UFOs, Worms, and Surfboards: What Shapes Teach Us About Cell Material Interactions

The success of regenerative materials is dependent on the ability to elicit cell interactions. Cell-material interactions, both desired and undesired, are dictated by the physical properties of the material. Previous research has focused on surface chemistry and feature size of biomaterials. The role of shape, in particular the ability of cells to recognize and respond to shape, has not been determined. This is primarily due to the limited availability of techniques to produce materials with features of controlled and varied morphologies. To this end, we have created a diverse collection of novel polymer micro- and nano-particle shapes and studied their phagocytosis by macrophages. The macrophage immune response to biomaterials is a formidable obstacle in delivery and integration of materials for successful tissue regeneration, engineering, and drug delivery. The results show that particle shape, from the point of view of the macrophage, profoundly impacts phagocytosis, more than particle size and independent of surface chemistry. We can use this understanding to design material features that will direct desired macrophage response and, in the future, study the effects of shape on other cell functions. This work demonstrates the importance of shape in the design of biomaterials and its influence on cell-material interactions.