MICROGRAVITY TISSUE ENGINEERING

Tissue engineering studies were done using isolated cells, three-dimen sional polymer scaffolds, and rotating bioreactors operated under cond itions of simulated microgravity. In particular, vessel rotation speed was adjusted such that 10 mm diameter x 2 mm thick cell-polymer const ructs were cultivated in a state of continuous free-fall. Feasibility was demonstrated for two different cell types: cartilage and heart. Co nditions of simulated microgravity promoted the formation of cartilagi nous constructs consisting of round cells, collagen and glycosaminogly can (GAG), and cardiac tissue constructs consisting of elongated cells that contracted spontaneously and synchronously. Potential advantages of using a simulated microgravity environment for tissue engineering were demonstrated by comparing the compositions of cartilaginous const ructs grown under four different in vitro culture conditions: simulate d microgravity in rotating bioreactors, solid body rotation in rotatin g bioreactors, turbulent mixing in spinner flasks, and orbital mixing in petri dishes. Constructs grown in simulated microgravity contained the highest fractions of total regenerated tissue (as a percent of con struct dry weight) and of GAG, the component required for cartilage to withstand compressive force.