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NF‐KB activity functions in primary pericytes in a cell‐ and non‐cell‐autonomous manner to affect myotube formation

Introduction: Skeletal muscle regeneration following damage relies on proliferation and differentiation of muscle precursor cells (MPCs). We recently observed increased NF‐kB activity in vascular‐associated muscle resident pericytes following muscle damage in humans. We determined how altered NF‐kB activity in human primary pericytes (HPPs) affects their myogenic differentiation (cell‐autonomous effects), as well as proliferation and differentiation of co‐cultured MPCs (non–cell‐autonomous effects). Methods: HPPs were transfected with vectors that increased or decreased NF‐kB activity. Transfected HPPs were co‐cultured with C2C12 myoblasts under differentiation conditions, and HPP fusion to myotubes was measured. We also co‐cultured HPPs with C2C12 myoblasts and measured proliferation and myotube formation. Results: Inhibition of NF‐kB activity increased HPP fusion to C2C12 myotubes. Moreover, enhanced NF‐kB activity in HPPs suppressed differentiation and enhanced proliferation of co‐cultured myoblasts. Conclusions: NF‐kB activity acts cell‐autonomously to inhibit HPP myogenic differentiation and non–cell‐autonomously to promote MPC proliferation and suppress MPC differentiation in vitro. Muscle Nerve, 2013