Concurrent Mechanical Stretching and Co-Cultivation for Promoting the Chondrogenesis of Human Adipose-Derived Stem Cells

Bones in articulating joints are cushioned with a viscoelastic tissue called Articular Cartilage (AC). AC acquires a unique mechanical structure that absorbs bodyweight loads on the knee vascularization. However, because AC is avascular in nature, cartilage lacks the intrinsic ability to regenerate but rather degenerates with wear and tear, causing osteoarthritis (OA). OA symptoms include pain, swelling, loss of flexibility, and, eventually, disability. Currently available treatments, including surgeries like total knee arthroscopy, alleviate the pain, but they can never be used to restore full joint mobility. Patients with OA never return to a completely healthy lifestyle even after treatment, and they become prone to developing severe additional health problems due to the inactivity. Articular cartilage tissue engineering (ACTE) is an emerging field in which regenerative options for AC are being developed. Although the field has potential, ACTE is critically limited by the availability of chondrogenic cell sources. In this work, the influence of combined co-cultivation, a biochemical stimuli, and cyclic tensile stretching (CTS), a mechanical stimuli, on chondrogenesis is investigated. The viability and biochemical content of human adipose-derived stem cells (hASCs) co-cultivated with human chondrocytes (hAChs) under 10% CTS at 1Hz for 3 h/day for 14 days are compared to statically cultured hASCs. Our findings indicate that collagen secretion was enhanced by at least 1.7-fold with co-cultivation, 1.8-fold with CTS, and by 6.2-fold with co-cultivation under CTS, when compared to static cultures of hASCs.