Towards 3D Printed Osteoimmunomodulatory Surface Patterns

Osteoimmunomodulation (OIM) is a mechanism through which orthopedic biomaterials may modulate the function of immune cells to promote osteogenesis. OIM is considered a potentially effective way for improving osseointegration. The surface characteristics of orthopedic implants (e.g., topography, wettability, surface chemistry, and charge) can significantly influence their potential OIM behavior. Modifying these properties can, therefore, be considered a powerful method for achieving the described OIM response. Among the different possible length scales of topographies, the role of submicron topographies on OIM functions has been less frequently studied. That is partially because it is quite challenging to fabricate surface topographies with controlled shapes and dimensions. Moreover, the currently available technologies for the fabrication of submicron features usually involve multiple fabrication techniques and steps.In this thesis, uniform submicron patterns are, for the first time, 3D printed with controlled dimensions using a single-step nanoprinting technique called two- photon polymerization (2PP). In addition, the effects of the dimensions of the 3D printed submicron pillars on the response of two types of cells involved in the OIM process (i.e., preosteoblast and immune cells) are extensively studied, both separately using monocultures and in interaction with each other using a direct co-culture model performed in the presence of submicron pillars. Our findings, reveal that 3D printed submicron scale patterns are able to generate both osteogenic and immunomodulatory in vitro cellular responses. This novel concept of multifunctional topographies opens up a new approach for enhancing the OIM behavior of orthopedic biomaterials.Biomaterials & Tissue Biomechanic