Differential effects of recombinant human endostatin treatment on differentiated and undifferentiated blood vessels in Lewis lung cancer.

In the present study, we evaluated the effects of recombinant human (rh-)endostatin treatment on differentiated and undifferentiated tumor vasculature in Lewis lung cancer for the first time. Lewis lung carcinoma models were established. The animals were treated daily with varying doses of rh-endostatin or physiological saline for 14 days. Intravital microscopy was performed following treatment. The expression of CD31 and CD34 was determined by immunohistochemical staining, and microvessel density (MVD) was determined. Rh-endostatin treatment significantly decreased the tumor volume compared with the control group. Rh-endostatin treatment normalized the architecture of the vascular network. CD31(+) cells decreased following rh-endostatin treatment, whereas CD34(+) cells were unaffected by the treatment. Accordingly, the MVD value of CD31(+) cells in rh-endostatin treatment groups significantly decreased (P<0.01), and the MVD value of CD34(+) cells in the rh-endostatin treatment groups did not decrease. Undifferentiated tumor blood vessels were significantly inhibited by rh-endostatin treatment. In conclusion, the normalization of the tumor vasculature by endostatin may be related to the differential effects of endostatin on differentiated and undifferentiated blood vessels.