Exosomes infl uence the engraftment of tumor cell lines in athymic mice BALB/c nude

The strain of mice with immunodeficit provides a popular experimental model in oncological, immunological, and transplantation studies. Athymic nude mice (Nudes) are usually used to explore the engraftment, growth, invasive infiltration, and potency to develop metastases for different types of cancer, as well as to test in preclinical assessment new anti-tumor medical products. Nude-mutation in Foxni gene results in the congenital thymus dysgenesis, and, as a consequence, in the lack of T-lymphocytes. In its turn, it leads to the suppression of the immune functions which involve T-cells. It is generally accepted that Nudes' immune deficiency provides an opportunity to engraft in them immunologically incompatible human tumors that are xenogeneic for mice.In our study we have shown that there are some types of tumors that cannot be engrafted in BALB/c Nude mice. In particular, we have discovered that tumor cells deficient in p53 gene are not able to grow in Nude mice.Furthermore, we have used in vitro model system to demonstrate that the exosomes released by the fibroblasts of BALB/c Nude mice suppress the growth of the very same tumor cell lines that cannot be engrafted in these mice, but the exosomes do not affect the growth of the tumor cells that can be engrafted successfully. One of the possible mechanisms of tumor growth suppression in BALB/c Nude mice is the transfer of the exosomes containing wild type p53 protein from the surrounding tissues to tumor cells with gene p53 damage.