Musculoskeletal Gene Therapy Laboratory, Mayo Clinic, Rochester, MN, USA.
Adv Exp Med Biol. 2023;1402:95-105. doi: 10.1007/978-3-031-25588-5_7.
Delivering genes to chondrocytes offers new possibilities both clinically, for treating conditions that affect cartilage, and in the laboratory, for studying the biology of chondrocytes. Advances in gene therapy have created a number of different viral and non-viral vectors for this purpose. These vectors may be deployed in an ex vivo fashion, where chondrocytes are genetically modified outside the body, or by in vivo delivery where the vector is introduced directly into the body; in the case of articular and meniscal cartilage in vivo delivery is typically by intra-articular injection. Ex vivo delivery is favored in strategies for enhancing cartilage repair as these can be piggy-backed on existing cell-based technologies, such as autologous chondrocyte implantation, or used in conjunction with marrow-stimulating techniques such as microfracture. In vivo delivery to articular chondrocytes has proved more difficult, because the dense, anionic, extra-cellular matrix of cartilage limits access to the chondrocytes embedded within it. As Grodzinsky and colleagues have shown, the matrix imposes strict limits on the size and charge of particles able to diffuse through the entire depth of articular cartilage. Empirical observations suggest that the larger viral vectors, such as adenovirus (~100 nm), are unable to transduce chondrocytes in situ following intra-articular injection. However, adeno-associated virus (AAV; ~25 nm) is able to do so in horse joints. AAV is presently in clinical trials for arthritis gene therapy, and it will be interesting to see whether human chondrocytes are also transduced throughout the depth of cartilage by AAV following a single intra-articular injection. Viral vectors have been used to deliver genes to the intervertebral disk but there has been little research on gene transfer to chondrocytes in other cartilaginous tissues such as nasal, auricular or tracheal cartilage.
将基因递送到软骨细胞为临床治疗影响软骨的疾病以及在实验室研究软骨细胞的生物学提供了新的可能性。基因治疗的进展为此创造了许多不同的病毒和非病毒载体。这些载体可以以离体方式（即在体外对软骨细胞进行基因修饰）或体内方式（即直接将载体引入体内）进行部署；在关节和半月板软骨的情况下，体内递送通常通过关节内注射进行。在增强软骨修复的策略中，离体递送是首选的，因为这些策略可以利用现有的基于细胞的技术（例如自体软骨细胞移植），或者与骨髓刺激技术（例如微骨折）结合使用。向关节软骨细胞的体内递送已被证明更加困难，因为软骨密集、带负电荷的细胞外基质限制了对嵌入其中的软骨细胞的接近。正如 Grodzinsky 及其同事所表明的那样，基质对能够扩散穿过整个关节软骨深度的颗粒的大小和电荷施加了严格的限制。经验观察表明，较大的病毒载体，如腺病毒（100nm），在关节内注射后无法转导原位软骨细胞。然而，腺相关病毒（AAV；25nm）能够在马关节中做到这一点。AAV 目前正在进行关节炎基因治疗的临床试验，因此，观察单次关节内注射后 AAV 是否也能将人软骨细胞转导到整个软骨深度，将是一件很有趣的事情。病毒载体已被用于将基因递送到椎间盘，但对于其他软骨组织（如鼻、耳或气管软骨）中的软骨细胞的基因转移研究甚少。
