Bone marrow–derived mononuclear cell transplantation improves myocardial recovery by enhancing cellular recruitment and differentiation at the infarction site

Revascularization of chronic total occlusion coronary artery and cardiac regeneration

Coronary chronic total occlusion (CTO) contributes to the progression of heart failure in patients with ischemic cardiomyopathy. Randomized controlled trials demonstrated that percutaneous coronary intervention (PCI) for CTO significantly improves angina symptoms and quality of life but fails to reduce clinical events compared with optimal medical therapy. Even so, intervening physicians strongly support CTO-PCI. Cardiac regeneration therapy after CTO-PCI should be a promising approach to improving the prognosis of ischemic cardiomyopathy. However, the relationship between CTO revascularization and cardiac regeneration has rarely been studied, and experimental studies on cardiac regeneration usually employ rodent models with permanent ligation of the coronary artery rather than reopening of the occlusive artery. Limited early-stage clinical trials demonstrated that cell therapy for cardiac regeneration in ischemic cardiomyopathy reduces scar size, reverses cardiac remodeling, and promotes angiogenesis. This review focuses on the status quo of CTO-PCI in ischemic cardiomyopathy and the clinical prospect of cardiac regeneration in this setting.

microRNA-497 inhibition mitigates myocardial infarction via enhancing wingless/integrated signal pathway in bone marrow mesenchymal stem cells

OBJECTIVE

High association between microRNA-497 (miR-497) inhibition and the improvement of myocardial infarction (MI) has been proved. Bone marrow mesenchymal stem cells (BMSCs) therapy is regarded as a highly promising approach to MI treatment. We studied the functional role of miR-497 inhibition in the transplantation of BMSCs for MI treatment.

METHODS

BMSCs were isolated from 10 to 14 days old male Sprague-Dawley (SD) rats for in vitro and in vivo experiments. First, flow cytometry was used for BMSCs identification. miR-497 antagomir and agomir were transfected into BMSCs, and the migratory capacity was detected by wound healing assay. Protein levels were analyzed by Western blot analysis. Second, rat MI models were constructed and injected with each experimental group BMSCs. Four weeks later, the cellular morphology of cardiomyocyte and infarcted size was observed after histopathologic evaluation (HE) and Masson's trichrome staining. Moreover, WNT3A siRNA (siWNT3A) was used for further investigating the involvement of Wnt/β-catenin pathway.

RESULTS

BMSCs were confirmed to be CD90+ CD45- CD11b/c- cells. The number of rats with wound closure increased more in miR-497 inhibitor group than that in agomir group, the number markedly decreased in agomir group ( P < 0.01). As the miR-497 decreased, the protein levels of WNT3A, matrix metalloproteinase-9 and β-catenin were notably increased. The injection of BMSCs inhibiting miR-497 repaired almost all infarcted zones. siWNT3A, on the contrary, could decrease the wound closure rate and relative protein levels and inhibit MI treatment.

CONCLUSION

miR-497 antagomir contributes to BMSCs transplantation for MI treatment by Wnt/β-catenin activation, and Wnt/β-catenin pathway is essential for the functional effects of miR-497 antagomir.

Two novel direct SPIO labels and in vivo MRI detection of labeled cells after acute myocardial infarct

BACKGROUND

Acute myocardial infarction (AMI) is a leading cause of morbidity and mortality worldwide. Cellular decay due hypoxia requires rapid and validated methods for possible therapeutic cell transplantation.

PURPOSE

To develop direct and rapid superparamagnetic iron oxide (SPIO) cell label for a large-animal model and to assess in vivo cell targeting by magnetic resonance imaging (MRI) in an experimental AMI model.

MATERIAL AND METHODS

Bone marrow mononuclear cells (BMMNCs) were labeled with SPIO particles using two novel direct labeling methods (rotating incubation method and electroporation). Labeling, iron incorporation in cells and label distribution, cellular viability, and proliferation were validated in vitro. An AMI porcine model was used to evaluate the direct labeling method (rotating incubation method) by examining targeting of labeled BMMNCs using MRI and histology.

RESULTS

Labeling (1 h) did not alter either cellular differentiation potential or viability of cells in vitro. Cellular relaxation values at 9.4 T correlated with label concentration and MRI at 1.5 T showing 89 ± 4% signal reduction compared with non-labeled cells in vitro. In vivo, a high spatial correlation between MRI and histology was observed. The extent of macroscopic pathological myocardial changes (hemorrhage) correlated with altered function detected on MRI.

CONCLUSION

We demonstrated two novel direct SPIO labeling methods and demonstrated the feasibility of clinical MRI for monitoring targeting of the labeled cells in animal models of AMI.

Bone Marrow Mononuclear Cell Transplantation Restores Inflammatory Balance of Cytokines after ST Segment Elevation Myocardial Infarction

Background

Acute myocardial infarction (AMI) launches an inflammatory response and a repair process to compensate cardiac function. During this process, the balance between proinflammatory and anti-inflammatory cytokines is important for optimal cardiac repair. Stem cell transplantation after AMI improves tissue repair and increases the ventricular ejection fraction. Here, we studied in detail the acute effect of bone marrow mononuclear cell (BMMNC) transplantation on proinflammatory and anti-inflammatory cytokines in patients with ST segment elevation myocardial infarction (STEMI).

Methods

Patients with STEMI treated with thrombolysis followed by percutaneous coronary intervention (PCI) were randomly assigned to receive either BMMNC or saline as an intracoronary injection. Cardiac function was evaluated by left ventricle angiogram during the PCI and again after 6 months. The concentrations of 27 cytokines were measured from plasma samples up to 4 days after the PCI and the intracoronary injection.

Results

Twenty-six patients (control group, n = 12; BMMNC group, n = 14) from the previously reported FINCELL study (n = 80) were included to this study. At day 2, the change in the proinflammatory cytokines correlated with the change in the anti-inflammatory cytokines in both groups (Kendall’s tau, control 0.6; BMMNC 0.7). At day 4, the correlation had completely disappeared in the control group but was preserved in the BMMNC group (Kendall’s tau, control 0.3; BMMNC 0.7).

Conclusions

BMMNC transplantation is associated with preserved balance between pro- and anti-inflammatory cytokines after STEMI in PCI-treated patients. This may partly explain the favorable effect of stem cell transplantation after AMI.

High number of transplanted stem cells improves myocardial recovery after AMI in a porcine model

OBJECTIVE

The clinical data considering the bone marrow mononuclear cell (BMMNC) therapy in treatment for acute myocardial infarction (AMI) are controversial and the mechanisms remain unknown. Our objective was to study the cardiac function and changes in cytokine levels after administration of BMMNC in experimental AMI model.

DESIGN

Unlabeled or Super-Paramagnetic-Iron-Oxide-labeled BMMNCs or saline was injected into myocardium of 31 pigs after circumflex artery occlusion. Ejection fraction (EF) was measured preoperatively, postoperatively and at 21 days by echocardiography. Cardiac MRI was performed postoperatively and after 21 days in 7 BMMNC animals. Serum cytokine levels were measured at baseline, 24 h and 21 days. Cellular homing was evaluated comparing MRI and histology.

RESULTS

From baseline to 21 days EF decreased less in BMMNC group (EF mean control -19 SD 12 vs. BMMNC -4 SD 15 percentage points p = 0.02). Cytokine concentrations showed high variability between the animals. MRI correlated with histology in cell detection and revealed BMMNCs in the infarction area. By MRI, EF improved 11 percentage points. The improvement in EF was associated with the number of transplanted BMMNCs detected in the myocardium.

CONCLUSION

BMMNC injection after AMI improved cardiac function. Quantity of transplanted BMMNCs correlated with the improvement in cardiac function after AMI.

Myocardial structural protein expression in umbilical cord blood mesenchymal stem cells after myogenic induction

To assess the effects of three methods of inducing myogenic cells differentiation, umbilical blood mesenchymal stem cells (UCMSCs) from nearly full-term pregnancy mongrel dogs were purified and cultured. Fourth-passage UCMSCs were used to detect surface antigens, including CD11a, CD11b, CD29, CD34 and CD71. The cells were induced by 5-azacytidine (5-aza), myocardial lysates and myocardial induced fluid. Positive expression of Nkx2.5, α-actin, desmin, β-MHC and troponin-I (TN I) were detected after 3 weeks. The immunohistochemical results were CD11a (-), CD11b (-), CD34 (-), CD29 (+) and CD71 (+). Nkx2.5 was detected in 5-aza group, myocardial lysates group and myocardial induced fluid group. Semi-quantitative analysis showed Nkx2.5 expression significantly higher in myocardial lysates group than in the 5-aza group or myocardial-induced fluid group (P < 0.05), but there was no significant difference between the 5-aza and myocardial-induced fluid groups for Nkx2.5 expression (P > 0.05). MSCs did not express myocardial structural proteins before differentiation, but α-actin, desmin, β-MHC and troponin-I were present after differentiation. The positive expression of four proteins differed with the differentiation conditions. The UCMSCs can be differentiated into myogenic cells by three methods, but the degrees of differentiation are inconsistent. Our results show that the effects of 5-aza and myocardial lysates are better than that of myocardial induced fluid.

Combination of bone marrow concentrate and PGA scaffolds enhance bone marrow stimulation in rabbit articular cartilage repair

Bone marrow stimulation (BMS) has been regarded as a first-line procedure for the repair of articular cartilage. However, cartilage repair using BMS alone has so far not been ideal because cell homing to the required area has not been sufficient. The aim of this study was to investigate the feasibility of autologous bone marrow concentrate transplantation for the repair of large, full-thickness cartilage defects. Thirty rabbits were divided into five groups: untreated (control); BMS only (BMS); BMS followed by PGA implantation (PGA); BMS followed by a combination of PGA and autologous bone marrow concentrate (BMC); and BMS together with a composite of PGA and cultured bone marrow stem cells (BME). The animals were sacrificed at week 8 after operation, and HE staining, toluidine blue staining and immunohistochemistry were used to assess the repair of defects. The results showed that improved repair, including more newly formed cartilage tissue and hyaline cartilage-specific extracellular matrix, was observed in BMC group relative to the first three groups, in addition similar results were found between BMC and BME groups, however it took longer time for in vitro cell expansion in the BME group. This study demonstrates that the transplantation of autologous bone marrow concentrate is an easy, safe and potentially viable method to contribute to articular cartilage repair.

Activity of mesenchymal stem cells in a nonperfused cardiac explant model

Stem cell therapy represents a potential novel additional therapy for acute myocardial infarction. Cardiac applications of stem cell therapy are now undergoing clinical trials though many properties, including localization, possible adhesion, and infiltration of the injected stem cells in the myocardium, have not been studied in detail even in vitro. To study these mechanisms in a controlled microenvironment, we developed a model where mesenchymal stem cells (MSCs) were transported into live, cultured cardiac explants for further co-culture. About 10×10(3) porcine MSCs were injected into freshly excised and isolated cardiac explants of the pig. The explants were present in the culture medium for up to 7 days, with the time course of viability of the myocardial tissue, and the migration and the localization of the injected MSCs were analyzed with histological and immunohistological stainings. The myocyte structure was observed to be well preserved, and proliferation of capillaries and myofibroblasts was detected at the explant periphery. There were injected MSCs localized in the capillaries and in contact with the endothelial cells. The migration range and the number of adherent MSCs increased over time, suggesting active movement of MSCs in the explant. Our results suggest that this cardiac explant culture model is a feasible method for studying the effects of stem cells in the myocardium in vitro.

Myocardial restoration: is it the cell or the architecture or both?

Myocardial infarction is the leading cause of death in developed countries. Cardiac cell therapy has been introduced to clinical trials for more than ten years but its results are still controversial. Tissue engineering has addressed some limitations of cell therapy and appears to be a promising solution for cardiac regeneration. In this review, we would like to summarize the current understanding about the therapeutic effect of cell therapy and tissue engineering under purview of functional and structural aspects, highlighting actual roles of each therapy towards clinical application.

Large animal models for cardiac stem cell therapies

Cardiovascular disease is the leading cause of death in developed countries and is one of the leading causes of disease burden in developing countries. Therapies have markedly increased survival in several categories of patients, nonetheless mortality still remains high. For this reason high hopes are associated with recent developments in stem cell biology and regenerative medicine that promise to replace damaged or lost cardiac muscle with healthy tissue, and thus to dramatically improve the quality of life and survival in patients with various cardiomyopathies. Much of our insight into the molecular and cellular basis of cardiovascular biology comes from small animal models, particularly mice. However, significant differences exist with regard to several cardiac characteristics when mice are compared with humans. For this reason, large animal models like dog, sheep and pig have a well established role in cardiac research. A distinct characteristic of cardiac stem cells is that they can either be endogenous or derive from outside the heart itself; they can originate as the natural course of their differentiation programme (e.g., embryonic stem cells) or can be the result of specific inductive conditions (e.g., mesenchymal stem cells). In this review we will summarize the current knowledge on the kind of heart-related stem cells currently available in large animal species and their relevance to human studies as pre-clinical models.

Myocardial remodeling: cellular and extracellular events and targets

The focus of this review is on translational studies utilizing large-animal models and clinical studies that provide fundamental insight into cellular and extracellular pathways contributing to post-myocardial infarction (MI) left ventricle (LV) remodeling. Specifically, both large-animal and clinical studies have examined the potential role of endogenous and exogenous stem cells to alter the course of LV remodeling. Interestingly, there have been alterations in LV remodeling with stem cell treatment despite a lack of long-term cell engraftment. The translation of the full potential of stem cell treatments to clinical studies has yet to be realized. The modulation of proteolytic pathways that contribute to the post-MI remodeling process has also been examined. On the basis of recent large-animal studies, there appears to be a relationship between stem cell treatment post-MI and the modification of proteolytic pathways, generating the hypothesis that stem cells leave an echo effect that moderates LV remodeling.

Mesenchymal stem cells improve the healing of ischemic colonic anastomoses (experimental study)

OBJECTIVE

The goal of this study is to examine if allogenic mesenchymal stem cell (MSC) transplantation is a useful therapy for left ischemic colon anastomosis in rats. Problems with anastomosis healing may lead to serious postoperative complications. Bone marrow-derived mesenchymal stem cells (BM-MSCs), which are also referred to as stromal progenitor cells, are self-renewing and expandable stem cells. Recent studies have suggested that BM-MSCs play a crucial role in the processes of intestinal repair and accelerate angiogenesis.

METHODS

MSCs were isolated from rats before analysis by light and scanning electron microscopy. Forty male Wistar albino rats weighing 250-280 g were divided into four equal groups (n = 10) as follows: group 1: control, ischemic left colonic anastomoses (fourth day); group 2: control, ischemic left colonic anastomoses (seventh day); group 3: ischemic left colonic anastomoses + locally transplanted BM-MSCs (fourth day); group 4: ischemic left colonic anastomoses + locally transplanted BM-MSCs (seventh day). Histopathological features and anastomotic strength were evaluated.

RESULTS

BM-MSCs therapy significantly accelerated all of the healing parameters for ischemic colonic anastomosis except for inflammation on the fourth day. On the seventh day, BM-MSCs augmented the levels of the hydroxyproline and bursting pressure. Histological parameters, especially angiogenesis, were also found to be important for healing of ischemic colonic anastomoses.

CONCLUSIONS

This is the first study to use locally transplanted cell therapy for the healing of ischemic colonic anastomosis. BM-MSCs therapy significantly accelerated all of the healing parameters for ischemic colonic anastomosis.

Mesenchymal stromal cell and mononuclear cell therapy in heart disease

Despite progress in percutaneous coronary intervention, bypass surgery and drug therapy, rates of mortality and morbidity after acute coronary syndrome are high due to ventricular remodeling and heart failure. Mesenchymal stromal cells (MSCs) from adult bone marrow or adipose tissue are considered potential candidates for therapeutic regenerative treatment in cardiovascular disease. Recent animal studies have demonstrated that MSCs can induce neovascularization and improve myocardial function in postinfarction myocardial ischemic hearts. This review will focus on the present preclinical and clinical knowledge about the use of mononuclear cells and MSCs for cardiac regenerative medicine, the source of MSCs for clinical use and problems to consider when conducting clinical MSC therapy.

Acute homing of bone marrow-derived mononuclear cells in intramyocardial vs. intracoronary transplantation

OBJECTIVES

Cell homing optimisation after transplantation is critical in myocardial infarction (MI) cell therapy.

DESIGN

Eight pigs were randomized to receiving autologous purified (111)indium-labeled bone marrow mononuclear cells (BMMCs) (10(8) cells/2 ml) by intramyocardial (IM) (n=4) or by intracoronary (IC) (n=4) transplantation after 90 minutes occlusion of the CX-coronary artery. Dual isotope SPECT imaging was performed 2 and 24 hours postoperatively. Two animals were additionally analyzed on the sixth postoperative day. Tissue samples from the major organs were analyzed.

RESULTS

In SPECT imaging revealed that BMMCs administered using IM injection remained in the injured area. In contrast, minor proportion of IC transplanted cells remained in the myocardium, as most of the cells showed homing in the lungs. Analysis of the biopsies showed a seven-fold greater number of cells in the myocardium for the IM method and a 10-fold greater number of cells in the lungs in the IC group (p < 0.001).

CONCLUSIONS

In producing persistently high cell homing at the infarction site, the IM transplantation is superior to the IC transplantation. However, the IC administration might be more specific in targeting injured capillaries and epithelial cells within the infarcted myocardium.

Mesenchymal stromal cells for cardiovascular repair: current status and future challenges

Ischemic heart disease is the most common cause of death in most industrialized countries. Early treatment with stabilizing drugs and mechanical revascularization by percutaneous coronary intervention or coronary bypass surgery has reduced the mortality significantly. In spite of improved offers of treatments in patients with heart failure, the 1-year mortality is still approximately 20% after the diagnosis has been established. Treatment with stem cells with the potential to regenerate the damaged myocardium is a relatively new approach. Mesenchymal stromal cells are a promising source of stem cells for regenerative therapy. Clinical studies on stem cell therapy for cardiac regeneration have shown significant improvements in ventricular pump function, ventricular remodeling, myocardial perfusion, exercise potential and clinical symptoms compared with conventionally treated control groups. The results of most studies are promising, but there are still many unanswered questions. In this review, we explore present preclinical and clinical knowledge regarding the use of stem cells in cardiovascular regenerative medicine, with special focus on mesenchymal stromal cells. We take a closer look at sources of stem cells, delivery method and methods for tracking injected cells.

Bone marrow-derived mesenchymal stem cells promote angiogenic processes in a time- and dose-dependent manner in vitro

Bone marrow-derived mesenchymal stem cells (MSCs) have received much attention as a potential treatment for myocardial infarction because of their potential to integrate into the host myocardium and repair the injured heart. The mode of action of stem cell-mediated cardiac repair is still somewhat unclear, including the potential role of MSCs in neovascularization. The objective of this study was to determine the in vitro effect of MSCs on angiogenesis-related endothelial cell (EC) behavior, including migration, monolayer permeability, and vessel formation and stabilization. In a noncontact coculture system, we found that MSCs increase EC proliferation and migration, promoting early events of angiogenesis, while also decreasing EC monolayer permeability. Further, in a time- and dose-dependent manner, MSCs in direct coculture with ECs on Matrigel can increase the persistence of preexisting vessels by greater than threefold, with complex vessels remaining stable for more than 10 days. The results demonstrate that MSCs play an active role in the cellular processes involved in the formation, stabilization, and maturation of newly formed vessels. Further, these outcomes are not governed solely by either paracrine or direct contact effects and are both time and dose dependent.

Novel cell-based therapeutic strategy for ischemic colitis with use of bone marrow-derived mononuclear cells in rats

PURPOSE

Ischemic colitis is a common disorder of the large bowel. In the clinical setting, some patients suffer refractory ischemic colitis regardless of conventional treatment. Meanwhile, bone marrow-derived mononuclear cells are known to accelerate neovascularization. The purpose of this study was to verify the effects of bone marrow-derived mononuclear cells on ischemic colitis in rats.

METHODS

An ischemic colitis model was established by partial obstruction of the rectum and interruption of the marginal vessel in the immunodeficient rat. Bone marrow-derived mononuclear cells from a Wistar rat were injected into the ischemic area one day later than the ischemia (Group MNC). As a control, phosphate-buffered saline was injected in the same manner (Group PBS). Seven days after cell transplantation, each rat was evaluated for histology and colic motility.

RESULTS

Compared with Group PBS scores, the Group MNC macroscopic and microscopic colitis severity scores were significantly reduced. Moreover, the density of the capillary and myenteric plexus was significantly higher in Group MNC than in Group PBS (9.55 +/- 0.74 vs. 4.61 +/- 0.22, respectively, P < 0.01; and 8.57 +/- 0.41 vs. 5.93 +/- 0.31, respectively, P < 0.02). The whole-gut transit time was significantly shorter in Group MNC compared with Group PBS (472.7 +/- 17.6 vs. 584.8 +/- 24.0 minutes, respectively, P < 0.01). Transplanted cells were detected in all layers of the intestinal wall; however, these cells did not differentiate into vascular or neural cells.

CONCLUSIONS

These results suggest that transplantation of bone marrow-derived mononuclear cells might enhance not only tissue regeneration and angiogenesis but also neurogenesis. Transplantation of bone marrow-derived mononuclear cells may be a useful therapeutic strategy for ischemic colitis.

Transvenous intramyocardial cellular delivery increases retention in comparison to intracoronary delivery in a porcine model of acute myocardial infarction

BACKGROUND

Clinical trials using intracoronary (IC) delivery of cells have addressed efficacy but the optimal delivery technique is unknown. Our study aimed to determine whether transvenous intramyocardial (TVIM) approach was advantageous for cellular retention in AMI.

METHODS

Domestic pigs (n = 4) underwent catheterization with coronary angiography and ventriculography prior to infarction and pre- and post-cells. Pigs underwent 90-minute balloon occlusion of the left anterior descending artery (LAD). After one week they were prepared for IC (n = 2) or TVIM (n = 2) delivery of bone marrow mononuclear cells (MNC) labeled with GFP. IC infusion used an over-the-wire catheter to engage the LAD and balloon inflation to prevent retrograde flow. Venography via the coronary sinus was used for TVIM delivery. The anterior interventricular vein was engaged with a guidewire allowing use of the TransAccess catheter that is outfitted with an ultrasound tip for visualization. Animals were sacrificed one hour after delivery and tissue was analyzed.

RESULTS

Procedures were performed without complication and monitoring was uneventful. 1 x 10(8) MNC were isolated from each bone marrow (BM) preparation and 1 x 10(7) MNC delivered. Ventriculography at one week revealed wall motion abnormalities consistent with an anterior AMI. TVIM and IC delivery revealed mean 452 cells per section and 235 cells per section on average, respectively, in the infarct zone (P = 0.01).

CONCLUSION

We have demonstrated that TVIM approach for cell delivery is feasible and safe. Moreover, this approach may provide an advantage over IC infusion in retention of the cellular product; however, larger studies will be necessary.