LAUSR

An estimated 500,000 people experience a spinal cord injury worldwide each year (1). At present, there is no treatment to repair spinal cord injury and restore lost function. Unlike mammals, animals such as fish, frogs, and salamanders display the amazing potential to regenerate their central nervous system through axonal regrowth and tissue regeneration (2). Since many molecular pathways are shared between zebrafish and mammals, zebrafish have emerged as a powerful model system to study central nervous system regeneration with a view toward informing therapeutic interventions in humans (3). Historically, axonal regeneration has been attributed almost exclusively to chemical cues. A growing body of evidence now suggests that mechanical cues could—at least in part— play a critical role in guiding axonal regrowth and spinal cord repair (4). The mechanical microenvironment of living cells is increasingly recognized as an important regulator of cellular development, aging, disease, and injury healing; however, we lack technologies to reliably characterize this environment in vivo. Optical tweezers, micropipette aspiration, and microfluidics allow us to characterize the stiffness of cells in solution, but not at subcellular resolution. Atomic force