Bioreactors with Laminar and Defined Gradient Hydrodynamics: Hydraulic Culture of Cells for Assessment of Effectors Controlling Regenerative Tissue Morphogenesis in Wound Healing

Abstract

Abstract The design and use of a new type of bioreactor is described. It allows to establish defined physical parameters around cells cultured on microcarriers in terms of laminar and flow velocity gradient hydrodynamics and other hydraulic conditions in vitro. It is an approach to investigate and to establish within analytical and biotechnical cell culture systems in vitro in the form of these physical parameters defined equivalents of different in vivo situations in viscoelestic properties of blood and hemodynamics to which the cells are exposed in their physiological and pathological environment (“normal”, “low” and “no” fluid flow) in vivo. The theoretical basis for the hydrodynamics in these bioreactors is particle flotation in cylinder- and cone-shaped vessels at analytical and technical scales, constraint by StokeS' and the laws of transport processes, or irreversible thermodynamics. The systems produced, being not in equilibrium and moving towards equilibrium, macroscopically may be maintained “stable” for the period of culture. Processing of cells in such bioreactors has further advantages in that collisions, and thus frictional damage of cultured cells anchored on microcarriers are minimized; since, theoretically, collision forces are absent, and minimized in practice when compared to conventional bioreactors with uncontrolled, turbulent hydrodynamics. Furthermore, the conditioning of cultured cells anchored on flotating microcarriers which are maintained in serum -free, fully synthetic, chemically defined, component-rich medium (composition: BM-86-Wissler, Boehringer Mannheim, Germany), exclusively is achieved by means external and/or remote to the bioreactor. Thus, these design and use characteristics alternatively allow culturing cells either in their own “aged” medium adapted by cellular chemostasis reactions; or, without being exposed at all to medium or cellular components being prior in contact with the cultured cells or any of their (exuded) constituents in the bioreactor. The novel types of bioreactors have been used, so far for our purposes, for culture of some anchorage-dependent cell types of mesenchymal origin (endothelial and white blood cells) in order to investigate the effects of some physical parameters of hydrodynamics on cellular reactions in culture in terms of production of, and interaction with defined chemical effectors controlling regenerative tissue morphogenesis in wound healing. An example is presented in terms of culture of a highly purified preparation of porcine peripheral monocytes (macrophage type) and their activation to exude some biologically active, chemical effectors of regenerative tissue morphogenesis in terms of wound hormone (for chemorecruitment of leukocyte phenotypes from their bone marrow storage pools into blood circulation, i.e. leukocytosis and leftward shift reactions) and a wound mediator (for chemotropism of blood vessels, i.e. angiogenesis).