Characterization of the Mechanical and Gene Expression Profile of Heterogeneous ASC Populations

Investigators: Rafael D. Gonzalez Cruz

Previous investigations in our lab show that cellular mechanical properties are indicative of the differentiation potential of adipose-derived stem cells (ASCs). However, ASCs exhibit heterogeneity in their mechanical properties at the cell population level. Interestingly, ASCs also exhibit heterogeneity in their gene expression of adipogenic and osteogenic markers at the cell population level.  We are considering the idea that ASCs are localized in neighborhoods within their culture, forming subpopulations that have characteristic mechanical and gene expression profiles. We hypothesize that these neighborhoods have mechanical and gene expression profiles that are indicative of the cells' ability to become either adipocyte or osteoblast. To test this hypothesis, we will combine atomic force microscope (AFM)-based microindentation measurements with live cell fluorescence imaging of adipogenic or osteogenic markers. Specifically, we will use molecular beacon technology to target mRNA of characteristic adipogenic or osteogenic markers and image the fluorescence of these markers in ASCs undergoing either adipogenic or osteogenic differentiation. Our experimental setup allows for not only this live cell, fluorescence imaging but we can also test the mechanical properties of the cells using AFM microindentation. We will explore methods to generate "mechanogenomic" heat maps that show the mechanical and gene expression profiles of ASC in different neighborhoods. We will then conduct neighborhood analyses and clustering techniques to characterize and quantify the mechanical and gene expression profiles of ASC subpopulations. The results will allow us to characterize the heterogeneity of the ASC populations and will provide insightful advice for devising stem cell enrichment strategies.