Stem cell therapy for heart disease

Pharmacological preconditioning with phosphodiestrase inhibitor: an answer to stem cell survival against ischemic injury through JAK/STAT signaling

Stem cell transplantation in regenerative medicine has been widely used in various disorders including cardiovascular diseases (CVD) and emerging next-generation therapy. However, transplanted stem cell encountered ischemia/reperfusion (IR) injury which is a major challenge for stem cell survival. During the acute phase after myocardial infarction (MI) cytokine-rich hostile microenvironment, extensive immune cell infiltration and lack of oxygen have been a bottleneck in cell-based therapy. During prolonged ischemia, intracellular pH and ATP level decrease results in anaerobic metabolism and lactate accumulation. Consequentially, ATPase-dependent ion transport becomes dysfunctional, contributing to calcium overload and cell death by apoptosis and necrosis. Although O₂ level revitalizes upon reperfusion, a surge in the generation of reactive oxygen species (ROS) occurs with neutrophil infiltration in ischemic tissues further aggravating the injury. Ischemic preconditioning (IPC) of stem cells with a repeated short cycle of IR results in the release of chemical signals such as NO, ROS, and adenosine which triggers a cascade of signaling events that activates protein kinase C (PKC), Src protein tyrosine kinases, and nuclear factor κB (NF-κB) and subsequently increased synthesis of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), Heme oxygenase-1 [HO-1], aldose reductase, Mn superoxide dismutase, and anti-apoptotic genes (Mcl-1, BCl-x_L, c-FLIP_L, c-FLIP_S). Pharmacological preconditioning uses a phosphodiestrase inhibitor, another mode of protecting stem cell or heart per se from impending ischemic injury in two phases. During the early phase of cardioprotection (2 h), PC leads to increased expression of survival factors like BCl₂/Bax ratio while late phase (24 h) showed activation of the JAK/STAT survival pathway. Phosphorylation of STAT3 at two crucial residues, Tyr-705 and Ser-727, allows its entry inside the nucleus and upregulates the expression of protein kinase G-1 (PKG1) which evokes cardioprotective signaling. To confirm, heart-specific conditional STAT3 knockout mice undergone IR surgery, abolishing late-phase cardioprotective effects.

Huo Xue Tong Luo capsule ameliorates osteonecrosis of femoral head through inhibiting lncRNA-Miat

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese medicine has a long history of treating various bone diseases including osteoporosis and osteonecrosis etc. In clinical treatment, Huo Xue Tong Luo capsule (HXTL capsule) containing Peach kernel, Safflower carthamus, Angelica sinensis, Ligusticum wallichii etc, is one of the mostly used prescriptions for treating osteonecrosis of the femoral head (ONFH) with promising effects.

OBJECTIVES

This study aims to identify the underlying molecular mechanism of how HXTL capsule exerts its function to ameliorate ONFH.

MATERIALS AND METHODS

All femoral bone tissues were collected during surgeries. Rat bone marrow mesenchymal stem cells (rMSCs) were used. Quantitative real time PCR was used to check the relative expression levels of genes. ChIP assay was performed to evaluate the binding of H3K4me3 and H3K27me3 in Miat promoter.

RESULTS

We showed that HXTL capsule promoted osteogenesis in rat MSCs as demonstrated by quantitative real time PCR and Alizarin Red S staining. Then we found silencing the endogenous lncRNA-Miat could promote osteogenesis of rMSCs. In addition, the ChIP assay showed that HXTL capsule significantly increased occupancy of H3K27me3 and decreased H3K4me3 in promoter regions of Miat, meaning HXTL capsule inhibited Miat expression through histone modifications. At last, by examining the femoral heads samples obtained from patients with ONFH during total hip arthroplasty surgery, we found the RNA level of hMiat in necrotic tissue was much higher than that of normal tissue.

CONCLUSIONS

Taken together, our study shows that lncRNA-Miat might play an important role in pathogenesis of ONFH, and HXTL capsule can promote osteogenesis to ameliorate ONFH through inhibiting the transcriptional expression of Miat, at least partially.

Involvement of tumor necrosis factor alpha in steroid-associated osteonecrosis of the femoral head: friend or foe?

Background

The etiology and pathology osteonecrosis of the femoral head (ONFH) are not completely clarified. As a cytokine participating in systemic inflammation, tumor necrosis factor alpha (TNFα) has been shown to be involved in the pathogenesis of ONFH. However, the role of TNFα in ONFH is not clearly clarified. In the present study, we investigated the effects of TNFα on proliferation, angiogenesis, and osteogenic differentiation of rat bone mesenchymal stem cells (rMSCs) and the underlying mechanisms.

Methods

All femoral bone tissues were separated in surgeries. After extracting total RNA and protein, we evaluated TNFα content by ELISA and the relative expression levels of genes by quantitative real-time PCR and western blot. Also, immunohistochemistry staining was performed to observe the expression of Runx2 in the bone samples. Chick embryo chorioallantoic membrane (CAM) assay was performed to observe the effect of TNFα on angiogenesis. The genomic DNAs were treated by bisulfite modification, and methylation status of CpG sites in the CpG islands of human and rat Runx2 gene promoter was determined by DNA sequencing. The binding of H3K4me3 and H3K27me3 in Runx2 promoter was checked by ChIP assay. RNA-seq analysis was used to find out the genes and pathways changed by TNFα in rMSCs.

Results

The results demonstrate TNFα promotes cell proliferation and angiogenesis whereas inhibits osteogenesis. Epigenetic regulations including DNA methylation and histone modifications play important roles in mediating the effect of TNFα on osteogenic differentiation. We find an increased rate of CpG methylation in rat Runx2 promoter in TNFα-treated rMSCs, as well as significantly increased occupancy of H3K27me3 in Runx2 gene promoter. The content of TNFα in necrotic tissue is much lower than that of normal tissue. And relevantly, human Runx2 promoter is demethylated in necrotic tissue using bone samples from patient with ONFH. In addition, we have observed that Wnt signaling pathway is inhibited by TNFα as multiple Wnts are markedly decreased in TNFα-treated rMSCs by RNA-seq analysis.

Conclusion

Taken together, our study shows that TNFα plays complicated roles in the pathogenesis of ONFH, including proliferation, angiogenesis, and osteogenesis. Targeting TNFα should not be considered as an applicable strategy to inhibit the progression of ONFH.

Electronic supplementary material

The online version of this article (10.1186/s13287-018-1112-x) contains supplementary material, which is available to authorized users.

Bone marrow-derived mononuclear cell therapy for nonischaemic dilated cardiomyopathy-A meta-analysis

OBJECTIVE

The therapeutic effects of bone marrow-derived mononuclear cells (BMMNCs) transplantation in patients with nonischaemic dilated cardiomyopathy (DCM) are still under debate. Current randomized controlled trials (RCTs) reported conflicting results. The aim of this study was to assess the effects of BMMNCs transplantation on left ventricular ejection fraction (LVEF) in patients with nonischaemic DCM.

METHODS

A comprehensive search of PubMed, EMBASE and Cochrane Controlled Trials Register was performed. We included RCTs reporting data on LVEF in patients with nonischaemic DCM after BMMNCs transplantation.

RESULTS

Seven RCTs including 463 patients were included. BMMNCs transplantation significantly improved LVEF by 3.79% (95% CI: 0.56%-7.03%; P = .007) and LVESV by -24.36 mL (95% CI: -46.36 to -2.36 mL; P = .03), while had no impact on the risk of all-cause death (OR 0.92; 95% CI: 0.41 to 2.08%; P = .84). Subgroup analysis demonstrated a more significant improvement of LVEF in patients with longer follow-up (~15 months to 5 years) than shorter ones (12 months). Moreover, using bone marrow mononuclear cells was more effective than using G-CSF-stimulated bone marrow/peripheral blood stem cells in the improvement of LVEF in patients with nonischaemic DCM.

CONCLUSIONS

Bone marrow-derived mononuclear cells transplantation is associated with a moderate, but significant, improvement in LVEF in patients with nonischaemic DCM. This meta-analysis supports further RCT conductions using BMMNCs transplantation with larger patient's population and longer term follow-up.

Clinical Benefits of Stem Cells for Chronic Symptomatic Systolic Heart Failure: A Systematic Review of the Existing Data and Ongoing Trials

The benefits of stem cell therapy for patients with chronic symptomatic systolic heart failure due to ischemic and nonischemic cardiomyopathy (ICM and NICM, respectively) are unclear. We performed a systematic review of major published and ongoing trials of stem cell therapy for systolic heart failure and compared measured clinical outcomes for both types of cardiomyopathy. The majority of the 29 published studies demonstrated clinical benefits of autologous bone marrow-derived mesenchymal stem cells (BM-MSCs). Left ventricular ejection fraction (LVEF) was improved in the majority of trials after therapy. Cell delivery combined with coronary artery bypass grafting was associated with the greatest improvement in LVEF. Left ventricular end-systolic volume (or diameter), New York Heart Association functional classification, quality of life, and exercise capacity were also improved in most studies after cell therapy. Most ICM trials demonstrated a significant improvement in perfusion defects, infarct size, and myocardial viability. Several larger clinical trials that are in progress employ alternative delivery modes, cell types, and longer follow-up periods. Stem cells are a promising therapeutic modality for patients with heart failure due to ICM or NICM. More data are required from larger blinded trials to determine which combination of cell type and delivery mode will yield the most benefit with avoidance of harm in these patient populations.

Stem cell transplantation dose in patients with acute myocardial infarction: A meta-analysis

OBJECTIVE

To evaluate whether stem cell transplantation improves global left ventricular ejection fraction (LVEF) in patients with acute myocardial infarction (AMI), and to determine the appropriate stem cell therapy dose as well as the effective period after stem cell transplantation for therapy.

METHODS

A systematic literature search included Pubmed, MEDLINE, China National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature Database (CBM), and Cochrane Evidence-Based Medicine databases. The retrieval time limit ranged from January 1990 to June 2016. We also obtained full texts through manual retrieval, interlibrary loan and document delivery service, or by contacting the authors directly. According to our inclusion and exclusion criteria, data were extracted independently by two evaluators. In case of disagreement, a joint discussion occurred and a third researcher was utilized. Data were analyzed quantitatively using Revman 5.2. Summary results are presented as the weighted mean difference (WMD) with 95% confidence intervals (CIs). We collected individual trial data and conducted a meta-analysis to compare changes in global left ventricular ejection fraction (ΔLVEF) after stem cell therapy. In this study, four subgroups were based on stem cell dose (≤1 × 10⁷ cells, ≤1 × 10⁸ cells, ≤1 × 10⁹ cells, and ≤1 × 10¹⁰ cells) and three subgroups were based on follow-up time (<6 months, 6-12 months, and ≥12 months).

RESULTS

Thirty-four studies, which included 40 randomized controlled trials, were included in this meta-analysis, and 1927 patients were evaluated. Changes in global LVEF were significantly higher in the stem cell transplantation group than in the control group (95% CI: 2.35-4.26%, P < 0.01). We found no significant differences in ΔLVEF between the bone marrow stem cells (BMCs) group and control group when the dose of BMCs was ≤1 × 10⁷ [ΔLVEF 95% CI: 0.12-3.96%, P = 0.04]. The ΔLVEF in the BMCs groups was significantly higher than in the control groups when the dose of BMCs was ≤1 × 10⁸ [ΔLVEF 95% CI: 0.95-4.25%, P = 0.002] and ≤1 × 10⁹ [ΔLVEF 95% CI: 2.31-4.20%, P < 0.01]. In addition, when the dose of BMCs was between 10⁹ and 10¹⁰ cells, we did not observe any significant differences [ΔLVEF 95% CI: -0.99-11.82%, P = 0.10]. Our data suggest stem cell therapy improves cardiac function in AMI patients when treated with an appropriate dose of BMCs.

CONCLUSION

Stem cell transplantation after AMI could improve global LVEF. Stem cells may be effectively administered to patients with AMI doses between 10⁸ and 10⁹ cells.

Metabolism Regulates Cellular Functions of Bone Marrow-Derived Cells used for Cardiac Therapy

Administration of bone marrow-derived mononuclear cells (BMC) may increase cardiac function after myocardial ischemia. However, the functional capacity of BMC derived from chronic heart failure (CHF) patients is significantly impaired. As modulation of the energy metabolism allows cells to match the divergent demands of the environment, we examined the regulation of energy metabolism in BMC from patients and healthy controls (HC). The glycolytic capacity of CHF-derived BMC is reduced compared to HC, whereas BMC of metabolically activated bone marrow after acute myocardial infarction reveal increased metabolism. The correlation of metabolic pathways with the functional activity of cells indicates an influence of metabolism on cell function. Reducing glycolysis without profoundly affecting ATP-production reversibly reduces invasion as well as colony forming capacity and abolishes proliferation of CD34(+) CD38(-) lin(-) hematopoietic stem and progenitor cells (HSPC). Ex vivo inhibition of glycolysis further reduced the pro-angiogenic activity of transplanted cells in a hind limb ischemia model in vivo. In contrast, inhibition of respiration, without affecting total ATP production, leads to a compensatory increase in glycolytic capacity correlating with increased colony forming capacity. Isolated CD34(+) , CXCR4(+) , and CD14(+) cells showed higher glycolytic activity compared to their negative counterparts. Metabolic activity was profoundly modulated by the composition of media used to store or culture BMC. This study provides first evidence that metabolic alterations influence the functional activity of human HSPC and BMC independent of ATP production. Changing the balance between respiration and glycolysis might be useful to improve patient-derived cells for clinical cardiac cell therapy. Stem Cells 2016;34:2236-2248.

Association of TNF-α with impaired migration capacity of mesenchymal stem cells in patients with systemic lupus erythematosus

Previous studies indicated that bone marrow mesenchymal stem cells (BMSCs) from patients with systemic lupus erythematosus (SLE) exhibited impaired capacities of proliferation, differentiation, and immune modulation. Considering that migration capacity is important for the exertion of BMSCs functions, the defects in migration might contribute to BMSCs dysfunction in SLE patients. In this study, we showed that the migration capacity of SLE BMSCs was remarkably impaired in comparison with those of healthy controls. Increased tumor necrosis factor α (TNF-α) in SLE serum significantly inhibited the migration capacity and in vivo homing capacity of SLE BMSCs via a specific TNF receptor I (TNFRI) manner, in which decreased HGF mRNA production caused by the activation of I kappa B kinase beta (IKK-β) pathway is partially involved. To our knowledge, this is the first report to discuss the possible mechanisms for impaired migration of BMSCs in SLE patients. Our results suggest that inhibition of TNF-α pathway might be helpful for accelerating BMSCs migration to the inflammatory microenvironment in SLE patients, thereby having a potential role in SLE treatment.

Cardiac regeneration: current therapies-future concepts

Cardiovascular disease (CVD) continues to be one of the main causes of death in the western world. A high burden of disease and the high costs for the healthcare systems claim for novel therapeutic strategies besides current conventional medical care. One decade ago first clinical trials addressed stem cell based therapies as a potential alternative therapeutic strategy for myocardial regeneration and repair. Besides bone marrow derived stem cells (BMCs), adult stem cells from adipose or cardiac tissue have been used in current clinical studies with inconsistent results. Although outcomes in terms of safety and feasibility are generally encouraging, functional improvements were mostly disappointingly low and have failed to reach expectations. In the future, new concepts for myocardial regeneration, especially concerning recovery of cardiomyocyte loss, have to be developed. Transplantation of novel stem or progenitor cell populations with "true" regenerative potential, direct reprogramming of scar tissue into functional myocardium, tissue engineering or stimulation of endogenous cardiac repair by pharmacological agents are conceivable. This review summarizes current evidence of stem cell based regenerative therapies and discusses future strategies to improve functional outcomes.