Evaluation of Biological Biomaterial Properties using Microfluidic Systems

Abstract: Despite increased orthopedic biomaterial research activity over previous decades, relatively few novel biomaterials have made it to clinical use. This may partially be due to the inability of existing in vitro testing routines to sufficiently replicate the physiological environment, leading to potentially inaccurate assessments of a biomaterial’s therapeutic potential. To address this, mathematical modelling and microfluidic design principles were assessed as possible supportive strategies to better improve the informativity of in vitro testing approaches.Using principles of the Langmuir isotherm, a predictive computational model was constructed to capture the dynamics of protein and cell adhesion on a biomaterial surface, specifically on calcium-deficient hydroxyapatite, which is a synthetic biomaterial that is compositionally similar to the inorganic phase of the bone. The results demonstrated the success of the model at capturing the trends of the data, thereby indicating potential use as a predicative tool to assist with in vitro data interpretation.Furthermore, attempts were made to improve the in vitro environment towards better physiological relevancy via the introduction of microfluidics, which is method of precise fluid control in micron-sized channels. For instance, the use of microfluidics allows for cell culture under more tissue relevant length scales, as well as the provision of a continuous media flow, which facilitates nutrient delivery and activation of mechanosensitive pathways through shear stress. Through development of such “Biomaterial-on-chip” microfluidic platforms, a general increase in cell viability and proliferation was seen when cells were cultured under flow. The effect of flow on other parameters such as material-induced ionic exchange, immunogenicity and mechanotransduction was also tested using the platform. By the culmination of the thesis work, the Biomaterial-on-chip platform was designed with inherent  standardization, allowing for the in vitro testing of different biomaterials of varying shapes and properties under the same conditions in the same platform. All in all, the main conclusion from this thesis work is that cell response can largely differ depending on the chosen culture conditions, which therefore necessities careful consideration of environmental parameters prior to the start of an in vitro biomaterial evaluation study.