Mechanical Loading-Dependence of mRNA Expressions of Extracellular Matrices of Chondrocytes Inoculated into Elastomeric Microporous Poly(L-lactide-co- ∊ -caprolactone) Scaffold

The temporal response of young rabbit chondrocyte metabolism (including biosynthesis of extracellular matrix macromolecules such as collagen and aggrecan, both of which are essential components of normal cartilage tissue, and their messenger ribonucleic acid (mRNA) expression) in microporous elastomeric scaffolds made of poly(L-lactide-co-∊-caprolactone) subjected to different compressive regimes (loading frequency, loading duration per cycle, loading period, and continuous or intermittent compression) were studied over a 6-day culture period at 10% of compressive strain. A continuous dynamic compression improved the production of sulfated glycosaminoglycan (S-GAG), most of which was released into the culture medium upon loading. High mRNA expression of type II collagen was exhibited at a frequency of 0.1 Hz. Little frequency dependency was observed for aggrecan. An intermittent loading (24-h cycle of loading and unloading) or short loading and unloading duration per cycle-compression regime maintained high levels of mRNA expression. This strongly suggests that well-controlled mechanical conditioning regimes may control the gene expression of key metabolic substances relevant to functional cartilage tissue while the degree of release of these substances into the culture medium is minimized.