无胸腺大鼠模型工程前交叉韧带移植评估
Summary
Animal models are important tools for the evaluation of tissue-engineered grafts. This paper presents the protocol for preparing an electrospun biodegradable polymer graft for use in anterior cruciate ligament tissue engineering, as well as a surgical protocol for implantation in a rat model.
Abstract
Anterior cruciate ligament (ACL) rupture is a common ligamentous injury that often requires surgery because the ACL does not heal well without intervention. Current treatment strategies include ligament reconstruction with either autograft or allograft, which each have their associated limitations. Thus, there is interest in designing a tissue-engineered graft for use in ACL reconstruction. We describe the fabrication of an electrospun polymer graft for use in ACL tissue engineering. This polycaprolactone graft is biocompatible, biodegradable, porous, and is comprised of aligned fibers. Because an animal model is necessary to evaluate such a graft, this paper describes an intra-articular athymic rat model of ACL reconstruction that can be used to evaluate engineered grafts, including those seeded with xenogeneic cells. Representative histology and biomechanical testing results at 16 weeks postoperatively are presented, with grafts tested immediately post-implantation and contralateral native ACLs serving as controls. The present study provides a reproducible animal model with which to evaluate tissue engineered ACL grafts, and demonstrates the potential of a regenerative medicine approach to treatment of ACL rupture.
Introduction
前十字韧带（ACL）的破裂是膝关节1的最常见的韧带损伤之一。由于破裂ACL的无法无手术干预治疗，在日常生活和参与体育活动的局限性开车超过175000例患者，每年2到接受手术，以每年十亿美元3估计成本。目前，无论是自体或异体肌腱用于韧带重建。尽管较高的成功率可以与自体移植和更换均可以实现，严重的并发症与这些重建方案4有关。自体移植的组织与供区的发病率相关联，并且在供水有限的，特别是在重新破裂或多韧带损伤的实例。另一方面，同种异体移植组织被延迟接枝集成，不利的炎症反应，理论上的传染疾病的风险，和有限的增刊联LY 5。合成的非降解的移植开发了20世纪70年代和80年代，但过早嫁接破裂，异物反应，骨溶解和滑膜炎6受阻。由于这些严重的问题的结果，目前有可用的在美国的临床使用中没有合成移植物。
由于与现有的移植选项和最近的事态发展在生物学，工程和再生医学这些限制，出现了为ACL移植组织工程解决方案极大的兴趣。当前组织工程策略采用可降解的生物材料和合成材料，以允许宿主的组织向内生长，同时避免与永久合成材料植入7相关的限制。
聚己内酯（PCL）是可生物降解的聚合物，其是FDA批准用于许多医疗应用中，包括粘连屏障和伤口敷料8，即一直Úsed的在各种各样的应用，包括血管，骨，软骨，神经，皮肤，食管组织工程5,9-16。良好的生物相容性，相对较长的体内半衰期，足够的机械强度，以及高弹性有助于该聚合物在组织工程的普及。在伤口愈合的啮齿动物模型中，注入的电纺PCL被证明是无免疫原性，并整合到局部组织无不良反应13。静电PCL的SEM图像示于图1中 。
当前FDA监管标准，疗效和安全性在小型和大型动物模型将需要一个PCL或任何其他工程ACL移植迁入在美国的临床试验。另外， 在体内条件往往能增加在体外组织工程的ACL移植物的性质。自体韧带重建的大鼠模型的屈digitor微米长肌腱先前已经描述的，在其中天然的ACL被切断，股骨和胫骨隧道钻，和接枝物通过并固定就位用缝合17-22。在本文中，我们将描述这个模型的变形对工程化的ACL替换的评价，而不是用于自体移植的基于重建（ 图2）。
尽管许多动物模型韧带组织工程存在，相比于许多原因较大的模型大鼠是有利的。这些优势包括更容易饲养和处理，减少伦理方面的考虑，并降低成本17,23。此外，鼠模型已被广泛地用作模型矫形组织再生，包括软骨，腱和骨组织工程24。特别是，无胸腺裸鼠被选择，因为它们缺乏的细胞介导的免疫应答25，允许最终植入Ò˚F异种供体细胞在此模型中，以进一步增强在未来的工程化移植物。在此方法本文中，我们描述了在ACL重建的无胸腺大鼠模型的制作和无细胞的手术植入，可生物降解的聚合物的接枝。
Protocol
Representative Results
Discussion
ACL损伤是一种常见的疾病在骨科运动手术，与在目前有限的选择重建。为了制定合适的组织工程替代，将允许再生体内 ACL中，需要一个合适的动物模型。在这项研究中，可生物降解的工程化移植物的制造中被描述，因为这是它在体内使用ACL重建的一个可重复模型中的无胸腺大鼠注入。该模型可以用于评估各种生物材料，包括细胞移植物和那些与PJ内置的生长因子组成的不同组织工程…
Declarações
The authors have nothing to disclose.
Acknowledgements
笔者想感谢加布里埃尔芳香化酶和迈克尔Yeranosian其早期这个项目的迭代技术贡献。该项目资金由临床医生OREF科学家培训格兰特（NL），HH李外科研究基金（NL），退伍军人管理局BLR＆D优异回顾1 I01 BX00012601（DM）和肌肉骨骼移植基金会青年科学家奖（FP）。
Materials
| Name of Material/ Equipment | Company | Catalog Number | Comments/Description |
| Medical grade ester terminated poly (ε-caprolactone), granule form (MW = 110,000) | Lactel Absorbable Polymers | Custom synthesized polymer to desired molecular weight | |
| 1,1,1,3,3,3-hexafluoro-2-propanol | Sigma-Aldrich | 105228 | Solvent for PCL polymer |
| 18G x 1 1/2"bevel needle | BD Medical | 305196 | |
| Remote Infuse/Withdraw Programmable Syringe Pump | Harvard Apparatus | 702101 | |
| VersaLaser VLS2.30 Laser Engraver | Microgeo USA | VLS2.30 | |
| Expanded Plasma Cleaner 115V | Harrick Plasma | PDC-001 | Plasma etch just prior to collagen coating for surface modification |
| PureCol Collagen Standard Solution, 3 mg/ml | Advanced Biomatrix | 5015-A | Mix 8:1:2.5 solution of PureCol, 10x PBS, 0.1N NaOH 1:9 in 1x PBS |
| Suture, 5-0 Vicryl | Henry Schein | 1086471 | |
| Suture, 4-0 Vicryl | Henry Schein | 6540072 | |
| Sharp-pointed Dissecting Scissors (Straight; 4.5 inch) | Fisher Scientific | 8940 | |
| Buphrenorphine hydrochloride | Sigma-Aldrich | B9275 | Use 0.03 mg/kg for both intra- and post-operatively for pain control |
| Ampicillin, injectable | Henry Schein | 1185678 | Use 25 mg/kg subcutaneously during the procedure |
| K-wire, 1.6 mm | Spectrum Surgical | SI040062 | |
| Keith Needle, Straight 1 1/2" | Delasco Dermatology Lab & Supply | KE-112 | |
| Immunocal Decalcifying Solution | Fisher Scientific | NC9491030 | |
| Opticryl Acrylic Resin Bone Cement (PMMA) (Monomer and polymer) | US Dental Depot | OPTICRYL 100410 | |
| Instron Model 5564 Tensile Testing Machine | Instron | 5564 | Any comparable tensile testing apparatus is suitable |
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