Spatial relationship between hypoxia and the (perfused) vascular network in a human glioma xenograft: A quantitative multi-parameter analysis

Purpose: To quantitatively study the spatial distribution of tumor hypoxia in relation to the perfused vasculature. Methods and Materials: Using a human glioma xenograft model, nude mice were administered two different hypoxia markers (NITP or pimonidazole) and the perfusion marker Hoechst 33342, Frozen tumor sections were sequentially sca nned for perfusion, hypoxia, and vasculature, respectively, to quantitate p erfusion, vasculature, and hypoxia parameters in the same section. Results: All tumors showed incomplete perfusion. Both NITP and pimonidazole stained the same hypoxic tumor areas. No statistically significant differe nces between the two markers were observed. The density of the perfused ves sels was inversely related to the hypoxic fraction, At critical distances f rom perfused vessels, hypoxia occurred. These data suggest that predominant ly diffusion-limited hypoxia was detected, based on the spatial distributio n of nearby vessels. Also, the proportion of hypoxia distributed over arbit rary zones of 50 mu m around perfused vessels was calculated. The largest p roportion of hypoxia was found at distances beyond 100 mu m from perfused v essels. Conclusion: With the multiple staining and functional microscopic imaging t echnique described here, the spatial relationship between perfused vessels and hypoxia was quantified in whole tumor cross-sections. The usefulness of this histologically-based method to quantitate morphological and physiolog ical aspects of the tumor microenvironment was evaluated. (C) 2000 Elsevier Science Inc.