The influence of the novel drug Ukrain on hemo- and immunopoiesis at the time of its maximum radioprotective effect

Several studies have demonstrated that when Ukrain, a complex preparation of great celandine alkaloids, is used as a preventive agent it increases the survival of animals exposed to whole body gamma-irradiation and enhances the restoration of hemopoiesis. The aim of this study was to describe qualitative and quantitative changes in hemopoietic precursor cells and in myelokaryocytes and leukocytes in the blood caused by Ukrain from its administration to the time the maximal radioresistance potential of the organism is reached. Ukrain was administered i.p. at the dose of 0.2 mg/kg, 24 h prior to investigation. Control animals were injected with saline. Colony-forming units (CFU) were counted in the spleen and bone marrow of the mice, and myelokaryocyte and leukocyte (lymphocyte and granulocyte) counts were determined. The results of this study suggest that Ukrain causes qualitative and quantitative alterations in different pools of hemopoietic cells (stem cells, proliferating cells, maturing cells, and competent cells). These alterations affect the size of the stem cell pool, the kinetics of stem cell proliferation, the direction of their differentiation pathways, the rate of circulation of stem cells and precursor cells, the efficiency of recolonization of cell-depleted sites, and other parameters, which in effect modify standard responses of hemopoiesis and immunogenesis to irradiation so that the radioresistance of the whole organism increases.     

Bone marrow transplantation: a new strategy for intractable diseases

Bone marrow transplantation is becoming a powerful strategy for the treatment of hematologic disorders (leukemia, aplastic anemia, etc.), congenital immunodeficiencies, metabolic disorders and also autoimmune diseases. Using various animal models for autoimmune diseases, we have previously found that allogeneic (not autologous) bone marrow transplantation can be used to treat autoimmune diseases such as systemic lupus erythematosus, rheumatoid arthritis, immune thrombocytic purpura, insulin-dependent diabetes mellitus, chronic glomerulonephritis and certain types of non-insulin-dependent diabetes mellitus. In contrast, we have found that the transplantation of T-cell-depleted bone marrow cells or partially purified hemopoietic stem cells from autoimmune-prone mice to normal mice leads to the induction of autoimmune diseases in the recipients. These findings have recently been confirmed even in humans; autoimmune diseases such as rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis and Crohn's disease were resolved after allogeneic bone marrow transplantation. However, there have recently been reports on the rapid recurrence or persistence of autoimmune diseases after autologous bone marrow transplantation. Conversely, the adoptive transfer of autoimmune diseases such as myasthenia gravis, insulin-dependent diabetes mellitus and Graves' disease by allogeneic bone marrow transplantation from donors to recipients has been reported. Owing to these findings, we have proposed that autoimmune diseases are "stem cell disorders." We have thus succeeded in treating autoimmune diseases in various autoimmune-prone mice, except MRL/lpr mice, by conventional bone marrow transplantation. The MRL/lpr mouse itself is radiosensitive (<8.5 Gy), while the abnormal hemopoietic stem cells of the MRL/lpr mouse are radioresistant (>8.5 Gy); conventional bone marrow transplantation (8.5 Gy plus bone marrow transplantation) has a transient effect on autoimmune diseases, which recur three months after the bone marrow transplantation. However, bone marrow transplantation plus bone grafts (to recruit donor stromal cells) completely prevents the recurrence of autoimmune diseases in MRL/lpr mice. Donor-derived stromal cells (including mesenchymal stem cells) thus seem to play a crucial role in successful allogeneic bone marrow transplantation, since there is a major histocompatibility complex restriction between hemopoietic stem cells and stromal cells. We have, however, found that the combination of bone marrow transplantation plus bone grafts has no effect on the treatment of autoimmune diseases in MRL/lpr mice, since MRL/lpr mice become more radiosensitive after the onset of lupus nephritis due to the development of uremic enterocolitis. To reduce the cytotoxic effect of radiation on the intestine, we carried out fractionated irradiation and devised a new strategy. We injected allogeneic whole bone marrow cells (including a small number [<3%] of T cells, hemopoietic stem cells and stromal cells) from donors directly into the intra-bone marrow of recipients so that donor-derived hemopoietic cells including stromal cells could effectively accumulate in the bone marrow. All the MRL/lpr mice survived more than one year (>60 weeks after birth) without the recurrence of autoimmune diseases, and immunological functions were completely restored even when the radiation dose was reduced to 5 Gy x 2. These findings suggest that intra-bone marrow injection-bone marrow transplantation can be used to treat intractable autoimmune diseases under reduced radiation doses without using any immunosuppressants.Intra-bone marrow injection-bone marrow transplantation seems to be the best strategy for allogeneic bone marrow transplantation: 1) no graft-versus-host disease develops even if T cells are not depleted from the bone marrow; 2) no graft failure occurs even if the dose of radiation as the conditioning for bone marrow transplantation is reduced to 5 Gy x 2; 3) hemopoietic recovery is rapid; and 4) T-cell functions are completely restored even in donor-recipient combinations across the major histocompatibility complex barriers. Using cynomolgus monkeys, we have recently established a new method (the "perfusion method") for collecting bone marrow cells from the long bones (femur, humerus, etc.) without peripheral blood contamination. This method has various advantages: 1) no graft-versus-host disease develops even in cynomolgus monkeys, since the percentage of T cells in the bone marrow cells collected is less than 3%; 2) a large number of bone marrow cells can be collected quickly and safely; and 3) the bone marrow cells collected contain stromal cells including mesenchymal stem cells. We therefore believe that this method (intra-bone marrow injection-bone marrow transplantation in conjunction with the perfusion method) will become a powerful new strategy for not only allogeneic bone marrow transplantation but also organ transplantation in conjunction with bone marrow transplantation. Furthermore, this method could become a valuable strategy in regeneration therapy for injured organs and tissues (myocardial infarction, cerebral infarction, Alzheimer's disease, etc.), since it can efficiently reconstitute the recipient with both donor-derived hemopoietic stem cells and mesenchymal stem cells.     

Potential of stem cell treatment in detrusor dysfunction

The current treatments of bladder dysfunctions, such as bladder overactivity and impaired ability to empty, have limitations, and new treatment alternatives are needed. Stem cell transplantation and tissue engineering have shown promising results in preclinical studies. Stem cells were originally thought to act by differentiating into various cell types, thereby replacing damaged cells and restoring functional deficits. Even if such a mechanism cannot be excluded, the current belief is that a main action is exerted by the stem cells secreting bioactive factors that direct other stem cells to the target organ. In addition, stem cells may exert a number of other effects that can improve bladder dysfunction, since they may have antiapoptotic, antifibrotic, and immunomodulatory properties, and can induce neovascularization. Tissue engineering for bladder replacement, which has had varying success in different animal species, has reached the proof-of-concept state in humans, but recent research suggests that the present approaches may not be optimal. Further studies on new approaches, using animal models with translational predictability, seem necessary for further progress.     

Stem Cell Plasticity and Tissue Bioengineering: Great Expectations and Some Concerns

"Stem cells" are by definition cells that self-renew and that have the capacity to differentiate into several lineages. A recent series of studies has challenged fundamental concepts of stem cell biology by suggesting that the functional potential of stem cells is not restricted to the tissue source from which they are derived. The ability for cells of one tissue to produce cells of other developmentally unrelated tissues has been defined as cellular plasticity. Therefore, the utility of stem cell plasticity in cell replacement therapy should be unlimited. Multipotent stem cells may be used to develop replacement tissues for congenital or degenerative disorders, either on their own or in combination with other therapeutic approaches such us gene therapy. There are, however, several concerns regarding the concept of stem cell plasticity and the methods used to evaluate the starting population. (c) 2002 Prous Science. All rights reserved.     

神经退行性或损伤性疾病防治的新视点——干细胞药物

干细胞药物是指可以通过调节生物体内干细胞的增殖与分化,来防治由于细胞缺失或损伤而引起疾病的一类治疗和预防药物。近年来发现:运用中药、生长因子和小分子化合物均可调节生物体内干细胞的增殖与分化;而神经系统退行性或损伤性疾病:包括帕金森病(PD)、阿尔采末病(AD)、亨廷顿病(HD)、药物滥用、抑郁症以及脑卒中等,均是由于神经细胞的缺失或损伤而引发的疾病。运用药物来调节自身神经干细胞的增殖与定向分化潜能,以重建受损的功能细胞,恢复其生物学功能,既解决了成体神经干细胞的来源困难和胚胎干细胞的伦理困惑问题,也避免了细胞移植的免疫排斥和手术后遗症问题。为细胞丢失或损伤性疾病的防治提供了崭新的视点和思路。     

Investigation of Non-Linear Adaptive Responses and Split Dose Recovery Induced by Ionizing Radiation in Three Human Epithelial Derived Cell Lines

Two almost completely exclusive fields in radiobiology deal with splitting doses of radiation and comparing the effect to a similar total dose given in one exposure. In radiotherapy, dose “fractionation” is used to “spare” normal tissue and in the low dose field, the adaptive response is well documented as a phenomenon where a small “priming” dose administered before the larger “challenge “ dose reduces the effect of the large dose. There have been very few studies where these fields overlap, thus it is not possible to ascertain whether common or distinct mechanisms underlie both phenomena but this is certainly an interesting question and relevant to our understanding of high and low dose radiobiology. This paper presents data for three human cell lines with varying p53 status and radiation responses, treated at a range of times between first and second dose and for 3 different first doses (0.1, 0.5 and 2Gy). The data show that time between doses is critical. Protective (adaptive) effects were seen in each cell line but most prominently in the malignant HT 29 cell line. Surprisingly none of the cell lines showed pronounced split dose recovery. This suggests different mechanisms may underlie the two phenomena.     

The mechanism for the ameliorative effect of CpG-oligodeoxynucleotides on bone marrow hemopoiesis radiation injury

Bone marrow is a major site of radiation injury. The extreme sensitivity of bone marrow cells to genotoxic stress largely determines the adverse side effects of radiation. CpG-oligodeoxynucleotide (ODN) is known to be radioprotective in extramedullary hemopoiesis, but its effect on bone marrow hemopoiesis remains unknown. In this study, we investigated whether CpG-ODN ameliorated hemopoiesis radiation injury when administered after total-body irradiation (TBI). Mice were treated with 50 μg of CpG-ODN via intraperitoneal injection (i.p) 30 min., 24 and 48 hr after TBI. Our results show that CpG-ODN was able to mediate the activation of nuclear factor κB (NF-κB) via degradation of inhibitor NF-κB (IκB-α), and some oxidative stress parameters (malondialdehyde, glutathione and superoxide dismutase) showed significant differences between the radiation control group and the radiation and administration of CpG-ODN group. White blood cell count, bone marrow cell count and bone marrow histological examination indicated that CpG-ODN minimized bone marrow damage induced by radiation. Exogenous colony-forming unit-spleen count indicated that CpG-ODN reduced primitive hemopoietic stem cell damage and reconstituted the hemopoietic system after TBI. The survival of mice was also enhanced after various levels of TBI. The calculated dose reduction factor was 1.2. Thus, we conclude that CpG-ODN may contribute to the amelioration of hemopoiesis radiation injury.     

Role of neural precursor cells in promoting repair following stroke

Stem cell-based therapies for the treatment of stroke have received considerable attention. Two broad approaches to stem cell-based therapies have been taken: the transplantation of exogenous stem cells, and the activation of endogenous neural stem and progenitor cells (together termed neural precursors). Studies examining the transplantation of exogenous cells have demonstrated that neural stem and progenitor cells lead to the most clinically promising results. Endogenous activation of neural precursors has also been explored based on the fact that resident precursor cells have the inherent capacity to proliferate, migrate and differentiate into mature neurons in the uninjured adult brain. Studies have revealed that these neural precursor cell behaviours can be activated following stroke, whereby neural precursors will expand in number, migrate to the infarct site and differentiate into neurons. However, this innate response is insufficient to lead to functional recovery, making it necessary to enhance the activation of endogenous precursors to promote tissue repair and functional recovery. Herein we will discuss the current state of the stem cell-based approaches with a focus on endogenous repair to treat the stroke injured brain.     

The New Radiobiology: Returning to Our Roots

In 2005, two expert advisory bodies examined the evidence on the effects of low doses of ionizing radiation. The U.S. National Research Council concluded that current scientific evidence is consistent with the linear no-threshold dose-response relationship (NRCNA 2005) while the French National Academies of Science and Medicine concluded the opposite (Aurengo et al. 2005). These contradictory conclusions may stem in part from an emphasis on epidemiological data (a “top down” approach) versus an emphasis on biological mechanisms (a “bottom up” approach). In this paper, the strengths and limitations of the top down and bottom up approaches are discussed, and proposals for strengthening and reconciling them are suggested. The past seven years since these two reports were published have yielded increasing evidence of nonlinear responses of biological systems to low radiation doses delivered at low dose-rates. This growing body of evidence is casting ever more doubt on the extrapolation of risks observed at high doses and dose-rates to estimate risks associated with typical environmental and occupational exposures. This paper compares current evidence on low dose, low dose-rate effects against objective criteria of causation. Finally, some questions for a post-LNT world are posed.     

Hormesis,Cell Death,and Regenerative Medicine for Neurode-Generative Diseases

Although the adult human brain has a small number of neural stem cells, they are insufficient to repair the damaged brain to achieve significant functional recovery for neurodegenerative diseases and stroke. Stem cell therapy, by either enhancing endogenous neurogenesis, or transplanting stem cells, has been regarded as a promising solution. However, the harsh environment of the diseased brain posts a severe threat to the survival and correct differentiation of those new stem cells. Hormesis (or preconditioning, stress adaptation) is an adaptation mechanism by which cells or organisms are potentiated to survive an otherwise lethal condition, such as the harsh oxidative stress in the stroke brain. Stem cells treated by low levels of chemical, physical, or pharmacological stimuli have been shown to survive better in the neurodegenerative brain. Thus combining hormesis and stem cell therapy might improve the outcome for treatment of these diseases. In addition, since the cell death patterns and their underlying molecular mechanism may vary in different neurodegenerative diseases, even in different progression stages of the same disease, it is essential to design a suitable and optimum hormetic strategy that is tailored to the individual patient.     

Rotary jet-spun porous microfibers as scaffolds for stem cells delivery to central nervous system injury

Stem cell transplantation is a promising strategy to treat brain injuries. However, cell-based therapies are limited because poor local cell engraftment. Here, we present a polylactic acid (PLA) scaffold to support mesenchymal stem cells (MSCs) delivery in stroke. We isolated bone marrow MSCs from adult C57/Bl6 mice, cultured them on PLA polymeric rough microfibrous (PRM) scaffolds obtained by rotary jet spinning, and transplanted over the brains of adult C57/Bl6 mice, carrying thermocoagulation-induced cortical stroke. No inflammatory response to PRM was found. MSCs transplantation significantly reduced the area of the lesion and PRM delivery increased MSCs retention at the injury site. In addition, PRM upregulated α6-integrin and CXCL12 production, which may be the cause for greater cell retention at the lesion site and may provide additional benefit to MSCs transplantation procedures. We conclude that PRM scaffolds offer a promising new system to deliver stem cells to injured areas of the brain.     

Effect of captopril on normal and injured hemopoietic stem cells

In vitro and in vivo studies of the effect of captopril on murine hemopoietic stem cells were performed to elucidate the pathogenic relationship between this drug and agranulocytosis. Up to 20 μg/ml of drug in vitro or 26 weeks of 450 mg of captopril per kilogram body weight per day by mouth in vivo failed to produce myelotoxicity in normal Swiss mice. However, the same high-dose oral captopril therapy given to Swiss mice with busulfan-induced stem cell damage produced myelo-suppression. The hematologic lesion was an isolated, highly significant depression of committed neutrophil-monocyte stem cells (CFU-NMs). These findings suggest that captopril may be selectively toxic for impaired neutrophilic stem cells, producing clinically significant neutropenia in individuals with a previously damaged bone marrow.     

Electrospun scaffolds for stem cell engineering

Stem cells interact with and respond to a myriad of signals emanating from their extracellular microenvironment. The ability to harness the regenerative potential of stem cells via a synthetic matrix has promising implications for regenerative medicine. Electrospun fibrous scaffolds can be prepared with high degree of control over their structure creating highly porous meshes of ultrafine fibers that resemble the extracellular matrix topography, and are amenable to various functional modifications targeted towards enhancing stem cell survival and proliferation, directing specific stem cell fates, or promoting tissue organization. The feasibility of using such a scaffold platform to present integrated topographical and biochemical signals that are essential to stem cell manipulation has been demonstrated. Future application of this versatile scaffold platform to human embryonic and induced pluripotent stem cells for functional tissue repair and regeneration will further expand its potential for regenerative therapies.     

Biomaterials reinforced MSCs transplantation for spinal cord injury repair

Due to the complex pathophysiological mechanism, spinal cord injury (SCI) has become one of the most intractable central nervous system (CNS) diseases to therapy. Stem cell transplantation, mesenchymal stem cells (MSCs) particularly, appeals to more and more attention along with the encouraging therapeutic results for the functional regeneration of SCI. However, traditional cell transplantation strategies have some limitations, including the unsatisfying survival rate of MSCs and their random di...     

Methods to assess stem cell lineage, fate and function

Stem cell therapy has the potential to regenerate injured tissue. For stem cells to achieve their full therapeutic potential, stem cells must differentiate into the target cell, reach the site of injury, survive, and engraft. To fully characterize these cells, evaluation of cell morphology, lineage specific markers, cell specific function, and gene expression must be performed. To monitor survival and engraftment, cell fate imaging is vital. Only then can organ specific function be evaluated to determine the effectiveness of therapy. In this review, we will discuss methods for evaluating the function of transplanted cells for restoring the heart, nervous system, and pancreas. We will also highlight the specific challenges facing these potential therapeutic areas.     

Stem cell therapy in ischemic heart disease

Coronary artery disease (CAD) remains the leading cause of death in the Western world. The high impact of its main sequelae, acute myocardial infarction and congestive heart failure (CHF), on the quality of life of patients and the cost of health care drives the search for new therapies. The recent finding that stem cells contribute to neovascularization and possibly improve cardiac function after myocardial infarction makes stem cell therapy the most highly active research area in cardiology. Although the concept of stem cell therapy may revolutionize heart failure treatment, several obstacles need to be addressed. To name a few: 1) Which patient population should be considered for stem cell therapy? 2) What type of stem cell should be used? 3) What is the best route for cell delivery? 4) What is the optimum number of cells that should be used to achieve functional effects? 5) Is stem cell therapy safer and more effective than conventional therapies? The published studies vary significantly in design, making it difficult to draw conclusions on the efficacy of this treatment. For example, different models of ischemia, species of donors and recipients, techniques of cell delivery, cell types, cell numbers and timing of the experiments have been used. However, these studies highlight the landmark concept that stem cell therapy may play a major role in treating cardiovascular diseases in the near future. It should be noted that stem cell therapy is not limited to the treatment of ischemic cardiac disease. Non-ischemic cardiomyopathy, peripheral vascular disease, and aging may be treated by stem cells. Stem cells could be used as vehicle for gene therapy and eliminate the use of viral vectors. Finally, stem cell therapy may be combined with pharmacological, surgical, and interventional therapy to improve outcome. Here we attempt a systematic overview of the science of stem cells and their effects when transplanted into ischemic myocardium.     

Intranasal delivery of stem cells to the brain

INTRODUCTION: Stem cell-based therapy has proved to be a promising treatment option for neurological disorders. However, there are difficulties in successfully administrating these stem cells. For example, the brain-blood barrier impedes the entrance of stem cells into the CNS after systemic administration. Direct transplantation or injection may result in brain injury, and these strategies are clinically less feasible. Intranasal administration is a non-invasive and effective alternative for the delivery of drugs, vector-encoded viruses or even phages to the CNS. Recent studies have in fact demonstrated that stem cells may enter the CNS after intranasal administration. These results suggest that intranasal delivery may provide an alternative strategy for stem cell-based therapy. AREAS COVERED: This review summarizes current studies that have applied the intranasal delivery of stem cells into the brain. In addition, the distribution and fate of stem cells in the brain and the potential opportunities as well as challenges of intranasal stem cell delivery are also discussed. EXPERT OPINION: Intranasal delivery of stem cells is a new method with great potential for the transplantation of stem cells into the brain, and it may provide an extraordinary approach to overcoming the existing barriers of stem cell delivery for the treatment of many neurological disorders. This potential benefit emphasizes the importance of future research into intranasal delivery of stem cells.     

Do adult stem cells ameliorate the damaged myocardium? Human cord blood as a potential source of stem cells

The heart does not mend itself after infarction. However, stem cells may revolutionize heart disease treatment. A vast and growing body of evidence indicates that cell-based strategies have promising therapeutic potential. Recent clinical and pre-clinical studies demonstrate varying degrees of improvement in cardiac function using different adult stem cell types such as bone marrow (BM)-derived progenitor cells and skeletal myoblasts. However, the efficacy of cell therapy after myocardial infarction (MI) is inconclusive and the cellular source with the highest potential for regeneration is unclear. Clinically, BM and skeletal muscle are the most commonly used sources of autologous stem cells. One major pitfall of using autologous stem cells is that the number of functional cells is generally depleted in the elderly and chronically ill. Therefore, there is an urgent need for a new source of adult stem cells. Human umbilical cord blood (CB) is a candidate and appears to have several key advantages. CB is a viable and practical source of progenitor cells. The cells are na?ve and what's more, CB contains a higher number of immature stem/progenitor cells than BM. We review recent clinical experience with adult stem cells and explore the potential of CB as a source of cells for cardiac repair following MI. We conclude that there is a conspicuous absence of clinical studies utilizing CB-derived cells and there is a pressing need for large randomized double-blinded clinical trials to assess the overall efficacy of cell-based therapy.     

An update of human mesenchymal stem cell biology and their clinical uses

In the past decade, an increasing urge to develop new and novel methods for the treatment of degenerative diseases where there is currently no effective therapy has lead to the emerging of the cell therapy or cellular therapeutics approach for the management of those conditions where organ functions are restored through transplantation of healthy and functional cells. Stem cells, because of their nature, are currently considered among the most suitable cell types for cell therapy. There are an increasing number of studies that have tested the stromal stem cell functionality both in vitro and in vivo. Consequently, stromal (mesenchymal) stem cells (MSCs) are being introduced into many clinical trials due to their ease of isolation and efficacy in treating a number of disease conditions in animal preclinical disease models. The aim of this review is to revise MSC biology, their potential translation in therapy, and the challenges facing their adaptation in clinical practice.