(165z) Abstract: Engineering of Heparin/Collagen Microcarrier Coatings for Human Mesenchymal Stromal Cells Manufacturing

Layer-by-layer (LbL) assembly is a surface modification technique used to create layers of alternating charged polymers on surfaces. In this study, we investigate three different techniques to create LbL films on spherical microcarriers. Furthermore, the microcarriers thus modified are used in human mesenchymal stromal cell (hMSC) culture, expanding on our previous work that demonstrated the efficacy of the films in improving cell proliferation, immunosuppression, and cytokine expression. Compared to the flat surface used in the previous work, microcarriers provide a larger surface area for the cells to adhere to and are used in bioreactors for large-scale cell production.

Two charged polymers are used in this study – heparin (negative) and collagen (positive). Three different methods are evaluated in their efficacy in preparing the multilayers – a centrifugation method, a fluidized-bed method, and a draining filter system. Fluorescent labeling of collagen is used to demonstrate the visual differences in the multilayers thus created using the three systems. Additionally, scanning electron microscopy, zeta potential analysis, and particle size analysis are used to characterize and observe the formation of the multilayers. Biological assays are used to evaluate the effect of the modified microcarriers on cell cultures. The results of this study will be used to improve cell proliferation, immunosuppression, and cytokine expression in bioreactor-based hMSC cultures.