Tumor interstitial fluid pressure may regulate angiogenic factors in osteosarcoma

We have previously shown that osteosarcomas (OS) have states of increased interstitial fluid pressure (IFP), which correlate with increased proliferation and chemosensitivity. In this study, we hypothesized that constitutively raised IFP in OS regulates angiogenesis. Sixteen patients with the clinical diagnosis of OS underwent blood flow and IFP readings by the wick‐in‐needle method at the time and location of open biopsy. Vascularity was determined by capillary density in the biopsy specimens. We performed digital image analysis of immunohistochemical staining for CD31, VEGF‐A, VEGF‐C, and TPA on paraffin‐embedded tissue blocks of the biopsy samples. Clinical results were validated in a pressurized cell culture system. Interstitial fluid pressures in the tumors (mean 33.5 ± SD 17.2 mmHg) were significantly higher (p = 0.00001) than that in normal tissue (2.9 ± 5.7 mmHg). Pressure readings were significantly higher in low vascularity tumors compared to high vascularity tumors (p