Effects of lithium chloride on chondrocyte primary cilia in 3D culture

Articular cartilage is unique and distinguishable amongst other tissue types due to its limited self-healing capacity, driving the need to investigate novel methods capable of replacing or repairing damaged or diseased tissue. In order to create tissue engineered constructs to repair cartilage defects, large populations of chondrocytes are needed, thereby requiring the expansion of primary cells. However, routine methods of cell expansion (e.g. monolayer expansion) tend to result in the loss of chondrogenic phenotype and insensitivity to mechanical stimuli. It has been suggested that the chondrocyte’s primary cilium is one factor responsible in transducing mechanical signals between the cell and its surrounding environment. Thus, this work focused on restoring primary cilia (length and incidence) and mechanoreceptive characteristics using lithium chloride (LiCl). Overall, results revealed that primary cilia length and incidence increased with LiCl concentration, pre-culture duration, and passage number. However, the mechanosensitivity of chondrocytes, as determined by changes in cartilaginous matrix synthesis after exposure to mechanical stimuli, appeared to be dependent on the degree of prior cell passaging. Thus, these results suggest that although the primary cilium acts as a transducer of mechanical signals, the effects of passaging might impact its functionality.