Chalmers Conferences, 9th European Conference on Mathematical and Theoretical Biology

Dendritic cell chemotaxis in physiological matrices in well-defined 3D gradients reveals differential response to CCL21 vs. CCL19
Ulrike Haessler

Last modified: 2014-06-09


Directed cell migration, namely chemotaxis, is a critical cellular behavior in the immunological response towards foreign pathogens. Despite the fact that an adequate immunological response requires a precise chemotactic control, the quantitative response of dendritic cells towards defined chemokine gradients remains elusive. This is mainly due to the lack of appropriate tools, which allow establishing gradients quick enough, stable over time and still precise within a physiological 3D environment. Previously, we presented a device meeting these requirements (Haessler, U., Y. Kalinin, et al. (2009). "An agarose-based microfluidic platform with a gradient buffer for 3D chemotaxis studies." Biomed Microdevices 11(4): 827-35). Here, we show how we used this microfluidic device to gain quantitative insights into how dendritic cells respond to the two CCR7-ligands responsible for lymph-node homing, soluble CCL19 versus matrix bound CCL21.

First, we developed an integrated computational model to precisely predict matrix bound and soluble chemokine fractions. Experimental data to determine matrix binding properties were gained by fluorescently labeled CCL19 and CCL21 in conjunction with modified an ELISA assay to determine the matrix binding KD for CCL21. In a following step we fine tuned the proportion of matrix bound versus soluble CCL21 by varying matrix compositions. As readout, we observed single cell migration live under a phase contrast microscope and quantified commonly used chemokinetic and chemotactic migratory parameters.

We show that chemokinesis as indicated by the percentage of migrating cells and cellular speed in the presence of both CCR7-ligands only plays a minor role in the context of a 3D microenvironment. Furthermore, dendritic cells respond similarly to CCL19 and CCL21 at lower concentration differences, but display enhanced chemotaxis towards CCL21 at higher concentration differences. If the cells are exposed to both chemokines simultaneously, CCL21 is clearly preferred, regardless if bound to the matrix or not.