Endothelial Cell Recovery Between Comparator Polymer-Based Drug-Eluting Stents
Michael Joner, MD*,
Gaku Nakazawa, MD ,
Aloke V. Finn, MD ,
Shawn Chin Quee, MS ,
Leslie Coleman, DVM,
Eduardo Acampado, DVM,
Patricia S. Wilson, BA,
Kristi Skorija, BS,
Qi Cheng, MD,
Xin Xu, PhD,
Herman K. Gold, MD||,
Frank D. Kolodgie, PhD and
Renu Virmani, MD, FACC,¶,*
* German Heart Center, Munich, Germany
CVPath Institute, Inc., Gaithersburg, Maryland
Cardiology Division, Emory University, Atlanta, Georgia
Abbott Vascular, Santa Clara, California
|| Cardiac Unit, Department of Internal Medicine, Massachusetts General Hospital, Boston, Massachusetts
¶ Jack H. Skirball Center for Cardiovascular Research, Orangeburg, New York.
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Figure 1 Quantitative Analysis of Endothelial Coverage Based on Morphometric Analysis
Bar graphs showing the quantitative analysis of endothelial coverage above (left) and between struts (right) at 14 (A) and 28 days (B). Comparator drug-eluting stents (DES) and bare-metal MULTI-LINK Vision control stents (BMS) based on morphometric analysis of images from scanning electron microscopy (SEM). EES = everolimus-eluting stents; PES = paclitaxel-eluting stents; SES = sirolimus-eluting stents; ZES = zotorolimus-eluting stents.
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Figure 2 Scanning Electron Micrographs of 14-Day Comparator DES and BMS Controls
The upper panels show corresponding radiographic images of each stent. The lumens are clearly patent and struts are easily discerned underneath a thin neointimal surface. Among DES, there is less endothelial cell surface coverage in SES and PES stents compared with ZES and EES. The panel insets are representative images at higher magnification (x200) from proximal and distal regions showing bare struts, surface thrombi, inflammatory cells, and endothelial cells. Abbreviations as in Figure 1.
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Figure 3 Scanning Electron Micrographs of 28-Day Comparator DES and BMS Controls
The upper panels show corresponding radiographic images of each stent. The lumens are patent and struts are less discernable under a thicker neointima relative to 14-day stents. Overall endothelial coverage is near complete in all DES although it remains poor above struts in PES and SES compared with ZES and EES. The panel insets are at higher magnification (x200) from the proximal and distal regions and show persistent uncovered struts, surface thrombi, inflammatory cells, and endothelial cells. Abbreviations as in Figure 1.
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Figure 4 Morphometric Analysis of Uncovered Strut Area (mm2) Among Comparator DES and BMS Control Stents
The summary table (A) shows the total area (mm2) of uncovered struts was significantly greater in SES, PES, and ZES compared to MULTI-LINK Vision, especially at 14 days. Panel B represents a series of line graphs representing the quantitative distribution of uncovered struts at each repeat crowns along the longitudinal axis of the stent from proximal to distal. Uncovered struts were more prevalent in the middle regions of most stents, except for SES at 14 days where uncovered struts were prominent along the entire stent length. Analysis of 28-day stents shows a persistent lack of strut coverage in the midsegment of SES and PES compared with BMS. Abbreviations as in Figure 1.
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Figure 5 Quantitative Analysis of Endothelial Coverage Based on Immunostaining Against PECAM-1
Bar graphs showing the quantitative analysis of endothelial coverage above (left) and between struts (right) at 14 (A) and 28 days (B). Comparator DES and BMS based on immunostaining against platelet-endothelial cell adhesion molecule (PECAM)-1. Abbreviations as in Figure 1.
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Figure 6 Dual Immunofluorescence for PECAM-1 and TM
Dual immunofluorescence for PECAM-1 and thrombomodulin (TM) in whole mount control non-stented (A1 to A3) and stented (B) arterial segments. Panel A1, control shows strong cell-cell border localization of PECAM-1 while panel A2 shows diffuse staining for TM with relatively weak staining at the cell periphery. The merged panel (A3) shows minimal fluorophore overlap (yellow); TOTO-3 (blue) was used as a nuclear counterstain. Panel B represents low (upper row) and higher magnification (bottom row) merged confocal images of 14-day stents dual stained for PECAM-1 (green) and TM (red). The extent of PECAM-1 positive endothelial cells was variable for each stent type, with more uniform expression above struts in EES and BMS. Struts with poor expression for PECAM-1 were more frequent in SES, PES, and ZES. Thrombomodulin expression was weak or absent in all DES, while mild to moderate staining was noted in BMS. Abbreviations as in Figures 1 and 5.
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Figure 7 Measurement of VEGF Production and mRNA Levels by Q-PCR at 14- and 28-Day Stent Implants
(A) Vascular endothelial growth factor (VEGF) secretion from stents (harvested at 14 and 28 days) maintained in organoid culture over 48 h showed a significant increase in SES, PES, and ZES relative to EES and BMS. (B) Concordant quantitative polymerase chain reaction (Q-PCR) analysis of VEGF messenger ribonucleic acid (mRNA) levels matches with DES showing higher released amounts of VEGF at 14 days.
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