Pre-procedural atorvastatin mobilizes endothelial progenitor cells: clues to the salutary effects of statins on healing of stented human arteries

Abstract

Objectives: Recent clinical trials suggest an LDL-independent superiority of intensive statin therapy in reducing target vessel revascularization and peri-procedural myocardial infarctions in patients who undergo percutaneous coronary interventions (PCI). While animal studies demonstrate that statins mobilize endothelial progenitor cells (EPCs) which can enhance arterial repair and attenuate neointimal formation, the precise explanation for the clinical PCI benefits of high dose statin therapy remain elusive. Thus we serially assessed patients undergoing PCI to test the hypothesis that high dose Atorvastatin therapy initiated prior to PCI mobilizes EPCs that may be capable of enhancing arterial repair.

Methods and results: Statin naïve male patients undergoing angiography for stent placement were randomized to standard therapy without Atorvastatin (n = 10) or treatment with Atorvastatin 80 mg (n = 10) beginning three days prior to stent implantation. EPCs were defined by flow cytometry (e.g., surface marker profile of CD45dim/34+/133+/117+). As well, we also enumerated cultured angiogenic cells (CACs) by standard in vitro culture assay. While EPC levels did not fluctuate over time for the patients free of Atorvastatin, there was a 3.5-fold increase in EPC levels with high dose Atorvastatin beginning within 3 days of the first dose (and immediately pre-PCI) which persisted at 4 and 24 hours post-PCI (p<0.05). There was a similar rise in CAC levels as assessed by in vitro culture. CACs cultured in the presence of Atorvastatin failed to show augmented survival or VEGF secretion but displayed a 2-fold increase in adhesion to stent struts (p<0.05).

Conclusions: High dose Atorvastatin therapy pre-PCI improves EPC number and CAC number and function in humans which may in part explain the benefit in clinical outcomes seen in patients undergoing coronary interventions.

Figure 1. Flow cytometric analysis of CD45dimCD34+CD133+CD117+ endothelial progenitor cells (EPC).

(A) Sample gating strategy. (B) EPC levels, expressed at each interval as a ratio to baseline levels (taken three days prior to PCI) for patients receiving and not receiving Atorvastatin therapy (n = 10 per group). * indicates p<0.05.

Figure 2. In vitro assessment of cultured angiogenic cells (CAC).

(A) Comparison of baseline CAC levels in patients with CAD (n = 32) vs. healthy controls (non-CAD). (B) CAC levels expressed at each interval as a ratio to baseline levels (taken three days prior to the procedure) for patients receiving and not receiving Atorvastatin therapy (n = 10 per group). * indicates p<0.05, # indicates p<0.01.

Figure 3. Effect of statin on cultured angiogenic cell (CAC) function in vitro.

(A) Atorvastatin supplementation of the media (0.1 mM). Statin treatment improves CAC attachment to bare metal stent struts in vitro (n = 10). * indicates p<0.01. (B) Representative photos showing DAPI nuclear staining of CAC attachment to stent struts. (C) Atorvastatin supplementation of the media at 0.1 mM does not effect VEGF secretion by EPCs (n = 6, p>0.05). (D) Statin does not ameliorate survival of CACs in culture (n = 6, p>0.05).