Polypeptide complexes derived from the bronchi, blood vessels, muscles, kidneys, ovaries, testes, and retina stimulated the processes of cell renewal in organotypic cultures of the corresponding organs of young and old animals. A correlation between the intensity of regeneration and animal' age was revealed. The polypeptide complexes reduced the expression of apoptotic factors p53 and caspase 3 and increased the expression of proliferation protein Ki-67. These results provide the basis for further study of the polypeptide complexes as stimulators of regenerative processes in different tissues during ageing.