(14c) Mechanical Characterization of Adult Bone Marrow Stem Cells for Injection or Implantation

Therapies using adult stem cells often require mechanical manipulation such as injection or incorporation of cells into scaffolds, but force-induced rupture and mechanosensitivity of cells during manipulation is largely ignored. We perform biophysical characterization of bone marrow CD34+ hematopoietic and bone marrow mesenchymal stromal cells. We use micropipette aspiration to characterize cell mechanics and quantify deformation of subcellular structures under force. Our results suggest that CD34+ cells are mechanically suitable for injection systems since cells transition from solid- to fluid-like at constant aspiration pressure, probably due to a fluid actin cytoskeleton. Conversely, mesenchymal stromal cells are more suitable for seeding into biomaterial scaffolds since they are mechanically robust and have developed cytoskeletal structures. We confirm the relevance of our measurements by injecting cells, and we find a 16 fold increased survival of CD34+ cells. Since different types of adult stem cells may be used for similar applications, we suggest considering optimal mechanical characteristics for therapies.