Mitochondrial crosstalk between bone marrow stromal cells and chondrocytes: implication for cartilage repair in...

Mitochondria are vital dynamic organelles released by cells into extracellular space, endocytosed in or transferred between cells in contact. Mitochondria from healthy bone marrow stem cells (MSCs) show rescue effects on chondrocytes, accordingly a concept of using healthy MSC mitochondria for cartilage regeneration is put forward. Therefore, whether mitochondria from healthy MSCs help to save chondrocytes in damaged cartilage microenvironment is intriguing. We answered this question by considering coexistent MSCs and chondrocytes, and their released mitochondria in damaged joint.

Mitochondria were extracted from primarily cultured MSCs and chondrocytes of osteoarthritis (OA) human patients to represent mitochondria released endogenously by MSCs and chondrocytes in damaged joint. While mitochondria were extracted from healthy rats to represent mitochondria exogenously added during MSC mitochondrial repair for the inaccessibility of healthy human. The mitochondria were co-cultured with another type of cells. Endocytosing and afterward positioning of exogenous mitochondria, as well as induced alterations in mitochondria and cellular behaviors of recipient cells were assayed.

Our results suggested that although mitochondria from healthy MSCs advantaged remedy for inflammatory chondrocytes, mitochondria from healthy and OA chondrocytes, as well as from OA MSCs disadvantaged chondrocytes remedy, no matter the mitochondria were from the same or different species. However, reactive oxygen species (ROS) modulation alleviated the disadvantage.

Our results provide a reminder for careful consideration of mitochondrial therapy, and explanation for unsuccessful repair of damaged cartilage by MSCs from aspect of mitochondria, as well as potential remedy through ROS modulation.