Size-dependent interaction of cells and hemoglobin-albumin based oxygen carriers prepared using the SPG membrane...

Hemoglobin-based oxygen carriers (HBOCs) of various sizes have been developed so far, but their optimum size has not been clarified yet. Here, we examined the effect of HBOCs size on their interaction with cells using Shirasu porous glass (SPG) membrane emulsification technique, which enables precise tuning of particle size. Microspheres composed of bovine hemoglobin (bHb) and bovine serum albumin (BSA) was fabricated with the average diameters of 1.2-18.3 μm and the coefficient of variation of below 13%. Cellular uptake of the microspheres by RAW264.7 was observed at a diameter below 5 μm; however, uptake of the microspheres by HepG2 and HUVEC were not observed at any diameter. No enhancement of the generation of reactive oxygen species in the cytoplasm was detected at diameters above 9.8 μm in the three cell lines, due to their low cellular uptake. In addition, cytotoxicity of the microspheres decreased with increasing microsphere diameter in the three cell lines and microspheres of 18.3 μm showed good cellular compatibility regardless of the oxyhemoglobin percentage. Since cytotoxicity is a crucial factor in their applications, our systemic investigation would provide a new insight into the design of HBOCs.