient intrinsic repair capacity to regenerate functionally sound bone and cartilage tissue. To this extent, cartilage ...

3D Printed Porous Cellulose Nanocomposite Hydrogel Scaffolds

This work demonstrates the use of three-dimensional (3D) printing to produce porous cubic scaffolds using cellulose nanocomposite hydrogel ink, with controlled pore structure and mechanical properties. Cellulose nanocrystals (CNCs, 69.62 wt%) based hydrogel ink with matrix (sodium alginate and gelatin) was developed and 3D printed into scaffolds with uniform and gradient pore structure (110-1,100 &#181;m). The scaffolds showed compression modulus in the range of 0.20-0.45 MPa when tested in simulated in vivo conditions (in distilled water at 37 &#176;C). The pore sizes and the compression modulus of the 3D scaffolds matched with the requirements needed for cartilage regeneration applications. This work demonstrates that the consistency of the ink can be controlled by the concentration of the precursors and porosity can be controlled by the 3D printing process and both of these factors in return defines the mechanical properties of the 3D printed porous hydrogel scaffold. This process method can therefore be used to fabricate structurally and compositionally customized scaffolds according to the specific needs of patients.&#160;

The three critical steps of this protocol are i) developing the right composition and consistency of the cellulose hydrogel ink, ii) 3D printing of scaffolds into various pore structures with good shape fidelity and dimensions and iii) demonstration of the mechanical properties in simulated body conditions for cartilage regeneration.

3 D プリントされた多孔性セルロース ナノコンポジット型ヒドロゲル足場

This work demonstrates the use of three-dimensional (3D) printing to produce porous cubic scaffolds using cellulose nanocomposite hydrogel ink, with ...