Extracellular Vesicles from Adipose-Derived Mesenchymal Stem Cells Improve Ligament-Bone Integration After Anterior Cruciate Ligament Primary Repair in Rabbit.

Backgrounds: In this research, we want to find out whether extracellular vesicles (EVs) from adipose-derived mesenchymal stem cells (MSCs) can improve ligament-bone integration after primary Anterior Cruciate Ligament (ACL) repair by performing immunological and biomechanical tests.

Methods: All of the rabbits underwent ACL resection at the proximal attachment to the femur bone, and then were divided into four groups. We performed an ELISA examination from the tissue at the bone-ligament interface of iNOS, CD206, MMP-3, and TIMP-1 to evaluate their levels at the inflammatory stage at the end of the first week. Immunoexpression of type I and III collagen and failure load biomechanical tests were performed at the end of the sixth week.

Result: The group that underwent ACL repair with EVs augmentation had significantly higher levels of CD206, significantly lower MMP-3 levels, and significantly higher TIMP-1 levels in the first week. The iNOS levels in the group that underwent ACL repair with EVs augmentation were significantly different compared to the control group that did not receive any. The number of type I collagen fibers and the failure load levels in the group that underwent ACL repair with EVs augmentation were significantly higher.

Conclusions: EVs from adipose-derived MSCs can improve the outcome of primary ACL repair in rabbits by regulating the inflammatory process during the healing period.