Transplanted bone marrow mesenchymal stem cell distribution pattern in the heart: comparison of delivery routes

Objective: To identify differences in bone marrow mesenchymal stem cell (BM‐MSCs) distribution when delivered by transendocardial (TE) or intracoronary (IC) route to a canine acute myocardial ischemia model. Methods: 10 adult dogs (6 TE, 6 IC) received DAPI‐labeled allogenic BM‐MSCs 7 days after a 3‐hour occlusion/reperfusion of the left anterior descending (LAD) and were sacrificed 14 days later. Hearts were excised, perfused and sliced into 4 transverse sections from apex to base. Each slice was separated into 9 segments. Frozen and formalin‐fixed tissue was preserved. Frozen sections were immunostained for α‐smooth muscle actin, α‐sarcomeric actinin, or factor VIII and analyzed by epifluorescence and deconvolution fluorescence microscopy (DFM). Results: At 2 weeks post delivery, the TE group showed characteristic cluster patterns at injection sites, versus a homogeneous distribution in the IC group. The total MSC density at the infarct was 715±426 and 329±56 for the TE and IC groups, respectively. By DVM, most DAPI+ BM‐MSC nuclei were localized to the interstitium, outside of cardiomyocytes. Conclusions: The TE group maintained a higher density of MSC in the infarct at 2 weeks post delivery.