Lack of cardiac nerve sprouting after intramyocardial transplantation of bone marrow-derived stem cells in a swine model of chronic ischemic myocardium

Potent immunomodulation and angiogenic effects of mesenchymal stem cells versus cardiomyocytes derived from pluripotent stem cells for treatment of heart failure

BACKGROUND

Optimal cell type as cell-based therapies for heart failure (HF) remains unclear. We sought to compare the safety and efficacy of direct intramyocardial transplantation of human embryonic stem cell-derived cardiomyocytes (hESC-CMs) and human induced pluripotent stem cell-derived mesenchymal stem cells (hiPSC-MSCs) in a porcine model of HF.

METHODS

Eight weeks after induction of HF with myocardial infarction (MI) and rapid pacing, animals with impaired left ventricular ejection fraction (LVEF) were randomly assigned to receive direct intramyocardial injection of saline (MI group), 2 × 10⁸ hESC-CMs (hESC-CM group), or 2 × 10⁸ hiPSC-MSCs (hiPSC-MSC group). The hearts were harvested for immunohistochemical evaluation after serial echocardiography and hemodynamic evaluation and ventricular tachyarrhythmia (VT) induction by in vivo programmed electrical stimulation.

RESULTS

At 8 weeks post-transplantation, LVEF, left ventricular maximal positive pressure derivative, and end systolic pressure-volume relationship were significantly higher in the hiPSC-MSC group but not in the hESC-CM group compared with the MI group. The incidence of early spontaneous ventricular tachyarrhythmia (VT) episodes was higher in the hESC-CM group but the incidence of inducible VT was similar among the different groups. Histological examination showed no tumor formation but hiPSC-MSCs exhibited a stronger survival capacity by activating regulatory T cells and reducing the inflammatory cells. In vitro study showed that hiPSC-MSCs were insensitive to pro-inflammatory interferon-gamma-induced human leukocyte antigen class II expression compared with hESC-CMs. Moreover, hiPSC-MSCs also significantly enhanced angiogenesis compared with other groups via increasing expression of distinct angiogenic factors.

CONCLUSIONS

Our results demonstrate that transplantation of hiPSC-MSCs is safe and does not increase proarrhythmia or tumor formation and superior to hESC-CMs for the improvement of cardiac function in HF. This is due to their immunomodulation that improves in vivo survival and enhanced angiogenesis via paracrine effects.

Remodelling of cardiac sympathetic re-innervation with thoracic spinal cord stimulation improves left ventricular function in a porcine model of heart failure

AIMS

Thoracic spinal cord stimulation (SCS) has been shown to improve left ventricular ejection fraction (LVEF) in heart failure (HF). Nevertheless, the optimal duration (intermittent vs. continuous) of stimulation and the mechanisms of action remain unclear.

METHODS AND RESULTS

We performed chronic thoracic SCS at the level of T1-T3 (50 Hz, pulse width 0.2 ms) in 30 adult pigs with HF induced by myocardial infarction and rapid ventricular pacing for 4 weeks. All the animals were treated with daily oral metoprolol succinate (25 mg) plus ramipril (2.5 mg), and randomized to a control group (n = 10), intermittent SCS (4 h ×3, n = 10) or continuous SCS (24 h, n = 10) for 10 weeks. Serial measurements of LVEF and +dP/dt and serum levels of norepinephrine and B-type natriuretic peptide (BNP) were measured. After sacrifice, immunohistological studies of myocardial sympathetic and parasympathetic nerve sprouting and innervation were performed. Echocardiogram revealed a significant increase in LVEF and +dP/dt at 10 weeks in both the intermittent and continuous SCS group compared with controls (P < 0.05). In both SCS groups, there was diffuse sympathetic nerve sprouting over the infarct, peri-infarct, and normal regions compared with only the peri-infarct and infarct regions in the control group. In addition, sympathetic innervation at the peri-infarct and infarct regions was increased following SCS, but decreased in the control group. Myocardium norepinephrine spillover and serum BNP at 10 weeks was significantly decreased only in the continuous SCS group (P < 0.05).

CONCLUSIONS

In a porcine model of HF, SCS induces significant remodelling of cardiac sympathetic innervation over the peri-infarct and infarct regions and is associated with improved LV function and reduced myocardial norepinephrine spillover.

Update on therapeutic mechanism for bone marrow stromal cells in ischemic stroke

Cerebral ischemia is a major cause of morbidity and mortality in the aged population, as well as a tremendous burden on the healthcare system. Despite timely treatment with thrombolysis and percutaneous intravascular interventions, many patients are often left with irreversible neurological deficits. Bone marrow stromal cells (BMSCs), also referred to as mesenchymal stem cells (MSCs), are a type of nonhematopoietic stem cells which exists in bone marrow mesh, with the potential to self-renew. Unlike cells in the central nervous system, BMSCs differentiate not only into mesodermal cells, but also endodermal and ectodermal cells. Moreover, it has been reported that BMSCs develop into cells with neural and vascular markers and play a role in recovery from ischemic stroke. These findings have fuelled excitement in regenerative medicine for neurological diseases, especially for ischemic stroke. There is now preclinical evidence to suggest that BMSCs grafted into the brain of ischemic models abrogate neurological deficits. Based on the overwhelming evidence from animal studies as well as in clinical trials, BMSC transplantation is considered a promising strategy for treatment of ischemic stroke. The goal of this review is to present an integrated consideration of molecular mechanisms in a chronological fashion and discuss an optimal BMSC delivery route for ischemic stroke.