Three-dimensional expansion: in suspension culture of SD rat's osteoblasts in a rotating wall vessel bioreactor / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To study large-scale expansion of SD (Sprague-Dawley) rat's osteoblasts in suspension culture in a rotating wall vessel bioreactor (RWVB).</p><p><b>METHODS</b>The bioreactor rotation speeds were adjusted in the range of 0 to 20 rpm, which could provide low shear on the microcarriers around 1 dyn/cm2. The cells were isolated via sequential digestions of neonatal (less than 3 days old) SD rat calvaria. After the primary culture and several passages, the cells were seeded onto the microcarriers and cultivated in T-flask, spinner flask and RWVB respectively. During the culture period, the cells were counted and observed under the inverted microscope for morphology every 12 h. After 7 days, the cells were evaluated with scanning electron microscope (SEM) for histological examination of the aggregates. Also, the hematoxylin-eosin (HE) staining and alkaline phosphatase (ALP) staining were performed. Moreover, von-Kossa staining and Alizarin Red S staining were carried out for mineralized nodule formation.</p><p><b>RESULTS</b>The results showed that in RWVB, the cells could be expanded by more than ten times and they presented better morphology and vitality and stronger ability to form bones.</p><p><b>CONCLUSIONS</b>The developed RWVB can provide the culture environment with a relatively low shear force and necessary three-dimensional (3D) interactions among cells and is suitable for osteopath expansion in vitro.</p>

Numerical simulation of microcarrier motion in a rotating wall vessel bioreactor / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To analyze the forces of rotational wall vessel (RWV) bioreactor on small tissue pieces or microcarrier particles and to determine the tracks of microcarrier particles in RWV bioreactor.</p><p><b>METHODS</b>The motion of the microcarrier in the rotating wall vessel (RWV) bioreactor with both the inner and outer cylinders rotating was modeled by numerical simulation.</p><p><b>RESULTS</b>The continuous trajectory of microcarrier particles, including the possible collision with the wall was obtained. An expression between the minimum rotational speed difference of the inner and outer cylinders and the microcarrier particle or aggregate radius could avoid collisions with either wall. The range of microcarrier radius or tissue size, which could be safely cultured in the RWV bioreactor, in terms of shear stress level, was determined.</p><p><b>CONCLUSION</b>The model works well in describing the trajectory of a heavier microcarrier particle in rotating wall vessel.</p>