Using Light-Activated EFG to Control Cell Behavior with Automated Instrumentation

A key interest in cell biology is the ability to control cell behavior, particularly for creating functional assemblies of cells to restore, maintain or enhance tissue and organ function. Success in controlling cell behavior must include techniques that provide signals which influence the organization, growth and activities of cells. Growth factors are naturally occurring proteins that act as external chemical signals and which play a key role in regulation and control of a variety of cellular processes, such as differentiation, proliferation and migration. One of the challenges in controlling these processes using growth factors is the ability to spatially direct their timed release to the cellular environment. Another challenge then becomes the continued ability to influence these processes with the dynamic flexibility to meet the changing cellular demands during tissue development. We have developed a technology that uses light-activated epidermal growth factor (EGF) to influence cell behavior. We used peptide synthesis to incorporate a photolabile caging group on a critical residue. The caged-growth factor was inactive until converted with light, which enabled the management of its effects with the precision with which light could be directed. Since the factor was a soluble, diffusible species, it was not limited to a static pattern or substrate. Thus, dynamic control over its mitogenic and chemotactic effects on cell behavior was achieved. To utilize the light-activated EGF we developed a device for its delivery and activation. The system was a fully automated machine capable of maintaining the strict requirements of cell culture, integrated with components that achieved interchangeable, high resolution patterns, along with an optical system for photo-activating caged growth factors. The instrument was designed, characterized and then used to investigate the effect of light-activated EGF on cell patterning and mobility. Using this device, spatially resolved fibroblast cell patterning and migration were achieved.