In one aspect, the invention provides methods of inhibiting the effects of MASP-2-dependent complement activation in a living subject suffering from, or at risk for developing a thrombotic microangiopathy (TMA). The methods comprise the step of administering, to a subject in need thereof, an amount of a MASP-2 inhibitory agent effective to inhibit MASP-2-dependent complement activation. In some embodiments, the MASP-2 inhibitory agent inhibits cellular injury associated with MASP-2-mediated alternative complement pathway activation, while leaving the classical (C1q-dependent) pathway component of the immune system intact.