In vitro polarized macrophages ameliorate adverse cardiac remodeling in a mouse model of transverse aortic constriction.

INTRODUCTION

Heart failure (HF) caused by pressure overload remains as one of the leading causes of morbidity and mortality worldwide, which can manifest itself in a wide range of clinical scenarios. Current therapeutic strategies are limited to lifestyle changes, pharmacological measures, and devices aimed at supporting heart function. This poses a challenge in the search for new strategies for disease management. Macrophages, constituting nearly 10 % of non-myocyte cells in a healthy heart are considered a means to fill this gap due to their pleiotropic phenotype, which extends beyond the well-known functions of phagocytosis and antigen presentation. In this study, we evaluated the efficacy of bone marrow mononuclear cell (BMNC)-derived macrophages (BMNC-Mφ) in treating a mouse model of transverse aortic constriction (TAC).

METHODS

In in vitro experiments, BMNC were polarized into BMNC-Mφ using a previously established protocol. We then performed transcriptomic analysis to confirm BMNC-Mφ marker genes compared to BMNC. BMNC-Mφ phenotypes were further validated by flow cytometry and RT-qPCR. In in vivo experiments, all mice underwent TAC surgery (day 0). On days 7 and 14 post-TAC, mice in the experimental and control groups received intravenous injections of approximately 3 × 106 BMNC-Mφ or PBS, respectively. Heart function was assessed weekly by transthoracic echocardiography at baseline and 7, 14, 21, and 28 days post-TAC. Additionally, we monitored in vivo transcriptome dynamics over time using time-resolved deep RNA sequencing profiles of heart tissues from healthy, 1 day post-TAC, 8 days post-TAC, and 16 days post-TAC mice. Time-course transcriptomic profiling was followed by histological analysis of excised hearts on day 28.

RESULTS

BMNC-Mφ showed phenotype similar to that of resident cardiac macrophages, with increased expression of key anti-inflammatory macrophage markers, including Igf1, Arg1, Retnla, Ang2, Anxa2, and others. In vivo application of BMNC-Mφ further confirmed their potential to mitigate adverse cardiac remodeling in TAC model. Mice receiving BMNC-Mφ better tolerated mechanical stress, as reflected in preserved LV function (LVEF [52.3 % vs. 45.6 %, p = 0.0152], LVFS [22.6 % vs. 19.2 %, p = 0.0208], and LVIDs [2.65 mm vs. 3.2 mm, p = 0.0261]), as well as structure (fibrosis area [5.6 % vs. 10.67 %, p < 0.01]). In addition, BMNC-Mφ promoted angiogenesis (2120.4 ± 25.5 per mm2 vs. 1512.4 ± 34 per mm2, p < 0.05) and controlled cardiomyocyte growth, which was seen in the smaller short-axis diameter of cardiomyocytes in BMNC-Mφ-treated group (17.2 ± 0.18 μm vs. 19.45 ± 0.46 μm, p < 0.05).

CONCLUSION

The main conclusion drawn from our results is that BMNC-Mφ improved or at least preserved LV function and architecture through metabolic recovery, immunosuppression, organized cell cycle/proliferation, and fibrosis modulation.