Epicardially Placed Bioengineered Cardiomyocyte Xenograft in Immune-Competent Rat Model of Heart Failure.

BACKGROUND: Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are under preclinical investigation as a cell-based therapy for heart failure post-myocardial infarction. In a previous study, tissue-engineered cardiac grafts were found to improve hosts' cardiac electrical and mechanical functions. However, the durability of effect, immune response, and in vitro properties of the tissue graft remained uncharacterized. This present study is aimed at confirming the graft therapeutic efficacy in an immune-competent chronic heart failure (CHF) model and providing evaluation of the in vitro properties of the tissue graft. METHODS: hiPSC-CMs and human dermal fibroblasts were cultured into a synthetic bioabsorbable scaffold. The engineered grafts underwent epicardial implantation in infarcted immune-competent male Sprague-Dawley rats. Plasma samples were collected throughout the study to quantify antibody titers. At the study endpoint, all cohorts underwent echocardiographic, hemodynamic, electrophysiologic, and histopathologic assessments. RESULTS: The epicardially placed tissue graft therapy improved (p < 0.05) in vivo and ex vivo cardiac function compared to the untreated CHF cohort. Total IgM and IgG increased for both the untreated and graft-treated CHF cohorts. An immune response to the grafts was detected after seven days in graft-treated CHF rats only. In vitro, engineered grafts exhibited responsiveness to beta-adrenergic receptor agonism/antagonism and SERCA inhibition and elicited complex molecular profiles. CONCLUSIONS: This hiPSC-CM-derived cardiac graft improved systolic and diastolic cardiac function in immune-competent CHF rats. The improvements were detectable at seven weeks post-graft implantation despite an antibody response beginning at week one and peaking at week three. This suggests that non-integrating cell-based therapy delivered by a bioengineered tissue graft for ischemic cardiomyopathy is a viable treatment option.

CD4+ T Cell-Specific Proteomic Pathways Identified in Progression of Hypertension Across Postmenopausal Transition.

Background Menopause is associated with an increase in the prevalence and severity of hypertension in women. Although premenopausal females are protected against T cell-dependent immune activation and development of angiotensin II (Ang II) hypertension, this protection is lost in postmenopausal females. Therefore, the current study hypothesized that specific CD4+ T cell pathways are regulated by sex hormones and Ang II to mediate progression from premenopausal protection to postmenopausal hypertension. Methods and Results Menopause was induced in C57BL/6 mice via repeated 4-vinylcyclohexene diepoxide injections, while premenopausal females received sesame oil vehicle. A subset of premenopausal mice and all menopausal mice were infused with Ang II for 14 days (Control, Ang II, Meno/Ang II). Proteomic and phosphoproteomic profiles of CD4+ T cells isolated from spleens were examined. Ang II markedly increased CD4+ T cell protein abundance and phosphorylation associated with DNA and histone methylation in both premenopausal and postmenopausal females. Compared with premenopausal T cells, Ang II infusion in menopausal mice increased T cell phosphorylation of MP2K2, an upstream regulator of ERK, and was associated with upregulated phosphorylation at ERK targeted sites. Additionally, Ang II infusion in menopausal mice decreased T cell phosphorylation of TLN1, a key regulator of IL-2Rα and FOXP3 expression. Conclusions These findings identify novel, distinct T cell pathways that influence T cell-mediated inflammation during postmenopausal hypertension.

Menopause and FOXP3+ Treg cell depletion eliminate female protection against T cell-mediated angiotensin II hypertension.

Although it is known that the prevalence and severity of hypertension increases in women after menopause, the contribution of T cells to this process has not been explored. Although the immune system is both necessary and required for the development of angiotensin II (ANG II) hypertension in men, we have demonstrated that premenopausal women are protected from T cell-mediated hypertension. The goal of the current study was to test the hypotheses that 1) female protection against T cell-mediated ANG II hypertension is eliminated following progression into menopause and 2) T regulatory cells (Tregs) provide premenopausal protection against ANG II-induced hypertension. Menopause was induced in Rag-1-/- mice (via 4-vinylcyclohexene diepoxide), and all mice received a 14-day ANG II infusion. Donor CD3+ T cells were adoptively transferred 3 wk before ANG II infusion. In the absence of T cells, systolic blood pressure responses to ANG II were similar to those seen in premenopausal mice (Δ12 mmHg). After adoptive transfer of T cells, ANG II significantly increased systolic blood pressure in postmenopausal females (Δ28 mmHg). A significant increase in F4/80 positive renal macrophages, an increase in renal inflammatory gene expression, along with a reduction in renal expression of mannose receptor C-type 1, a marker for M2 macrophages, accompanied the increase in systolic blood pressure (SBP). Flow cytometric analysis identified that Tregs were significantly decreased in the spleen and kidneys of Rag-1-/- menopausal mice versus premenopausal females, following ANG II infusion. In a validation study, an anti-CD25 antibody was used to deplete Tregs in premenopausal mice, which induced a significant increase in SBP. These results demonstrate that premenopausal protection against T cell-mediated ANG II hypertension is eliminated once females enter menopause, suggesting that a change in hormonal status upregulates macrophage-induced proinflammatory and T cell-dependent responses. Furthermore, we are the first to report that the presence of Tregs are required to suppress ANG II hypertension in premenopausal females.NEW & NOTEWORTHY Whether progression into menopause eliminated female protection against T cell-mediated hypertension was examined. Menopausal mice without T cells remained protected against angiotensin II (ANG II) hypertension; however, in the presence of T cells, blood pressure responses to ANG II increased significantly in menopause. Underlying mechanisms examined were anti-inflammatory protection provided by T regulatory cells in premenopausal females and renal inflammatory processes involving macrophage infiltration and cytokine activation.