XFM-guided delivery of imaging-visible human mesenchymal stem cells into the pericardial space in a porcine model
Journal of Cardiovascular Magnetic Resonance volume 14, Article number: P63 (2012)
Transmyocardial delivery of stem cells in the setting of acute myocardial ischemia has shown promise to prevent adverse ventricular remodeling1. However, the efficacy is limited by poor cell retention and low survival rates, even for autologous cells. Intrapericardial delivery of microencapsulated stem cells may offer a local and minimally invasive route to enhance cell survival and retention. In this study, we assess the delivery of human mesenchymal stem cells (hMSCs) in a radiopaque microcapsule to the pericardium using x-ray fused with magnetic resonance imaging (XFM) in a porcine model.
Stem cell microencapsulation was performed using a modification of the alginate microencapsulation method by the addition of 10% (w/v) BaSO4 (BaCaps, Fig.1A)2. Female Yorkshire pigs (~25 kg, n=7) were randomized to receive either empty BaCaps (~10 ml), naked hMSCs (1x108), saline, or BaCaps with hMSCs (8x107) using a percutaneous approach. Prior to delivery, cine breath-held short-axis images were acquired to determine ventricular function (Argus, Siemens). A navigator-gated 3D whole heart MRI (1.5T Espree, Siemens SSFP, TR/TE=290/1.67 ms, FOV=320x240 mm, image matrix=256x173, iPAT=2, slice=64, slice thickness=2 mm) was also obtained to define ventricular borders for intrapericardial injection. A cardiac-gated c-arm CT (dynaCT, Axiom Artis dFA, Siemens, 190° rotation; 0.5° angle; 20s acquisition; 48 cm FOV) was then obtained and fused with the whole heart MRI and overlaid on live fluoroscopy to guide percutaneous access to the pericardial space. For chronic studies, MRI and c-arm CT imaging were repeated one week after injection. Animals were sacrificed immediately or one week post-delivery for histological analysis.
The viability of Ba-encapsulated hMSCs was 94.8±6% two days after encapsulation (Fig.1B). Using XFM (Fig.1C), successful puncture and delivery of BaCaps or Ba-encapsulated hMSCs was achieved in all animals. BaCaps were detected on fluoroscopic and c-arm CT images immediately and one week after delivery (Fig.1D). Whereas BaCaps were free floating immediately after delivery, at one week the BaCaps had consolidated as a pseudo epicardial tissue patch. Cardiac function was maintained 1 week post-delivery (LVEF: 36.8±4% at baseline vs. 41.5±5% at 1 week, n=5). Pericardial adhesions and effusion were absent at one week.
XFM-guided intrapericardial injection of Ba-encapsulated hMSCs was safe and reliable. This approach holds promise for safe delivery of allogeneic cellular therapeutics to the heart in patients without pericardial effusion.
Funding was provided by grants: R21/R33-HL89029, MD-SCRFII-0399 and Siemens healthcare.
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Fu, Y., Azene, N., Ehtiati, T. et al. XFM-guided delivery of imaging-visible human mesenchymal stem cells into the pericardial space in a porcine model. J Cardiovasc Magn Reson 14 (Suppl 1), P63 (2012). https://doi.org/10.1186/1532-429X-14-S1-P63