Emerging Gene-Editing Modalities for Osteoarthritis

Figure 1. Articular joint structure. (a) Bone and cartilage of a healthy tibiofemoral joint (b) Simulation of cartilage degeneration and bone spur formation in an osteoarthritic knee.

Figure 2. CRISPR/Cas mechanism. Trans-activating RNA (orange) with CRISPR RNA (blue) the guide RNA. The guide RNA assembles with the Cas9 protein to form the CRISPR complex. Using the guide RNA for specificity, the CRISPR complex binds to the target DNA. Transgenic DNA can be inserted using homology arm inserts.

Figure 3. Extracellular vesicle delivery of CRISPR/Cas9 in the treatment of OA. Inside a producer cell (left), engineered OA-targeted sgRNA transcription may occur. SgRNA combines with Cas9 to form CRISPR/Cas9 sgRNA complexes. CRISPR/Cas9 complexes load into extracellular vesicles with fluorescent tags containing a dimerization domain compatible with a dimerization domain in engineered CRISPR/Cas9 complexes. These fluorescent tags also contain targets for the target osteoarthritic cell (right). Loaded EVs attach to target cells and unload the CRISPR/Cas9 complexes, which are then transported to the nucleus to perform gene modification.