PTEN and intervertebral disk degenerative disorder: [31] reported that MSC‐derived exosomes containing miR‐21 inhibited phosphatase and tensin homolog (PTEN) and activated the phosphoinositide 3‐kinase/protein kinase B (PI3K/Akt) pathway in a rat model of IDD, preventing TNF‐α‐mediated apoptosis.