Effect of intravenous cell therapy in rats with old myocardial infarction

Abstract

Mounting evidence shows that cell therapy provides therapeutic benefits in experimental and clinical settings of chronic heart failure. However, direct cardiac delivery of cells via transendocardial injection is logistically complex, expensive, entails risks, and is not amenable to multiple dosing. Intravenous administration would be a more convenient and clinically applicable route for cell therapy. Thus, we determined whether intravenous infusion of three widely used cell types improves left ventricular (LV) function and structure and compared their efficacy. Rats with a 30-day-old myocardial infarction (MI) received intravenous infusion of vehicle (PBS) or 1 of 3 types of cells: bone marrow mesenchymal stromal cells (MSCs), cardiac mesenchymal cells (CMCs), and c-kit-positive cardiac cells (CPCs), at a dose of 12 × 10⁶ cells. Rats were followed for 35 days after treatment to determine LV functional status by serial echocardiography and hemodynamic studies. Blood samples were collected for Hemavet analysis to determine inflammatory cell profile. LV ejection fraction (EF) dropped ≥ 20 points in all hearts at 30 days after MI and deteriorated further at 35-day follow-up in the vehicle-treated group. In contrast, deterioration of EF was halted in rats that received MSCs and attenuated in those that received CMCs or CPCs. None of the 3 types of cells significantly altered scar size, myocardial content of collagen or CD45-positive cells, or Hemavet profile. This study demonstrates that a single intravenous administration of 3 types of cells in rats with chronic ischemic cardiomyopathy is effective in attenuating the progressive deterioration in LV function. The extent of LV functional improvement was greatest with CPCs, intermediate with CMCs, and least with MSCs.

Keywords: Cell therapy; Fibrosis; Inflammation; Intravenous; Ischemic cardiomyopathy; Myocardial infarction; Repair; Stem cells.

Fig. 1

A Experimental protocol. Echo, echocardiogram; PBS, Dulbecco’s phosphate-buffered saline; MSCs bone marrow-derived mesenchymal stromal cells, CMCs cardiac mesenchymal cells, CPCs c-kit-positive cardiac cells, Pre-Rx pretreatment (30 days after MI)

Fig. 2

Echocardiographic assessment of LV function. Bar graph illustrating LV EF (A), FAC (C), ESV (E), and SV (G) at baseline (BSL), before treatment (Pre-Rx) (i.e., 30 days after MI), and 35 days after the treatment (Post-Rx). △ change (absolute units) in echocardiographic parameters at 35 days after treatment (Post-Rx) vs. pretreatment values (Pre-Rx): EF ejection fraction (B), FAC fractional area change (D), ESV end-systolic volume (F), and SV stroke volume (H). Data are means±SEM

Fig. 3

Hemodynamic assessment of LV function. Hemodynamic studies were performed with a Millar conductance catheter at 35 days after treatment, just before euthanasia. Quantitative analysis of hemodynamic variables: LV end-diastolic pressure (A), stroke volume (B), stroke work (C), dP/dt (D), ejection fraction (E), dP/dt_maxEDV (F), end-systolic elastance (G), and tau_weiss (H). Data are means±SEM

Fig. 4

Morphometric analysis (A) and myocardial collagen content (B). A Quantitative analysis of LV morphometric parameters. The risk region comprises both the border zones and the scarred region. B Quantitative analysis of polarized light microscopic images showing total collagen content as a percent of the risk and noninfarcted regions. Data are means±SEM

Fig. 5

Myocardial content of CD45-positive cells. Quantitative analysis of CD45-positive cells was performed in the risk (border and infarcted region) and noninfarcted regions of the LV sections. Values are mean±SEM

Fig. 6

Hemavet analysis of inflammatory cells in the blood. Shown are WBCs, neutrophils (Ne), lymphocytes (Ly), the Ne/Ly ratio, and the platelet/Ly ratio at baseline (before cell infusion [0 day]), and 48 h (2 days) and 35 days (35 days) after intravenous infusion of vehicle (solid circles, n = 7), MSCs (solid squares, n = 11), CMCs (solid upward triangles, n = 5), or CPCs (solid inverted triangles, n = 7). Dots represent individual animals and bars represent means