Blood-brain barrier permeability is not altered by allograft or xenograft fetal neural cell suspension grafts

Abstract

Alterations in blood-brain barrier (BBB) function after brain grafting seem dependent on the donor phenotype and possibly on the grafting technique. Intracerebral block grafts of nonneural tissue permanently disrupt the host BBB, while fetal neural block grafts probably do not. Cell suspensions, an alternative technique in brain grafting, disrupt the extracellular matrix of the graft. Fetal cell suspension allografts appear to form a functional BBB. We confirm and extend this finding to include fetal neural xenografts. Allograft and xenograft fetal neural cell suspensions were intracerebrally injected, and the BBB was examined using intravenous horseradish peroxidase (HRP). Neither graft type showed disruption of the BBB at the graft site from 2 weeks to more than 6 months after grafting. Vascular supply was prominent at all time points. Xenograft survival was improved with cyclosporine, yet cyclosporine did not affect BBB permeability. Cyclosporine did not interfere with repair of the BBB after simple brain trauma was induced by a control injection of saline. We conclude that fetal allograft and xenograft neural cell suspensions rapidly form and maintain a BBB impermeable to intravenous HRP.