The invention pertains to a method for identifying and sorting live, label-free mesenchymal stromal cells (MSCs) by size, which correlates with their telomere length. This can be applied in regenerative medicine and cosmetology. The method for identifying and sorting live, unlabelled cells includes sorting MSCs into a certain number of subsets based on their size using dielectrophoresis by polarizing cells in the spatial gradient of the electrical field. Since MSC size correlates with their telomere length, this method allows the indirect separation of live, label-free MSCs from a heterogenous stromal cell population according to their telomere length. The sorted live MSC subset with longer telomeres can be used in cell therapies, in the development of organ–on–a–chip platforms (3D in vitro models) to study aging changes in organs, in the creation of new drugs or in studies of age-related diseases.