Compared to uninjured mice, the concentration of plasma angiopoietin-2 increased significantly within a few hours post-injury (Figure 5A—day “0”), remained significantly elevated in mice that developed progressive IH, but fell progressively in mice injected with cells from CD31-TFPI-Tg, unless the mice were given an anti-TFPI antibody (Figure 5B), in which case plasma levels normalized, in association with development of IH. Here, ANGPT2 is linked to isolated hemihyperplasia.