Real Time Cell Analysis of Model Target Cell Lines Exposed to Purified Lipoprotein (a)

Lipoprotein (a) [Lp(a)] is a novel independent cardiovascular risk factor and it includes, beyond apoB100, apolipoprotein (a), whose molecular weight is dependent on the number of genetically encoded kringle IV type 2 repeats and inversely related with Lp(a) plasma concentration. Risk thresholds for molecular weights have been proposed, but there is not a full consensus and the role of the different isoforms in pathogenesis has not yet been clarified. The aim of the present work is to explore the biological effect of low and high molecular weight Lp(a) isoforms on cultured cells. Real-time impedance analysis has been performed on model cell lines of atherogenesis and Lp(a) metabolism (THP-1, HUVEC, HASMC and HepG2) using affinity purified Lp(a) with 22 (low number) and 31 (high number) kringle IV type 2 repeats, respectively. Normalized Cell Index data show that all the cell lines tested are modified by Lp(a), though with a variable intensity. Low and high molecular weight Lp(a) isoforms at similar concentrations can exert opposite modifications onthe impedance kinetics of different cell lines. These data suggest that purified Lp(a) can modify the behaviour of adherent cell lines, an effect which can be detected as impedance variation and which is influenced by its specific isoform.