Design and performance of a bioreactor system for mechanically promoted three-dimensional tissue engineering

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Cell Biology

Background:

• Mesenchymal cells respond to physical forces, driving interest in skeletal tissue formation.
• Existing loading devices aim to enhance in vivo and in vitro skeletal tissue development.
• Controlled mechanical stimulation is crucial for directing cell behavior in tissue engineering.

Purpose of the Study:

• To develop and evaluate a novel bioreactor system for applying controlled cyclic strains to three-dimensional tissue specimens.
• To investigate the effects of varying mechanical strain levels on osteoblast and chondrocyte proliferation and extracellular matrix synthesis.
• To determine the optimal range of mechanical stimulation for promoting hard tissue formation.

Main Methods:

• Development of a piezoelectric-driven bioreactor for precise control of cyclic strains (0-20,000 microstrain).
• Finite-element analysis to model tissue deformation under applied loads.
• Testing the bioreactor performance with three-dimensional specimens containing osteoblasts and chondrocytes.
• Assessing cell proliferation, differentiation, and extracellular matrix protein synthesis at different strain levels.

Main Results:

• Biaxial tissue straining at 2,000 microstrain significantly increased osteoblast and chondrocyte numbers compared to controls.
• Physiological loads (2,000 microstrain) enhanced the synthesis of cell-specific extracellular matrix proteins.
• Higher deformations (20,000 microstrain) led to reduced cell proliferation and differentiation.

Conclusions:

• The developed bioreactor effectively applies controlled mechanical stimuli to tissue specimens.
• Physiological levels of mechanical strain promote mesenchymal cell proliferation and extracellular matrix production.
• Optimized mechanical stimulation via bioreactors shows promise for hard tissue engineering, while excessive strain is detrimental.