title: t-PA, but not desmoteplase, induces plasmin-dependent opening of a blood-brain barrier model under normoxic and ischaemic conditions.
abstract: Tissue-type plasminogen activator (t-PA) is the only thrombolytic treatment available for patients with acute ischaemic stroke. However, t-PA can increase permeability of the blood-brain barrier (BBB). Desmoteplase is a plasminogen activator derived from the common vampire bat, currently under clinical development for ischaemic stroke. We compared how t-PA and desmoteplase influenced BBB permeability using a human in vitro model where primary brain endothelial cells (BEC) and astrocytes are co-cultured on the opposite sides of a porous membrane. Permeability changes were evaluated 6 or 24h post-stimulation by passage of fluorescent albumin across the membrane. Under normoxic conditions, t-PA, but not desmoteplase, increased BBB permeability. Surprisingly, the ability of t-PA to affect the barrier was lost under conditions of oxygen-glucose deprivation (OGD). Addition of plasminogen re-sensitised the BBB to the action of t-PA under both normoxia and OGD, but did not affect the inert behaviour of desmoteplase, even when digested fibrinogen was added to ensure optimal plasmin generation. These observations coincided with plasmin-dependent changes in astrocyte and BEC morphology and disruption of tight junction proteins in BECs, specifically initiated by t-PA but not by desmoteplase. Finally, inhibition of plasmin post-stimulation with t-PA and plasminogen, especially within 2h, protected the BBB against t-PA-mediated barrier opening. Hence t-PA, but not desmoteplase, increases BBB permeability under both normoxic and OGD conditions in a reversible, plasmin-dependent process. The inability of desmoteplase to increase permeability despite its capacity to generate plasmin provides further support for its use as thrombolytic in patients with ischaemic stroke.
authors.affiliation: Australian Centre for Blood Diseases, Monash University, Melbourne, Australia.
authors.forename: Roxann
authors.initials: R
authors.lastname: Freeman
authors.affiliation: Australian Centre for Blood Diseases, Monash University, Melbourne, Australia.
authors.forename: Be'eri
authors.initials: B
authors.lastname: Niego
authors.affiliation: University of Wollongong, New South Wales, Australia.
authors.forename: David R
authors.initials: DR
authors.lastname: Croucher
authors.affiliation: Lundbeck A/S, Copenhagen, Denmark.
authors.forename: Lars O
authors.initials: LO
authors.lastname: Pedersen
authors.affiliation: Australian Centre for Blood Diseases, Monash University, Melbourne, Australia. Electronic address: Robert.medcalf@monash.edu.
authors.forename: Robert L
authors.initials: RL
authors.lastname: Medcalf
mesh_terms: D001812:Blood-Brain Barrier / Q000187:drug effects* / Q000378:metabolism*; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism; D006801:Humans; D010100:Oxygen / Q000378:metabolism; D010539:Permeability; D010958:Plasminogen / Q000494:pharmacology*; D010960:Plasminogen Activators / Q000494:pharmacology*; D010959:Tissue Plasminogen Activator / Q000494:pharmacology*
chemical_list: D005343:Fibrinolytic Agents; C069588:salivary plasminogen activator alpha 1, Desmodus rotundus; D010958:Plasminogen; D010960:Plasminogen Activators; D010959:Tissue Plasminogen Activator; D005947:Glucose; D010100:Oxygen
keywords: Blood-brain barrier; Desmoteplase; ICH; Oxygen-glucose deprivation; Plasmin; Stroke; Tissue-type plasminogen activator