The present disclosure relates to methods for increasing telomere length in one or more human cells and/or increasing genome stability of one or more human cells, for example by contacting one or more human cells with an agent that increases expression of Zscan4 in the one or more human cells. Methods of treating a subject in need of telomere lengthening, treating a disease or condition associated with a genomic and/or chromosome abnormality, of rejuvenating one or more human cells, of rejuvenating tissues or organs, and of rejuvenating a subject in need thereof, for example by contacting one or more human cells in the subject with an agent that increases expression of Zscan4, or by administering to a subject in need thereof, an agent that increases expression of Zscan4 are also provided.