title: Circulating Stromal Cell-Derived Factor 1α Levels in Heart Failure: A Matter of Proper Sampling.
abstract: BACKGROUND
  The chemokine Stromal cell-derived factor 1α (SDF1α, CXCL12) is currently under investigation as a biomarker for various cardiac diseases. The correct interpretation of SDF1α levels is complicated by the occurrence of truncated forms that possess an altered biological activity.
  
  
  METHODS
  We studied the immunoreactivities of SDF1α forms and evaluated the effect of adding a DPP4 inhibitor in sampling tubes on measured SDF1α levels. Using optimized sampling, we measured DPP4 activity and SDF1α levels in patients with varying degrees of heart failure.
  
  
  RESULTS
  The immunoreactivities of SDF1α and its degradation products were determined with three immunoassays. A one hour incubation of SDF1α with DPP4 at 37°C resulted in 2/3 loss of immunoreactivity in each of the assays. Incubation with serum gave a similar result. Using appropriate sampling, SDF1α levels were found to be significantly higher in those heart failure patients with a severe loss of left ventricular function. DPP4 activity in serum was not altered in the heart failure population. However, the DPP4 activity was found to be significantly decreased in patients with high SDF1α levels.
  
  
  CONCLUSIONS
  We propose that all samples for SDF1α analysis should be collected in the presence of at least a DPP4 inhibitor. In doing so, we found higher SDF1α levels in subgroups of patients with heart failure. Our work supports the need for further research on the clinical relevance of SDF1α levels in cardiac disease.
authors.affiliation: Laboratory of Medical Biochemistry, University of Antwerp, Antwerp, Belgium.
authors.forename: Lesley
authors.initials: L
authors.lastname: Baerts
authors.affiliation: Laboratory of Medical Biochemistry, University of Antwerp, Antwerp, Belgium.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Waumans
authors.affiliation: Laboratory of Clinical Chemistry, OLV Hospital Aalst, Aalst, Belgium.
authors.forename: Inger
authors.initials: I
authors.lastname: Brandt
authors.affiliation: Division of Thoracic Surgery, University Hospital Zurich, Zürich, Switzerland.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Jungraithmayr
authors.affiliation: Laboratory of Medicinal Chemistry, University of Antwerp, Antwerp, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Van der Veken
authors.affiliation: Cardiovascular Center, OLV Hospital Aalst, Aalst, Belgium.
authors.forename: Marc
authors.initials: M
authors.lastname: Vanderheyden
authors.affiliation: Laboratory of Medical Biochemistry, University of Antwerp, Antwerp, Belgium.
authors.forename: Ingrid
authors.initials: I
authors.lastname: De Meester
mesh_terms: D000368:Aged; D001774:Blood Chemical Analysis / Q000379:methods*; D054377:Chemokine CXCL12 / Q000097:blood* / Q000378:metabolism; D018819:Dipeptidyl Peptidase 4 / Q000097:blood; D054873:Dipeptidyl-Peptidase IV Inhibitors / Q000494:pharmacology; D006333:Heart Failure / Q000097:blood* / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D059748:Proteolysis
chemical_list: D054377:Chemokine CXCL12; D054873:Dipeptidyl-Peptidase IV Inhibitors; D018819:Dipeptidyl Peptidase 4