Robust mechanics of ameboid cells leading to emergence of self-tuning, biohybrid microtransporter.*

Targeted delivery is one of the key limits of precision medicine, a prime challenge in today’s medical science. Inspired by the motility of leukocytes, we introduce a biohybrid microtransporter with crawling ameboid D.discoideum cells acting as the active element. The microtransport process begins once a motile cell meets a cargo. The dynamics of the resultant two body system is dictated by the cargo size and can possibly spread faster than individual cells in the absence of cargo.

The forces exerted actively by the agent cell on the spherical cargo are estimated in the range of femto Newton. The mean force grows monotonously with cargo radius, reaching approximately 400 fN for cargo particles with a redius of 62 micrometers. Surprisingly, the exerted force is not limited to this value. In the presence of continues fluid flow, the cells are still able to maintain their adhesion to the cargo for drag forces of up to approximately 500 pico Newton. The latter observation suggests an adaptive mechanism by which the cells increase their grip on a cargo particle if exerted forces are actively pulling on the cargo, trying to break the cell-cargo bound.

These findings will serve as a basis for understanding cell-mediated microtransport also in more complex environments.