Measurement of Forces and Their Role in Stem Cell Differentiation Using Suspended Fiber Networks

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Stem cells are the essential bridge connecting embryos to the adult life span through amazing capability of unlimited self-renewal and commitment to become (differentiate into) specialized cells representing tissues and organs. In addition, they are key players in repair mechanisms as impairment of stem cell functionality is directly related to disease models including cancer. Cells in their native environment are constantly subjected to both biochemical and biophysical signals. While the role of biochemical cues on stem cell behavior is well documented, only recently have we begun to understand the role of biophysical cues. In this context, very little is known on the role of ubiquitous forces cells feel or exert constantly during differentiation. This award funds fundamental research in determining these forces and their role in stem cell differentiation. The new knowledge will allow development of scaffolds capable of providing simultaneous biochemical and biophysical factors specific to a cell type, thus impacting both developmental and disease biology. This research involves multiple disciplines including engineering (mechanical, biomedical), polymer physics, biology and mathematics under the umbrella of rapidly growing mechanobiology. The knowledge from this research will benefit the U.S. economy and society, while also providing pathways for increased participation of underrepresented groups in research and engineering.This research plans to build extracellular matrix (ECM)-mimicking nanofiber-based scaffolds called 'nanonets' as force measurement probes. Nanonets are composed of aligned and suspended nanofibrous assemblies of a mix of diameters, lengths, and spacing in double layer configuration. Furthermore, nanonets contain fused fiber intersections, which allow migrating single cells to deflect fiber segments, thus providing a measure of forces using inverse methods. This multiscale approach will permit simultaneous investigations on the role of biophysical (curvature, structural stiffness (N/m)) and biochemical (growth factor concentrations) cues on differentiation of single human bone-marrow derived mesenchymal stem cells (h-MSCs) attached to suspended nanonets. This will allow development of a set of force-differentiation (F-D) master curves calibrating the optimal biophysical and biochemical contributions to mesenchymal stem cell differentiation. The fundamental knowledge will contribute significantly by unraveling the role of cell-ECM mechanobiological interactions at the single-cell level and provide insights in development of implantable platforms for tissue regeneration, wound healing sutures, single cell force measurement assays for early diagnosis and drug testing for a wide variety of diseases including cancer.