Bone marrow (BM)-derived precursor cells are thought to be involved in tumor angiogenesis but their precise role in tumor growth remains unknown. In November Nature Medicine, David Lyden and colleagues from Memorial Sloan-Kettering Cancer Center, New York report that tumor angiogenesis is dependent on recruitment of specific hematopoietic and circulating endothelial precursor cells (CEP). Blocking this process can efficiently inhibit tumor growth.

Lyden et al. used angiogenic defective, tumor resistant Id-mutant mice and observed that transplantation of wild-type BM or vascular endothelial growth factor (VEGF)-mobilized stem cells restored tumor angiogenesis and growth. They also explained that the angiogenic defect in Id-mutant mice was due to impaired VEGF-driven mobilization and proliferation of CEPs. In addition they showed that inhibition of both VEGFR1 and VEGFR2 was necessary to completely block tumor growth (Nat Med 2001, 7:1194-1201).

These results suggest new clinical strategies to stop tumor growth. "There are...