Cellular "backpacks" are a new type of anisotropic, nanoscale thickness microparticle that may be attached to the surface of living cells creating a "bio-hybrid" material. Previous work has shown that these backpacks do not impair cell viability or native functions such as migration in a B and T cell line, respectively. In the current work, we show that backpacks, when added to a cell suspension, assemble cells into aggregates of reproducible size. We investigate the efficiency of backpack cell binding using flow cytometry and laser diffraction, examine the influence of backpack diameter on aggregate size, and show that even when cell backpack complexes are forced through small pores, backpacks are not removed from the surfaces of cells.