In utero transplantation of wild-type fetal liver cells rescues factor X-deficient mice from fatal neonatal bleeding diatheses.

Factor X (FX)-deficient embryos suffer partial embryonic lethality with approximately 30% of the embryos arresting at midgestation. The remaining animals survive to term but die perinatally mainly from abdominal or intracranial hemorrhage. We have rescued FX-deficient mice by transplanting fetal liver cells from FX+/+, Rosa26 fetuses into midgestation embryos derived from FX+/- heterozygous crosses. FX-/- embryos were born at the expected frequency and approximately 50% of the FX-/- neonates survived longer than 4 months. FX-/- embryos receiving saline injections that survived to term died perinatally similar to untreated FX-deficient mice. The plasma levels of FX in the rescued 16-week-old FX-/- mice were approximately 1-6% of wild-type levels. beta-Galactosidase-staining cells derived from the donor Rosa26 fetal liver cells were detected in 47% of the livers of adult mice. In addition, donor-derived cells were also recovered in the bone marrow, spleen, lung, and occasionally in the brain and testis. These results suggest that in utero cell transplantation could be an effective therapeutic strategy to treat pathologies resulting from the deficiency of hepatic-expressed factors.

Laser-induced noninvasive vascular injury models in mice generate platelet- and coagulation-dependent thrombi.

A minimally invasive laser-induced injury model is described to study thrombus development in mice in vivo. The protocol involves focusing the beam of an argon-ion laser through a compound microscope on the vasculature of a mouse ear that is sufficiently thin such that blood flow can be visualized by intravital microscopy. Two distinct injury models have been established. The first involves direct laser illumination with a short, high-intensity pulse. In this case, thrombus formation is inhibited by the GPIIb/IIIa antagonist, G4120. However, the anticoagulants, hirulog, PPACK, and NapC2 have minimal effect. This indicates that thrombus development induced by this model mainly involves platelet interactions. The second model involves low-intensity laser illumination of mice injected with Rose Bengal dye to induce photochemical injury in the region of laser illumination. Thrombi generated by this latter procedure have a slower development and are inhibited by both anticoagulant and anti-platelet compounds.