Aquaporin 1 and CXCR4 expression in human and sheep mesenchymal stem cells

Mesenchymal stem cells (MSCs) are adult stem cells with a self-renewal and multipotent capability and are expressed extensively in multiple tissues. Their possible use in the treatment of many degenerative diseases such as Alzheimer, multiple sclerosis, diabetes, etc., has increased the research for their biochemical characterization. Further, recent evidences show that bone marrow derived mesenchymal stem cells (BM-MSCs) are recruited into the stroma of developing tumors where they contribute to progression by enhancing tumor growth and metastasis, or by inducing anticancer-drug resistance. In particular, BM-MSCs are able to selectively migrate and home to sites of tissue damage as well as to tumors. Therefore, the aim of this work was to determine whether chemokine receptor type 4 (CXCR4) and water channel molecule, aquaporin 1 (AQP1), known be involved in cell migration, could be expressed in human and sheep BM-MSCs to mediate their behavior in the target tissue microenvironment. We used human and sheep mesenchymal stem cell isolated from bone marrow aspirates by gradient centrifugation and seeded in standard cell culture conditions. Both human and sheep BM-MSCs were tested for CXCR4 and AQP1 expression by western blot and FACS analysis. Furthermore, human hepatocarcinoma (SNU-398) and osteosarcoma (U2OS) cells were used to test the cross-talk between BM-MSCs and tumor cells. BM-MSCs and tumor cells were grown for 48 h in medium without fetal bovine serum to obtain conditioned medium (CM) that was collected, filtered and stored at -20 °C. BM-MSCs and tumor cells were cultured in complete medium and allowed to attach for 24 h. BM-MSCs were exposed to CM obtained by tumor cells whereas SNU-398 and U2OS were exposed to CM obtained by BM-MSCs for 72 h. Morphological changes of cells exposed to CM were observed by light microscope. Then, whole protein extracts were prepared and analyzed for CXCR4 and AQP1 expression. Our results showed that CXCR4 and AQP1 are overexpressed in human and sheep mesenchymal stem cells as well as in human hepatocarcinoma (SNU-398) and osteosarcoma (U2OS) cells. BM-MSCs grown in presence of conditioned medium obtained by tumor cells showed an increase of CXCR4 and AQP1 expression and morphological changes of cells were observed. In conclusion these findings suggest that both mesenchymal stem cells and tumor cells express high level of CXCR4 and AQP1 that play a key role in cell migration. Furthermore, cross-talk between mesenchymal stem cells and tumor cells causes an enhancement of CXCR4 and AQP1 expression in mesenchymal stem cells thus increasing their capacity to migrate.