Effect of a mechanical stimulation bioreactor on tissue engineered, scaffold‐free cartilage

Abstract

Achieving sufficient functional properties prior to implantation remains a significant challenge for the development of tissue engineered cartilage. Many studies have shown chondrocytes respond well to various mechanical stimuli, resulting in the development of bioreactors capable of transmitting forces to articular cartilage in vitro. In this study, we describe the production of sizeable, tissue engineered cartilage using a novel scaffold-free approach, and determine the effect of perfusion and mechanical stimulation from a C9-x Cartigen bioreactor on the properties of the tissue engineered cartilage. We created sizable tissue engineered cartilage from porcine chondrocytes using a scaffold-free approach by centrifuging a high-density chondrocyte cell-suspension onto an agarose layer in a 50 mL tube. The gross and histological appearances, biochemical content, and mechanical properties of constructs cultured in the bioreactor for 4 weeks were compared to constructs cultured statically. Mechanical properties were determined from unconfined uniaxial compression tests. Constructs cultured in the bioreactor exhibited an increase in total GAG content, equilibrium compressive modulus, and dynamic modulus versus static constructs. Our study demonstrates the C9-x CartiGen bioreactor is able to enhance the biomechanical and biochemical properties of scaffold-free tissue engineered cartilage; however, no additional enhancement was seen between loaded and perfused groups.

Effects of Perfusion and Dynamic Loading on Human Neocartilage Formation in Alginate Hydrogels

“…Davisson et al 28 showed that perfusion alone was sufficient to increase stiffness of engineered neocartilage (bovine chondrocytes seeded on polyglycolic acid felts) and comparable with perfused and compressed (10% offset and -5% dynamic strain oscillations at 0.001 Hz). Most recently, Tran et al 29 utilized a commercially available bioreactor system capable of perfusion and loading. In comparison to the FS condition, the biomechanical and biochemical properties of the scaffold-free engineered porcine cartilage were enhanced.…”

Joint Cartilage Tissue Engineering and Pre-Clinical Safety and Efficacy Testing

“…A general starting point for direct compression studies of cells adhered to a scaffold is 10% or 15% compression at a frequency of 1Hz (Grad et al, 2011;Terraciano et al, 2007;Mouw et al, 2007;Huang et al, 2004). Recently, mechanical stimulation showed improved cartilage formation of porcine chondrocyte cartilage constructs compared to static culture, but no difference was noted between perfusion and perfusion-compression constructs (Tran et al, 2011). In the compression group, constructs where cultured with perfusion alone at a flow rate of 0.5ml/min for the first week followed by 1 Hz sinusoidal unconfined compression, 4 hours a day, 5 days a week, starting with a load of 0.5 N until 20 N by the third week (Tran et al, 2011).…”

“…Recently, mechanical stimulation showed improved cartilage formation of porcine chondrocyte cartilage constructs compared to static culture, but no difference was noted between perfusion and perfusion-compression constructs (Tran et al, 2011). In the compression group, constructs where cultured with perfusion alone at a flow rate of 0.5ml/min for the first week followed by 1 Hz sinusoidal unconfined compression, 4 hours a day, 5 days a week, starting with a load of 0.5 N until 20 N by the third week (Tran et al, 2011). Perfusion was maintained in this compression group for the 4-week duration of the study and compared to a control group of perfusion only.…”

Regulation of gene expression in articular cells is influenced by biomechanical loading

“…Among other things, cell proliferation can be improved significantly by biomechanical loading [12][13][14][15][16]. To what extent cell functions of different articular cells are affected by a defined biomechanical stimulus remains largely unknown.…”