Abstract: The invention relates to a process for preparing a non-expanded tissue derivative, that is not subjected to cell proliferation in vitro, which has a vascular-stromal fraction enriched in stem and multipotent elements, such as pericytes and/or mesenchymal stem cells, or for preparing non-embryonic stem cells obtained from a tissue sample or from such tissue derivative, wherein the tissue derivative or such cells are subjected to vibrations derived from a heart sound to control the degree of differentiation or possible differentiation of the stem and multipotent elements into several other types of cells and optimize their potency. The invention relates also to a device for carrying out the process, to stem cells obtainable by the process as well as a drug for the regeneration of an animal tissue.