Human umbilical cord blood mononuclear cells for the treatment of acute myocardial infarction

Human cord blood mononuclear cells decrease cytokines and inflammatory cells in acute myocardial infarction

We investigated whether human umbilical cord blood mononuclear cells (HUCBC), which contain hematopoietic and mesenchymal progenitor cells, can limit myocardial cytokine expression and inflammatory cell infiltration in acute myocardial infarction. We permanently ligated the left coronary artery of rats and injected into the myocardium either Isolyte or 4 x 10(6) HUCBC in Isolyte and measured myocardial cytokines with antibody arrays at 2, 6, 12, 24, and 72 hours after infarction. We then measured with flow cytometry myocardial macrophages, neutrophils and lymphocytes at 12, 24, and 72 hours after infarctions in rats treated with either intramyocardial Isolyte or 4 x 10(6) HUCBC. In the Isolyte-treated hearts, between 2 and 12 hours after myocardial infarction, tumor necrosis factor-alpha increased from 6.7 +/- 0.9% to 52.3 +/- 4.7%, monocyte chemoattract protein increased from 9.5 +/- 1.2% to 39.8 +/- 2.1%, fractalkine increased from 11 +/- 1.5% to 28.1 +/- 1.3%, ciliary neurotrophic factor increased from 12.1 +/- 0.02% to 25.9 +/- 1.1%, macrophage inflammatory protein increased from 10.3 +/- 1.5% to 23.9.0 +/- 1.4%, interferon-gamma increased from 8.7 +/- 0.4% to 26.0 +/- 1.6%, interleukin-1beta increased from 6.1 +/- 0.04% to 19.0 +/- 1.2%, and IL-4 increased from 5.9 +/- 0.03% to 15 +/- 1.5% (all p < 0.001 compared with controls). The concentrations of fractalkine remained significantly increased at 72 hours after acute infarction. In contrast, the myocardial concentrations of these cytokines did not significantly change in HUCBC treated hearts at 2, 6, 12, 24, or 72 hours after infarction. The percentage of neutrophils increased from 0.04 +/- 0.2%/50,000 heart cells in the controls to 5.3 +/- 1.2%/50,000 heart cells 12 hours after infarction in Isolyte-treated hearts but averaged only 1.3 +/- 0.7%/50,000 heart cells in HUCBC treated hearts (p < 0.02). Thereafter, the percentages of neutrophils rapidly decreased at 24 and at 72 hours after infarction and averaged 0.6 +/- 0.2%/50,000 heart cells at 72 hours after infarction in Isolyte-treated hearts in contrast to 0.2 +/- 0.1%/50,000 cells in HUCBC hearts (p < 0.05). Moreover, the percentages of neutrophils at 24 and 72 hours in HUCBC hearts were not significantly different from controls. At 24 hours post infarction, the percentage of CD3 and CD4 lymphocytes were 10.7 +/- 1.4% and 6.3 +/- 1.1%/50,000 cells in Isolyte hearts in comparison with only 4.9 +/- 0.8% and 2.9 +/- 0.5% in HUCBC hearts (p < 0.005 for Isolyte versus HUCBC). The percentage of CD11b macrophages was 2.8 +/- 0.3% in Isolyte hearts and 1.9 +/- 0.2% in HUCBC treated hearts (p < 0.05). At 72 hours after infarction, the percentage of CD3 and CD4 lymphocytes averaged 8.0 +/- 1.1% and 5.1 +/- 0.8%/50,000 heart cells in Isolyte hearts in comparison with only 4.1 +/- 0.5% and 2.3 +/- 0.4%/50,000 heart cells in the HUCBC treated infarctions (p < 0.005). Left ventricular infarct sizes in Isolyte-treated hearts at 72 hours post infarction averaged 15.7 +/- 1.4% of the left ventricular muscle area in contrast to HUCBC treated infarctions that averaged 6.9 +/- 1.4% of the left ventricular muscle area (p < 0.02). Moreover in rats followed for 2 months post infarction, the LV ejection fractions decreased to 65.4 +/- 1.9% and 69.1 +/- 1.9% at 1 and 2 months after infarction in Isolyte-treated hearts and were significantly different from HUCBC treated hearts that averaged 72.1 +/- 1.3% and 75.7 +/- 1.4% (both p < 0.02). The present experiments suggest that an important mechanism whereby HUCBC limit infarct size and improve left ventricular ejection fraction is by significantly limiting inflammatory cytokines and inflammatory cells in infarcted myocardium.

Umbilical cord blood cells

The umbilical cord of a healthy neonate contains within it a multipotential treatment for a myriad of diseases and injuries. What was once tossed into the biohazard waste without a second thought is now known to be a goldmine of antigenically immature cells that rival the use of bone marrow for reconstitution of blood lineages. Umbilical cord blood (UCB) is emerging as an effective and feasible clinical treatment as its availability increases and benefits are realized. Basic science research has demonstrated a broad therapeutic capacity ranging from cell replacement to cell protection and anti-inflammation in a number of animal disease and injury models. UCB is easily obtained with no harm to infant or mother and can be stored at cryogenic temperatures with relatively little loss of cells upon thaw. The heterogeneous mononuclear fraction has been identified and characterized and transplanted both locally and systemically to treat animal models of stroke, myocardial infarction, Amytrophic Lateral Sclerosis, San Filippo, spinal cord injury, traumatic brain injury, and age-related neurodegeneration, among others. In the pages to follow, we share protocols for the identification and research use of the mononuclear cell fraction of UCB.

Stem cell therapy for heart failure: the science and current progress

Cell therapy, particularly with stem cells, has created great interest as a solution to the fact that there are limited treatments for postischemic heart disease and none that can regenerate damaged heart cells to strengthen cardiac performance. From the first efforts with myoblasts to recent clinical trials with bone marrow-derived stem cells, early reports of cell therapy suggest improvement in cardiac performance as well as other clinical end points. Based on these exciting but tentative results, other stem cell types are being explored for their particular advantages as a source of adult stem cells. Autologous adipose-derived stem cells are multilinear and can be obtained relatively easily in large quantities from patients; cardiac-derived stem cells are highly appropriate for engraftment in their natural niche, the heart. Human umbilical cord blood cells are potentially forever young and allogenic adult mesenchymal stem cells appear not to evoke the graft versus host reaction. Human embryonic stem cells are effective and can be scaled up for supply purposes. The recent discovery of induced pluripotentcy in human adult stem cells, with only three transcription factor genes, opens a whole new approach to making autologous human pluripotent stem cells from skin or other available tissues. Despite the excitement, stem cells may have to be genetically modified with heme oxygenase, Akt or other genes to survive transplantation in a hypoxic environment. Homing factors and hormones secreted from transplanted stem cells may be more important than cells if they provide the necessary stimulus to trigger cardiac regrowth to replace scar tissue. As we await results from larger and more prolonged clinical trials, the science of stem cell therapy in cardiac disease keeps progressing.

Cord blood cell therapy alters LV remodeling and cytokine expression but does not improve heart function after myocardial infarction in rats

OBJECTIVE

In this study the ability of unrestricted somatic stem cells (USSC) and mononuclear cord blood cells (MN-CBC) was tested to improve heart function and left ventricular (LV) remodeling after myocardial infarction (MI).

METHODS

The cells were delivered by i.v. or intramyocardial injections in rat models of MI by permanent coronary artery occlusion and by ischemia/reperfusion (I/R) injury. Heart function and remodeling was followed by recurrent echocardiography over 8 or 12 weeks after which catheterization was performed.

RESULTS

Although injected labeled cells could be observed within the myocardium for up to 6 d, there was no sign of cardiac regeneration 8 or 12 weeks after MI. However, the mRNA expression of components of the extracellular matrix was attenuated in the infarct scar 12 weeks after MI and cell injection. Additionally, the expression of interleukin (IL)-6 but not of IL-1 beta increased at the site of injury and the adjacent border-zone 12 weeks after I/R and USSC-injection. However, these effects did not translate into improved heart function or attenuated LV dilatation.

CONCLUSION

These data indicate that cord blood cell implantation after MI acts through paracrine mechanisms to modify remodeling rather than myocyte regeneration. The role of myofibroblasts and the optimal conditions of cell application need to be determined to translate these mechanisms into functional improvement.

Human cord blood cells and myocardial infarction: effect of dose and route of administration on infarct size

There is no consensus regarding the optimal dose of stem cells or the optimal route of administration for the treatment of acute myocardial infarction. Bone marrow cells, containing hematopoietic and mesenchymal stem cells, in doses of 0.5 x 10(6) to >30 x 10(6) have been directly injected into the myocardium or into coronary arteries or infused intravenously in subjects with myocardial infarctions to reduce infarct size and improve heart function. Therefore, we determined the specific effects of different doses of human umbilical cord blood mononuclear cells (HUCBC), which contain hematopoietic and mesenchymal stem cells, on infarct size. In order to determine the optimal technique for stem cell administration, HUCBC were injected directly into the myocardium (IM), or into the LV cavity with the ascending aorta transiently clamped to facilitate coronary artery perfusion (IA), or injected intravenously (IV) in rats 1-2 h after the left anterior coronary artery was permanently ligated. Immune suppressive therapy was not given to any rat. One month later, the infarct size in control rat hearts treated with only Isolyte averaged 23.7 +/- 1.7% of the LV muscle area. Intramyocardial injection of HUCBC reduced the infarct size by 71% with 0.5 x 10(6) HUCBC and by 93% with 4 x 10(6) HUCBC in comparison with the controls (p < 0.001). Intracoronary injection reduced the infarction size by 47% with 0.5 x 10(6) HUCBC and by 80% with 4 x 10(6) HUCBC (p < 0.001), and IV HUCBC reduced infarct size by 51% with 0.5 x 10(6) and by 75-77% with 16-32 million HUCBC (p < 0.001) in comparison with control hearts. With 4 x 10(6) HUCBC, infarction size was 65% smaller with IM HUCBC than with IA HUCBC and 78% smaller than with IV HUCBC (p < 0.05). Nevertheless, IM, IA, and IV HUCBC all produced significant reductions in infarct size in comparison with Isolyte-treated infarcted hearts without requirements for host immune suppression. The present experiments demonstrate that the optimal dose of HUCBC for reduction of infarct size in the rat is 4 x 10(6) IM, 4 x 10(6) IA, and 16 x 10(6) IV, and that the IM injection of HUCBC is the most effective technique for reduction in infarct size.

Stem cells and cardiac repair: a critical analysis

Utilizing stem cells to repair the damaged heart has seen an intense amount of activity over the last 5 years or so. There are currently multiple clinical studies in progress to test the efficacy of various different cell therapy approaches for the repair of damaged myocardium that were only just beginning to be tested in preclinical animal studies a few years earlier. This rapid transition from preclinical to clinical testing is striking and is not typical of the customary timeframe for the progress of a therapy from bench-to-bedside. Doubtless, there will be many more trials to follow in the upcoming years. With the plethora of trials and cell alternatives, there has come not only great enthusiasm for the potential of the therapy, but also great confusion about what has been achieved. Cell therapy has the potential to do what no drug can: regenerate and replace damaged tissue with healthy tissue. Drugs may be effective at slowing the progression of heart failure, but none can stop or reverse the process. However, tissue repair is not a simple process, although the idea on its surface is quite simple. Understanding cells, the signals that they respond to, and the keys to appropriate survival and tissue formation are orders of magnitude more complicated than understanding the pathways targeted by most drugs. Drugs and their metabolites can be monitored, quantified, and their effects correlated to circulating levels in the body. Not so for most cell therapies. It is quite difficult to measure cell survival except through ex vivo techniques like histological analysis of the target organ. This makes the emphasis on preclinical research all the more important because it is only in the animal studies that research has the opportunity to readily harvest the target tissues and perform the detailed analyses of what has happened with the cells. This need for detailed and usually time-intensive research in animal studies stands in contrast to the rapidity with which therapies have progressed to the clinic. It is now becoming clear through a number of notable examples that progress to the clinic may have occurred too quickly, before adequate testing and independent verification of results could be completed (Check, Nature 446:485-486, 2007; Chien, J Clin Investig 116:1838-1840, 2006; Giles, Nature 442:344-347, 2006). Broad reproducibility and transfer of results from one lab to another has been and always will be essential for the successful application of any cell therapy. So, what is the prognosis for cell therapy to repair heart damage? Will there be an approved cell therapy, or multiple ones, or will it require combinations of more than one cell type to be successful? These are questions often asked. The answers are difficult to know and even more difficult to predict because there are so many variables associated with cell-based therapies. There is much about the biology of cell systems that we still do not understand. Much of the pluripotency or transdifferentiation phenomena (see below) being observed go against accepted and well-tested principles for cell development and fate choice, and has caused a reevaluation of long-accepted theories. Clearly, new pathways for tissue repair and regeneration have been uncovered, but will these new pathways be sufficient to effect significant tissue repair and regeneration? Despite the false starts so far, there is the strong likelihood one or possibly multiple cell therapies will succeed. Clearly, important information has been gained, which should better guide the field to achieving success. When there is the successful verification in patients of a cell therapy, there will be an explosion of technological advances around the approach(es) that succeed. Whatever cells get approved accompanying them will be: more effective delivery methods; growth and storage methods; combination therapies, mixes of cells or cells + gene therapies; combinations with biomaterials and technologies for immune protection, allowing allografting. There are many parallel paths of technology development waiting to be brought together once there is an effective cellular approach. The coming years will no doubt bring some exciting developments.

Association between a cell-seeded collagen matrix and cellular cardiomyoplasty for myocardial support and regeneration

The objective of cellular cardiomyoplasty is to regenerate the myocardium using implantation of living cells. Because the extracellular myocardial matrix is deeply altered in ischemic cardiomyopathies, it could be important to create a procedure aiming at regenerating both myocardial cells and the extracellular matrix. We evaluated the potential of a collagen matrix seeded with cells and grafted onto infarcted ventricles. A myocardial infarction was created in 45 mice using coronary artery ligation. Animals were randomly assigned to 4 local myocardial treatment groups. Group I underwent sham treatment (injection of cell culture medium). Group II underwent injection of human umbilical cord blood mononuclear cells (HUCBCs). Group III underwent injection of HUCBCs and fixation onto the epicardium of a collagen matrix seeded with HUCBCs. Group IV underwent fixation of collagen matrix (without cells) onto the infarct. Echocardiography was performed on postoperative days 7 and 45, followed by histological studies. Echocardiography showed that the association between the cell-loaded matrix and the intrainfarct cell implants was the most efficient approach to limiting postischemic ventricular dilation and remodeling. Ejection fraction improved in both cell-treated groups. The collagen matrix alone did not improve left ventricular (LV) function and remodeling. Histology in Group III showed fragments of the collagen matrix thickening and protecting the infarct scars. Segments of the matrix were consistently aligned along the LV wall, and cells were assembled within the collagen fibers in large populations. Intramyocardial injection of HUCBCs preserves LV function following infarction. The use of a cell-seeded matrix combined with cell injections prevents ventricular wall thinning and limits postischemic remodeling. This tissue engineering approach seems to improve the efficiency of cellular cardiomyoplasty and could emerge as a new therapeutic tool for the prevention of adverse remodeling and progressive heart failure.

The potential of umbilical cord blood multipotent stem cells for nonhematopoietic tissue and cell regeneration

Stem cells have been isolated from human embryos, fetal tissue, umbilical cord blood (UCB), and also from "adult" sources. Adult stem cells are found in many tissues of the body and are capable of maintaining, generating, and replacing terminally differentiated cells. A source of pluripotent stem cells has been recently identified in UCB that can also differentiate across tissue lineage boundaries into neural, cardiac, epithelial, hepatocytic, and dermal tissue. Thus, UCB may provide a future source of stem cells for tissue repair and regeneration. Its widespread availability makes UCB an attractive source for tissue regeneration. UCB-derived stem cells offer multiple advantages over adult stem cells, including their immaturity, which may play a significant role in reduced rejection after transplantation into a mismatched host and their ability to produce larger quantities of homogenous tissue or cells. While research with embryonic stem cells continues to generate considerable controversy, human umbilical stem cells provide an alternative cell source that has been more ethically acceptable and appears to have widespread public support. This review will summarize the in vitro and in vivo studies examining UCB stem cells and their potential use for therapeutic application for nonhematopoietic tissue and cell regeneration.

The potential of cord blood stem cells for use in regenerative medicine

It is estimated that up to 128 million individuals might benefit from regenerative medicine therapy, or almost 1 in 3 individuals in the US. If accurate, the need to relieve suffering and reduce healthcare costs is an enormous motivator to rapidly bring stem cell therapies to the clinic. Unfortunately, embryonic stem (ES) cell therapies are limited at present by ethical and political constraints and, most importantly, by significant biologic hurdles. Thus, for the foreseeable future, the march of regenerative medicine to the clinic will depend on the development of non-ES cell therapies. At present, non-ES cells easily available in large numbers can be found in the bone marrow, adipose tissue and umbilical cord blood (CB). Each of these stem cells is being used to treat a variety of diseases. This review shows that CB contains multiple populations of pluripotent stem cells, and can be considered the best alternative to ES cells. CB stem cells are capable of giving rise to hematopoietic, epithelial, endothelial and neural tissues both in vitro and in vivo. Thus, CB stem cells are amenable to treat a wide variety of diseases including cardiovascular, ophthalmic, orthopedic, neurologic and endocrine diseases.

UC blood-derived mesenchymal stromal cells: an overview

The UC is a readily available source of blood that may be used for analysis and treatment. Some authors suggest that within the UC blood (UCB) are cells with potential for differentiation down mesenchymal lineages. Isolation and characterization of these cells has been accomplished in some centers. Differentiation of these cells down multiple lineages has been documented. Surface marker expression and gene expression profiling has been performed, and mesenchymal stromal cells (MSC) from BM and adipose tissue have been compared with those derived from UCB. The use of UCB-derived stem cells has been investigated in pre-clinical studies. As this field is rapidly advancing, this review summarizes the current state of our knowledge of MSC derived from UCB.

Combined therapy with human cord blood cell transplantation and basic fibroblast growth factor delivery for treatment of myocardial infarction

BACKGROUND

Transplanting cord blood-derived cells has been shown to augment neovascularization in ischaemic tissue.

AIM

To test whether sustained delivery of basic fibroblast growth factor (bFGF) enhances the efficacy of angiogenic cord blood mononuclear cell (CBMNC) transplantation therapy in treating myocardial infarction.

METHODS

Three weeks after myocardial infarction, Sprague-Dawley rats were randomised to either injection of medium only (control), CBMNC transplantation, sustained bFGF delivery, or combined CBMNC transplantation and sustained bFGF delivery. Six weeks after treatment, tissue formation, neovascularization, and apoptotic activity in the infarct regions were evaluated by histology and immunohistochemistry. Left ventricular (LV) dimensions and function were evaluated by magnetic resonance imaging.

RESULTS

Combined bFGF delivery and CBMNC transplantation significantly enhanced neovascularization in the ischaemic myocardium, as compared with either therapy alone. The enhanced neovascularization was likely due to increased VEGF and bFGF expression. The combined therapy also exhibited a reduced infarct area and apoptosis in the ischaemic myocardium, as compared with either individual therapy. The combined therapy did not attenuate LV dilation or increase ejection fraction significantly over either individual therapy.

CONCLUSION

This study demonstrates that sustained bFGF delivery enhances the angiogenic efficacy of CBMNC transplantation in rat myocardial infarction models.

A hypothesis for an embryonic origin of pluripotent Oct-4(+) stem cells in adult bone marrow and other tissues

Accumulating evidence demonstrates that adult tissues contain a population of stem cells that express early developmental markers such as stage-specific embryonic antigen and transcription factors Oct-4 and Nanog. These are the markers characteristic for embryonic stem cells, epiblast stem cells and primordial germ cells. The presence of these stem cells in adult tissues including bone marrow, epidermis, bronchial epithelium, myocardium, pancreas and testes supports the concept that adult tissues contain some population of pluripotent stem cells that is deposited in embryogenesis during early gastrulation. In this review we will discuss these data and present a hypothesis that these cells could be direct descendants of the germ lineage. The germ lineage in order to pass genes on to the next generations creates soma and thus becomes a 'mother lineage' for all somatic cell lineages present in the adult body.

Intracoronary delivery of umbilical cord blood derived unrestricted somatic stem cells is not suitable to improve LV function after myocardial infarction in swine

Regeneration of infarcted myocardium by injecting stem cells has been proposed to prevent heart failure. We studied the i.c. administration of human umbilical cord blood stem cells (USSC) in a porcine model of myocardial infarction (MI) and reperfusion. In 15 swine, MI was induced by balloon-occlusion of the left circumflex coronary artery (LCX) for 2 h followed by reperfusion. Five swine served as healthy controls. One week later, magnetic resonance imaging (MRI) was performed to assess left ventricular (LV) function and infarct size. Then, under immune suppression, 6 of the 12 surviving MI swine received intracoronary injection of approximately 10(8) human USSC in the LCX while the other MI-swine received medium. Four weeks later all swine underwent follow-up MRI, and were sacrificed for histology. One week after MI, end-diastolic volume (92+/-3 mL) and LV mass (75+/-2 g) were larger, while ejection fraction (42+/-2%) was smaller than in healthy control (68+/-3 mL, 66+/-3 g and 55+/-3%, all P<0.05). Regional wall thickening (-7+/-2%) in the LCX area became akinetic. No difference in global and regional LV function at 5 weeks was observed between MI animals receiving USSC or medium. Infarct size after USSC treatment was significantly larger (20+/-3 g vs. 8+/-2 g, P<0.05). USSC survived only in the infarct border zone at 5 weeks and did not express cardiomyocyte or endothelial markers. Histology showed that intracoronary injection of USSC caused micro infarctions by obstructing blood vessels. In swine with a 1 week old MI, injection of USSC via the intracoronary route does not improve LV function 4 weeks later.

Human umbilical cord blood progenitor cells are attracted to infarcted myocardium and significantly reduce myocardial infarction size

We are investigating the effects of human umbilical cord blood mononuclear progenitor cells (HUCBC) for the treatment of acute myocardial infarction because human cord blood is a readily available and an abundant source of primitive cells that may be beneficial in myocardial repair. However, there is currently no scientific consensus on precisely when to inject stem/progenitor cells for the optimal treatment of acute myocardial infarction. We used an in vitro assay to determine the attraction of infarcted rat myocardium at 1, 2, 2.5, 3, 6, 12, 24, 48, and 96 h after left anterior descending coronary artery (LAD) occlusion from 45 rats for HUCBC in order to determine the optimal time to transplant HUCBC after myocardial infarction. Our assay is based on the migration of fluorescent DAPI-labeled HUCBC from wells in an upper chamber of a modified Boyden apparatus through a semiporous polycarbonate membrane into wells in a lower chamber that contain either normal or infarcted myocardium. DAPI-labeled HUCBC (100,000) were placed in each of the separate wells above the membrane that corresponded to normal or infarct homogenate in the lower wells. The greatest HUCBC migration to infarcted myocardium occurred at 2 h and 24 h after LAD occlusion in comparison with normal controls. A total of 76,331 +/- 3384 HUCBC migrated to infarcted myocardium at 2 h and 69,911 +/- 2732 at 24 h after LAD occlusion (both p < 0.001) and significantly exceeded HUCBC migration to normal heart homogenate. The HUCBC migration remained greatest at 2 and 24 h after LAD occlusion when the number of migrated cells was adjusted for the size of each myocardial infarction. Injection of 106 HUCBC in saline into infarcted myocardium of non immunosuppressed rats within 2 h (n=10) or at 24 h (n=5) after LAD occlusion resulted in infarction sizes 1 month later of 6.4 +/- 0.01% and 8.4 +/- 0.02% of the total left ventricular muscle area, respectively, in comparison with infarction sizes of 24.5 +/- 0.02% (n=10) in infarcted rat hearts treated with only saline (p < 0.005). Acute myocardial infarction in rats treated with only saline increased the myocardial concentration of tumor necrosis factor-alpha (TNF-alpha) from 6.9 +/- 0.8% to 51.3 +/- 4.6%, monocyte/macrophage chemoattractant protein (MCP-1) from 10.5 +/- 1.1% to 39.2 +/- 2.0%, monocyte inflammatory protein (MIP) from 10.6 +/- 1.6% to 23.1 +/- 1.5%, and interferon-gamma (INF-gamma) from 8.9 +/- 0.3% to 25.0 +/- 1.7% between 2 and 12 h after coronary occlusion in comparison with known controls (all p < 0.001). In contrast, the myocardial concentrations of these cytokines in rat hearts treated with HUCBC did not significantly change from the controls at 2, 6, 12, and 24 h after coronary occlusion. The present investigations suggest that infarcted myocardium significantly attracts HUCBC, that HUCBC can substantially reduce myocardial infarction size, and that HUCBC can limit the expression of TNF-alpha, MCP-1, MIP, and INF-gamma in acutely infarcted myocardium.

The future of cell therapy for myocardial regeneration

There are a number of promising cell therapy products under development for the treatment of heart failure, whether due to myocardial infarction or cardiomyopathy. Looking forward beyond current products in development, there are a multitude of possibilities that hold significant promise; however, cell-based therapies present challenges that are unique to this platform. Results from transplant studies can often be misleading and need to be interpreted in the context of fundamental biologic properties of cells and development. Provided here is a summary of the current and future developments in the field of cell therapy for cardiac regeneration along with some critical insights to interpret the multitude of studies recently undertaken. Summarized are both clinical and preclinical studies that should serve as a useful entrée into this exciting new field of therapeutic development.

Comparison of intracardiac cell transplantation: autologous skeletal myoblasts versus bone marrow cells

An increasing number of patients living with cardiovascular disease (CVD) and still unacceptably high mortality created an urgent need to effectively treat and prevent disease-related events. Within the past 5 years, skeletal myoblasts (SKMBs) and bone marrow (or blood)-derived mononuclear cells (BMNCs) have demonstrated preclinical efficacy in reducing ischemia and salvaging already injured myocardium, and in preventing left ventricular (LV) remodeling, respectively. These findings have been translated into clinical trials, so far totaling over 200 patients for SKMBs and over 800 patients for BMNCs. These safety/feasibility and early phase II studies showed promising but somewhat conflicting symptomatic and functional improvements, and some safety concerns have arisen. However, the patient population, cell type, dose, time and mode of delivery, and outcome measures differed, making comparisons problematic. In addition, the mechanisms through which cells engraft and deliver their beneficial effects remain to be fully elucidated. It is now time to critically evaluate progress made and challenges encountered in order to select not only the most suitable cells for cardiac repair but also to define appropriate patient populations and outcome measures. Reiterations between bench and bedside will increase the likelihood of cell therapy success, reduce the time to development of combined of drug- and cell-based disease management algorithms, and offer these therapies to patients to achieve a greater reduction of symptoms and allow for a sustained improvement of quality of life.

Bone marrow-derived very small embryonic-like stem cells: Their developmental origin and biological significance

Data from our and other laboratories provide evidence that bone marrow (BM) contains a population of stem cells that expresses early developmental markers such as (1) stage-specific embryonic antigen (SSEA) and (2) transcription factors Oct-4 and Nanog. These are the markers characteristic for embryonic stem cells, epiblast stem cells, and primordial germ cells (PGC). The presence of these stem cells in adult BM supports the concept that this organ contains some population of pluripotent stem cells that is deposited in embryogenesis during early gastrulation. We hypothesize that these cells could be direct descendants of the germ lineage that, to pass genes on to the next generations, has to create soma and, thus, becomes a "mother lineage" for all somatic cell lineages present in the adult body. Germ potential is established after conception in totipotent zygotes and retained in blastomeres of morula, cells from the inner cell mass of blastocyst, epiblast, and population of PGC. We will present a concept that SSEA(+) Oct-4(+) Nanog(+) cells identified in BM could be descendants of epiblast cells as well as some rare migrating astray PGC.

Stem Cells in Cell Transplantation

This commentary documents the increased number of stem cell-related research reports recently published in the cell transplantation field in the journal Cell Transplantation. The journal covers a wide range of issues in cell-based therapy and regenerative medicine and is attracting clinical and preclinical articles from around the world. It thereby complements and extends the basic coverage of stem cell physiology reported in Stem Cells and Development. Sections in Cell Transplantation cover neuroscience, diabetes, hepatocytes, bone, muscle, cartilage, skin, vessels, and other tissues, as well as tissue engineering that employs novel methods with stem cells. Clearly, the continued use of biomedical engineering will depend heavily on stem cells, and these two journals are well positioned to provide comprehensive coverage of these developments.

Enhancement of angiogenic efficacy of human cord blood cell transplantation

We tested the hypotheses that angiogenic efficacy of cord blood mononuclear cell (CBMNC) transplantation would be enhanced by using matrix and that combined therapy of CBMNC transplantation using matrix and sustained delivery of basic fibroblast growth factor (bFGF) would be synergistic in angiogenesis induction in ischemic limbs. One day after surgical induction of hindlimb ischemia, C57BL/6J mice were randomized to receive either medium injection, CBMNC transplantation using medium, CBMNC transplantation using fibrin matrix, sustained delivery of bFGF, or a combination of sustained delivery of bFGF and CBMNC transplantation using fibrin matrix. Four weeks after treatment, the angiogenic efficacy of the treatments was evaluated by immunohistochemical examinations and microvessel density determination in the ischemic sites. Transplanted CBMNCs survived, proliferated, and participated in capillary formation in ischemic limbs. CBMNC transplantation using fibrin matrix significantly increased the densities of capillaries and arterioles compared with CBMNC transplantation using medium. Importantly, combined therapy of sustained delivery of bFGF and CBMNC transplantation using fibrin matrix further increased the densities of capillaries and arterioles compared with either therapy alone. The angiogenic efficacy of angiogenic cell transplantation is enhanced by cell transplantation using matrix. Combined therapy of sustained release of angiogenic protein and angiogenic cell transplantation synergistically enhances angiogenesis in ischemic limbs compared to each therapy separately.

From cardiac repair to cardiac regeneration – ready to translate?

Cardiovascular disease is a major public health challenge in the western world. Mortality of acute events has improved, but more patients develop HF--a condition affecting up to 22 million people worldwide. Cell transplantation is the first therapy to attempt replacement of lost cardiomyocytes and vasculature to restore lost contractile function. Since the first reported functional repair after injection of autologous skeletal myoblasts into the injured heart in 1998, a variety of cell types have been proposed for transplantation in different stages of cardiovascular disease. Fifteen years of preclinical research and the rapid move into clinical studies have left us with promising results and a better understanding of cells as a potential clinical tool. Cell-based cardiac repair has been the first step, but cardiac regeneration remains the more ambitious goal. Promising new cell types and the rapidly evolving concept of adult stem and progenitor cell fate may enable us to move towards regenerating viable and functional myocardium. Meeting a multidisciplinary consensus will be required to translate these findings into safe and applicable clinical tools.

Transplantation of a novel cell line population of umbilical cord blood stem cells ameliorates neurological deficits associated with ischemic brain injury

Umbilical cord blood (UCB) is a rich source of hematopoetic stem cells (HSCs). We have isolated a novel cell line population of stem cells from human UCB that exhibit properties of self-renewal, but do not have cell-surface markers that are typically found on HSCs. Analysis of transcripts revealed that these cells express transcription factors Oct-4, Rex-1, and Sox-2 that are typically expressed by stem cells. We refer to these novel cells as nonhematopoietic umbilical cord blood stem cells (nh-UCBSCs). Previous studies have shown that the intravenous infusion of UCBCs can ameliorate neurological deficits arising from ischemic brain injury. The identity of the cells that mediate this restorative effect, however, has yet to be determined. We postulate that nh-UCBSCs may be a source of the UCB cells that can mediate these effects. To test this hypothesis, we intravenously injected one million human nh-UCBSCs into rats 48 h after transient unilateral middle cerebral artery occlusion. Animals in other experimental groups received either saline injections or injections of RN33b neural stem cells. Animals were tested for neurological function before the infusion of nh-UCBSCs and at various time periods afterwards using a battery of behavioral tests. In limb placement tests, animals treated with nh-UCBSCs exhibited mean scores that were significantly better than animals treated with RN33b neural stem cells or saline. Similarly, in stepping tests, nh-UCBSC-treated animals again exhibited significantly better performance than the other experimental groups of animals. Analysis of infarct volume revealed that ischemic animals treated with nh-UCBSCs exhibited a 50% reduction in lesion volume in comparison to saline-treated controls. Histological analysis of brain tissue further revealed the presence of cells that stained for human nuclei. Some human nuclei-positive cells were also co-labeled for NeuN, indicating that the transplanted cells expressed markers of a neuronal phenotype. Cells expressing the human nuclei marker within the brain, however, were rather scant, suggesting that the restorative effects of nh-UCBSCs may be mediated by mechanisms other than cell replacement. To test this hypothesis, nh-UCBSCs were directly transplanted into the brain parenchyma after ischemic brain injury. Sprouting of nerve fibers from the nondamaged hemisphere into the ischemically damaged side of the brain was assessed by anterograde tracing using biotinylated dextran amine (BDA). Animals with nh-UCBSC transplants exhibited significantly greater densities of BDA-positive cells in the damaged side of the brain compared to animals with intraparenchymal saline injections. These results suggest that restorative effects observed with nh-UCBSC treatment following ischemic brain injury may be mediated by trophic actions that result in the reorganization of host nerve fiber connections within the injured brain.

Human Umbilical Cord Blood-Derived CD133+Cells Enhance Function and Repair of the Infarcted Myocardium

The use of adult stem cells for myocardial tissue repair might be limited in elderly and sick people because their cells are depleted and exhausted. The present study was conducted to explore the potential of human umbilical cord blood (UCB) CD133+ progenitor cells for myocardial tissue repair in a model of extensive myocardial infarction (MI). CD133+ progenitor cells were isolated from newborn UCB. Cells (1.2-2 x 10(6)) or saline (control) was infused intravenously 7 days after permanent coronary artery ligation in athymic nude rats. Left ventricular (LV) function was assessed before and 1 month after infusion by echocardiography. Tracking of human cells was performed by fluorescent in situ hybridization for human X and Y chromosomes or by immunostaining for HLA-DR or HLA-ABC. One month after delivery, LV fractional shortening improved by 42 +/- 17% in cell-treated hearts and decreased by 39 +/- 10% in controls (p = .001). Anterior wall thickness decreased significantly in controls but not in treated hearts. Microscopic examination revealed that the UCB cells were able to migrate, colonize, and survive in the infarcted myocardium. Human cells were identified near vessel walls and LV cavity and were occasionally incorporated into endothelial cells in six of nine cell-treated animals but not in controls. Scar tissue from cell-treated animals was significantly populated with autologous myofibroblasts as indicated by colocalization of HLA-DR and alpha-smooth muscle actin staining. In conclusion, the present work suggests that, after MI, intravenous delivery of human UCB-derived CD133+ cells can produce functional recovery by preventing scar thinning and LV systolic dilatation.

Fibroblast growth factor-4 and hepatocyte growth factor induce differentiation of human umbilical cord blood-derived mesenchymal stem cells into hepatocytes

AIM

To investigate the differentiation of human umbilical cord blood (HUCB)-derived mesenchymal stem cells (MSCs) into hepatocytes by induction of fibroblast growth factor-4 (FGF-4) and hepatocyte growth factor (HGF), and to find a new source of cell types for therapies of hepatic diseases.

METHODS

MSCs were isolated by combining gradient density centrifugation with plastic adherence. When HUCB-derived MSCs reached 70% confluence, they were cultured in Iscove modified Dulbecco medium (IMDM) supplemented with 10 mL/L FBS, 20 ng/mL HGF and 10 ng/mL FGF-4. The medium was changed every 4 d and stored for albumin, alpha-fetoprotein (AFP) and urea assay. Expression of CK-18 was detected by immunocytochemistry. Glycogen storage in hepatocytes was determined by PAS staining.

RESULTS

By combining gradient density centrifugation with plastic adherence, we could isolate MSCs from 25.6% of human umbilical cord blood. When MSCs were cultured with FGF-4 and HGF, approximately 63.6% of cells became small, round and epithelioid on d 28 by morphology. Compared with the control, the level of AFP increased significantly from d 12 to 18.20+/-1.16 microg/L (t = 2.884, P<0.05) in MSCs cultured with FGF-4 and HGF, and was higher (54.28+/-3.11 microg/L) on d 28 (t = 13.493, P<0.01). Albumin increased significantly on d 16 (t = 6.68, P<0.01) to 1.02+/-0.15 microg/mL, and to 3.63+/-0.30 microg/mL on d 28 (t = 11.748, P<0.01). Urea (4.72+/-1.03 micromol/L) was detected on d 20 (t = 4.272, P<0.01), and continued to increase to 10.28+/-1.06 micromol/L on d 28 (t = 9.276, P<0.01). Cells expressed CK-18 on d 16. Glycogen storage was observed on d 24.

CONCLUSION

HUCB-derived MSCs can differentiate into hepatocytes by induction of FGF-4 and HGF. HUCB-derived MSCs are a new source of cell types for cell transplantation therapy of hepatic diseases.

Anti-inflammatory effects of human cord blood cells in a rat model of stroke

When human umbilical cord blood cells (HUCBCs) are administered intravenously after a middle cerebral artery occlusion, they reliably produce behavioral and anatomical recovery, and protect neural tissue from progressive change. However, our results indicate that the cells do not exert their effects by engraftment in the peri-infarct region, even though they migrate to the site of injury. The objective of the present study was to determine if the cells induce recovery by decreasing inflammation. We used a combination of in vivo and in vitro studies to show that HUCBCs decrease inflammation in the brain after stroke and thereby enhance neuroprotection. After stroke and transplantation, there was a decrease in CD45/CD11b- and CD45/B220-positive (+) cells. This decrease was accompanied by a decrease in mRNA and protein expression of pro-inflammatory cytokines and a decrease in nuclear factor kappaB (NF-kappaB) DNA binding activity in the brain of stroke animals treated with HUCBCs. In addition to modulating the inflammatory response, we demonstrate that the cord blood cells increase neuronal survival through non-immune mechanisms. Once thought of as "cell replacement therapy," we now propose that cord blood treatment in stroke reduces inflammation and provides neuroprotection. Both of these components are necessary for effective therapy.

Human umbilical cord blood cells: a new alternative for myocardial repair?

Cell therapy for myocardial disease is a rapidly progressive field. However, present strategies of cell transplantation into the infarcted myocardium have limitations from practical points of view. One of the biggest challenges is to achieve a sufficient number of suitable cells. Umbilical cord blood (UCB), an unlimited source of stem/progenitor cells that could be used for transplantation into the injured heart, is readily available. The aim of our review is to describe the potential and prospect of UCB as a new supplier of cells for myocardial repair. The use of UCB stem cells might be of importance to elderly and sick people in whom the availability of autologous stem cells is limited.

Cell Therapy for Heart Failure—Muscle, Bone Marrow, Blood, and Cardiac-Derived Stem Cells

Heart failure (HF) affects a rapidly growing population of patients. Despite improvements in the understanding and therapy of many stages of cardiovascular disease, there has been little progress in treating HF. In the late-stage disease, current options are cardiac transplantation and mechanical support--options that are limited to a small patient collective. The ischemically injured failing heart lacks contractile myocardium, functional vasculature, and electrical integrity, which has made treatment of the underlying injury untenable in the past. Restoring all of these components seems an overwhelming challenge. Yet, the concept of cell therapy--tissue repair by transplantation of stem and progenitor cells--has opened new potential options for patients with heart failure. Skeletal myoblasts, bone marrow, and blood-derived stem cells have all shown considerable myogenic and angiogenic potential in vitro and have rapidly moved from bench to bedside. A number of nonrandomized, non-placebo-controlled safety and feasibility studies have been reported and now double-blinded randomized controlled trials are underway. Despite this rapid clinical pace, the exact mechanisms underlying the functional benefits of different cell types are not well understood. Instead, multiple similar mechanism have been ascribed to virtually every cell type. Thus, while the field is exciting and offers unheralded promise to treat patients with CVD, we must proceed with due diligence and caution. Only a deep understanding of the benefits versus the risks, and the mechanisms involved in cell-mediated cardiac repair, will allow us to design clinically valuable tools and fulfill the potential of this exciting 21st century approach to treating cardiovascular disease.

Gene Therapy Progress and Prospects: In tissue engineering

Tissue engineering (TE) has existed for several years as an area spanning many disciplines, including medicine and engineering. The use of stem cells as a biological basis for TE coupled with advances in materials science has opened up an entirely new chapter in medicine and holds the promise of major contributions to the repair, replacement and regeneration of damaged tissues and organs. In this article, we review the spectrum of stem cells and scaffolds being investigated for their potential applications in medicine.

Transplantation of Human Umbilical Cord Blood Cells Benefits an Animal Model of Sanfilippo Syndrome Type B

Sanfilippo syndrome type B is caused by alpha-N-acetylglucosaminidase (Naglu) enzyme deficiency leading to an accumulation of undegraded heparan sulfate, a glycosaminoglycan (GAG). Cell therapy is a promising new treatment and human umbilical cord blood (hUCB) cell transplantation may be preferred for delivery of the missing enzyme. We investigated the ability of mononuclear hUCB cells administered into the lateral cerebral ventricle to ameliorate/prevent histopathological changes in mice modeling Sanfilippo syndrome type B. These are the first results supporting enzyme replacement by administered hUCB cells. In vivo, transplanted hUCB cells survived long-term (7 months), migrated into the parenchyma of the brain and peripheral organs, expressed neural antigens, and exhibited neuron and astrocyte-like morphology. Transplant benefits were also demonstrated by stable cytoarchitecture in the hippocampus and cerebellum, and by reduced GAGs in the livers of treated mutant mice. A hUCB cell transplant may be an effective therapeutic strategy for enzyme delivery in Sanfilippo syndrome type B.

Healing a broken heart with stem cells

We discuss here the rapid progress of stem cell therapy in myocardial infarction. In particular, we focus on the issue of transdifferentiation as a "hallmark" of the stem cell's potential to replace damaged cells of the heart. A study by Henning and colleagues in this issue of Cell Transplantation supports the alternative notion of a nontransdifferentiation-mediated protection of the heart as an equally robust mechanism underlying the therapeutic potential of stem cells.