Xenogenic Transplantation into Newborn Rodent Brain: Neovascularization of the Graft by the Host

Abstract

Neoangiogenesis of transplants implanted into the brains of newborn rodent hosts was evaluated by immunohistochemistry for 2 weeks after the operation. The use of species-specific antibodies directed against mouse endothelial cells demonstrated the respective participation of the host and the donor in the formation of new vessels in the graft after crossed rabbit into mouse and mouse into rat transplantation experiments. We show that blood vessels made by host endothelial cells begin to penetrate the transplant 24 h after grafting, and cross it completely by 72 h. Simultaneously, host astrocytes invade the transplant.

Long-term delayed vascularization of human neural transplants to the rat brain

“…Reappearance of human endothelial cells in the 2-and 3-month-old grafts strongly suggests that they were substained at an immature stage rather than eliminated. In that sense, our results compare with those obtained by Broadwell et al (1987, 199 1) and Dusart et al (1989), who demonstrated that blood circulation occurs after a delay of more than a week in allo-and xenografts in rodents, even though endothelial cells are present at earlier stages (Lawrence et al, 1984;Krum and Rosenstein, 1988;Krum et al, 199 1;Mrejen et al, 1992). The main difference between the present results and those quoted above is the length of the delay before vascularization, which in the humanto-rat xenografts of this study amounted to more than a month.…”

“…For instance, acidic FGF, which is the principal angiogenic factor in the brain, is highly conserved among vertebrates (Risau et a1.,1988). Otherwise, in other models of xenografts, angiogenesis occurs clearly within 10 d (mouse to rat, Nakano et al, 1989;Mrejen et al, 1992;rabbit to mouse, Mrejen et al, 1992).…”

“…This delayed angiogenesis also implies that host endothelial cells do not form blood vessels rapidly in the graft. Using various markers, a number of researchers have demonstrated that capillary walls in transplants derive from endothelial cells of both donor and host origin (Lindsay and Raisman, 1984;IQ-urn and Rosenstein, 1988;Nakano et al, 1989;Sloan et al, 1990;Mrejen et al, 1992). The fast migration of host cells into rodent transplants is most probably related to the presence of angiogenic factors.…”