Effect of cyclic three-dimensional strain on cell proliferation and collagen synthesis of fibroblast-seeded chitosan-hyaluronan hybrid polymer fiber

Tissue engineering techniques using biodegradable three-dimensional (3D) scaffolds with cultured cells offer more potential alternatives for the treatment of severe ligament and tendon injuries. In tissue engineering, one of the crucial roles of 3D scaffolds is to provide a temporary template with the biomechanical characteristics of the native extracellular matrix (ECM) until the regenerated tissue matures. The purpose of the present study was to assess the effect of various cyclic mechanical stresses on cell proliferation and ECM production in a 3D scaffold made from chitosan and hyaluronan for ligament and tendon tissue engineering. Three-dimensional scaffolds seeded with rabbit patella tendon fibroblasts were attached to a bioreactor under various conditions: static group, no strain; stretch group, tensile strain; rotational group, rotational strain; combined group, rotational and tensile strain. In the Static group, 3 weeks of stationary culture was performed. In the remaining three groups, a loading regimen of 0.5 Hz for 18 h and then 6 h rest was carried out for 2 weeks after 1 week of static culture. The DNA content was determined to quantify cell proliferation. Real-time reverse transcription polymerase chain reaction analysis was performed to assess the mRNA levels of the ECM products. DNA content of the combined group was significantly higher than that of the static and stretch groups, and that of the rotational group was significant higher than that of the static and stretch groups at 21 days after cultivation. The mRNA level of types I and III collagen and fibromodulin in the combined group was significantly higher than that in the other three groups. The amount of collagen synthesis in the combined group was higher than that in the static group, but the difference was not significant. Multidimensional cyclic mechanical strain to mimic the physiological condition in vivo has the potential to improve or accelerate tissue regeneration in ligament and tendon tissue engineering using 3D scaffolds in vitro.