Cardiogen

In organotypic myocardial tissue cultures from young (3-month) and old (24-month) rats, the synthetic tetrapeptide cardiogen (applied at 10^-12 M) produced a marked stimulation of cell proliferation in tissue from both age groups, whereas of 20 individual amino acids tested, seven stimulated proliferation in young tissue and only two in aged myocardium. Immunohistochemistry showed that cardiogen reduced p53 protein expression, interpreted by the authors as inhibition of apoptosis in the myocardial tissue. This tissue-specific, age-independent pro-proliferative effect distinguished the peptide from its constituent amino acids.

Researchers grew small pieces of rat heart tissue in the lab, using both young and old rats, and treated them with the peptide cardiogen. Cardiogen boosted the growth of heart cells in both young and old tissue, working better than individual amino acids, especially in aged tissue. It also lowered a cell-death marker (p53), suggesting it helped protect heart cells from dying. This is early lab-tissue research, not a human study.

In senescent rats bearing M-1 sarcoma, injections of the cardiogen peptide produced dose-dependent inhibition of tumor growth. The effect was mediated by hemorrhagic necrosis and stimulation of tumor-cell apoptosis rather than a direct cytostatic action, with apoptosis levels in treated groups exceeding controls. The authors concluded cardiogen acted through the tumor's vascular network.

In aged rats with a type of tumor, the cardiogen peptide slowed tumor growth in a dose-dependent way. Rather than killing cancer cells directly, it appeared to act on the tumor's blood vessels, causing tissue death and pushing tumor cells into self-destruction. This was an animal study exploring a different use of the same heart peptide.