Multipotent mesenchymal stem/stromal cells (MSCs) have strong tropism towards cancer cells, thus being tested as tools for the targeted delivery of therapeutic substances for the treatment of melanoma. However, different experimental approaches for melanoma induction and MSC treatment can have a direct impact on the outcomes. Systematic search was carried out in three databases (PubMed, Scopus, and Web of Science) to include all studies, where stem cells were used as intervention for animal models for melanoma. Selected articles were classified according to SYRCLE's risk of bias tool for animals' studies. Experimental variables and published data for tumor incidence and growth were extracted from the eligible articles and standardized using Hedge's G for random effects meta-analysis and meta-regression. From 627 entries, 11 articles were eligible for meta-analysis. All studies tested the effects of a single injection of mesenchymal stem/stromal cells (MSCs) (from bone marrow or adipose tissue) admixed with B16 mouse melanoma cells (B16-F0 or B16-F10) or with human melanoma cells (A375 or M4Beu) in mice. Mean SYRCLE score was 3.09 out of 10. Results from random effects meta-analysis indicate that MSCs favored both tumor incidence and tumor growth (p = 0.001) in melanoma. Our results show that MSCs are protumorigenic in co-injection mice models for melanoma, increasing both tumor incidence and growth.
Keywords: Animal model; Cell therapy; Melanoma; Pre-clinical trial.