title: The isolated human umbilical vein as a bioassay for kinin-generating proteases: An in vitro model for therapeutic angioedema agents.
abstract: OBJECTIVE
  The isolated human umbilical vein is a robust contractile bioassay for ligands of the bradykinin (BK) B2 receptor (B2R), also extendable to B1 receptor (B1R) pharmacology. We hypothesized that, as a freshly isolated vessel, it also contains traces of plasma proteins that may confer responses to exogenous proteases via the formation of kinins.
  
  
  METHODS
  Rings of human umbilical veins were mounted in organ baths containing Krebs buffer maintained at 37°C and purified proteases were introduced in the bathing fluid along with additional drugs/proteins that permit mechanistic analysis of effects.
  
  
  RESULTS
  The previously described contractile response to human recombinant tissue kallikrein (KLK-1, 1-10nM) is not influenced by metabolic inhibitors, suggesting its dependence on a preexisting reservoir of low molecular weight-kininogen (LK). Active plasma kallikrein (apK, ≤5nM) was inactive in fresh tissues, unless high molecular weight-kininogen (HK, 39-197nM) replenishment was applied. The effects of KLK-1 and HK+apK are abolished by pretreating tissues with icatibant, but not with tranexamic acid. C1-esterase inhibitor inhibited only HK+apK. Purified plasmin and neutrophil proteinase-3 produced small contractions in the presence of HK only, and tissue plasminogen activator, none. B1R stimulation was pharmacologically evidenced in response to KLK-1 if LK was supplied.
  
  
  CONCLUSIONS
  The pharmacology of KLK-1 and HK+apK in the human isolated umbilical vein is essentially based on the activity of locally generated kinins and this assay models the inhibitory action of some therapeutic agents active in angioedema states. Proteases that indirectly generate kinins have little activity in the system.
authors.affiliation: Axe Microbiologie-Infectiologie et Immunologie, CHU de Québec, Faculté de Médecine, Université Laval, Québec, QC G1V 4G2, Canada.
authors.forename: Melissa
authors.initials: M
authors.lastname: Jean
authors.affiliation: Tansna Therapeutics, St. Louis, MO 63108, USA.
authors.forename: Arvind
authors.initials: A
authors.lastname: Raghavan
authors.affiliation: Minnetonka, MN, USA.
authors.forename: Matthew L
authors.initials: ML
authors.lastname: Charles
authors.affiliation: Tansna Therapeutics, St. Louis, MO 63108, USA; Kodiak Strategic Consultants, LLC, Minneapolis, MN, USA.
authors.forename: Mark S
authors.initials: MS
authors.lastname: Robbins
authors.affiliation: Axe Microbiologie-Infectiologie et Immunologie, CHU de Québec, Faculté de Médecine, Université Laval, Québec, QC G1V 4G2, Canada.
authors.forename: Eric
authors.initials: E
authors.lastname: Wagner
authors.affiliation: Division of Hematology/Oncology, CHU Sainte-Justine, Montréal, QC, Canada.
authors.forename: Georges-Étienne
authors.initials: GÉ
authors.lastname: Rivard
authors.affiliation: Axe Microbiologie-Infectiologie et Immunologie, CHU de Québec, Faculté de Médecine, Université Laval, Québec, QC G1V 4G2, Canada.
authors.forename: Xavier
authors.initials: X
authors.lastname: Charest-Morin
authors.affiliation: Axe Microbiologie-Infectiologie et Immunologie, CHU de Québec, Faculté de Médecine, Université Laval, Québec, QC G1V 4G2, Canada. Electronic address: francois.marceau@crchul.ulaval.ca.
authors.forename: François
authors.initials: F
authors.lastname: Marceau
mesh_terms: D000799:Angioedema / Q000188:drug therapy*; D001681:Biological Assay; D006801:Humans; D066298:In Vitro Techniques; D007610:Kallikreins / Q000494:pharmacology*; D008954:Models, Biological; D010447:Peptide Hydrolases / Q000378:metabolism*; D043782:Receptor, Bradykinin B2 / Q000187:drug effects; D014471:Umbilical Veins / Q000187:drug effects* / Q000201:enzymology
chemical_list: D043782:Receptor, Bradykinin B2; D010447:Peptide Hydrolases; D007610:Kallikreins
keywords: Bradykinin B(2) receptor; Plasma kallikrein; Plasmin; Tissue kallikrein