MMP13 and osteoarthritis: When administered intra-articularly to rats with osteoarthritis, these hybrid CAP-exosomes (hybrid CAP-Exo/CRISPR/Cas9 sgMMP–13) penetrated deep into the cartilage matrix, delivered the plasmid to chondrocytes, and knocked down the expression of matrix metalloproteinase 13 (MMP–13) (Figure 8C).