Bone-marrow-derived cells and heart repair

Autologous Dermal Fibroblast Injections Slow Atrioventricular Conduction and Ventricular Rate in Atrial Fibrillation in Swine

Background—

Nonpharmacological ventricular rate control in atrial fibrillation (AF) without producing atrioventricular (AV) block remains a clinical challenge. We investigated the hypothesis that autologous dermal fibroblast (ADF) injection into the AV nodal area would reduce ventricular response during AF without causing AV block.

Methods and Results—

Fourteen pigs underwent electrophysiology study before, immediately, and 28 days after ≈200 million cultured ADFs (n=8) or saline (n=6) were injected under electroanatomical guidance in the AV nodal area, with continuous 28-day ECG recording. In the ADF group at 28 days postinjection, there were prolongations of PR interval (after versus before: 130±13 versus 113±14 ms, P =0.04), of AH interval during both sinus rhythm (92±13 versus 76.8±8 ms, P <0.01) and atrial pacing at 400 ms (102±13 versus 91±9 ms, P <0.01), and of AV node Wenckebach cycle length (230±19 versus 213±24 ms, P <0.01), with no changes in the control group. The RR interval during induced AF 28 days after injections was 24% longer in ADF-treated group compared with controls (488±120 versus 386±116 ms, P <0.001). Histological analysis revealed presence of ADF-labeled cells in the AV nodal area at 28 days. Transient accelerated junctional rhythm during injections, and transient nocturnal Mobitz I AV conduction occurred early postinjection in both groups.

Conclusions—

Cells survived for 4 weeks and significantly slowed AV conduction and ventricular rate in acutely induced AF. Critically, despite a large number of injections in the AV nodal area and marked effects on AV conduction, AV block did not occur. Further studies are necessary to determine the clinical feasibility and safety of this strategy for ventricular rate control in AF.

Therapeutic outcomes of transplantation of amniotic fluid-derived stem cells in experimental ischemic stroke

Accumulating preclinical evidence suggests the use of amnion as a source of stem cells for investigations of basic science concepts related to developmental cell biology, but also for stem cells’ therapeutic applications in treating human disorders. We previously reported isolation of viable rat amniotic fluid-derived stem (AFS) cells. Subsequently, we recently reported the therapeutic benefits of intravenous transplantation of AFS cells in a rodent model of ischemic stroke. Parallel lines of investigations have provided safety and efficacy of stem cell therapy for treating stroke and other neurological disorders. This review article highlights the need for investigations of mechanisms underlying AFS cells’ therapeutic benefits and discusses lab-to-clinic translational gating items in an effort to optimize the clinical application of the cell transplantation for stroke.

Intravenous grafts of amniotic fluid-derived stem cells induce endogenous cell proliferation and attenuate behavioral deficits in ischemic stroke rats

We recently reported isolation of viable rat amniotic fluid-derived stem (AFS) cells [1]. Here, we tested the therapeutic benefits of AFS cells in a rodent model of ischemic stroke. Adult male Sprague-Dawley rats received a 60-minute middle cerebral artery occlusion (MCAo). Thirty-five days later, animals exhibiting significant motor deficits received intravenous transplants of rat AFS cells or vehicle. At days 60–63 post-MCAo, significant recovery of motor and cognitive function was seen in stroke animals transplanted with AFS cells compared to vehicle-infused stroke animals. Infarct volume, as revealed by hematoxylin and eosin (H&E) staining, was significantly reduced, coupled with significant increments in the cell proliferation marker, Ki67, and the neuronal marker, MAP2, in the dentate gyrus (DG) [2] and the subventricular zone (SVZ) of AFS cell-transplanted stroke animals compared to vehicle-infused stroke animals. A significantly higher number of double-labeled Ki67/MAP2-positive cells and a similar trend towards increased Ki67/MAP2 double-labeling were observed in the DG and SVZ of AFS cell-transplanted stroke animals, respectively, compared to vehicle-infused stroke animals. This study reports the therapeutic potential of AFS cell transplantation in stroke animals, possibly via enhancement of endogenous repair mechanisms.

Mesenchymal stem cells and cardiovascular disease: a bench to bedside roadmap

In recent years, the incredible boost in stem cell research has kindled the expectations of both patients and physicians. Mesenchymal progenitors, owing to their availability, ease of manipulation, and therapeutic potential, have become one of the most attractive options for the treatment of a wide range of diseases, from cartilage defects to cardiac disorders. Moreover, their immunomodulatory capacity has opened up their allogenic use, consequently broadening the possibilities for their application. In this review, we will focus on their use in the therapy of myocardial infarction, looking at their characteristics, in vitro and in vivo mechanisms of action, as well as clinical trials.

Long-term results of autologous stem cell transplantation in the treatment of patients with congestive heart failure

BACKGROUND

The aim of this study was to assess the long-term efficacy of stem cell transplantation with revascularization for patients with ischemic cardiomyopathy.

METHODS

We enrolled 17 patients with ischemic cardiomyopathy who had undergone autologous stem cell treatment. To assess myocardial ischemia and viability they underwent coronary angiography, stress tests with dobutamine, echocardiography, and positron emission tomography. Peripheral stem cells mobilized using granulocyte colony-stimulating factor (G-CSF) were collected by aphseresis for transplantation transmyocardially into the areas of injury during coronary artery bypass surgery to increase blood flow to the engrafted areas.

RESULTS

Three patients died in the early follow-up period and 4 patients with cardiac failure died during mid-term follow-up; they all underwent stem cell transplantation at 6 months after acute myocardial infarction. The mean follow-up period of the remaining 10 patients was 85.8 ± 9.2 months (range, 70-100). Mean left ventricular ejection fraction improved to 30.0 ± 6.7, whereas the preoperative mean left ventricular ejection fraction of the surviving patients was 25.6 ± 4.5 (P = .035). Mean New York Heart Association (NYHA) functional class decreased from 3.2 to 1.5 (P = .006). When the study population was divided into 2 subgroups according to the interval between acute myocardial infraction and surgery, the patients who underwent autologous stem cell transplantation within the first 6 months after myocardial infraction (Group 1) showed significantly lower NYHA scores at the last follow-up (P = .024 in Group 1 and P = .102 in Group 2). No side effects were observed to be due to the stem cell or G-CSF injections.

CONCLUSION

Treatment of ischemic cardiomyopathy with autologous stem cell transplantation is easy and safe, opening a new window in the treatment of "no hope" patients.

Guided cardiopoiesis enhances therapeutic benefit of bone marrow human mesenchymal stem cells in chronic myocardial infarction

OBJECTIVES

The goal of this study was to guide bone marrow-derived human mesenchymal stem cells (hMSCs) into a cardiac progenitor phenotype and assess therapeutic benefit in chronic myocardial infarction.

BACKGROUND

Adult stem cells, delivered in their naïve state, demonstrate a limited benefit in patients with ischemic heart disease. Pre-emptive lineage pre-specification may optimize therapeutic outcome.

METHODS

hMSC were harvested from a coronary artery disease patient cohort. A recombinant cocktail consisting of transforming growth factor-beta(1), bone morphogenetic protein-4, activin A, retinoic acid, insulin-like growth factor-1, fibroblast growth factor-2, alpha-thrombin, and interleukin-6 was formulated to engage hMSC into cardiopoiesis. Derived hMSC were injected into the myocardium of a nude infarcted murine model and followed over 1 year for functional and structural end points.

RESULTS

Although the majority of patient-derived hMSC in their native state demonstrated limited effect on ejection fraction, stem cells from rare individuals harbored a spontaneous capacity to improve contractile performance. This reparative cytotype was characterized by high expression of homeobox transcription factor Nkx-2.5, T-box transcription factor TBX5, helix-loop-helix transcription factor MESP1, and myocyte enhancer factor MEF2C, markers of cardiopoiesis. Recombinant cardiogenic cocktail guidance secured the cardiopoietic phenotype across the patient cohort. Compared with unguided counterparts, cardiopoietic hMSC delivered into infarcted myocardium achieved superior functional and structural benefit without adverse side effects. Engraftment into murine hearts was associated with increased human-specific nuclear, sarcomeric, and gap junction content along with induction of myocardial cell cycle activity.

CONCLUSIONS

Guided cardiopoiesis thus enhances the therapeutic benefit of bone marrow-derived hMSC in chronic ischemic cardiomyopathy.

Telocytes in human epicardium

The existence of the epicardial telocytes was previously documented by immunohistochemistry (IHC) or immunofluorescence. We have also demonstrated recently that telocytes are present in mice epicardium, within the cardiac stem-cell niches, and, possibly, they are acting as nurse cells for the cardiomyocyte progenitors. The rationale of this study was to show that telocytes do exist in human (sub)epicardium, too. Human autopsy hearts from 10 adults and 15 foetuses were used for conventional IHC for c-kit/CD117, CD34, vimentin, S-100, τ, Neurokinin 1, as well as using laser confocal microscopy. Tissue samples obtained by surgical biopsies from 10 adults were studied by digital transmission electron microscopy (TEM). Double immunolabelling for c-kit/CD34 and, for c-kit/vimentin suggests that in human beings, epicardial telocytes share similar immunophenotype features with myocardial telocytes. The presence of the telocytes in human epicardium is shown by TEM. Epicardial telocytes, like any of the telocytes are defined by telopodes, their cell prolongations, which are very long (several tens of μm), very thin (0.1-0.2 μm, below the resolving power of light microscopy) and with moniliform configuration. The interconnected epicardial telocytes create a 3D cellular network, connected with the 3D network of myocardial telocytes. TEM documented that telocytes release shed microvesicles or exocytotic multivesicular bodies in the intercellular space. The human epicardial telocytes have similar phenotype (TEM and IHC) with telocytes located among human working cardiomyocyte. It remains to be established the role(s) of telocytes in cardiac renewing/repair/regeneration processes, and also the pathological aspects induced by their 'functional inhibition', or by their variation in number. We consider telocytes as a real candidate for future developments of autologous cell-based therapy in heart diseases.

Insights into neurogenesis and aging: potential therapy for degenerative disease?

Neurogenesis is the process by which new neural cells are generated from a small population of multipotent stem cells in the adult CNS. This natural generation of new cells is limited in its regenerative capabilities and also declines with age. The use of stem cells in the treatment of neurodegenerative disease may hold great potential; however, the age-related incidence of many CNS diseases coincides with reduced neurogenesis. This review concisely summarizes current knowledge related to adult neurogenesis and its alteration with aging and examines the feasibility of using stem cell and gene therapies to combat diseases of the CNS with advancing age.

Beneficial effects of VEGF secreted from stromal cells in supporting endothelial cell functions: therapeutic implications for critical limb ischemia

Critical limb ischemia (CLI) is the end stage of peripheral vascular disease (PVD). One third of CLI patients progresses to leg amputation with high associated morbidity and mortality. In no-option patients with end-stage critical limb ischemia, bone marrow cell transplantation has shown promising results, improving leg perfusion to the level of reducing major amputations and allowing limb salvage. We recently reported the successful application of an innovative protocol based on repeated autologous bone marrow cell transplantation, which resulted in an effective and feasible strategy for achieving long-term revascularization in patients with severe CLI. In an effort to understand the clinical benefit provided by stem cells therapy in patients with CLI, we characterized the marrow-derived stromal cells of CLI patients and we provided a correlation between the in vitro features of these cells and the clinical follow up at 12 months. We showed that cells derived from CLI patients had a reduced capacity to proliferate, adhere, and migrate, but that they stimulated proliferation and migration of endothelial cells through the release of VEGF-A, supporting the idea that the paracrine mechanisms underpinned the biological effects of long-term angiogenesis in CLI patients.

Cardiac renewing: interstitial Cajal-like cells nurse cardiomyocyte progenitors in epicardial stem cell niches

Recent studies suggested that various cell lineages exist within the subepicardium and we supposed that this area could host cardiac stem cell niches (CSCNs). Using transmission electron microscopy, we have found at least 10 types of cells coexisting in the subepicardium of normal adult mice: adipocytes, fibroblasts, Schwann cells and nerve fibres, isolated smooth muscle cells, mast cells, macrophages, lymphocytes, interstitial Cajal-like cells (ICLCs) and cardiomyocytes progenitors (CMPs). The latter cells, sited in the area of origin of coronary arteries and aorta, showed typical features of either very immature or developing cardiomyocytes. Some of these cells were connected to each other to form columns surrounded by a basal lamina and embedded in a cellular network made by ICLCs. Complex intercellular communication occurs between the ICLCs and CMPs through electron-dense nanostructures or through shed vesicles. We provide here for the first time the ultrastructural description of CSCN in the adult mice myocardium, mainly containing ICLCs and CMPs. The existence of resident CMPs in different developmental stages proves that cardiac renewing is a continuous process. We suggest that ICLCs might act as supporting nurse cells of the cardiac niches and may be responsible for activation, commitment and migration of the stem cells out of the niches. Briefly, not only resident cardiac stem cells but also ICLCs regulate myocyte turnover and contribute to both cardiac cellular homeostasis and endogenous repair/remodelling after injuries.