Single-cell transcriptomics reveals an angiogenic cell population for therapeutic angiogenesis in adipose tissue

Background

Therapeutic angiogenesis mediated by stem/progenitor cells is an attractive therapeutic option against cardiovascular disease (CVD). Adipose tissue (AT) can be safely obtained even in CVD patients with anti-platelet medications, and it is a readily available source of culture-expanded adipose-derived stem cells (ADSCs) for transplantation. Single-cell transcriptome enables us to screen all the surface markers at once, while conventional strategies have been limited for the number of target markers. Furthermore, gene profiling at single-cell resolution can be used for the quantification of each marker by how many favorable cells can be purified without mixing of detrimental cells.

Purpose

We aimed to identify and characterize a cell population with in vivo angiogenic potential by single-cell RNA sequencing (scRNA-seq) analysis and xenograft experiments.

Methods

We revisited scRNA-seq datasets of single cell fraction from AT, bone-marrow (BM), and umbilical-cord blood (UCB, n=6/organ) to find cell populations with pro-angiogenic potential. Next, we collected AT from CVD patients (n=23) and used multicolor flow cytometry to quantify and sort the specific populations. PBS, the specific marker-negative and unsorted ADSCs were used as controls. Xenograft models of PKH26 pre-labeled human ADSC transplantation in limb ischemia were used to evaluate the lectin capillary density, PKH+ engrafted ADSCs, and blood flow recovery.

Results

Clustering divided CD45–CD31–CD34+ progenitor fraction into 3 clusters. We identified pro-/anti-angiogenic clusters based on the expressions of well-known pro-/anti-angiogenic factors. All genes encoding cell-surface proteins were compared in this functional clustering, resulted in 17 markers screened (Fig. 1A, B). Taken together with enrichment analysis, CD271+ cells showed predominant and pro-angiogenic gene profile from the other top candidates including CD36 and CD54 (Fig. 1C, D). Next, we evaluated the number and gene profile of CD271+ cells in well-known stem cell sources including BM and UCB. Surprisingly, the number of CD271 expressing cells were significantly lower and did not show angiogenic gene profile in BM and UCB (Fig. 2A). In analysis of AT from 23 CVD patients, CD271+ cells were significantly decreased by donor insulin resistance (Fig. 2B). Cell therapy using CD271+ ADSCs demonstrated in vivo angiogenic capacity compared to those of CD271– ADSCs and PBS in limb ischemia model. Furthermore, CD271+ ADSC transplantation showed enhanced efficacy compared to unsorted ADSCs from the same donors (Fig. 2C–E).

Conclusion

In this study, we identified CD271+ cell population in AT as an angiogenic cell population through scRNA-seq analysis and cell therapy experiments. AT obtained from donors without insulin resistance would be the most suitable for CD271+ ADSC isolation. CD271+ ADSC transplantation with a promising angiogenic capacity could contribute better cell-based therapy tackling CVD.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Japan Society for the Promotion of Science (JSPS) KAKENHI (Tokyo, Japan)

Progression of liver fibrosis in pulmonary arterial hypertension

Background

Pulmonary arterial hypertension (PAH) causes congestive liver due to right heart failure. There are few cases of PAH that lead to liver cirrhosis, and little attention is paid to liver function in PAH patients. However, it is certain that long-term congestion due to right heart failure in PAH causes a gradual exacerbation of liver dysfunction and affects metabolic function.

Purpose

The purpose of this study is to investigate liver fibrosis associated with the severity and prognosis of PAH.

Methods

This retrospective observational study was included 57 PAH patients and 22 control subjects. PAH patients were assigned to three risk variables according to the simplified risk stratification proposed at the 6thWSPH 2018 after measuring hemodynamic parameters using right heart catheterization, WHO functional class, 6- minutes walking distance (6MWD), and BNP plasma levels. The Fibrosis-4 (FIB4)-index, a liver fibrosis marker, was calculated using the formula: FIB-4 = Age (years) × AST (U/L) / [PLT (109/L) × ALT1/2 (U/L)], and assessed for association with severity of PAH. PAH patients were followed up for 12 years to assess the occurrence of major adverse event, such as death or lung transplantation.

Next, adult 8-week-old C57BL/6 mice were exposed to chronic hypoxia (10% O2) or normoxia for 6 weeks. Then, mice were anesthetized and performed right heart catheterization. Liver tissue was collected for histological assessment by Hematoxylin and eosin and Azan staining, and evaluated RNA expression involved in liver fibrosis by real-time PCR.

Results

The levels of FIB4-index in intermediate and high risk groups of PAH patients had significantly increased compared to those in control group. In PAH patients, FIB4-index was not obviously correlated with hemodynamic parameters, BNP, or 6MWD. Major adverse events occurred in 18 PAH patients (32%): death in 18 (100%) and lung transplant in none (0%). Kaplan-Meier curves for PAH patients with and without major adverse events were constructed based on a cut-off frequency of 2.001 for FIB4-index. During the 12-years follow-up period, major-event-free survival was significantly better in PAH patients with FIB4-index <2.001 than in patients with FIB4-index >2.001 (hazard ratio, 3.3; P=0.038).

In a PAH model mice, hemodynamic parameters showed that chronic hypoxia significantly increased the right ventricular systolic pressure. In histological analysis, there was no significantly difference in liver fibrosis in hypoxia or normoxia group. However, the RNA expression such as αSMA and TGFβ1 associated with liver fibrosis in PAH model mice was increased compared to control mice.

Conclusion

This study showed that the liver fibrosis gradually progressed subsurfacely with severity of PAH. Even the slight liver dysfunction may affect metabolism and cause exacerbation of PAH, so it might be necessary to pay attention to liver fibrosis as one of the risk factors of PAH.

Funding Acknowledgement

Type of funding sources: None.

Nerve growth factor receptor is involved in maintaining homeostasis of pulmonary arterial hypertension

Introduction

Pulmonary arterial hypertension (PAH), characterized by vascular remodeling, is still disease with poor prognosis although many pulmonary vasodilators have been developed, and new mechanism of treatment for PAH is desired. Nerve growth factor receptor (Ngfr) is known to relate to inflammatory reaction and repair process in the damaged tissue. We have reported that Ngfr is associated to vascular remodeling in patients with acute coronary syndrome. However, it is unclear how Ngfr is involved in the pathogenesis of PAH.

Purpose

In this study, we investigated whether Ngfr relate to pathophysiology in PAH.

Methods

We estimated the frequency of Ngfr positive cells (% Ngfr+) in peripheral blood mononuclear cells obtained from PAH and non-PAH patients using flowcytometric analysis. In PAH patients, the hemodynamic parameters such as mean pulmonary arterial pressure (mPAP), pulmonary vascular resistance (PVR), and cardiac index (CI) were obtained by right heart catheterization, and evaluated for correlation with the % Ngfr+.

Next, adult 8-week-old C57BL/6 (WT) mice and Ngfr knock out (KO) mice were exposed to chronic hypoxia (10% O2) or normoxia for 6 weeks. Then, mice were anesthetized and performed echocardiography and right heart catheterization. Then, mice were exsanguinated and blood sample was collected to evaluate the % Ngfr+ by flow cytometry. Right ventricular weight was measured and lung tissue was also collected for histological assessment and molecular pathway profiling.

Results

PAH (n=24) patients and non-PAH patients (n=17) were enrolled. The % Ngfr+ was significantly higher in PAH patients than that in non-PAH patients (0.056% versus 0.019%, p<0.0001). In PAH patients, the % Ngfr+ was correlated with severity of hemodynamic parameters such as mPAP (R=0.64 p<0.001), PVR (R=0.62 p<0.005), and CI (R=−0.48 p<0.05).

In WT mice, chronic hypoxia significantly increased the right ventricular systolic pressure and induced vascular medial thickness and fibrosis around the pulmonary artery. Flow cytometry analysis revealed that the % Ngfr+ was significantly increased in the hypoxia compared to that in the normoxia. Under hypoxic conditions, the right ventricular systolic pressure was significantly increased in Ngfr KO mice compared to that in WT mice. In histological analysis, hypoxia-induced peripheral vascular fibrosis and medial thickness was more severe in Ngfr KO than that in WT mice.

Conclusion

Circulating Ngfr-positive cells are associated with severity of PAH in patients. In the hypoxia-induced PH model, gene deletion of Ngfr shows the progression of the pathogenesis of PAH. These results suggest that circulating Ngfr-positive cells have an important role in the pathogenesis of PAH and may be a novel target for PAH therapy.

Funding Acknowledgement

Type of funding source: None

Bone marrow-derived NGFR+ cells regulate arterial remodeling and those poor mobilizations in peripheral blood in acute coronary syndrome predicts plaque progression at the non-targeted lesion

Background

In our previous 5-year cohort study, we demonstrated that low gene expression of nerve growth factor receptor (NGFR) in peripheral leucocytes in acute coronary syndrome (ACS) predicted repetitive coronary interventions at the de novo lesions. An NGFR-positive cell has been demonstrated to reside in bone marrow (BM) stromal fraction and to be increased in peripheral blood mononuclear cell (MNCs) fraction in patients with ischemic heart disease.

Purpose

To investigate whether the BM-NGFR+ cell is associated with arterial remodeling and the relationship between the levels of peripheral NGFR+ cells after ACS and coronary plaque progression in an experimental and prospective clinical study.

Methods and results

In an experimental study, 8-week-old C57B6/J wild type male mice were subjected to irradiation with 9.6 Gy and transplantation with BM (BMT) isolated from GFP-transgenic NGFR wild type (WT) or knock-out (KO) mice at day 1. Four weeks after BMT, the right carotid artery was ligated for 4 weeks. Induced neointimal area was increased (p<0.05), where cells under apoptosis were decreased (p<0.05) in NGFR-KO-BMT group compared to WT-BMT group (n=4). NGFR+ cells were not detected in wild type sham-operated artery, whereas in the ligated artery in WT-BMT group NGFR+ cells assembled in the developed neointima and exclusively presented double positive with GFP, but absent in NGFR-KO-BMT group (p<0.05, n=4). In a clinical study, thirty patients with ACS who underwent primary percutaneous coronary intervention (PCI) were enrolled. The peripheral blood sample was collected on days 0, 3 and 7, and 9 months follow-up and the number of NGFR+MNCs were measured by flowcytometric analysis. The plaque volume at non-targeted coronary lesion (non-TL:>5 mm proximal or distal to the implanted stents) were quantitatively analysed using gray-scale intravascular ultrasound (IVUS) and Q-IVUS™ software at the acute phase and 9 months follow-up. The number of NGFR+MNCs in peripheral blood was 1.5-fold increased at day 3 (0.064±0.056%) compared to day 0 (0.042±0.030%) (p<0.05). The change in normalized total plaque volume (TAVN) at non-TL at 9 months was negatively correlated with the number of NGFR+MNCs at day 0 (r=−0.51), day 3 (r=−0.51) and 9 months (r=−0.59) after ACS (p<0.05). Multiple regression analysis showed that NGFR+MNCs at day 0 (β=−0.48, p=0.01) and CRP (β=−0.53, P<0.01) are independent factors associating with TAVN change at non-TL at 9 months, regardless of LDL-cholesterol control level. ROC analysis revealed that NGFR+MNCs <0.049 at day 0 predicted the increase of TAVN with AUC 0.78; sensitivity 0.82 and specificity 0.67.

Conclusions

Bone marrow-derived peripheral NGFR+ cells negatively regulate arterial remodeling through appropriate apoptosis of neointimal cells and the peripheral level of NGFR+ cells in ACS predicts plaque progression at the non-targeted lesion.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): KAKENHI

P3495Long-term engraftment of human CD271-positive adipose-derived stem cells with pericytic and less-aged gene profile in a mouse model of hindlimb ischemia

Background

Therapeutic angiogenesis using adipose-derived stem cells (ADSCs) is an attractive strategy for ischemic cardiovascular diseases. We previously reported that human CD271+ population of adipose-derived stem cells (ADSCs) promoted neovascularization with enhanced engraftment in a mouse model of hindlimb ischemia. However, whether and how CD271+ ADSCs promote the long-term engraftment is still uncertain.

Purpose

We aimed to examine whether the angiogenic effect and cell engraftment capacity of CD271+ ADSCs would be sustained in long-term period. Then, comparative gene profiling between CD271+ and CD271- ADSCs were analyzed. Finally, cell proliferation and endothelial differentiation assays were conducted.

Methods

ADSCs were isolated from subcutaneous adipose tissue of 5 patients received cardiovascular surgery. CD271+ and CD271- ADSCs were sorted from CD45-CD31-CD34+ ADSCs fraction by FACS sorting (Fig. A). Cultured CD271+ and CD271- ADSCs at passage 6 were labeled by PKH26 cell linker dye and used for xenograft experiments. Briefly, athymic nude mice were subjected to hindlimb ischemia and one million of human ADSCs were injected into the ischemic muscles. In control group, PBS was solely injected. At 2 and 5 weeks, neovascularization was evaluated by immunohistochemistry (capillary density using lectin perfusion). Cell engraftment was assessed by counting PKH26-positive cells. Furthermore, we compared gene profiling between CD271+ and CD271- ADSCs by microarray. Proliferative capacity was evaluated by colony-forming unit (CFU) assay with Giemsa staining. In endothelial differentiation assay, CD271+ and CD271- ADSCs were cultured in differentiation induction medium containing vascular endothelial growth factor for 2 weeks and stained with anti-human CD31 antibody.

Results

Cell therapy using CD271+ ADSCs demonstrated approximately 3-fold more enhanced neovascularization than those using CD271- ADSCs or PBS in histological analysis of capillary density at 2 weeks from cell therapy (Fig. B and C). At 5 weeks, mice treated with CD271+ ADSCs were significantly rescued from limb ischemia and this was accompanied by sustained engraftment of ADSCs (Fig. D). In microarray analysis, the differentially expressed 2167 genes were extracted to classify CD271+ and CD271- ADSCs. Pathway analysis demonstrated CD271 expression on ADSCs was associated with the pathways related to stemness and cell differentiation. Indeed, we found that genes related to cell proliferation (PI3K, Cyclin D, and Cyclin D2) were up-regulated in CD271+ ADSCs. Additionally, we found the pericytic marker nestin which was significantly up-regulated in CD271+ ADSCs. Consistent with these findings, CD271+ ADSCs were more proliferative and capable for endothelial differentiation while CD271- ADSCs were not.

FACS and cell therapy experiments

Conclusion

These results suggest that CD271+ ADSCs possess long-term engraftment and angiogenic capacity due to their less-aged and more pericytic gene profile.

Acknowledgement/Funding

Japan Society for the Promotion of Science (JSPS) KAKENHI (Tokyo, Japan) Grant Number JP16H06828

P2590A liver-derived secretory protein, selenoprotein P causes pressure overload-induced cardiac hypertrophys

Background

Hepatokine selenoprotein P (SeP) contributes to insulin resistance and hyperglycemia in patients with type 2 diabetes. Inhibition of SeP protects the heart from ischemia reperfusion injury and serum levels of SeP are elevated in patients with heart failure with reduced ejection fraction.

Objective

We investigated the role of SeP in the regulation of cardiac remodeling in response to pressure overload.

Methods and results

To examine the role of SeP in cardiac remodeling, transverse aortic constriction (TAC) was subjected to SeP knockout (KO) and wild-type (WT) mice for 2 weeks. Hepatic expression of SeP in WT was significantly increased by TAC. LV weight/tibial length (TL) was significantly smaller in SeP KO mice than in WT mice (6.75±0.24 vs 8.33±0.32, p<0.01). Lung weight/TL was significantly smaller in SeP KO than in WT mice (10.46±0.44 vs 16.38±1.12, p<0.05). TAC-induced cardiac upregulation of the fetal type genes, including atrial and brain natriuretic factors, was significantly attenuated in SeP KO compared to WT. Furthermore, azan staining revealed that there was significantly less interstitial fibrosis in hearts after TAC in SeP KO than in WT mice. To determine whether hepatic overexpression of SeP affects TAC-induced cardiac hypertrophy, a hydrodynamic injection method was used to generate mice that overexpress SeP mRNA in the liver. Hepatic overexpression of SeP in SeP KO mice lead to a significant increase in LV weight/TL and Lung weight/TL after TAC compared to that in other SeP KO mice.

Conclusions

These results suggest that cardiac pressure overload induced hepatic expression of SeP and the absence of endogenous SeP attenuated cardiac hypertrophy, dysfunction and fibrosis in response to pressure overload in mice. SeP possibly plays a maladaptive role against progression of heart failure through the liver-heart axis.