Advantages of microfluidic systems for studying cell-biomaterial interactions-focus on bone regeneration applications

The poor correlation between in vitro and in vivo studies emphasises the lack of a reliable methodology for testing the biological properties of biomaterials in the bone tissue regeneration field. Moreover, the success of clinical trials is not guaranteed even with promising results in vivo. Therefore, there is a need for a more physiologically relevant in vitro model to test the biological properties of biomaterials. Microfluidics, which is a field concerning the manipulation and control of liquids at the submillimetre scale, can use channel geometry, cell confinement and fluid flow to recreate a physiological-like environment. This technology has already proven to be a powerful tool in studying the biological response of cells in defined environments, since chemical and mechanical inputs as well as cross-talk between cells can be finely controlled. Moving a step further in complexity, biomaterials can be integrated into microfluidic systems to evaluate biomaterial-cell interactions. The biomaterial-microfluidics combination has the potential to produce more physiologically relevant models to better screen the biological interactions established between biomaterials and cells. This review is divided into two main sections. First, several possible cell-based assays for bone regeneration studies in microfluidic systems are discussed. Second, and the ultimate goal of the review, is to discuss how the gap between in vitro and in vivo studies can be shortened by bridging the biomaterials and microfluidics fields.