Lipoprotein(a) Impairs Endothelial Progenitor Cells By Down-regulating AKt/eNOS Pathway

Objective: Endothelial progenitor cells (EPCs) have become a crucial emphasisthough repairing vascellum to therapy diseas of ischemia. Our work aimed to studythe impact of Lipoprotein(a)[Lp(a)] on endothelial progenitor cells and determinewhether Lp(a) affects EPCs by an inhibitory effect on survival, immigration and tube-formation capacities, furthermore, we also interpreted that whether Lp(a) had aninhibitory effect on serine/threonine (Akt)/endothelial nitric oxide synthase (eNOS)signal pathway to impair its function, and wether LOX-1had participate in theprocess.Method: The improved Ficoll density gradient centrifugation integrate withdifferential attachment technique can efficiently isolate and culture mouse bonemarrow-derived EPCs, EGM-2cultered cells and inducted differentiation, to chooseisland-like cells colony, EPCs were subjected to flow cytometric analysis to examinethe expression of CD34+/CD133+, CD14+/CD133+EPCs. After amplification culturing,we choose the third generation cells for experiment, and plate the cells in24-wellculture plates with densities of107/ml, and divide into8groups (treated for24h):0μg/ml Lp(a),25μg/ml Lp(a),50μg/ml Lp(a),100μg/ml Lp(a),100μmol/ml L-Arginine (NO precursor)+100μg/ml Lp(a),10μg/ml LOX-1mAb(LOX-1monoclonalantibody)+100μg/ml Lp(a), L-NAME (eNOS inhibitor), Triciribine(Akt blocker). Wetake MTT to analysis the survival rate and activity; The proapoptotic potential of Lp(a)on EPCs was assessed by Hoechst33288staining; The migration of EPCs wasperformed in a Transwell Chamber; An Matrigel was used to determin the Tube-formation, RT-PCR and Westernbloting were applied to examine the mRNA of eNOS and LOX-1and protein of eNOS, LOX-1and p-Akt.Result: Lp(a) dose-dependently inhabits survival, adhere, migration, tube formati-on and NO generation of EPCs, at the same time had the role in proapoptotic potential,however,25μg/ml Lp(a) had not a distinguished effect on biological function(P>0.05,n=3);50μg/ml Lp(a) showed a conspicuous action of inhibition in survival, adhere,migration, tube formation and NO generation (P<0.05, n=3),50μg/ml Lp(a) signific-antly improve EPCs apoptosis, and100μg/ml Lp(a) was most effective(P<0.001, n=3);at this concentration, it depicted a significant decrease in eNOS mRNA and proteinexpression of EPCs after incubation with Lp(a), and as well as the protein of p-Akt,while increase in LOX-1mRNA.100μmol/l L-Arginine and10μg/ml LOX-1mAbcould strikingly rivalry the inhibition effect of Lp(a) on EPCs biological function, andthere were increasing in eNOS mRNA and protein, as well as the protein of p-Akt.L-NAME and Triciribine also could block the fuction of EPCs and accelerate EPCsapoptosis.Conclusions: Lp(a) dose-dependently impairs survival, migration, adhere andtube formation of bone marrow-derived EPCs and inducing apoptosis, and theimpairing fuction of EPCs concerned with Akt/eNOS signal pathway; LOX-1mayparticipate in the impaird process.