Hematopoietic stem cells (HSCs) play an important role in the regeneration of blood as well as the function and maintenance of the immune system, due to their ability to differentiate into all types of blood cells. Moreover, HSCs are used for the treatment of malignant diseases of the blood system (e.g. leukemia). Unfortunately, the demand for HSCs exceeds the current supply from donors. The targeted in vitro culture of HSCs in an undifferentiated state would provide an elegant solution to overcome this problem. At present, this approach is strongly limited by currently available cell culture techniques. The reliable maintenance of the HSC properties is only possible in the stem cell niche, their natural environment located in the bone marrow. There, the proliferation and differentiation is regulated by both biochemical and physical cues. Thus, the development of fully synthetic cell culture systems, mimicking specific bone marrow properties, is critical for determining factors that control cell proliferation and differentiation, allowing for the future expansion of HSCs’ clinical applications.
We are aiming for the development of nanostructured polymer coatings with tailored domains bearing different biomolecules to conduct systematic studies of their influence on the behavior of HSCs. Here we introduce multifunctional honeycomb-patterned porous polymer films prepared via the breath figure approach as potential cell culture systems. Block copolymers as well as random copolymers with domains bearing different functional groups suitable for an orthogonal modification with ligands are synthesized. A polymer solution is then casted onto a substrate and exposed to a humid airflow. As the solvent evaporates, condensation and growth of water droplets occur on the organic surface while the polymer concentrates at the interface stabilizing the water droplets. With further evaporation of the liquids, pores are created by the water droplets leading to honeycomb-patterned polymer films when proper conditions are applied. In the future, this polymer films will be compared to natural ECM derived surface coatings with regards to their effects on the proliferation of undifferentiated HSCs in order to establish the applicability of this approach.