The Cell Technology workgroup is concerned with three subjects: The development of devices and software for image-based cytometry; the development of bioreactors and new reactor principles for adherent growing cells; and finally with the optimization and development of devices for fast cell culturing from biopsies and investigating the transition of tissue to cell culture. In general terms, the workgroup develops innovative tools and devices for cell culture, cell handling and cell logistics. The workgroup thus operates in the highly exciting border area shared by cell biology, process engineering, computer science, materials science and laboratory tool building. The special competence of the Cell Technology workgroup lies in bringing together these individual disciplines.
,The workgroup has made decisive progress in image-based cytometry in recent years. Image-based cytometry is the quantitative analysis of cell cultures by means of a software-based evaluation of microscopic cell images and image sequences. As early as 2011, the Cell Technology workgroup managed to develop a process able to detect possible errors in tracking individual cells systematically, thus increasing cell tracking reliability to the point that it is equivalent to manual cell tracking by specialists. This breakthrough could have enormous importance for future cell cultures. It is now possible to track what is going on in the cell culture dish fully automatically and to perform a quantitative analysis of cells in real time. Both static parameters (cell shape, size and number) and dynamic parameters (movement analysis, cell divisions) are determined automatically and with high statistical relevance.
Among the cytometric analytical processes that the workgroup has developed is the recent mitosis detection (which works independently from cell detection, see project example). Mitoses or cell divisions are the actual starting and final stages in a cell’s life cycle. Each cell comes to life as a daughter and disappears by forming daughter cells itself. For this reason, mitoses are the most important events in a cell culture and their detection is of eminent importance in cytometry. To perform this work, the EMB developed various algorithms that allow very precise detection of mitotic events. They are used to determine the distribution of cell cycle times in a cell culture. These parameters, although indispensable for describing and understanding complex cell cultures, are almost impossible to ascertain with conventional methods.
Last year, improvements were made in isolating adult stem cells from glandular tissue too. The yield from the isolation was multiplied by optimizing the procedures, process parameters and enzymes used. It is also possible to fully dissociate tissue in vital individual cells, which is a prerequisite for cell population cleaning or fractioning.
Finally, last year the workgroup drove new developments in the area of bioreactors for adherent growing cells. In particular, a novel method for growing cells in bioreactors on microcarriers or hollow fibers is now being implemented. Since most adherent cells generally proliferate only within a restricted density range of approx. 500-50,000 cells/cm2, the achievable proliferation rates – irrespective of method and absolute growth surface – are restricted to about 102 to a maximum of 103. Compared with this, our new methodology allows a cyclically controlled process, in which each cycle yields about ten times the cell quantity. This makes it possible to have expansion factors beyond 104. The principle here is based on the encapsulation of cells in a hydrogel so they can grow in it. Once the capsule is filled with cells, the capsule material can be dissolved and the cell suspension is available for the next encapsulation cycle.
This process offers many advantages: On the one hand, the inoculation/cell harvesting steps are fully dispensed with and are replaced by the encapsulation and capsule-dissolving processes. Thereafter, the reactor can already be operated at its final size, even with small starting cell numbers, and the number of intermediate steps can be drastically reduced. Furthermore, the cells are mechanically protected inside the capsule. Apart from higher survival rates owing to the protection from shear and impact forces, higher flow speeds and volumetric flow rates are also achieved. Finally, the cells grow in a threedimensional environment that allows them to proliferate while maintaining their biological function and identity. This is especially indispensable for stem cell proliferation.