D. M. Irizarry1, J. S. Flacco1, C. P. Blackshear1, C. F. Montenegro1, D. Nguyen1, N. Quarto1, A. Giaccia1, M. T. Longaker1,2, D. C. Wan1 1Stanford University,Plastic And Reconstructive Surgery,Palo Alto, CA, USA 2Institute For Stem Cell Research And Regenerative Medicine,Palo Alto, CA, USA
Introduction: Many oncologic surgeries create significant defects with a need for reconstruction. Further, radiation therapy induces fibrotic damage to skin. Fat grafting has been utilized to address these soft tissue deficiencies, and studies have suggested a regenerative effect on radiation-damaged skin. Inclusion of supplemental mesenchymal cells to fat grafts have also been shown to augment these effects. However, mesenchymal cells have been described in animal models to promote carcinoma growth, and with head and neck cancer, may enhance tumor invasion and formation of micrometastases. As cancer of the oral cavity is among the most common types of head and neck cancer, we chose to evaluate the effects of ASCs on the SAS HNSCC cell line.
Methods: SAS HNSCC cells were plated with either regular or ASC conditioned media. They were lifted and counted every other day for 6 days. For the in-vivo arm, 5X105 GFP labeled SAS HNSCC cells were injected into the subcutaneous plane of the scalp of mice either alone, in addition to a 200uL fat graft, or in addition to a 200uL fat graft and 10,000 ASCs. CT scans were taken weekly for 4 weeks. To examine what factors released by ASCs might be responsible for promoting cancer proliferation, differential protein component analysis was performed on conditioned media from co-cultured ASCs and cancer cells and compared to media from cancer cells alone and ASCs alone.
Results: Cancer cells grown in ASC conditioned media show greater proliferation than those grown in regular media. At the 3 and 4 week timepoints, there was significantly greater tumor volume by microCT in mice receiving cancer with fat graft and ASCs compared to mice receiving cancer alone or in addition to a fat graft. Multiple upregulated factors were identified in the ASC-cancer co-culture medium when compared to cancer alone or ASCs alone, most notably epidermal growth factor was upregulated 1.4-fold, hepatocyte growth factor was upregulated 1.9-fold, and monocyte chemotactic protein was upregulated 5.0-fold. Interestingly, each of these three factors have been implicated in growth and/or metastatic development in head and neck cancer.
Conclusion: While the risk for head and neck cancer recurrence following fat grafting with or without ASC enrichment remains unclear, our preliminary data have shown that ASCs potentially stimulate cancer cell proliferation and tumor formation, and that this may be secondary to one or more likely multiple of the factors we have identified in our component screen. Our ongoing studies are currently testing this hypothesis. Although ASCs and fat grafting may have enormous regenerative potential, the oncologic ramifications of their use must therefore be carefully considered before widespread application.
