Construction strategies for tissue-engineered ligaments

doi:10.3969/j.issn.2095-4344.2016.29.016

Abstract

Abstract:

BACKGROUND: Until now, musculoskeletal bioengineering used in the orthopedic surgery and regenerative medicine are developing.
OBJECTIVE: To summarize the construction strategies for tissue-engineered knee ligaments.
METHODS: A computer-based online search was conducted in PubMed to screen the relevant literatures using the terms “knee ligament” AND “tissue engineering” OR “regenerative medicine”. The literature retrieval, data assessment and extraction were performed by both authors independently. The relevant literatures were included through reviewing preclinical and clinical studies to display the preclinical and clinical medicine progresses in the construction strategies for tissue-engineered ligaments.
RESULTS AND CONCLUSION: Included 224 literatures focus on the construction strategies for tissue-engineered ligaments, including stem cell therapy, growth factors, biomaterials and scaffolds, and mechanical stimulation pattern. Construction techniques for tissue-engineered ligaments have some potential advantages, such as rapid function recovery, good tenacity, and reduced relapse. However, rigorous and high-level randomized controlled clinical trials are needed for the translation of preclinical results into successful clinical trials.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

Key words: Ligaments, Regenerative Medicine, Tissue Engineering

CLC Number:

R318

Di Ya-long, Han Chang-xu, Zhao Liang, Ren Yi-zhong. Construction strategies for tissue-engineered ligaments[J]. Chinese Journal of Tissue Engineering Research, 2016, 20(29): 4368-4375.

Figures/Tables 1

2.1 细胞治疗最近，应用干细胞性组织工程方法已经证实，可以加速肌腱移植物的愈合和融入骨道[18]。间充质干细胞，由于他们的高增殖率，多能，和从各种组织中相对简单的分离对促进肌腱及腱骨交界处愈合有很大的吸引力[22]。研究表明，血管丰富的干细胞/祖细胞表面特征性的表达CD34[23-24]。Matsumoto等[20]最近报道，人类前交叉韧带的破裂和隔膜区域包含表达CD34的血管来源的干细胞被赋予了高增殖和多向分化潜能并定向迁移到前交叉韧带破裂的部位促进韧带愈合。此外，他们发现在前交叉韧带重建的大鼠模型中通过血管生成和骨生成促进作用，这些干细胞可以促进腱骨愈合[25]。Mifune等[26]用细胞片包裹肌腱实现干细胞直接传递到肌腱和骨道，并表明CD34细胞片包裹的移植物比其他技术对于前交叉韧带重建后的恢复更迅速。已经探索了其他细胞来源用于前交叉韧带修复。Lui等[27]报道，从髌腱中分离来的肌腱来源的干细胞表现出了干细胞特性和更高的成骨细胞分化。此外，Chang等[28]研究表明，骨膜祖细胞片可以提供一个可行的治疗策略，以提高腱骨交界处的愈合。脂肪来源的干细胞也被提出作为细胞治疗韧带重建一个替代选择[29]。 2.2 人工韧带系统使用非降解人工韧带尚未流行，因为30年前引进的设备导致不可接受的高失败率[30-31]。韧带先进强化系统(LARS)用于前交叉韧带和后交叉韧带重建得到了安全、满意的结果[32-36]。韧带先进强化系统是一个聚对苯二甲酸乙二醇酯制成的非可降解人工移植和植入后可保持良好持久的力学性。然而，已经注意到术后并发症的发生率[37-39]。Guidoin等[37]对117例前交叉韧带损伤后离断假体植入移植物后发展为滑膜炎的病例进行了分析。在聚酯为基础的韧带上观察巨噬细胞和巨细胞的慢性炎症反应。其缺乏有序结构和杂乱无序的胶原组织就像瘢痕组织一样，愈合过程中浸润的纤维组织引起韧带网状结构完整性的破坏最终导致失败。这些失败表明，聚对苯二甲酸乙酯人工韧带移植物在移植膝关节后几乎没有韧带化[39]。组织工程的新兴领域认为人工韧带作为一种可行的结构去替代自体移植物和同种异体移植物是有希望的，但还需要在这个舞台上更多的进步。 2.3 富血小板血浆富血小板血浆是通过离心的方法从自体血中提取出来的血小板浓缩物，具有用自体生物活性物质加强自身修复和再生能力，近来得到越来越多的科学关注，用于肌肉骨骼损伤(包括前交叉韧带和其他韧带损伤)的治疗[40-42]。富血小板血浆中的血小板可以分泌具有多种功能的蛋白质，包括转化生长因子、血小板源生长因子、肝细胞生长因子、血管内皮生长因子等促进组织的再生[43]。损伤引起出血之后，血小板活化并且聚集，释放包括生长因子在内的颗粒，激活治愈过程。富血小板血浆可以影响血管形成，而早期的血管形成对肌腱的修复非常重要。富血小板血浆的应用将激增的化学递质传递到损伤部位的微环境中，包括血小板A-颗粒源性因子等[44]。研究者通过体外研究和动物实验证实了富血小板血浆在腱骨愈合界面对成骨细胞和肌腱细胞增殖有积极影响[45-46]。富血小板血浆除了对细胞修复有刺激作用外，对某些促炎细胞因子也有抑制作用，这可能不利于早期阶段的愈合，尤其是通过抑制活化的巨噬细胞释放白介素1[47]。Xie等[48]在一个犬的模型中证实富血小板血浆可促进血管重建和神经恢复，这或许可以解释富血小板血浆对前交叉韧带移植成熟的促进作用。在前交叉韧带重建中应用富血小板血浆治疗应当考虑到生理情况下细胞因子和生长因子的局部传递。这或许可以解决单一疗法的局限性，如仅诱导界面愈合的某一方面。虽然基础科学研究表明富血小板血浆治疗对腱骨愈合有积极影响，但到目前为止，在前交叉韧带重建时显示富血小板血浆增加对于临床结果，隧道扩大和移植物融合无统计学显著差异[49]。在另一方面，一些研究人员报道在骨髌腱骨韧带重建后的供区富血小板血浆可有效降低主观疼痛[50-51]。 2.4 生长因子和细胞因子使用骨诱导性生长因子增强腱骨愈合是当前最集中的研究策略之一。这些生长因子包括转化生长因子、骨形成蛋白、成纤维细胞生长因子、粒细胞集落刺激因子，已显示出在重建前交叉韧带的动物模型的修复和愈合有积极效果[52-57]。从这些研究结果的基础上可以得出，骨诱导生长因子在前交叉韧带重建中具有治疗潜力。 2.5 磷酸钙杂交肌腱磷酸钙生物水泥或黏合剂可以作为替代的治疗策略，以提高前交叉韧带重建后腱骨愈合，因为他们提供了一个骨传导性和生物相容的环境，促进界面的细胞增殖和生长因子聚集。Matsuzaki等[58]在兔模型中使用磷酸钙杂交肌腱，以提高前交叉韧带移植物在腱骨界面的愈合过程，重新生成一个与正常健康的前交叉韧带止点类似的结构。 2.6 可降解生物材料生物可降解植入物应该在对移植物最小损伤基础上提供强有力的初始固定。最近Emond等[59]Meta分析结果显示，在前交叉韧带重建中使用生物可吸收螺钉与金属螺钉相比其临床结果没有显著差异。然而，使用生物吸收挤压螺钉引起的一些相关问题包括术中螺钉断裂，炎症反应导致螺钉加速的或不完整的吸收，关节积液，螺钉移位，以及骨道增宽的可能性。Pereira等[60]在他们的回顾性文章提到，迁移是生物可吸收挤压螺丝潜在的并发症。生物可吸收螺钉对临床相关影响的信息是罕见的，这可能存在发表偏倚。此外，人体对螺钉可能存在的复杂反应与在实验室条件下反应是不同的。可以明确的是，材料科学的发展将继续在生物相容性固定系统中发挥重要作用。 Farraro等[61]表明，在前交叉韧带重建时使用镁挤压螺钉固定移植物，关节稳定性和移植物功能的恢复与钛螺钉基本相似。此外，镁环修复的前交叉韧带可以消除损伤前交叉韧带的两端部之间的间隙，以恢复关节的稳定性和正常功能。尽管如此，广泛的临床使用前仍然存在一些挑战，最显著的是如何控制腐蚀速率，这高度依赖于其几何形状，组成成分和植入物的位置。 Murray等[62]提出了一个治疗前交叉韧带损伤的可能性，即强化生物修复前交叉韧带。他们在猪身上证明，使用生物活性支架(胶原血小板复合体)可显著改善传统前交叉韧带修复的结果，结构性质与传统修复相当。除此之外，在临床前期的模型中生物强化的前交叉韧带修复可以减少创伤后骨关节炎的发生。然而，临床前模型不同与人体的情况，该方法的临床安全性和有效性需要在此技术上进一步研究[63]。 2.7 力学刺激食品和药物管理局批准应用能量为30 mW/cm2的低强度脉冲超声波(LIPUS)刺激干预用于增强骨折愈合和慢性骨不连，以及用于软骨缺损和韧带损伤的治疗得到了广泛的应用[64-68]。最近的动物研究表明，超声不仅加速腱骨愈合而且还创建了一个类似于天然附着点的连接点[64，69-70]。用低强度脉冲超声波治疗改善预后的可能性解释是促进附着点的愈合。低强度脉冲超声波治疗促进成骨细胞和成纤维细胞增殖，这有助于改善胶原形成和骨重建[71]。血管内皮生长因子和白细胞介素1的水平增加，从而提高了先前缺血性环境中的血管生成和蛋白合成[72-73]。此外，低强度脉冲超声波治疗增加骨形成蛋白的表达可能增加腱骨愈合[74]。低强度脉冲超声波改善局部血液灌注和血管生成，刺激软骨成熟，提高成骨细胞的分化和增殖，并刺激间充质干细胞的成骨分化；因此它似乎是韧带重建后的早期康复阶段的促使腱骨愈合的无创工具。可以想象，在家中使用低强度脉冲超声波来刺激腱骨愈合，目的是加速康复，使患者在不久的将来早期恢复正常活动。在腱骨延迟愈合的模型中证明体外冲击波疗法可以增强纤维软骨再生[75]。体外冲击波疗法不仅为纤维软骨和细胞因子生成提供了力学环境，还正向调节了其表达。 2.8 内侧副韧带内侧副韧带损伤，特别是股骨内侧髁近端损伤模式没有手术干预很可能自愈，因此优先选择保守治疗。典型的关节外韧带自然愈合可分为4个阶段，其包括血肿形成，细胞增殖，基质沉积和组织结构形成。尽管内侧副韧带损伤后功能恢复相对较快，但生物力学调查显示愈合后的组织不如正常的内侧副韧带，甚至是在受伤多年后。在这方面，组织工程方法修复或重建被视为一种恢复内侧副韧带组织类型接近正常的手段，因此该方面研究或许可以成为一个新的主题。Aragona等[76]在一篇经典的文章中提到在犬体内使用碳纤维增强聚乳酸复合材料组成的部分可吸收组织支架重建内侧副韧带，在植入26周后该材料比形成的瘢痕组织更稳定。Musahl等[77]报道了在兔体内利用猪小肠黏膜下层作为支架来评估是否小肠黏膜下层提高了内侧副韧带损伤处的愈合。小肠黏膜下层的使用改善了手术12周后内侧副韧带的力学性能和组织学表观。Liang等[78-79]进行了一项长达26周的术后跟踪调查证实了上述结论，并在进一步的研究中发现在小肠黏膜下层增强损伤模型中V型胶原蛋白，核心蛋白多糖的基因表达显著降低，从而增强了其力学性能。人们对注射生长因子的生物方法也进行了研究。Hildebrand等[80]在兔模型中发现使用血小板源性生长因子BB 6周后可以改善愈合后内侧副韧带的生物力学。力学方面，血小板源性生长因子BB组显示出更大的极限载荷，吸收更多的能量和更大的极限延伸值。最近，Yoshioka等[81]研究在兔模型中注射富生长因子血浆对内侧副韧带愈合的影响，认为可以刺激成纤维细胞增殖以及新生血管形成，且愈合后内侧副韧带结构在统计学上与未经处理的对照组相比更好。 2.9 局限性随着研究的继续，期待合适的组织工程策略用于膝关节韧带重建，尽可能避免当前自体肌腱移植和异体肌腱移植技术的缺点，同时允许术后患者立即进行功能锻炼尽快参与体育活动。然而，尽管目前显示有一些好处，但必须承认许多组织工程为基础的治疗仍然缺乏强大的临床支持。关于这些新疗法潜在的好处和安全性的推论必须考虑少数的研究，少样本量和证据水平。此外，严格的局部条件和机制成功促进韧带生长和修复的说法还有待澄清。需要通过更多高质量长期随访的随机临床试验，建立治疗韧带伤的可靠、有效和安全的组织工程策略。"

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