Cao lab’s study has revealed that the subchondral osteoclasts triggered the progression of pain via sensory innervation in arthritis.47 To further confirm the effect of Sr-SMSC-EXOs on pain alleviation, immunofluorescence, and tartrate resistant acid phosphatase (TRAP) staining were conducted to assess the expression of CGRP and osteoclast activity in subchondral bone. This evidence concerns the gene ACP5 and arthritic joint disease.