Magnetically Targeted Endothelial Cell Localization in Stented Vessels
Sorin V. Pislaru, MD, PhD*,
Adriana Harbuzariu, MD*,
Rajiv Gulati, MD, PhD*,
Tyra Witt*,
Nicole P. Sandhu, MD, PhD ,
Robert D. Simari, MD, FACC* and
Gurpreet S. Sandhu, MD, PhD, FACC*,*
* Division of Cardiovascular Diseases
Division of General Internal Medicine, Mayo Clinic College of Medicine, Rochester, Minnesota
View larger version (20K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 1 Escalating superparamagnetic microsphere dose inhibits cell proliferation. Exposure of endothelial outgrowth cell (EOC) to escalating doses of superparamagnetic microsphere (SPM) results in a small but significant decrease in bromo-deoxyuridine (BrdU) incorporation at high, but not at low doses. * p < 0.05 versus no SPM.
|
|
View larger version (139K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2 Apoptosis and secretory profiles are stable with low-dose SPM. (A and B) Terminal deoxynucleotidyl transferase mediated dUTP nick end labeling (TUNEL) assays: composite confocal images. Green fluorescence is given by SPM whereas red fluorescence represents TUNEL-positive apoptotic cells. Exposure to SPM at a 500:1 ratio results in minimal apoptosis (A), whereas significantly increased presence of apoptotic cells is evident at a higher SPM to EOC ratio (B, 4,000:1 ratio). (C and D) Cytokine array studies. EOC secretory profile was very similar for untreated cells (C) and cells exposed to SPM at a 500:1 ratio (D). The top four left dots and bottom two right dots are built-in positive controls of the array. All other dots represent an individual cytokine (72 in total). With these studies, secretion of interleukins (IL)-8 and IL-10; growth factors EGF, HGF, and GDNF; and metalloproteinase inhibitors TIMP-1 and TIMP-2 and MIP-1b were identified. Other abbreviations as in Figure 1.
|
|
View larger version (69K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 3 SPM-labeled EOCs: interactions with magnetic fields. (A and B) Stacked confocal images obtained along the z-axis (100x magnification). EOCs are labeled with CM-DiI (red) and SPM (green). Exposure of SPM-loaded EOCs to a degaussed stainless steel loop does not result in significant cell attraction (A). On the contrary, in the presence of a magnetized stainless steel loop, SPM-loaded cells are rapidly cleared from the suspension and accumulate predominantly on the loop bend (B). A green reflection from the stainless-steel loop is evident. (C and D) Nickel coating of a commercially available stent results in multiple, small, uniformly distributed magnetic domains, as shown in ferrofluid studies (C). Presence of numerous magnetic microdomains is evident (arrows). This translated into a more uniform coverage of the stent surface (D). Endothelial outgrowth cells are labeled with SPM (green). (E and F) Transmission electronic microscopy confirms uniform cytoplasmic capture of SPM microspheres (E). Scanning electron microscopy shows early accumulation of rounded cells to the metal surface (F). (G and H) Representative en face fluorescent microscopy images (200x magnification) from explanted coronary arteries. Local delivery of CM-DiI (red)–labeled EOCs to a non-magnetized stent containing arterial segment results in retention of cells in small numbers (G). Local delivery is greatly enhanced in the segment that received a nickel-coated, magnetized stent before EOC delivery. Note presence of CM-diI–labeled cells along a stent strut (H). Abbreviations as in Figure 1.
|
|
View larger version (39K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 4 Arteries retain more EOCs in the presence of magnetized stents. (A) Cell retention in vivo was significantly higher on magnetized (solid bars) versus non-magnetized control stents (open bars) for both femoral and coronary position. *p < 0.05 for magnetized versus non-magnetized stent. (B) Overlapping, composite, low-power microscopic images of the luminal surface of a porcine coronary artery showing distribution of labeled cells along stent tines and the adjacent denuded endothelium. Abbreviations as in Figure 1.
|
|
|
