Epicardial Placement of Mesenchymal Stromal Cell-sheets for the Treatment of Ischemic Cardiomyopathy; In Vivo Proof-of-concept Study

Abstract

Transplantation of bone marrow mesenchymal stromal cells (MSCs) is an emerging treatment for heart failure. We have reported that epicardial placement of MSC-sheets generated using temperature-responsive dishes markedly increases donor MSC survival and augments therapeutic effects in an acute myocardial infarction (MI) model, compared to intramyocardial (IM) injection. This study aims to expand this knowledge for the treatment of ischemic cardiomyopathy, which is likely to be more difficult to treat due to mature fibrosis and chronically stressed myocardium. Four weeks after MI, rats underwent either epicardial MSC-sheet placement, IM MSC injection, or sham treatment. At day 28 after treatment, the cell-sheet group showed augmented cardiac function improvement, which was associated with over 11-fold increased donor cell survival at both days 3 and 28 compared to IM injection. Moreover, the cell-sheet group showed improved myocardial repair, in conjunction with amplified upregulation of a group of reparative factors. Furthermore, by comparing with our own previous data, this study highlighted similar dynamics and behavior of epicardially placed MSCs in acute and chronic stages after MI, while the acute-phase myocardium may be more responsive to the stimuli from donor MSCs. These proof-of-concept data encourage further development of the MSC-sheet therapy for ischemic cardiomyopathy toward clinical application.

Allogeneic Mesenchymal Stromal Cells Transplanted Onto the Heart Surface Achieve Therapeutic Myocardial Repair Despite Immunologic Responses in Rats

“…To generate an MSC sheet, 4×10 6 bone marrow–derived MSCs from male Lewis (RT1 l ) or male Fischer 344 (RT1 lvl ) rats (150 g; Charles River UK) at passage 3 or 4 were plated onto a 35‐mm temperature‐responsive culture dish (UpCell; CellSeed) 11. After 12‐hour incubation at 37°C, the culture dish was placed at 22°C, and the MSC sheet detached as a free membrane from the dish.…”

“…At the end of 12‐hour culture, the cell numbers included in a cell sheet were unchanged before the culture in both types of MSCs (4.1±0.3×10 6 for Lewis and 4.0±0.4×10 6 for Fischer 344). For histological tracking, MSCs were labeled with CM‐DiI (Life Technologies), as described previously 11. There was no difference in readiness of cell‐sheet production between Lewis and Fischer 344 rats.…”

“…MI was induced in female Lewis rats (150–200 g; Charles River UK) by ligating the left coronary artery under isoflurane anesthesia and mechanical ventilation, as described previously 11, 13. At 4 weeks after MI, rats were subjected to echocardiography, and those showing appropriate cardiac dysfunction (left ventricular [LV] ejection fraction 25–40%) were selected for further studies.…”

“…The selected animals were randomly grouped to receive epicardial placement of MSC sheets composed of 4×10 6 MSCs from syngeneic (Lewis; auto group) or allogeneic (Fischer 344; allo group) male rats. The MSC sheet was placed onto the epicardial surface of the infarcted heart to cover the infarct and border areas 11. For the sham group, sham treatment (open chest only) was performed at 4 weeks after MI induction.…”

“…We recently reported the therapeutic potential of epicardial placement (ie, not injection) of scaffold‐free “MSC sheets,” which were produced using temperature‐responsive polymer‐coated culture dishes in a rat ischemic cardiomyopathy model 11. This cell‐delivery method, compared with intramyocardial injection, achieved markedly increased initial retention and survival of MSCs.…”