The invention relates to a process for preparing a non-expanded tissue derivative, that is not subjected to cell proliferation in vitro, comprising 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 said derivative, wherein said tissue derivatives or said cells are subjected to vibrations derived from a heart sound such to control the degree of differentiation or possible differentiation of said stem and multipotent elements into several other types of cells that is to optimize their potency. The invention relates also to a device for carrying out said process, to stem cells obtainable by the process as well as a drug for the regeneration of an animal tissue.
