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

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).

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.

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).

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.