Oncological Safety of High Hydrostatic Pressure Treatment: Effects on Cancer-Associated Fibroblast-like Transdifferentiation of Adipose Stromal Cells

Oncological safety is essential for autologous reconstruction after resection of cartilage-infiltrating head and neck tumors. High hydrostatic pressure (HHP) enables complete devitalization of tumor-infiltrated tissue while preserving extracellular matrix integrity. However, residual soluble tumor-derived products may influence infiltrating stromal cells. This study examined whether conditioned media (CM) from HHP-treated head and neck squamous cell carcinoma (HNSCC) cells induce cancer-associated fibroblast (CAF)-like transdifferentiation of human adipose stromal cells (hASCs). HASCs were exposed to CM from untreated or HHP-treated (300 MPa) HNSCC cells, tumor-CM (TCM), or TGF-β1. Morphological changes in hASCs were evaluated, and CAF marker expression was analyzed by qRT-PCR, immunofluorescence, Western blot, and ELISA. Cytokines were quantified via multiplex analysis. TGF-β1 induced a CAF-like phenotype with α-SMA upregulation, whereas TCM and 0 MPa-CM caused only modest increases in selected markers. Although 300 MPa-CM did not induce CAF-associated molecular signatures, hASCs exhibited morphological alterations, underscoring that morphology alone is insufficient to define CAF transdifferentiation. Cytokine secretion was elevated in response to all CM conditions. These findings indicate that HHP treatment at 300 MPa abolishes the paracrine CAF-inducing potential of tumor-derived mediators in vitro, supporting the oncological safety of HHP-treated tissues under these experimental condition, although further in vivo validation is warranted.