A method for treating a condition, comprising administering to a subject in need thereof a composition that contains somatic stem cells that are 2 to less than 6 micrometers in size and Lgr5+, wherein the condition is selected from the group consisting of neurodegenerative disorder, muscle-degenerative disease, cancer, metabolic disorder, autoimmune disorder, inflammatory disorder, heart disorder, circulatory disorder, a condition associated with aging, and damaged tissue.