In addition, hyperbaric oxygen was used to treat CCl4-induced liver fibrosis rats and free radical antagonists were added to eliminate excessive free radicals produced by hyperbaric oxygen, which not only alleviated liver injury and delayed the progress of liver fibrosis, but also significantly decreased expression of matrix Metallo proteinase-2 (MMP-2) in HSC. Here, MMP2 is linked to Hepatic fibrosis.