3D Bone tissue engineered with bioactive microspheres in simulated microgravity

Three-dimensional (3D) osteoblast cell cultures were obtained in rotating-w all vessels (RWV), simulating microgravity. Three types of bioactive microc arriers, specifically modified bioactive glass particles, bioceramic hollow microspheres, and biodegradable bioactive glass-polymer composite microsph eres, were developed and used with osteoblasts. The surfaces of composite m icrospheres fully transformed into bone apatite after 2-wk immersion in sim ulated physiological fluid, which demonstrated their bone-bonding ability. The motion of microcarriers in RWVs was photographically recorded and numer ically analyzed. The trajectories of hollow microspheres showed that they m igrated anti eventually staved around at the central region of the RWV. At their surfaces, shear stresses were low. In contrast, solid glass or polyme r particles moved toward and finally bounced off the outer wall of the RWVs . Cell culture studies in the RWV using bone marrow stromal cells showed th at the cells attached to and formed 3D aggregates with the hollow microsphe res. Extracellular matrix and mineralization were observed in the aggregate s. Cell culture studies also confirmed the ability of the composite microsp heres to support 3D bone-like tissue formation. These data suggest that the new hollow bioceramic microspheres and degradable composite microspheres c an be used as microcarriers for 3D bone tissue engineering in microgravity. They also have potential applications as drug delivery systems.