Differential Gene Expression in Cells Cultured in Rotating Wall Vessel Bioreactors

The generation of tissue-engineered replacement organs by means of three-dimensional (3D) in vitro cell culture is a current research focus in many tissue engineering laboratories. Rotating Wall Vessel (RWV) Bioreactors offer a unique cell culture venue for advanced tissue engineering applications. We have exploited this unique culture venue to produce functional “organoids.” Cells and cell assemblies cultured in the RWV Bioreactors are concomitantly exposed to low laminar shear stress and to “simulated or modeled microgravity” (Unsworth and Lelkes, 1998). We have shown that the component that which simulates/models microgravity by “randomizing” the gravitational vector, is crucial for modulating gene expression and functional differentiation of cell/cell assemblies in the RWV Bioreactors (Unsworth and Lelkes, 2000).

In addition to their potential usefulness as a cell culture venue for mass-producing replacement “prototissues” simulated microgravity in the RWV Bioreactors also offers an innovative, in vitro tool for studying instructional cues and mechanisms involved in organogenesis. Importantly, the RWV environment supports both cellular differentiation and tissue expansion. We are using RWV bioreactors for in vitro embryology, in order to understand mechanisms controlling neuroendocrine differentiation of bi-potential, sympathoadrenal cells of the adrenal gland (Lelkes, et. al., 1998). The culture environment of the RWV specifically induces the formation of macroscopic, 3D organoids and causes differentiation of PC12 cells, an adrenal medullary tumor cell line, along the neuroendocrine pathway (Lelkes, et. al., 1998). Rapid activation of intracellular signaling pathways may control organ-specific differentiation. The tissue-specific differentiation in the RWV Bioreactors appears to mimic events occurring during in vivo organogenesis. Thus we are exploiting this in vitro system to investigate molecular mechanisms operating during in vivo embryogenesis. The possibility for recapitulating in vitro, the complex cellular events occurring during organogenesis may lead us to a comprehensive analysis of the molecular control of developmental processes that depend on cell-cell and cell-extracellular matrix interactions.

Selected References:

P.I. Lelkes, et. al. (1998) Simulated microgravity conditions enhance differentiation of cultured PC12 cells towards the neuroendocrine phenotype. In: Vitro Cell Dev. Biol. 34:316-325.

Unsworth, B.R. and P.I. Lelkes (1998) Growing tissues in microgravity. Nature Medicine 4:901-907.

Unsworth, B.R. and P.I. Lelkes (2000) Tissue Assembly in Microgravity. In: Principles of Tissue Engineering, Eds: R.P. Lanza, R. Langer and J. Vacanti. Academic Press. PP 157-164.

Lelkes, P.I. and B.R .Unsworth (2002) Endocrine Cells. In: Methods of Tissue Engineering, Eds: A. Atala and R. Lanza. Academic Press.