Abstract 527: A Novel Stem Cell Delivery Model for Evaluation of Delivery Using Targeted Bifunctional Liposomes with Ultrasound Enhancement
Introduction. We have developed bifunctional echogenic liposomes (BF-ELIP) targeted to both CD34 and ICAM-1 to facilitate delivery of CD34+ stem cells to inflammatory endothelium. We previously confirmed that BF-ELIP enhanced CD34+ stem cell adherence to ICAM-1-expressing endothelium in vitro and in vivo and showed that ultrasound (US) facilitated penetration of stem cells into the endothelial cell layer.
Hypothesis. The transwell culture system can serve as an in vitro model for study of US-enhanced targeted delivery of stem cells to atheroma.
Methods. BF-ELIP were prepared by evaporation-rehydration-sonication-lyophilization, followed by conjugating antibodies specific for CD34 and ICAM-1 through a thioether linkage. TNFα-pretreated HUVEC monolayers on transwell (6 wells/plate) insert membranes were incubated with nonspecific IgG-ELIP or BF-ELIP (1mg/well) for 15 minutes, followed by human monocytes labeled with Oregon Green. Half the inserts were subjected to 6 MHz color Doppler ultrasound (MI = 0.4) for 5 minutes. Fluorescence of resuspended cells was measured after treatment of both inserts and wells with 0.25% trypsin/0.1% EDTA 24 hours later.
Results. BF-ELIP enhanced adherence of monocytes to the ICAM-1-expressing HUVEC monolayer relative to untreated controls and IgG-ELIP, but did not increase the number (Fig. 1) or proportion (Fig. 2) of monocytes traversing the monolayer. US greatly increased the number of monocytes both adhering to and passing through the monolayer in all groups.
Conclusions. We have succeeded in developing a transwell cultured HUVEC system as a model for US-enhanced, BF-ELIP-mediated stem cell delivery to inflammatory endothelium.
- © 2013 by American Heart Association, Inc.