Chemical Surface Modification Tolerance of Primary and Immortalized Macrophages and Stem Cells

Cells are being utilized across various applications, including as self-regenerating materials, imaging and/or therapeutic entities, and delivery vehicles, and have the potential to do more. In biological and medical applications, specific cell types, including macrophages and mesenchymal stem cells (MSCs), have often been used on account of their recruitment to disease sites and desirable biodistribution properties. Typically, delivery applications involve the internalization of substrates within the cell, however, this approach presents drawbacks and is not amenable to some uses. Alternatively, chemically modifying cell surfaces using the toolbox of biocompatible chemistries has been broadly applied, but with few direct comparisons, including regarding assessment(s) of effects on the cells. In this work, we sought to compare commonly utilized N-hydroxysuccinimide ester and hydrazide-based conjugations to immortalized and primary macrophages and MSCs. We incorporated both small molecules and avidin proteins using each approach, finding that cargo size plays a substantial role in modifications. Overall, conjugations were well-tolerated by primary and immortalized macrophages and MSCs; we observed no major impacts on viability and chemotactic response, but found some slight changes and trends depending on cell and modification type. This foundational work directly comparing the results and effects of multiple conjugation strategies across different cell types will benefit their use across a variety of applications.