Disclosed herein are compositions and methods for monitoring hematopoietic reconstitution or suppression in a subject. Also disclosed are compositions and methods for reconstituting the hematopoietic compartment of a subject in need thereof. Also disclosed is a method for monitoring the effect of ionizing radiation on the lung in a subject. Also disclosed is the ability to use detection of the one or more microRNA indicative of radiation-induced lung injury to guide therapy of the subject. Also disclosed is the ability to use detection of the one or more microRNA indicative of radiation-induced lung injury to evaluate the efficacy of a lung treatment following radiation exposure.
