Immunohistochemical study on the distribution of telocytes in the knee joint components in a rat osteoarthritis model

[Purpose] Telocytes are stromal cells that participate in tissue homeostasis. Osteoarthritis is a common degenerative disorder of multiple joint components that causes inflammation; however, the distribution of telocytes in joint components and the impact of osteoarthritis on telocytes is unclear. Therefore, we aimed to clarify the distribution of the telocyte in the joint components and determine the effect of osteoarthritis on telocytes. [Participants and Methods] We divided 30 male rats into control and osteoarthritis groups and surgically induced osteoarthritis by destabilizing the medial meniscus. At two and eight weeks after surgery, we evaluated the changes in CD34-positive and CD31-negative area sizes in the joint components by immunohistochemistry. [Results] The results showed CD34-positive and CD31-negative areas in the loose connective tissue of the lateral meniscus attachment and the infrapatellar fat pad. However, it was not observed in the cartilage, subchondral bone, cruciate ligament, and meniscus. Moreover, there were no significant differences between the CD34-positive and CD31-negative area sizes in control and osteoarthritis groups at both time points. [Conclusion] CD34-positive and CD31-negative cells are distributed in multiple joint components; however, CD34-positive and CD31-negative areas are not affected by the progression of osteoarthritis. This result provides information on telocytes distribution in the knee joint and the impact of osteoarthritis on these cells.