Cold Atmospheric Plasma Selectively Disrupts Breast Cancer Growth in a Bioprinted 3D Tumor Microenvironment Model

Spine metastases are the most common bone site for breast cancer, with evolving surgery and multidisciplinary care improving outcomes. Current treatments, including chemotherapy and invasive surgery, may damage healthy tissue and may leave residual tumors that lead to recurrence. Cold atmospheric plasma (CAP) offers a non-invasive alternative by delivering reactive oxygen and nitrogen species (RONS) locally to tumor sites, selectively targeting cancer cells while sparing healthy tissue. To assess the impact and selectivity toward tumor cells adjacent to bone-like tissue, we develop a 3D bioprinted tumor-stroma model using a 1% alginate and 7% gelatin cell-laden hydrogel to mimic a bone-like microenvironment. The model co-cultures triple-negative MDA-MB-231 human breast cancer cells with primary human bone marrow mesenchymal stromal cells to simulate tumor-stroma interactions. The effects of CAP treatments are assessed through metabolic activity and viability assays over three days. Results show significant selectivity for cancer cells in both 2D and 3D cultures. CAP minimizes damage to healthy cells, offering the potential for localized treatment over systemic chemotherapies such as doxorubicin. Our novel bioprinted model, combined with a plasma source controlling RONS composition, enables detailed studies of redox-based cancer cell inactivation and highlights CAP as a personalized, non-invasive treatment for bone metastases.