Carlo Tremolada and Carlo Ventura received a patent for an invention that relates to a process of 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.