Background:

Gene transfer of the transcription factor SOX9 with clinically adapted recombinant adeno-associated virus (rAAV) vectors offers a powerful tool to durably enhance the repair process at sites of osteochondral injuries and counteract the development of perifocal osteoarthritis (OA) in the adjacent articular cartilage.

Purpose:

To examine the ability of an rAAV sox9 construct to improve the repair of focal osteochondral defects and oppose perifocal OA development over time in a large translational model relative to control gene transfer.

Study Design:

Controlled laboratory study.

Methods:

Standardized osteochondral defects created in the knee joints of adult sheep were treated with rAAV-FLAG-hsox9 relative to control (reporter) rAAV-lacZ gene transfer. Osteochondral repair and degenerative changes in the adjacent cartilage were monitored using macroscopic, histological, immunohistological, and biochemical evaluations after 6 months. The microarchitecture of the subchondral bone was assessed by micro–computed tomography.

Results:

Effective, prolonged sox9 overexpression via rAAV was significantly achieved in the defects after 6 months versus rAAV-lacZ treatment. The application of rAAV-FLAG-hsox9 improved the individual parameters of defect filling, matrix staining, cellular morphology, defect architecture, surface architecture, subchondral bone, and tidemark as well as the overall score of cartilage repair in the defects compared with rAAV-lacZ. The overexpression of sox9 led to higher levels of proteoglycan production, stronger type II collagen deposition, and reduced type I collagen immunoreactivity in the sox9- versus lacZ-treated defects, together with decreased cell densities and DNA content. rAAV-FLAG-hsox9 enhanced semiquantitative histological subchondral bone repair, while the microstructure of the incompletely restored subchondral bone in the sox9 defects was not different from that in the lacZ defects. The articular cartilage adjacent to the sox9-treated defects showed reduced histological signs of perifocal OA changes versus rAAV-lacZ.

Conclusion:

rAAV-mediated sox9 gene transfer enhanced osteochondral repair in sheep after 6 months and reduced perifocal OA changes. These results underline the potential of rAAV-FLAG-hsox9 as a therapeutic tool to treat cartilage defects and afford protection against OA.

Clinical Relevance:

The delivery of therapeutic rAAV sox9 to sites of focal injuries may offer a novel, convenient tool to enhance the repair of osteochondral defects involving both the articular cartilage and the underlying subchondral bone and provide a protective role by reducing the extent of perifocal OA.

中文翻译：

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随着时间的推移，rAAV 介导的 sox9 过表达改善了临床相关大型动物模型中骨软骨缺陷的修复，并减少了周围骨关节炎的变化

背景：

转录因子 SOX9 与临床适应的重组腺相关病毒 (rAAV) 载体的基因转移提供了一种强大的工具，可以持久地增强骨软骨损伤部位的修复过程，并抵消邻近关节软骨中局灶性骨关节炎 (OA) 的发展。

目的：

在相对于控制基因转移的大型转化模型中，检查 rAAV sox9构建体改善局灶性骨软骨缺损修复和反对局灶周围 OA 发展的能力。

学习规划：

受控实验室研究。

方法：

相对于对照（报告基因）rAAV - lacZ基因转移，用 rAAV-FLAG-h sox9治疗成年绵羊膝关节中产生的标准化骨软骨缺损。6 个月后，使用宏观、组织学、免疫组织学和生化评估监测相邻软骨的骨软骨修复和退行性变化。通过微型计算机断层扫描评估软骨下骨的微结构。

结果：

与 rAAV- lacZ治疗相比，6 个月后通过 rAAV 的有效、延长的 sox9过表达在缺陷中显着实现。与 rAAV-相比，rAAV-FLAG-h sox9的应用改善了缺损填充、基质染色、细胞形态、缺损结构、表面结构、软骨下骨和潮位标记的单个参数以及缺损中软骨修复的总体评分。拉克兹_ 与lacZ相比， sox9的过表达导致更高水平的蛋白多糖产生、更强的 II 型胶原沉积，以及降低sox9中的 I 型胶原免疫反应性- 处理过的缺陷，以及细胞密度和 DNA 含量降低。rAAV-FLAG-h sox9增强了半定量组织学软骨下骨修复，而sox9缺损中未完全恢复的软骨下骨的微观结构与lacZ缺损中的微观结构没有区别。与 rAAV- lacZ相比，与sox9处理的缺损相邻的关节软骨显示出局灶周围 OA 变化的组织学迹象减少。

结论：

rAAV 介导的sox9基因转移增强了 6 个月后绵羊的骨软骨修复并减少了病灶周围 OA 的变化。这些结果强调了 rAAV-FLAG-h sox9作为治疗软骨缺损和预防 OA 的治疗工具的潜力。

临床相关性：

将治疗性 rAAV sox9 输送到局灶性损伤部位可能提供一种新的、方便的工具来增强涉及关节软骨和下面的软骨下骨的骨软骨缺损的修复，并通过减少病灶周围 OA 的程度来提供保护作用。