Clinical applications of blood-derived and marrow-derived stem cells for nonmalignant diseases

Crawling from soft to stiff matrix polarizes the cytoskeleton and phosphoregulates myosin-II heavy chain

Cytoskeletal polarization occurs in response to mechanosensing of a transition from soft to stiff matrix during migration and promotes dephosphorylation of myosin-IIA, rearward localization of myosin-IIB, and durotaxis.

On rigid surfaces, the cytoskeleton of migrating cells is polarized, but tissue matrix is normally soft. We show that nonmuscle MIIB (myosin-IIB) is unpolarized in cells on soft matrix in 2D and also within soft 3D collagen, with rearward polarization of MIIB emerging only as cells migrate from soft to stiff matrix. Durotaxis is the tendency of cells to crawl from soft to stiff matrix, and durotaxis of primary mesenchymal stem cells (MSCs) proved more sensitive to MIIB than to the more abundant and persistently unpolarized nonmuscle MIIA (myosin-IIA). However, MIIA has a key upstream role: in cells on soft matrix, MIIA appeared diffuse and mobile, whereas on stiff matrix, MIIA was strongly assembled in oriented stress fibers that MIIB then polarized. The difference was caused in part by elevated phospho-S1943–MIIA in MSCs on soft matrix, with site-specific mutants revealing the importance of phosphomoderated assembly of MIIA. Polarization is thus shown to be a highly regulated compass for mechanosensitive migration.

Antiarrhythmic potential of mesenchymal stem cell is modulated by hypoxic environment

OBJECTIVES

The purpose of this study was to evaluate the antiarrhythmic potential of mesenchymal stem cells (MSC) under a different environment.

BACKGROUND

Little is known about how environmental status affects antiarrhythmic potential of MSCs.

METHODS

To investigate the effect of paracrine factors secreted from MSCs under different circumstances on arrhythmogenicity in rats with myocardial infarction, we injected paracrine media (PM) secreted under hypoxic, normoxic conditions (hypoxic PM and normoxic PM), and MSC into the border zone of infarcted myocardium in rats.

RESULTS

We found that the injection of hypoxic PM, but not normoxic PM, markedly restored conduction velocities, suppressed focal activity, and prevented sudden arrhythmic deaths in rats. Underlying this electrophysiological alteration was a decrease in fibrosis, restoration of connexin 43, alleviation of Ca(2+) overload, and recovery of Ca(2+)-regulatory ion channels and proteins, all of which is supported by proteomic data showing that several paracrine factors including basic fibroblast growth factor, insulinlike growth factor 1, hepatocyte growth factor, and EF-hand domain-containing 2 are potential mediators. When compared with PM, MSC injection did not reduce or prevent arrhythmogenicity, suggesting that the antiarrhythmic or proarrhythmic potential of MSC is mainly dependent on paracrine factors.

CONCLUSIONS

A hypoxic or normoxic environment surrounding MSC affects the type and properties of the growth factors or cytokines, and these secreted molecules determine the characteristics of the electro-anatomical substrate of the surrounding myocardium.

Hematopoietic stem cell transplantation for systemic lupus erythematosus

Two streams of research are at the origin of the utilization of hematopoietic stem cell transplantation (HSCT) for severe autoimmune diseases (SADs). The allogeneic approach came from experimental studies on lupus mice, besides clinical results in coincidental diseases. The autologous procedure was encouraged by researches on experimental neurological and rheumatic disorders. At present the number of allogeneic HSCT performed for human SADs can be estimated to not over 100 patients, and the results are not greatly encouraging, considering the significant transplant-related mortality (TRM) and the occasional development of a new autoimmune disorder and/or relapses notwithstanding full donor chimerism. Autologous HSCT for refractory SLE has become a major target. Severe cases have been salvaged, TRM is low and diminishing, and prolonged clinical remissions are obtainable. Two types of immune resetting have been established, "re-education" and regulatory T cell (Tregs) normalization. Allogeneic HSCT for SLE seems best indicated for patients with disease complicated by an oncohematologic malignancy. Autologous HSCT is a powerful salvage therapy for otherwise intractable SLE. The duration of remission in uncertain, but a favorable response to previously inactive treatments is a generally constant feature. The comparison with new biological agents, or the combination of both, are to be ascertained.

Mitotically inactivated embryonic stem cells can be used as an in vivo feeder layer to nurse damaged myocardium after acute myocardial infarction: a preclinical study

RATIONALE

Various types of viable stem cells have been reported to result in modest improvement in cardiac function after acute myocardial infarction. The mechanisms for improvement from different stem cell populations remain unknown.

OBJECTIVE

To determine whether irradiated (nonviable) embryonic stem cells (iESCs) improve postischemic cardiac function without adverse consequences.

METHODS AND RESULTS

After coronary artery ligation-induced cardiac infarction, either conditioned media or male murine or male human iESCs were injected into the penumbra of ischemic myocardial tissue of female mice or female rhesus macaque monkeys, respectively. Murine and human iESCs, despite irradiation doses that prevented proliferation and induced cell death, significantly improved cardiac function and decreased infarct size compared with untreated or media-treated controls. Fluorescent in situ hybridization of the Y chromosome revealed disappearance of iESCs within the myocardium, whereas 5-bromo-2'-deoxyuridine assays revealed de novo in vivo cardiomyocyte DNA synthesis. Microarray gene expression profiling demonstrated an early increase in metabolism, DNA proliferation, and chromatin remodeling pathways, and a decrease in fibrosis and inflammatory gene expression compared with media-treated controls.

CONCLUSIONS

As a result of irradiation before injection, ex vivo and in vivo iESC existence is transient, yet iESCs provide a significant improvement in cardiac function after acute myocardial infarction. The mechanism(s) of action of iESCs seems to be related to cell-cell exchange, paracrine factors, and a scaffolding effect between iESCs and neighboring host cardiomyocytes.

Regenerative pulmonary medicine: potential and promise, pitfalls and challenges

BACKGROUND

Chronic lung diseases contribute significantly to the morbidity and mortality of the population. There are few effective treatments for many chronic lung diseases, and even fewer therapies that can arrest or reverse the progress of the disease.

DESIGN

In this review, we present the current state of regenerative therapies for the treatment of chronic lung diseases. We focus on endothelial progenitor cells, mesenchymal stem cells, and endogenous lung stem/progenitor cells; summarize the work to date in models of lung diseases for each of these therapies; and consider their potential benefits and risks as viable therapies for patients with lung diseases.

CONCLUSIONS

Cell-based regenerative therapies for lung diseases offer great promise, with preclinical studies suggesting that the next decade should provide the evidence necessary for their ultimate application to our therapeutic armamentarium.

Transplantation for autoimmune diseases in north and South America: a report of the Center for International Blood and Marrow Transplant Research

Hematopoietic cell transplantation (HCT) is an emerging therapy for patients with severe autoimmune diseases (AID). We report data on 368 patients with AID who underwent HCT in 64 North and South American transplantation centers reported to the Center for International Blood and Marrow Transplant Research between 1996 and 2009. Most of the HCTs involved autologous grafts (n = 339); allogeneic HCT (n = 29) was done mostly in children. The most common indications for HCT were multiple sclerosis, systemic sclerosis, and systemic lupus erythematosus. The median age at transplantation was 38 years for autologous HCT and 25 years for allogeneic HCT. The corresponding times from diagnosis to HCT were 35 months and 24 months. Three-year overall survival after autologous HCT was 86% (95% confidence interval [CI], 81%-91%). Median follow-up of survivors was 31 months (range, 1-144 months). The most common causes of death were AID progression, infections, and organ failure. On multivariate analysis, the risk of death was higher in patients at centers that performed fewer than 5 autologous HCTs (relative risk, 3.5; 95% CI, 1.1-11.1; P = .03) and those that performed 5 to 15 autologous HCTs for AID during the study period (relative risk, 4.2; 95% CI, 1.5-11.7; P = .006) compared with patients at centers that performed more than 15 autologous HCTs for AID during the study period. AID is an emerging indication for HCT in the region. Collaboration of hematologists and other disease specialists with an outcomes database is important to promote optimal patient selection, analysis of the impact of prognostic variables and long-term outcomes, and development of clinical trials.

Haematopoietic SCT in severe autoimmune diseases: updated guidelines of the European Group for Blood and Marrow Transplantation

In 1997, the first consensus guidelines for haematopoietic SCT (HSCT) in autoimmune diseases (ADs) were published, while an international coordinated clinical programme was launched. These guidelines provided broad principles for the field over the following decade and were accompanied by comprehensive data collection in the European Group for Blood and Marrow Transplantation (EBMT) AD Registry. Subsequently, retrospective analyses and prospective phase I/II studies generated evidence to support the feasibility, safety and efficacy of HSCT in several types of severe, treatment-resistant ADs, which became the basis for larger-scale phase II and III studies. In parallel, there has also been an era of immense progress in biological therapy in ADs. The aim of this document is to provide revised and updated guidelines for both the current application and future development of HSCT in ADs in relation to the benefits, risks and health economic considerations of other modern treatments. Patient safety considerations are central to guidance on patient selection and HSCT procedural aspects within appropriately experienced and Joint Accreditation Committee of International Society for Cellular Therapy and EBMT accredited centres. A need for prospective interventional and non-interventional studies, where feasible, along with systematic data reporting, in accordance with EBMT policies and procedures, is emphasized.

Osteogenesis imperfecta and bone marrow transplant

The first attempted bone marrow transplant (BMT) dates back to 1896. In the following centuries, the medical community pioneered an ongoing progression of breakthroughs. In 1954 the first successful solid organ transplant, the kidney, was performed. In the 1960s advances led to the first successful lung, pancreas, liver and heart transplant and in 1973 the first successful BMT was achieved. BMT has traditionally been used to treat malignant diseases. However, scientific and technological progress has expanded its scope and today, BMT is used to treat a spectrum of diseases. While BMT is a complex procedure, the medical community expects that it will one day play a role in the treatment of other diseases. As the science evolves, it is essential that nurses educate themselves about these emerging transplant populations, one of which is children with osteogenesis impefecta. This manuscript will provide nurses with a critical background on the disease, a description of the transplant theory, and the implications for the nursing care of these children.

Role of pigment epithelium-derived factor in stem/progenitor cell-associated neovascularization

Pigment epithelium-derived factor (PEDF) was first identified in retinal pigment epithelium cells. It is an endogenously produced protein that is widely expressed throughout the human body such as in the eyes, liver, heart, and adipose tissue; it exhibits multiple and varied biological activities. PEDF is a multifunctional protein with antiangiogenic, antitumorigenic, antioxidant, anti-inflammatory, antithrombotic, neurotrophic, and neuroprotective properties. More recently, PEDF has been shown to be the most potent inhibitor of stem/progenitor cell-associated neovascularization. Neovascularization is a complex process regulated by a large, interacting network of molecules from stem/progenitor cells. PEDF is also involved in the pathogenesis of angiogenic eye disease, tumor growth, and cardiovascular disease. Novel antiangiogenic agents with tolerable side effects are desired for the treatment of patients with various diseases. Here, we review the value of PEDF as an important endogenous antiangiogenic molecule; we focus on the recently identified role of PEDF as a possible new target molecule to influence stem/progenitor cell-related neovascularization.

Regenerative medicine as applied to general surgery

The present review illustrates the state of the art of regenerative medicine (RM) as applied to surgical diseases and demonstrates that this field has the potential to address some of the unmet needs in surgery. RM is a multidisciplinary field whose purpose is to regenerate in vivo or ex vivo human cells, tissues, or organs to restore or establish normal function through exploitation of the potential to regenerate, which is intrinsic to human cells, tissues, and organs. RM uses cells and/or specially designed biomaterials to reach its goals and RM-based therapies are already in use in several clinical trials in most fields of surgery. The main challenges for investigators are threefold: Creation of an appropriate microenvironment ex vivo that is able to sustain cell physiology and function in order to generate the desired cells or body parts; identification and appropriate manipulation of cells that have the potential to generate parenchymal, stromal and vascular components on demand, both in vivo and ex vivo; and production of smart materials that are able to drive cell fate.

Gastrointestinal and hepatic complications of hematopoietic stem cell transplantation

Recognition and management of gastrointestinal and hepatic complications of hematopoietic stem cell transplantation has gained increasing importance as indications and techniques of transplantation have expanded in the last few years. The transplant recipient is at risk for several complications including conditioning chemotherapy related toxicities, infections, bleeding, sinusoidal obstruction syndrome, acute and chronic graft-versus-host disease (GVHD) as well as other long-term problems. The severity and the incidence of many complications have improved in the past several years as the intensity of conditioning regimens has diminished and better supportive care and GVHD prevention strategies have been implemented. Transplant clinicians, however, continue to be challenged with problems arising from human leukocyte antigen-mismatched and unrelated donor transplants, expanding transplant indications and age-limit. This review describes the most commonly seen transplant related complications, focusing on their pathogenesis, differential diagnosis and management.

Effect of transendocardial delivery of autologous bone marrow mononuclear cells on functional capacity, left ventricular function, and perfusion in chronic heart failure: the FOCUS-CCTRN trial

CONTEXT

Previous studies using autologous bone marrow mononuclear cells (BMCs) in patients with ischemic cardiomyopathy have demonstrated safety and suggested efficacy.

OBJECTIVE

To determine if administration of BMCs through transendocardial injections improves myocardial perfusion, reduces left ventricular end-systolic volume (LVESV), or enhances maximal oxygen consumption in patients with coronary artery disease or LV dysfunction, and limiting heart failure or angina.

DESIGN, SETTING, AND PATIENTS

A phase 2 randomized double-blind, placebo-controlled trial of symptomatic patients (New York Heart Association classification II-III or Canadian Cardiovascular Society classification II-IV) with a left ventricular ejection fraction of 45% or less, a perfusion defect by single-photon emission tomography (SPECT), and coronary artery disease not amenable to revascularization who were receiving maximal medical therapy at 5 National Heart, Lung, and Blood Institute-sponsored Cardiovascular Cell Therapy Research Network (CCTRN) sites between April 29, 2009, and April 18, 2011.

INTERVENTION

Bone marrow aspiration (isolation of BMCs using a standardized automated system performed locally) and transendocardial injection of 100 million BMCs or placebo (ratio of 2 for BMC group to 1 for placebo group).

MAIN OUTCOME MEASURES

Co-primary end points assessed at 6 months: changes in LVESV assessed by echocardiography, maximal oxygen consumption, and reversibility on SPECT. Phenotypic and functional analyses of the cell product were performed by the CCTRN biorepository core laboratory.

RESULTS

Of 153 patients who provided consent, a total of 92 (82 men; average age: 63 years) were randomized (n = 61 in BMC group and n = 31 in placebo group). Changes in LVESV index (-0.9 mL/m(2) [95% CI, -6.1 to 4.3]; P = .73), maximal oxygen consumption (1.0 [95% CI, -0.42 to 2.34]; P = .17), and reversible defect (-1.2 [95% CI, -12.50 to 10.12]; P = .84) were not statistically significant. There were no differences found in any of the secondary outcomes, including percent myocardial defect, total defect size, fixed defect size, regional wall motion, and clinical improvement.

CONCLUSION

Among patients with chronic ischemic heart failure, transendocardial injection of autologous BMCs compared with placebo did not improve LVESV, maximal oxygen consumption, or reversibility on SPECT.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00824005.

Granulocyte colony-stimulating factor and interleukin-1β are important cytokines in repair of the cirrhotic liver after bone marrow cell infusion: comparison of humans and model mice

We previously described the effectiveness of autologous bone marrow cell infusion (ABMi) therapy for patients with liver cirrhosis (LC). We analyzed chronological changes in 19 serum cytokines as well as levels of specific cytokines in patients after ABMi therapy and in a mouse model of cirrhosis generated using green fluorescent protein (GFP)/carbon tetrachloride (CCl4). We measured expression profiles of cytokines in serum samples collected from 13 patients before and at 1 day and 1 week after ABMi. Child-Pugh scores significantly improved in all of these patients. To analyze the meaning of early cytokine change, we infused GFP-positive bone marrow cells (BMCs) into mice with CCl4-induced LC and obtained serum and tissue samples at 1 day and as well as at 1, 2, 3, and 4 weeks later. We compared chronological changes in serum cytokine expression in humans and in the model mice at 1 day and 1 week after BMC infusion. Among 19 cytokine, both granulocyte colony-stimulating factor (G-CSF) and interleukin-1β(IL-1β) in serum was found to show the same chronological change pattern between human and mice model. Next, we examined changes in cytokine expression in cirrhosis liver before and at 1, 2, 3, and 4 weeks after BMC infusion. Both G-CSF and IL-1β were undetectable in the liver tissues before and at 1 week after BMC infusion but increased at 2 weeks and continued until 4 weeks after infusion. The infused BMCs induced an early decrease of both G-CSF and IL-1β in serum and an increase in the model mice with LC. These dynamic cytokine changes might be important to repair liver cirrhosis after BMC infusion.

Autologous stem cell therapy in the treatment of limb ischaemia induced chronic tissue ulcers of diabetic foot patients

BACKGROUND AND AIM

Despite improvements in surgical revascularisation, limitations like anatomical factors or atherosclerosis limit the success of revascularisation in diabetic patients with critical limb ischaemia. Stem cells were shown to improve microcirculation in published studies. The aim of this study was to evaluate safety, feasibility and efficacy of transplantation of bone marrow derived cellular products regarding improvement in microcirculation and lowering of amputation rate.

METHODS

Bone marrow mononuclear cells (BMCs) in comparison with expanded bone marrow cells enriched in CD90+ cells ('tissue repair cells', TRCs) were used in the treatment of diabetic ulcers to induce revascularisation. Diabetic foot patients with critical limb ischaemia without option for surgical or interventional revascularisation were eligible. Parameters examined were ABI, TcPO(2) , reactive hyperaemia and angiographic imaging before and after therapy.

RESULTS

Of 30 patients included in this trial, 24 were randomised to receive either BMCs or TRCs. The high number of drop-outs in the control group (4 of 6) led to exclusion from evaluation. A total of 22 patients entered treatment; one patient in the TRC group and two in the BMC group did not show wound healing during follow up, one patient in each treatment group died before reaching the end of the study; one after having achieved wound healing (BMC group), the other one without having achieved wound healing (TRC group). Thus, 18 patients showed wound healing after 45 weeks. The total number of applicated cells was 3.8 times lower in the TRC group, but TRC patients received significantly higher amounts of CD90+ cells. Improvement in microvascularisation was detected in some, but not all patients by angiography, TcPO(2) improved significantly compared with baseline in both therapy groups.

CONCLUSION

The transplantation of BMCs as well as TRCs proved to be safe and feasible. Improvements of microcirculation and complete wound healing were observed in the transplant groups.

Randomized, double-blind pilot study of transendocardial injection of autologous aldehyde dehydrogenase-bright stem cells in patients with ischemic heart failure

BACKGROUND

The optimal type of stem cell for use in patients with ischemic heart disease has not been determined. A primitive population of bone marrow-derived hematopoietic cells has been isolated by the presence of the enzyme aldehyde dehydrogenase and comprises a multilineage mix of stem and progenitor cells. Aldehyde dehydrogenase-bright (ALDH(br)) cells have shown promise in promoting angiogenesis and providing perfusion benefits in preclinical ischemia studies. We hypothesize that ALDH(br) cells may be beneficial in treating ischemic heart disease and thus conducted the first randomized, controlled, double-blind study to assess the safety of the transendocardial injection of autologous ALDH(br) cells isolated from the bone marrow in patients with advanced ischemic heart failure.

METHODS

Aldehyde dehydrogenase-bright cells were isolated from patients' bone marrow on the basis of the expression of a functional (aldehyde dehydrogenase) marker. We enrolled 20 patients (treatment, n = 10; control, n = 10). Safety (primary end point) and efficacy (secondary end point) were assessed at 6 months.

RESULTS

No major adverse cardiovascular or cerebrovascular events occurred in ALDH(br)-treated patients in the periprocedural period (up to 1 month); electromechanical mapping-related ventricular tachycardia (n = 2) and fibrillation (n = 1) occurred in control patients. Aldehyde dehydrogenase-bright-treated patients showed a significant decrease in left ventricular end-systolic volume at 6 months (P = .04) and a trend toward improved maximal oxygen consumption. The single photon emission computed tomography delta analysis showed a trend toward significant improvement in reversibility in cell-treated patients (P = .053).

CONCLUSIONS

We provide preliminary evidence that treatment with the novel cell population, ALDH(br) cells, is safe and may provide perfusion and functional benefits in patients with chronic myocardial ischemia.

Hematopoietic stem cell transplantation for systemic sclerosis: history and current status

PURPOSE OF REVIEW

Systemic sclerosis (SSc) remains one of the last severe autoimmune disease with a poor prognosis and modest response to immunosuppressive therapy. Mortality in severe diffuse disease with internal organ involvement is elevated. Autologous hematopoietic transplantation (HSCT) has emerged in the last decade as a promising disease-modifying treatment.

RECENT FINDINGS

In phase I/II trials, HSCT has demonstrated to induce impressive reversal of skin fibrosis, neoangiogenesis, improved functionality and quality of life, and stabilization of internal organ function. Treatment-related mortality was reduced over time by better pretransplant evaluation and by treating patients earlier in disease.

SUMMARY

Two out of three randomized trials of autologous HSCT for SSc have been concluded: the nonmyeloablative American Systemic Sclerosis Immune Suppression versus Transplant, and Autologous Stem cell Transplantation International Scleroderma. The myeloablative Scleroderma Cyclophosphamide versus Transplant instead is still recruiting patients. The soon expected results from these trials should clarify the role of autologous HSCT in the challenging management of severe SSc.

Role of heat shock proteins in stem cell behavior

Stress response is well appreciated to induce the expression of heat shock proteins (Hsps) in the cell. Numerous studies have demonstrated that Hsps function as molecular chaperones in the stabilization of intracellular proteins, repairing damaged proteins, and assisting in protein translocation. Various kinds of stem cells (embryonic stem cells, adult stem cells, or induced pluripotent stem cells) have to maintain their stemness and, under certain circumstances, undergo stress. Therefore, Hsps should have an important influence on stem cells. Actually, numerous studies have indicated that some Hsps physically interact with a number of transcription factors as well as intrinsic and extrinsic signaling pathways. Importantly, alterations in Hsp expression have been demonstrated to affect stem cell behavior including self-renewal, differentiation, sensitivity to environmental stress, and aging. This chapter summarizes recent findings related to (1) the roles of Hsps in maintenance of stem cell dormancy, proliferation, and differentiation; (2) the expression signature of Hsps in embryonic/adult stem cells and differentiated stem cells; (3) the protective roles of Hsps in transplanted stem cells; and (4) the possible roles of Hsps in stem cell aging.

Vascular progenitor cell mobilization

Blood vessel formation plays a key role in both physiologic and pathologic tissue growth and healing. Thus, a thorough understanding of the mechanisms underlying neovascularization will translate into innovative clinical treatment strategies for a wide variety of disease processes. Vascular precursor/progenitor cell populations have been isolated from several different tissue types and have a rich potential for use in vascular regenerative strategies. Furthermore, levels of circulating endothelial progenitor cells (EPC) have been shown to correlate with outcomes in cardiovascular and vascular diseases. Treatment with EPC has been shown to improve functional outcomes following cardiac and peripheral vascular ischemia. Recent studies have also demonstrated a role for EPC in pediatric disease processes such as retinopathy of prematurity and bronchopulmonary dysplasia. In addition, many of the drugs utilized to treat vascular disease impact EPC mobilization and function. Importantly, the type of vascular injury appears to dictate the mechanism of neovascularization, highlighting the importance of carefully selected vascular regenerative strategies.

TGF-β1 signaling and Krüppel-like factor 10 regulate bone marrow-derived proangiogenic cell differentiation, function, and neovascularization

Emerging evidence demonstrates that proangiogenic cells (PACs) originate from the BM and are capable of being recruited to sites of ischemic injury where they contribute to neovascularization. We previously determined that among hematopoietic progenitor stem cells, common myeloid progenitors (CMPs) and granulocyte-macrophage progenitor cells (GMPs) differentiate into PACs and possess robust angiogenic activity under ischemic conditions. Herein, we report that a TGF-β1-responsive Krüppel- like factor, KLF10, is strongly expressed in PACs derived from CMPs and GMPs, ∼ 60-fold higher than in progenitors lacking PAC markers. KLF10(-/-) mice present with marked defects in PAC differentiation, function, TGF-β responsiveness, and impaired blood flow recovery after hindlimb ischemia, an effect rescued by wild-type PACs, but not KLF10(-/-) PACs. Overexpression studies revealed that KLF10 could rescue PAC formation from TGF-β1(+/-) CMPs and GMPs. Mechanistically, KLF10 targets the VEGFR2 promoter in PACs which may underlie the observed effects. These findings may be clinically relevant because KLF10 expression was also found to be significantly reduced in PACs from patients with peripheral artery disease. Collectively, these observations identify TGF-β1 signaling and KLF10 as key regulators of functional PACs derived from CMPs and GMPs and may provide a therapeutic target during cardiovascular ischemic states.

Cell therapies for the central nervous system

PURPOSE OF REVIEW

Central to the obstacles to be overcome in moving promising cell-based therapies from the laboratory to the clinic is that of determining which of the many cell types being examined are optimal for repairing particular lesions.

RECENT FINDINGS

Our studies on astrocyte replacement therapies demonstrate clearly that some cells are far better than others at promoting recovery in spinal cord injury and that, at least in some cases, transplanting undifferentiated precursor cells is far less useful than transplanting specific astrocytes derived from those precursor cells. But further comparison between different approaches is hindered by the difficulties in replicating results between laboratories, even for well defined pharmacological agents and bioactive proteins. These difficulties in replication appear most likely to be due to unrecognized nuances in lesion characteristics and in the details of delivery of therapies.

SUMMARY

We propose that the challenge of reproducibility provides a critical opportunity for refining cell-based therapies. If the utility of a particular approach is so restricted that even small changes in lesions or treatment protocols eliminate benefit, then the variability inherent in clinical injuries will frustrate translation. In contrast, rising to this challenge may enable discovery of refinements needed to confer the robustness needed for successful clinical trials.

10 years of intracoronary and intramyocardial bone marrow stem cell therapy of the heart: from the methodological origin to clinical practice

Intracoronary and intramyocardial stem cell therapy aim at the repair of compromised myocardium thereby--as a causal treatment--preventing ventricular remodeling and improving overall performance. Since the first-in-human use of bone marrow stem cells (BMCs) after acute myocardial infarction in 2001, a large number of clinical studies have demonstrated their clinical benefit: BMC therapy can be performed with usual cardiac catheterization techniques in the conscious patient as well as also easily during cardiosurgical interventions. New York Heart Association severity degree of patients as well as physical activity improve in addition to ("on top" of) all other therapeutic regimens. Stem cell therapy also represents an ultimate approach in advanced cardiac failure. For acute myocardial infarction and chronic ischemia, long-term mortality after 1 and 5 years, respectively, is significantly reduced. A few studies also indicate beneficial effects for chronic dilated cardiomyopathy. The clinical use of autologous BMC therapy implies no ethical problems, when unmodified primary cells are used. With the use of primary BMCs, there are no major stem cell-related side effects, especially no cardiac arrhythmias and inflammation. Various mechanisms of the stem cell action in the human heart are discussed, for example, cell transdifferentiation, cell fusion, activation of intrinsic cardiac stem cells, and cytokine-mediated effects. New techniques allow point-of-care cell preparations, for example, within the cardiac intervention or operation theater, thereby providing short preparation time, facilitated logistics of cell transport, and reasonable cost effectiveness of the whole procedure. The 3 main indications are acute infarction, chronic ischemic heart failure, and dilated cardiomyopathy. Future studies are desirable to further elucidate the mechanisms of stem cell action and to extend the current use of intracoronary and/or intramyocardial stem cell therapy by larger and presumably multicenter and randomized trials.

Mesenchymal stem cells restore frataxin expression and increase hydrogen peroxide scavenging enzymes in Friedreich ataxia fibroblasts

Dramatic advances in recent decades in understanding the genetics of Friedreich ataxia (FRDA)--a GAA triplet expansion causing greatly reduced expression of the mitochondrial protein frataxin--have thus far yielded no therapeutic dividend, since there remain no effective treatments that prevent or even slow the inevitable progressive disability in affected individuals. Clinical interventions that restore frataxin expression are attractive therapeutic approaches, as, in theory, it may be possible to re-establish normal function in frataxin deficient cells if frataxin levels are increased above a specific threshold. With this in mind several drugs and cytokines have been tested for their ability to increase frataxin levels. Cell transplantation strategies may provide an alternative approach to this therapeutic aim, and may also offer more widespread cellular protective roles in FRDA. Here we show a direct link between frataxin expression in fibroblasts derived from FRDA patients with both decreased expression of hydrogen peroxide scavenging enzymes and increased sensitivity to hydrogen peroxide-mediated toxicity. We demonstrate that normal human mesenchymal stem cells (MSCs) induce both an increase in frataxin gene and protein expression in FRDA fibroblasts via secretion of soluble factors. Finally, we show that exposure to factors produced by human MSCs increases resistance to hydrogen peroxide-mediated toxicity in FRDA fibroblasts through, at least in part, restoring the expression of the hydrogen peroxide scavenging enzymes catalase and glutathione peroxidase 1. These findings suggest, for the first time, that stem cells may increase frataxin levels in FRDA and transplantation of MSCs may offer an effective treatment for these patients.

Mesenchymal Stromal Cells as a Therapeutic Strategy to Support Islet Transplantation in Type 1 Diabetes Mellitus

Type 1 diabetes is an autoimmune disorder that leads to destruction of pancreatic β islet cells and is a growing global health issue. While insulin replacement remains the standard therapy for type 1 diabetes, exogenous insulin does not mimic the physiology of insulin secretion. Transplantation of pancreatic islets has the potential to cure this disease; however, there are several major limitations to widespread implementation of islet transplants. The use of mesenchymal stromal cells (MSCs) in the treatment of type 1 diabetes has been investigated as an adjunct therapy during islet graft administration to prevent initial islet loss and promote engraftment and revascularization of islets. In this review we will discuss the results of recent MSC studies in animal models of diabetes with a focus on islet transplantation and explore the potential for these findings to be extended to clinical use for the treatment of type 1 diabetes.

Mesenchymal stem cells stimulate endogenous neurogenesis in the subventricular zone of adult mice

Mammalian neurogenesis has been demonstrated in the subventricular zone (SVZ) of the lateral ventricles and the subgranular zone (SGZ) of the dentate gyrus in the hippocampus. However, the low rate and the restricted long term survival of newborn cells limit the restorative ability of this process. Adult bone marrow derived mesenchymal stem cells (MSCs) have been extensively studied due to their wide therapeutic potential. The aim of this study was to determine if MSC transplantation to the normally restrictive SVZ of mice housed in an enriched environment stimulates endogenous neurogenesis. In the presented study 30 C57BL/6 female mice were divided into 3 groups: standard environment injected with phosphate buffered saline (PBS) and enriched environment injected with either PBS or MSCs. Bromodeoxyuridine was injected for 6 days, and 3 weeks later the mice were sacrificed and the brain tissue analyzed immunohistochemically. PBS-treated mice housed in enriched cages showed augmented neurogenesis in the SGZ but not the SVZ. MSC transplantation was associated with increased proliferation and neuronal differentiation of neural progenitors within the SVZ and an increase in the proportion of the newborn neurons out of the total proliferating cells. Histological analysis confirmed the survival of a significant amount of the transplanted cells at least 3 weeks after transplantation, and the presence of brain-derived neurotrophic factor expression. To our knowledge, this is the first study to show that MSCs might interfere with the tight regulation of the SVZ, independent of the induced brain lesion.

Stromal cell derived factor-1 (SDF-1) targeting reperfusion reduces myocardial infarction in isolated rat hearts

Recent studies have shown that stromal cell derived factor-1 (SDF-1), first known as a cytokine involved in recruiting stem cells into injured organs, confers myocardial protection in myocardial infarction, which is not dependent on stem cell recruitment but related with modulation of ischemia-reperfusion (I/R) injury. However, the effect of SDF has been studied only in a preischemic exposure model, which is not clinically relevant if SDF is to be used as a therapeutic agent. Our study was aimed at evaluating whether or not SDF-1 confers cardioprotection during the reperfusion period. Hearts from SD rats were isolated and perfused with the Langendorff system. Proximal left coronary artery ligation, reperfusion, and SDF perfusion in KH buffer was done according to study protocol. Area of necrosis (AN) relative to area at risk (AR) was the primary endpoint of the study. Significant reduction of AN/AR by SDF in an almost dose-dependent manner was noted during both the preischemic exposure and reperfusion periods. In particular, infusion of a high concentration of SDF (25 nM/L) resulted in a dramatic reduction of infarct size, which was greater than that achieved with ischemic pre- or postconditioning. SDF perfusion during reperfusion was associated with a similar significant reduction of infarct size as preischemic SDF exposure. Further studies are warranted to assess the potential of SDF as a therapeutic agent for reducing I/R injury in clinical practice.

Stem cell therapy for diabetes mellitus

In this review, we present (1) a brief discussion of hematopoietic stem cell transplantation (HSCT) for severe and refractory autoimmune diseases (AIDs) from its beginning in 1996 through recently initiated prospective randomized clinical trials; (2) an update (up to July 2009) of clinical and laboratory outcomes of 23 patients with newly diagnosed type 1 diabetes mellitus (T1DM), who underwent autologous HSCT at the Bone Marrow Transplantation Unit of the Ribeirão Preto Medical School, University of São Paulo, Brazil; (3) a discussion of possible mechanisms of action of HSCT in AIDs, including preliminary laboratory data obtained from our patients; and (4) a discussion of future perspectives of stem cell therapy for T1DM and type 2 DM, including the use of stem cell sources other than adult bone marrow and the combination of cell therapy with regenerative compounds.

Transplantation of human pericyte progenitor cells improves the repair of infarcted heart through activation of an angiogenic program involving micro-RNA-132

RATIONALE

Pericytes are key regulators of vascular maturation, but their value for cardiac repair remains unknown.

OBJECTIVE

We investigated the therapeutic activity and mechanistic targets of saphenous vein-derived pericyte progenitor cells (SVPs) in a mouse myocardial infarction (MI) model.

METHODS AND RESULTS

SVPs have a low immunogenic profile and are resistant to hypoxia/starvation (H/S). Transplantation of SVPs into the peri-infarct zone of immunodeficient CD1/Foxn-1(nu/nu) or immunocompetent CD1 mice attenuated left ventricular dilatation and improved ejection fraction compared to vehicle. Moreover, SVPs reduced myocardial scar, cardiomyocyte apoptosis and interstitial fibrosis, improved myocardial blood flow and neovascularization, and attenuated vascular permeability. SVPs secrete vascular endothelial growth factor A, angiopoietin-1, and chemokines and induce an endogenous angiocrine response by the host, through recruitment of vascular endothelial growth factor B expressing monocytes. The association of donor- and recipient-derived stimuli activates the proangiogenic and prosurvival Akt/eNOS/Bcl-2 signaling pathway. Moreover, microRNA-132 (miR-132) was constitutively expressed and secreted by SVPs and remarkably upregulated, together with its transcriptional activator cyclic AMP response element-binding protein, on stimulation by H/S or vascular endothelial growth factor B. We next investigated if SVP-secreted miR-132 acts as a paracrine activator of cardiac healing. In vitro studies showed that SVP conditioned medium stimulates endothelial tube formation and reduces myofibroblast differentiation, through inhibition of Ras-GTPase activating protein and methyl-CpG-binding protein 2, which are validated miR-132 targets. Furthermore, miR-132 inhibition by antimiR-132 decreased SVP capacity to improve contractility, reparative angiogenesis, and interstitial fibrosis in infarcted hearts.

CONCLUSION

SVP transplantation produces long-term improvement of cardiac function through a novel paracrine mechanism involving the secretion of miR-132 and inhibition of its target genes.

Heterogeneity in SDF-1 expression defines the vasculogenic potential of adult cardiac progenitor cells

Rationale

The adult myocardium has been reported to harbor several classes of multipotent progenitor cells (CPCs) with tri-lineage differentiation potential. It is not clear whether c-kit+CPCs represent a uniform precursor population or a more complex mixture of cell types.

Objective

To characterize and understand vasculogenic heterogeneity within c-kit+presumptive cardiac progenitor cell populations.

Methods and Results

c-kit+, sca-1+ CPCs obtained from adult mouse left ventricle expressed stem cell-associated genes, including Oct-4 and Myc, and were self-renewing, pluripotent and clonogenic. Detailed single cell clonal analysis of 17 clones revealed that most (14/17) exhibited trilineage differentiation potential. However, striking morphological differences were observed among clones that were heritable and stable in long-term culture. 3 major groups were identified: round (7/17), flat or spindle-shaped (5/17) and stellate (5/17). Stellate morphology was predictive of vasculogenic differentiation in Matrigel. Genome-wide expression studies and bioinformatic analysis revealed clonally stable, heritable differences in stromal cell-derived factor-1 (SDF-1) expression that correlated strongly with stellate morphology and vasculogenic capacity. Endogenous SDF-1 production contributed directly to vasculogenic differentiation: both shRNA-mediated knockdown of SDF-1 and AMD3100, an antagonist of the SDF-1 receptor CXC chemokine Receptor-4 (CXCR4), reduced tube-forming capacity, while exogenous SDF-1 induced tube formation by 2 non-vasculogenic clones. CPCs producing SDF-1 were able to vascularize Matrigel dermal implants in vivo, while CPCs with low SDF-1 production were not.

Conclusions

Clonogenic c-kit+, sca-1+ CPCs are heterogeneous in morphology, gene expression patterns and differentiation potential. Clone-specific levels of SDF-1 expression both predict and promote development of a vasculogenic phenotype via a previously unreported autocrine mechanism.

Bone marrow-derived CMPs and GMPs represent highly functional proangiogenic cells: implications for ischemic cardiovascular disease

Clinical studies using bone marrow-derived proangiogenic cells (PACs) have demonstrated modest improvements of function and/or perfusion of ischemic myocardium or skeletal muscle. Because the identities of these PACs and their functional ability to promote neovascularization remain poorly understood, it is possible that a subset of robust PACs exists but is obscured by the heterogeneous nature of this cell population. Herein, we found that common myeloid progenitors (CMPs) and granulocyte-macrophage progenitors (GMPs) preferentially differentiate into PACs compared with megakaryocyte-erythrocyte progenitors, hematopoietic stem cells, and common lymphoid progenitors. In vivo hindlimb ischemia studies and Matrigel plug assays verified the enhanced neovascularization properties uniquely associated with PACs derived from CMPs and GMPs. Taken together, these observations identify CMPs and GMPs as key bone marrow progenitors for optimal PAC function in vitro and in vivo and provide a foundation for novel therapeutic approaches to modulate angiogenesis.

Autologous non-myeloablative haemopoietic stem-cell transplantation compared with pulse cyclophosphamide once per month for systemic sclerosis (ASSIST): an open-label, randomised phase 2 trial

BACKGROUND

Non-randomised studies of haemopoietic stem-cell transplantation (HSCT) in systemic sclerosis have shown improvements in lung function and skin flexibility but high treatment-related mortality. We aimed to assess safety and efficacy of autologous non-myeloablative HSCT in a phase 2 trial compared with the standard of care, cyclophosphamide.

METHODS

In our open-label, randomised, controlled phase 2 trial, we consecutively enrolled patients at Northwestern Memorial Hospital (Chicago, IL, USA) who were aged younger than 60 years with diffuse systemic sclerosis, modified Rodnan skin scores (mRSS) of more than 14, and internal organ involvement or restricted skin involvement (mRSS <14) but coexistent pulmonary involvement. We randomly allocated patients 1:1 by use of a computer-generated sequence with a mixed block design (blocks of ten and four) to receive HSCT, 200 mg/kg intravenous cyclophosphamide, and 6·5 mg/kg intravenous rabbit antithymocyte globulin or to receive 1·0 g/m(2) intravenous cyclophosphamide once per month for 6 months. The primary outcome for all enrolled patients was improvement at 12 months' follow-up, defined as a decrease in mRSS (>25% for those with initial mRSS >14) or an increase in forced vital capacity by more than 10%. Patients in the control group with disease progression (>25% increase in mRSS or decrease of >10% in forced vital capacity) despite treatment with cyclophosphamide could switch to HSCT 12 months after enrolment. This study is registered with ClinicalTrials.gov, number NCT00278525.

FINDINGS

Between Jan 18, 2006, and Nov 10, 2009 we enrolled 19 patients. All ten patients randomly allocated to receive HSCT improved at or before 12 months' follow-up, compared with none of nine allocated to cyclophosphamide (odds ratio 110, 95% CI 14·04-∞; p=0·00001). Eight of nine controls had disease progression (without interval improvement) compared with no patients treated by HSCT (p=0·0001), and seven patients switched to HSCT. Compared with baseline, data for 11 patients with follow-up to 2 years after HSCT suggested that improvements in mRSS (p<0·0001) and forced vital capacity (p<0·03) persisted.

INTERPRETATION

Non-myeloablative autologous HSCT improves skin and pulmonary function in patients with systemic sclerosis for up to 2 years and is preferable to the current standard of care, but longer follow-up is needed.

FUNDING

None.

Implanted bone marrow-derived mesenchymal stem cells fail to metabolically stabilize or recover electromechanical function in infarcted hearts

Mesenchymal stem cells (MSCs) have been used with success in several clinical applications for clinical treatment of ischemic hearts. However, the reported effects of MSC-based therapy on myocardial infarction (MI) are inconsistent. In particular, the preventive effects of MSC-based therapy on arrhythmic sudden death and metabolic disorders after infarction remain controversial. Here, we investigated the effects of MSCs on reverse remodeling in an infarcted myocardium, and found that MSC-therapy failed to achieve the complete regeneration of infarcted myocardium. Histological analyses showed that although infarct size and interstitial fibrosis induced by MI recovered significantly after MSC treatment, these improvements were marginal, indicating that a significant amount of damaged tissue was still present. Furthermore, transplanted MSCs had slight anti-apoptotic and anti-inflammatory effects in MSC-implanted regions and no significant improvements in cardiac function were observed, suggesting that naïve MSCs might not be the right cell type to treat myocardial infarction. Furthermore, small ion profiling using ToF-SIMS revealed that the metabolic stabilization provided by the MSCs implantation was not significant compared to the sham group. Together, these results indicate that pretreatment of MSCs is needed to enhance the benefits of MSCs, particularly when MSCs are used to treat arrhythmogenicity and metabolically stabilize infarcted myocardium.

Adult stem cells and multiple sclerosis

Multiple sclerosis (MS) is a common neurological disease and a major cause of disability, particularly affecting young adults. It is characterized by patches of damage occurring throughout the brain and spinal cord, with loss of myelin sheaths - the insulating material around nerve fibres that allows normal conduction of nerve impulses - accompanied by loss of cells that make myelin (oligodendrocytes). In addition, we now know that there is damage to nerve cells (neurones) and their fibres (axons) too, and that this occurs both within these discrete patches and in tissue between them. The cause of MS remains unknown, but an autoimmune reaction against oligodendrocytes and myelin is generally assumed to play a major role, and early acute MS lesions almost invariably show prominent inflammation. Efforts to develop cell therapy in MS have long been directed towards directly implanting cells capable of replacing lost oligodendrocytes and regenerating myelin sheaths. Accordingly, the advent of techniques to generate large numbers of oligodendrocytes from embryonic stem cells appeared a significant step towards new stem cell treatments for MS; while the emerging consensus that adult stem cells from, for example, the bone marrow had far less potential to turn into oligodendrocytes was thought to cast doubt on their potential value in this disease. A number of scientific and medical concerns, not least the risk of tumour formation associated with embryonic stem cells, have however, prevented any possible clinical testing of these cells in patients. More recently, increasing understanding of the complexity of tissue damage in MS has emphasized that successful cell therapy may need to achieve far more than simply offering a source of replacement myelin-forming cells. The many and varied reparative properties of bone marrow-derived (mesenchymal) stem cells may well offer new and attractive possibilities for developing cell-based treatments for this difficult and disabling condition.

[Stem and progenitor cell-based therapy approaches: current developments on treatment of acute myocardial infarction and chronic ischemic cardiomyopathy]

Percutaneous coronary intervention (PCI) for coronary revascularization in conjunction with an optimized pharmacological treatment can reduce adverse left ventricular remodeling and dysfunction in patients with acute myocardial infarction. Despite these modern therapeutic strategies a significant number of these patients continue to develop adverse cardiac remodeling and LV dysfunction which is associated with a poor prognosis. Stem and progenitor cell-based approaches for treatment of acute myocardial infarction and chronic ischemic cardiomyopathy are an interesting direction of current experimental and clinical research. The current review article provides a summary of recent developments of cell-based therapies of ischemic heart disease, including the assessment of the repair and regeneration capacity of different stem and progenitor cell populations. In addition the advantages and disadvantages of different modes of cell application and potential strategies for the improvement of stem and progenitor cell function for their use in cell-based cardiovascular therapies will be described.

Microchimerism in salivary glands after blood- and marrow-derived stem cell transplantation

Blood- and marrow-derived stem cells (BMDSCs) provide disease-ameliorating effects for cardiovascular and autoimmune diseases. Microchimerism from donor BMDSCs has been reported in several recipient tissues. We hypothesized that this finding suggests a potential use of BMDSCs in the treatment of salivary dysfunctions. We investigated the presence of Y chromosome-positive cells in salivary gland biopsies of 5 females who had received a marrow or blood stem cell transplant from male donors. One to 16 years after transplantation, all recipients exhibited scattered Y chromosome-positive cells in the acini, ducts, and stroma of their salivary glands (mean of 1.01%). Potentially, these cells can be markers of transplantation tolerance, contribute to neoplastic epithelial tissues, or engraft at sites of injury. In addition, transplantation of BMDSCs could be used for treatment of Sjögren's syndrome and salivary glands damaged by therapeutic irradiation for cancers of the head and neck.

G-CSF downregulates natural killer cell-mediated cytotoxicity in donors for hematopoietic SCT

In G-CSF-mobilized hematopoietic SCT (HSCT), natural killer (NK) cells have a critical role in GVHD and GVL effects. However, regulation of NK cell response to G-CSF remains unclear. This study assayed G-CSF effects in both HSCT donors and NK-92MI cells. The donors who received G-CSF had significantly decreased NK cell cytotoxicity. Levels of phosphatidylinositol 3-kinase (PI3K) and phosphorylated (p)-Akt, but not mammalian target of rapamycin (mTOR), were downregulated in NK cells from G-CSF-injected donors. G-CSF also decreased cytotoxicity without affecting viability and NF-κB of NK-92MI cells. PI3K and p-ERK expression were also decreased in G-CSF-treated NK-92MI cells, and their inhibitors, wortmannin and PD98059, respectively, both enhanced the downregulation of cytotoxicity. These effects were accompanied by decreased expression of a cytotoxicity-related gene, triosephosphate isomerase (TPI). Wortmannin, but not PD98059, enhanced the downregulation of TPI in G-CSF-treated NK-92MI cells, indicating a correlation between PI3K and TPI. We conclude that G-CSF-impaired NK cell cytotoxicity may accompany PI3K/Akt signaling. The effect is transient and NK cells may recover after G-CSF clearance, suggesting that G-CSF-mobilized HSCT may benefit both acute GVHD prevention and late-phase GVL promotion in HSCT recipients.

Embryonic stem cells: are useful in clinic treatments?

It is not uncommon to find statements in the social media and even in some scientific journals declaring that embryonic stem cells can be used in human medicine for therapeutic purposes. In our opinion, this statement does not fit the medical reality. To go into this subject in depth, and if possible to clarify it, we reviewed the most recent literature on clinical trials conducted with embryonic stem cells, concluding that up to the present time, there is only one ongoing clinical trial being carried out with these types of cells to treat a small group of patients with spinal cord injury. The results of this trial have still not been published. In conclusion, at present, there is only evidence of one phase I clinical trial conducted with embryonic stem cells, in comparison to the numerous trials conducted with adult stem cells.

Glucose challenge increases circulating progenitor cells in Asian Indian male subjects with normal glucose tolerance which is compromised in subjects with pre-diabetes: A pilot study

BACKGROUND

Haematopoietic stem cells undergo mobilization from bone marrow to blood in response to physiological stimuli such as ischemia and tissue injury. The aim of study was to determine the kinetics of circulating CD34+ and CD133+CD34+ progenitor cells in response to 75 g glucose load in subjects with normal and impaired glucose metabolism.

METHODS

Asian Indian male subjects (n = 50) with no prior history of glucose imbalance were subjected to 2 hour oral glucose tolerance test (OGTT). 24 subjects had normal glucose tolerance (NGT), 17 subjects had impaired glucose tolerance (IGT) and 9 had impaired fasting glucose (IFG). The IGT and IFG subjects were grouped together as pre-diabetes group (n = 26). Progenitor cell counts in peripheral circulation at fasting and 2 hour post glucose challenge were measured using direct two-color flow cytometry.

RESULTS

The pre-diabetes group was more insulin resistant (p < 0.0001) as measured by homeostasis assessment model (HOMA-IR) compared to NGT group. A 2.5-fold increase in CD34+ cells (p = 0.003) and CD133+CD34+ (p = 0.019) cells was seen 2 hours post glucose challenge in the NGT group. This increase for both the cell types was attenuated in subjects with IGT. CD34+ cell counts in response to glucose challenge inversely correlated with neutrophil counts (ρ = -0.330, p = 0.019), while post load counts of CD133+CD34+ cells inversely correlated with serum creatinine (ρ = -0.312, p = 0.023).

CONCLUSION

There is a 2.5-fold increase in the circulating levels of haematopoietic stem cells in response to glucose challenge in healthy Asian Indian male subjects which is attenuated in subjects with pre-diabetes.

Intracoronary bone marrow cell transfer after myocardial infarction: 5-year follow-up from the randomized-controlled BOOST trial

AIMS

We assessed whether a single intracoronary infusion of autologous bone marrow cells (BMCs) can have a sustained impact on left ventricular ejection fraction (LVEF) in patients after ST-elevation myocardial infarction (STEMI). In the BOne marrOw transfer to enhance ST-elevation infarct regeneration (BOOST) trial, 60 patients with STEMI and successful percutaneous coronary intervention were randomized to a control and a cell therapy group. As previously reported, BMC transfer led to an improvement of LVEF by 6.0% at 6 months (P = 0.003) and 2.8% at 18 months (P = 0.27).

METHODS AND RESULTS

Left ventricular ejection fraction and clinical status were re-assessed in all surviving patients after 61 +/- 11 months. Major adverse cardiac events occurred with similar frequency in both groups. When compared with baseline, LVEF assessed by magnetic resonance imaging at 61 months decreased by 3.3 +/- 9.5% in the control group and by 2.5 +/- 11.9% in the BMC group (P = 0.30). Patients with an infarct transmurality > median appeared to benefit from BMC transfer throughout the 61-month study period (P = 0.040).

CONCLUSION

A single intracoronary application of BMCs does not promote a sustained improvement of LVEF in STEMI patients with relatively preserved systolic function. It is conceivable that a subgroup of patients with more transmural infarcts may derive a sustained benefit from BMC therapy. However, this needs to be tested prospectively in a randomized trial.

Cardiomyocytes from phorbol myristate acetate-activated mesenchymal stem cells restore electromechanical function in infarcted rat hearts

Despite the safety and feasibility of mesenchymal stem cell (MSC) therapy, an optimal cell type has not yet emerged in terms of electromechanical integration in infarcted myocardium. We found that poor to moderate survival benefits of MSC-implanted rats were caused by incomplete electromechanical integration induced by tissue heterogeneity between myocytes and engrafted MSCs in the infarcted myocardium. Here, we report the development of cardiogenic cells from rat MSCs activated by phorbol myristate acetate, a PKC activator, that exhibited high expressions of cardiac-specific markers and Ca(2+) homeostasis-related proteins and showed adrenergic receptor signaling by norepinephrine. Histological analysis showed high connexin 43 coupling, few inflammatory cells, and low fibrotic markers in myocardium implanted with these phorbol myristate acetate-activated MSCs. Infarct hearts implanted with these cells exhibited restoration of conduction velocity through decreased tissue heterogeneity and improved myocardial contractility. These findings have major implications for the development of better cell types for electromechanical integration of cell-based treatment for infarcted myocardium.

Cell surface engineering of mesenchymal stem cells

By leveraging the capacity to promote regeneration, stem cell therapies offer enormous hope for solving some of the most tragic illnesses, diseases, and tissue defects world-wide. However, a significant barrier to the effective implementation of cell therapies is the inability to target a large quantity of viable cells with high efficiency to tissues of interest. Systemic infusion is desired as it minimizes the invasiveness of cell therapy, and maximizes practical aspects of repeated doses. However, cell types such as mesenchymal stem cells exhibit a poor homing capability or lose their capacity to home following culture expansion (i.e. FASEB J 21:3197-3207, 2007; Circulation 108:863-868, 2003; Stroke: A Journal of Cerebral Circulation 32:1005-1011; Blood 104:3581-3587, 2004). To address this challenge, we have developed a simple platform technology to chemically attach cell adhesion molecules to the cell surface to improve the homing efficiency to specific tissues. This chemical approach involves a stepwise process including (1) treatment of cells with sulfonated biotinyl-N-hydroxy-succinimide to introduce biotin groups on the cell surface, (2) addition of streptavidin that binds to the biotin on the cell surface and presents unoccupied binding sites, and (3) attachment of biotinylated targeting ligands that promote adhesive interactions with vascular endothelium. Specifically, in our model system, a biotinylated cell rolling ligand, sialyl Lewisx (SLeX), found on the surface of leukocytes (i.e., the active site of the P-selectin glycoprotein ligand (PSGL-1)), is conjugated on MSC surface. The SLeX engineered MSCs exhibit a rolling response on a P-selectin coated substrate under shear stress conditions. This indicates that this approach can be used to potentially target P-selectin expressing endothelium in the more marrow or at sites of inflammation. Importantly, the surface modification has no adverse impact on MSCs' native phenotype including their multilineage differentiation capacity, viability, proliferation, and adhesion kinetics. We anticipate that the present approach to covalently modify the cell surface and immobilize required ligands is not limited to MSCs or the SLeX ligand. Therefore, this technology should have broad implications on cell therapies that utilize systemic administration and require targeting of cells to specific tissues. The approach may also be useful to promote specific cell-cell interactions. In this protocol, we describe the conjugation of SLeX on MSC surface and methods to study cell rolling behaviors of SLeX-modified MSCs on a P-selectin coated substrate using an in vitro flow chamber assay. We also provide a brief description of cell characterization assays that can be used to examine the impact of the chemical modification regimen.

Prolongation of cardiac allograft survival by a novel population of autologous CD117+ bone marrow-derived progenitor cells

Autologous CD117(+) progenitor cells (PC) have been successfully utilized in myocardial infarction and ischemic injury, potentially through the replacement/repair of damaged vascular endothelium. To date, such cells have not been used to enhance solid organ transplant outcome. In this study, we determined whether autologous bone marrow-derived CD117(+) PC could benefit cardiac allograft survival, possibly by replacing donor vascular cells. Autologous, positively selected CD117(+) PC were administered posttransplantation and allografts were assessed for acute rejection. Although significant generation of recipient vascular cell chimerism was not observed, transferred PC disseminated both to the allograft and to peripheral lymphoid tissues and facilitated a significant, dose-dependent prolongation of allograft survival. While CD117(+) PC dramatically inhibited alloreactive T cell proliferation in vitro, this property did not differ from nonprotective CD117(-) bone marrow populations. In vivo, CD117(+) PC did not significantly inhibit T cell alloreactivity or increase peripheral regulatory T cell numbers. Thus, rather than inhibiting adaptive immunity to the allograft, CD117(+) PC may play a cytoprotective role in prolonging graft survival. Importantly, autologous CD117(+) PC appear to be distinct from bone marrow-derived mesenchymal stem cells (MSC) previously used to prolong allograft survival. As such, autologous CD117(+) PC represent a novel cellular therapy for promoting allograft survival.

Bone marrow-derived cells rescue salivary gland function in mice with head and neck irradiation

Treatment for most patients with head and neck cancers includes ionizing radiation. A consequence of this treatment is irreversible damage to salivary glands (SGs), which is accompanied by a loss of fluid-secreting acinar-cells and a considerable decrease of saliva output. While there are currently no adequate conventional treatments for this condition, cell-based therapies are receiving increasing attention to regenerate SGs. In this study, we investigated whether bone marrow-derived cells (BMDCs) can differentiate into salivary epithelial cells and restore SG function in head and neck irradiated mice. BMDCs from male mice were transplanted into the tail-vein of 18Gy-irradiated female mice. Salivary output was increased in mice that received BMDCs transplantation at week 8 and 24 post-irradiation. At 24 weeks after irradiation (IR), harvested SGs (submandibular and parotid glands) of BMDC-treated mice had greater weights than those of non-treated mice. Histological analysis shows that SGs of treated mice demonstrated an increased level of tissue regenerative activity such as blood vessel formation and cell proliferation, while apoptotic activity was increased in non-transplanted mice. The expression of stem cell markers (Sca-1 or c-kit) was detected in BMDC-treated SGs. Finally, we detected an increased ratio of acinar-cell area and approximately 9% of Y-chromosome-positive (donor-derived) salivary epithelial cells in BMDC-treated mice. We propose here that cell therapy using BMDCs can rescue the functional damage of irradiated SGs by direct differentiation of donor BMDCs into salivary epithelial cells.

Intracoronary administration of bone marrow-derived mononuclear cells and arrhythmic events in patients with chronic heart failure

AIMS

There are continued debates on potential proarrhythmic effects of intracoronary bone marrow-derived progenitor cell (BMC) therapy for treatment of chronic heart failure. Implantable cardioverter-defibrillators (ICDs), a mainstay of heart failure therapy, provide the possibility of validly assessing arrhythmias in patients with chronic heart failure. The aim of this analysis was to assess the arrhythmogenic potential of intracoronary BMC therapy, continuously documented by ICD-stored intracardiac electrograms.

METHODS AND RESULTS

Matched cohort study of 112 patients receiving intracoronary administration of autologous BMC and 224 heart failure patients, matched for age, gender, and left ventricular ejection fraction fitted with an ICD. Within a follow-up period of 2 years (total patient-years at risk: 595 years), no significant difference was detected for ICD-stored episodes of ventricular tachycardia (VT; 25.0 vs. 27.1%; P = 0.779), VT/ventricular fibrillation treated by antitachycardia pacing or ICD shock (15.6 vs. 15.5%; P = 0.956), or death from arrhythmic cause (4.2 vs. 1.0%; P = 0.667). Predictors of occurrence of major arrhythmic events were parameters of advanced heart failure and implantation of ICD for secondary prevention; no influence could be detected for BMC administration (odds ratio = 1.198; P = 0.440).

CONCLUSION

There is no evidence that intracoronary administration of BMC aggravates life-threatening arrhythmias in patients with chronic heart failure.

Capturing the stem cell paracrine effect using heparin-presenting nanofibres to treat cardiovascular diseases

The mechanism for stem cell-mediated improvement following acute myocardial infarction has been actively debated. We support hypotheses that the stem cell effect is primarily paracrine factor-linked. We used a heparin-presenting injectable nanofibre network to bind and deliver paracrine factors derived from hypoxic conditioned stem cell media to mimic this stem cell paracrine effect. Our self-assembling peptide nanofibres presenting heparin were capable of binding paracrine factors from a medium phase. When these factor-loaded materials were injected into the heart following coronary artery ligation in a mouse ischaemia-reperfusion model of acute myocardial infarction, we found significant preservation of haemodynamic function. Through media manipulation, we were able to determine that crucial factors are primarily < 30 kDa and primarily heparin-binding. Using recombinant VEGF- and bFGF-loaded nanofibre networks, the effect observed with conditioned media was recapitulated. When evaluated in another disease model, a chronic rat ischaemic hind limb, our factor-loaded materials contributed to extensive limb revascularization. These experiments demonstrate the potency of the paracrine effect associated with stem cell therapies and the potential of a biomaterial to bind and deliver these factors, pointing to a potential therapy based on synthetic materials and recombinant factors as an acellular therapy.