Background: A DNA-RNA-lipoprotein complex, termed as virtosome, is released spontaneously from
healthy human, other mammalian, avian, amphibian and plant cells in a regulated and energy-dependent manner.
Studies on human and mouse lymphocytes, hepatocytes, NIH 3T3 cells and mouse tumour cell lines have shown that
virtosomes may be acting as inter-cellular messengers. In particular, virtosomes from non-dividing cells blocked
3H-thymidine incorporation into DNA in tumour cell lines.
Objective: Study of the effect of virtosomes on tumors “in vivo” and “in vitro”.
Methods and Results: The present study shows in vitro effects of virtosomes isolated from rat liver, essentially nondividing
cell populations, on cultures of healthy smooth muscle cells (SMC), human umbilical vein endothelial cells
(HUVEC), human fibroblasts (h-fibroblasts) and mouse embryonic fibroblasts (NIH-3T3) together with two tumour
cell lines, human Duke's type B colorectal adenocarcinoma cells (SW480) and human connective tissue fibrosarcoma
cells (HT1080). Multiplication of all cell lines was inhibited by the liver virtosomal preparation even with various
dilutions of the extract (100 - 0.5%). In an in vivo study, tumours were initiated by subcutaneous injection of 1.0 x 106
DHD/K12-PROb cells in 6 weeks old male BIDX rats. Visible tumours (<1cm) appeared after 3 weeks and lung
metastases after 8 weeks (80%). Virtosomes introduced via a tail vein on tumour initiation resulted in a reduction in
tumour size and number.
Conclusion: Virtosomal preparation from a non-dividing cell population inhibited cell division, reduced tumour size
and partially blocked metastasis.