c-Kit-Positive Adipose Tissue-Derived Mesenchymal Stem Cells Promote the Growth and Angiogenesis of Breast Cancer.

Background. Adipose tissue-derived mesenchymal stem cells (ASCs) improve the regenerative ability and retention of fat grafts for breast reconstruction in cancer patients following mastectomy. However, ASCs have also been shown to promote breast cancer cell growth and metastasis. For the safety of ASC application, we aimed to identify specific markers for the subpopulation of ASCs that enhance the growth of breast cancer. Methods. ASCs and bone marrow-derived vascular endothelial progenitor cells (EPCs) were isolated from Balb/c mice. c-Kit-positive (c-Kit(+)) or c-Kit-negative (c-Kit(-)) ASCs were cocultured with 4T1 breast cancer cells. Orthotropic murine models of 4T1, EPCs + 4T1, and c-Kit(+/) ASCs + 4T1/EPCs were established in Balb/c mice. Results. In coculture, c-Kit(+) ASCs enhanced the viability and proliferation of 4T1 cells and stimulated c-Kit expression and interleukin-3 (IL-3) release. In mouse models, c-Kit(+) ASCs + 4T1/EPCs coinjection increased the tumor volume and vessel formation. Moreover, IL-3, stromal cell-derived factor-1, and vascular endothelial growth factor A in the c-Kit(+) ASCs + 4T1/EPCs coinjection group were higher than those in the 4T1, EPCs + 4T1, and c-Kit(+) ASCs + 4T1/EPCs groups. Conclusions. c-Kit(+) ASCs may promote breast cancer growth and angiogenesis by a synergistic effect of c-Kit and IL-3. Our findings suggest that c-Kit(+) subpopulations of ASCs should be eliminated in fat grafts for breast reconstruction of cancer patients following mastectomy.