Measuring gene expression changes on biomaterial surfaces
P. Morissette Martin, K. Creber, D.W. Hamilton The University of Western Ontario, London, ON, Canada
Assessing cell responses to biomaterials has evolved significantly through the continued development, refinement, and improvement of technologies for measuring cell response, particularly in applications of molecular biology and analysis of gene expression. When mammalian cells attach to biomaterials, it sets in motion cascades of complex molecular signals that regulate downstream processes including cell spreading, migration, proliferation, survival, and gene expression (Liu and Chen, 2005). The ability of a biomaterial to influence and regulate these types of cellular responses is essential for the functional integration of the material into the host tissue.
A commonly used method of assessing cell response to a biomaterial is measurement of gene expression (Groen et al., 2016). Understanding which genes are active in a cell gives an insight into cell phenotype, maturation state, and overall bioactivity. As will be discussed in this chapter, this is typically done in vitro, with specific cells being seeded onto, or into, a biomaterial or scaffold. In vivo assessment of a biomaterial efficacy is more complicated, as will be illustrated in Section 6.4. The continued development of techniques for assessing gene expression (quantitative PCR and microarray technology, for example) and gene localization (in situ hybridization) has permitted increased accuracy in profiling active and inactive genes. These assays also allow for a reduction in cell density required for techniques such as northern blotting, although such techniques still have validity (Roth, 2002). Technological advances in gene expression have been, and will continue to be, paramount in the development of specific biologically active materials through assessment of their functionality in biological systems (Groen et al., 2016; Hanagata, 2015).
The goal of this chapter is not to discuss the details underlying the technical aspect of each methodology for assessing gene expression, but rather to discuss the relevance and design of experiments to maximize the information that can be gained through gene expression profiling as a method of quantifying cell response to a given biomaterial. In addition, assumptions, limitations, and potential pitfalls related to the analysis of gene expression in biomaterial research will be discussed.