Mesenchymal stem cells protect from sub-chronic phencyclidine insult in vivo and counteract changes in astrocyte gene expression in vitro

Mesenchymal stem cells (MSCs) are an attractive cell source for regenerative medicine strategies in brain diseases. Experimental studies have shown that repeated administration of phencyclidine (PCP) leads to schizophrenia-like behavioral changes in mice. The aim of the present study was to explore the effectiveness of MSC transplantation into the hippocampus in attenuating PCP-induced social behavior deficits. PCP was administered subcutaneously to C57bl mice (10 mg/kg daily) for 2 weeks. On the first day of PCP administration, adult human MSCs were transplanted into the hippocampus. A week after the last PCP dose, the mice underwent social preference testing. MSC transplantation was associated with a significant reduction in the adverse social behavior induced by PCP. Immunohistochemical analysis revealed that the stem cells survived in the mouse brain, and hippocampal Western blot analysis revealed a statistical trend towards a decrease in cleaved caspase 3 protein levels in the stem cell treated group. Upon in vitro co-culture of astrocytes and MSCs, the MSCs, in the presence of PCP, positively regulated astrocyte expression of genes involved in glutamate metabolism and antioxidant defenses. These findings suggest that MSC transplantation into the hippocampus may serve as a novel neuroprotective tool for the treatment of the PCP-induced schizophrenia-like social endophenotype. The mechanism underlying the beneficial behavioral effect may involve modulation of host astrocyte functioning, including glutamate processing and antioxidant capacity.     

Genetically modified mesenchymal stem cells for improved islet transplantation

The use of adult stem cells for therapeutic purposes has met with great success in recent years. Among several types of adult stem cells, mesenchymal stem cells (MSCs) derived from bone marrow (BM) and other sources have gained popularity for basic research and clinical applications because of their therapeutic potential in treating a variety of diseases. Because of their tissue regeneration potential and immune modulation effect, MSCs were recently used as cell-based therapy to promote revascularization, increase pancreatic β-cell proliferation, and avoid allograft rejection in islet transplantation. Taking advantage of the recent progress in gene therapy, genetically modified MSCs can further enhance and expand the therapeutic benefit of primary MSCs while retaining their stem-cell-like properties. This review aims to gain a thorough understanding of the current obstacles to successful islet transplantation and discusses the potential role of primary MSCs before or after genetic modification in islet transplantation.     

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.     

Autotransplantation of bone marrow-derived stem cells as a therapy for neurodegenerative diseases

Neurodegenerative diseases are characterized by a progressive degeneration of selective neural populations. This selective hallmark pathology and the lack of effective treatment modalities make these diseases appropriate candidates for cell therapy. Bone marrow-derived mesenchymal stem cells (MSCs) are self-renewing precursors that reside in the bone marrow and may further be exploited for autologous transplantation. Autologous transplantation of MSCs entirely circumvents the problem of immune rejection, does not cause the formation of teratomas, and raises very few ethical or political concerns. More than a few studies showed that transplantation of MSCs resulted in clinical improvement. However, the exact mechanisms responsible for the beneficial outcome have yet to be defined. Possible rationalizations include cell replacement, trophic factors delivery, and immunomodulation. Cell replacement theory is based on the idea that replacement of degenerated neural cells with alternative functioning cells induces long-lasting clinical improvement. It is reasoned that the transplanted cells survive, integrate into the endogenous neural network, and lead to functional improvement. Trophic factor delivery presents a more practical short-term approach. According to this approach, MSC effectiveness may be credited to the production of neurotrophic factors that support neuronal cell survival, induce endogenous cell proliferation, and promote nerve fiber regeneration at sites of injury. The third potential mechanism of action is supported by the recent reports claiming that neuroinflammatory mechanisms play an important role in the pathogenesis of neurodegenerative disorders. Thus, inhibiting chronic inflammatory stress might explain the beneficial effects induced by MSC transplantation. Here, we assemble evidence that supports each theory and review the latest studies that have placed MSC transplantation into the spotlight of biomedical research.     

Amniotic fluid stem cells: a promising therapeutic resource for cell-based regenerative therapy

Stem cells have been proposed as a powerful tool in the treatment of several human diseases, both for their ability to represent a source of new cells to replace those lost due to tissue injuries or degenerative diseases, and for the ability of produce trophic molecules able to minimize damage and promote recovery in the injured tissue. Different cell types, such as embryonic, fetal or adult stem cells, human fetal tissues and genetically engineered cell lines, have been tested for their ability to replace damaged cells and to restore the tissue function after transplantation. Amniotic fluid -derived Stem cells (AFS) are considered a novel resource for cell transplantation therapy, due to their high renewal capacity, the "in vitro" expression of embryonic cell lineage markers, and the ability to differentiate in tissues derived from all the three embryonic layers. Moreover, AFS do not produce teratomas when transplanted into animals and are characterized by a low antigenicity, which could represent an advantage for cell transplantation or cell replacement therapy. The present review focuses on the biological features of AFS, and on their potential use in the treatment of pathological conditions such as ischemic brain injury and bone damages.     

Immunomodulatory properties of mesenchymal stem cells and their therapeutic applications

Mesenchymal stem cells (MSCs) are adult stem cells that can be isolated from most adult tissues, including bone marrow, adipose, liver, amniotic fluid, lung, skeletal muscle and kidney. The term MSC is currently being used to represent both mesenchymal stem cells and multipotent mesenchymal stromal cells. Numerous reports on systemic administration of MSCs leading to functional improvements based on the paradigm of engraftment and differentiation have been published. However, it is not only difficult to demonstrate extensive engraftment of cells, but also no convincing clinical results have been generated from phase 3 trials as of yet and prolonged responses to therapy have been noted after identification of MSCs had discontinued. It is now clear that there is another mechanism by which MSCs exert their reparative benefits. Recently, MSCs have been shown to possess immunomodulatory properties. These include suppression of T cell proliferation, influencing dendritic cell maturation and function, suppression of B cell proliferation and terminal differentiation, and immune modulation of other immune cells such as NK cells and macrophages. In terms of the clinical applications of MSCs, they are being tested in four main areas: tissue regeneration for cartilage, bone, muscle, tendon and neuronal cells; as cell vehicles for gene therapy; enhancement of hematopoietic stem cell engraftment; and treatment of immune diseases such as graft-versus-host disease, rheumatoid arthritis, experimental autoimmune encephalomyelitis, sepsis, acute pancreatitis and multiple sclerosis. In this review, the mechanisms of immunomodulatory effects of MSCs and examples of animal and clinical uses of their immunomodulatory effects are described.     

A novel therapeutic regimen for hepatic fibrosis using the combination of mesenchymal stem cells and baicalin

Baicalin, isolated from the root of Scutellaria baicalensis Georgi, has shown anti-inflammatory and antioxidant activities, while mesenchymal stem cells (MSCs) have the capability of self-renewal and multilineage differentiation. In the present study, we found that baicalin could promote differentiation of bone marrow-derived MSCs into hepatocytes in vitro. We then compared the therapeutic effects of five therapeutic regimens for hepatic fibrosis induced by carbon tetrachloride in vivo by analysis of serum enzymes, morphological characteristics, cytokines and cell engraftment. Transplantation of MSCs alone was able to promote partial recovery of liver function and suppression of liver inflammation, but showed little effect on reducing the fibrotic area; transplantation with baicalin-treated MSCs gave an improved therapeutic effect; MSC transplantation and baicalin administration showed a synergistic effect; transplantation with baicalin-treated MSCs in combination with baicalin administration had the best therapeutic effect for hepatic fibrosis. Therefore, we conclude that transplantation of pre-differentiated MSC together with baicalin administration may serve as an effective therapeutic regimen for severe liver diseases.     

Development of fluorescent labeling methods for stem cells

For successful development of cell-based therapy, both the disposition and differentiation of transplanted cells are directly related to therapeutic effects. In vivo imaging is an attractive tool to obtain real-time information on the disposition of target cells. In various types of imaging methods such as positron emission tomography(PET) and magnetic resonance imaging(MRI), fluorescence imaging is suitable for visualizing the disposition of cells because it can visualize single cells both in vitro and in vivo. For the trafficking of stem cells after transplantation, it is necessary to label living cells for long time periods without disturbing the function or differentiation of the labeled cells. Recently, we have developed quantum dots modified with polyamidoamine(PAMAM) dendrimers. These can more rapidly escape from endosomes and sustain their fluorescence intensity compared with unmodified quantum dots in primary cultured mesenchymal stem cells (MSCs). Fluorescence intensity was also sustained after intravenous injection of MSCs labeled with PAMAM dendrimer-modified quantum dots. To study the dynamics of MSCs in vivo, we constructed a piggyBack transposon vector that can integrate the target gene into the genome in mammalian cells, and established primary MSCs with long-term expression of EmGFP. In addition, we also developed a suction device stabilizing tissue for in vivo real time imaging. In this section, I present our recent findings on long-term fluorescent labeling of MSCs and in vivo visualizing of cell dynamics in a living mouse.     

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.     

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 diffusion from the injection site to ambient tissues. The application of biomaterials in tissue engineering provides a new horizon. Biomaterials can not only confine MSCs in the injured lesions with higher cell viability, but also promote their therapeutic efficacy. This review summarizes the strategies and advantages of biomaterials reinforced MSCs transplantation to treat SCI in recent years, which are clarified in the light of various therapeutic effects in pathophysiological aspects of SCI.     

新型超顺磁性氧化铁在干细胞活体示踪中的应用研究

目的：研究超顺磁性氧化铁（superparamagnetic iron oxide,SP10）标记干细胞的效率及其在磁共振活体示踪中的应用价值。方法：以3-氨丙基三乙氧基硅烷（APTS）修饰Fe2O3配制成SP10,用SP10转染标记骨髓间充质干细胞（MSCs）,对标记后的MSCs行普鲁士蓝染色鉴定、MTT测试细胞相对数量。最后将标记后的MSCs移植入大鼠脑内,磁共振（MRI）扫描示踪显示。结果：普鲁士蓝染色可直接显示SP10高效率标记MSCs,MTT测试表明SP10标记对MSCs增殖数量及其活力无明显影响,MRI检查发现脑内移植的SP10标记MSCs在T2上呈明显的低信号。结论：APTS修饰Fe2O3配制而成的新型SP10对细胞无明显毒性,没有多聚赖氨酸（PLL）等转染剂仍可直接高效率标记MSCs,MRI活体显影示踪效果良好。     

From bone to brain: human skeletal stem cell therapy for stroke

Human adult skeletal stem cells, a.k.a. mesenchymal stem cells or marrow stromal cells (MSCs), have been identified as precursors of several different mesenchymal cellular lineages, including osteoblasts, chondrocytes, myoblasts, adipocytes, and fibroblasts, as well as non-mesenchymal lineages including neurons and glial cells. Adult stem cell transplantation is a promising strategy for the treatment of stroke. MSCs are also used as a platform for gene therapies and therapeutic agents. In this review, we discuss recent progress of human skeletal stem cell biology, in vitro differentiation of MSCs into neural stem cells and neurons, MSC therapy for stroke, MSC aging and the challenge of autologous cell therapy for stroke in elderly patients.     

Cell therapy for inner ear diseases

Degeneration of inner ear cells, especially sensory hair cells and associated neurons, results in hearing impairment and balance disorders. These disabilities are incurable because loss of hair cells and associated neurons is currently irreversible. Protection or regeneration of hair cells and associated neurons is an important area of research for developing an effective treatment for inner ear diseases. Cell therapy is a rapidly growing area of research and has potential applications in the treatment of inner ear disorders. The first attempts to examine the feasibility of cell therapy in the treatment of inner ear disorders have been performed using neural stem cells (NSCs). Grafted NSCs can survive in the inner ear and differentiate into neural, glial and/or hair cell-phenotypes, making NSC transplantation for the restoration of inner ear cells a potentially viable treatment. Further studies have suggested embryonic stem cells (ESCs), dorsal ganglion cells and cell lines derived from fetal inner ear cells could be used to restore damaged inner ear cells. Cell transplantation has also been suggested as a strategy for drug delivery into the inner ear, and the ability of NSC-derived cells to produce neurotrophins in the inner ear has been demonstrated. Results from studies using autologous bone marrow stromal cells (MSCs) indicate a high survival and migration potential suggesting that MSCs can be used as a drug delivery vehicle to the inner ear. These cell transplantation findings provide a sound foundation for the development of therapies to treat inner ear disorders.     

Embryonic stem cell-derived hematopoietic stem cells: challenges in development, differentiation, and immunogenicity

Embryonic stem cells (ESC) can potentially be manipulated in vitro to differentiate into cells and tissues of all three germ layers. This pluripotent feature is being exploited to use ESC-derived tissues as therapies for degenerative diseases and replacement of damaged organs. Although their potential is great, the promise of ESC-derived therapies will be unfulfilled unless several challenges are overcome. For example, inefficient production of ESC-derived tissues before transplantation, inability of ESC-derived tissues to integrate well into the adult microenvironments due to developmental stage incompatibility, or active immune rejection of the ESC-derived graft are all potential challenges to successful ESC-derived therapies. One way to induce immunological tolerance to allogeneic tissues is via the establishment of mixed hematopoietic chimerism in which the host and donor cells are educated to recognize each other as "self". Proof of principle that in vitro cultured ESC-derived hematopoietic progenitors can be transplanted and induce immunological tolerance to allogeneic tissues exists in mouse models. In this review, we discuss the challenges to in vitro development of a bona fide ESC-derived hematopoietic stem cell and their differentiation fate in vivo, and provide suggestions to predict the immunogenicity of specific ESC-derived hematopoietic populations before transplantation that could be used to prevent their rejection after transplantation into an adult host.     

基因修饰间充质干细胞治疗肿瘤研究进展

间充质干细胞（MSCs）是来源于中胚层的成体干细胞,体内分布广泛,可从骨髓、脂肪、牙髓、脐带/胎盘等组织中分离获取,具有高度的可增殖和分化潜能,较低的免疫原性,同时具有向炎症损伤部位微环境的趋向性,在疾病治疗方面可作为基因药物的载体实现精准治疗。癌症被认为是永远无法愈合的伤口,其组织微环境在损伤与修复中呈无休止的动态变化,MSCs在其中扮演了重要角色。利用MSCs具有的向肿瘤组织中归巢及定位的特点,对其进行抗肿瘤药物的基因工程改造可能在癌症的治疗上是一种新的策略。概述MSCs在癌症发生发展中的作用以及基因修饰MSCs治疗癌症的研究进展,旨在为临床使用基因修饰MSCs治疗癌症提供策略和见解。     

Transplanting stem cells: potential targets for immune attack. Modulating the immune response against embryonic stem cell transplantation

The curative promise of stem cells and their descendants for tissue regeneration and repair is currently the subject of an intense research effort worldwide. If it proves feasible to differentiate stem cells into specific tissues reliably and safely, this approach will be invaluable in the treatment of diseases that lead to organ degeneration or failure, providing an alternative or supplementary source of tissue for transplantation. Embryonic stem (ES) cells are pluripotent cells derived from the inner cell mass of a pre-implantation blastocyst that can produce all cells and tissues of the foetus. In recent years, several laboratories have described the directed differentiation of ES cells into multiple mature cell types including: cardiomyocytes; haemopoietic cells; hepatocytes; neurones; muscle cells and both endocrine and exocrine cells of the pancreas. How the immune system of the host will respond when these ES cell-derived mature cells are transplanted is ill defined. This review will focus on the potential mechanisms that the immune system could use to target ES cell-derived transplants and how unwanted responses might be prevented.     

Cell-based therapy for management of osteoarthritis

Osteoarthritis(OA)is a most common form of degenerative joint disease,primarily characterized by the degradation of articular cartilage,subchondral sclerosis and inflammation of the synovial membrane.Mesenchymal stem cells(MSCs),a multipotent adult stem cell population,can be isolated from many connective tissue lineages,including those of the diarthrodial joint.Joint-resident MSCs or MSC-like progenitor cells contribute to the maintenance of healthy microenvironment or to the response to trauma.The onset of degenerative changes in the joint related to abnormal condition or depletion of these endogenous MSCs and native host hyaline cartilage cells,leading to limited selfrepair potential of the joint and advance of the degradation.To date,no acknowledged medical treatment strategies,including non-operative and classical surgical techniques,are efficient in restoring normal anatomy and function of hyaline cartilage in OA.This highlights an urgent need for better celled-based therapeutic strategies that supplement these functional cel s exogenously to recover the tissue homeostasis and repair in joint cavity via chondrogenic and anti-in fl ammatory functions.In this review we focus on the role of native MSCs in healthy or OA joint and recent progress in cel-based researches utilizing culture-expanded chondrocytes,pluripotent stem cel s,or MSCs from different sources for treating OA.     

Characterization,in vitro cytotoxicity assessment,and in vivo visualization of multimodal,RITC-labeled,silica-coated magnetic nanoparticles for labeling human cord blood–derived mesenchymal stem cells

Live imaging is a powerful technique that can be used to characterize the fate and location of stem cells in animal models. Here we investigated the characteristics and in vitro cytotoxicity of human mesenchymal stem cells (MSCs) labeled with silica-coated magnetic nanoparticles incorporating rhodamine B isothiocyanate, MNPs@SiO₂(RITC). We also conducted various in vivo–uptake tests with nanoparticle-labeled human MSCs. MNPs@SiO₂(RITC) showed photostability against ultraviolet light exposure and were nontoxic to human MSCs, based on the MTT, apoptosis, and cell cycle arrest assays. In addition, MNPs@SiO₂(RITC) did not affect the surface phenotype or morphology of human MSCs. We also demonstrated that MNPs@SiO₂(RITC) have stable retention properties in MSCs in vitro. Furthermore, using optical and magnetic resonance imaging, we successfully detected a visible signal from labeled human MSCs that were transplanted into NOD.CB17-Prkdc^SCID (NOD-SCID) mice. These results demonstrate that MNPs@SiO₂(RITC) are biocompatible and useful tools for human MSC labeling and bioimaging.From the Clinical EditorThe characteristics and in vitro cytotoxicity of human mesenchymal stem cells (MSCs) labeled with silica-coated magnetic nanoparticles incorporating rhodamine B isothiocyanate, RITC were investigated in this study. RITC showed photostability against ultraviolet light exposure and was nontoxic to human MSCs. Using both optical and magnetic resonance imaging, successful detection of signal from labeled human MSCs transplanted into mice is demonstrated.     

Mesenchymal stem cells for cardiac regenerative therapy

Until recently, the concept of treating the injured or failing heart by generating new functional myocardium was considered physiologically impossible. Major scientific strides in the past few years have challenged the concept that the heart is a post-mitotic organ, leading to the hypothesis that cardiac regeneration could be therapeutically achieved. Bone marrow-derived adult stem cells were among the first cell populations that were used to test this hypothesis. Animal studies and early clinical experience support the concept that therapeutically delivered mesenchymal stem cells (MSCs) safely improve heart function after an acute myocardial infarction (MI). MSCs produce a variety of cardio-protective signalling molecules, and have the ability to differentiate into both myocyte and vascular lineages. Additionally, MSCs are attractive as a cellular vehicle for gene delivery, cell transplantation or for tissue engineering because they offer several practical advantages. They can be obtained in relatively large numbers through standard clinical procedures, and they are easily expanded in culture. The multi-lineage potential of MSC, in combination with their immunoprivileged status, make MSCs a promising source for cell therapy in cardiac diseases. Here we provide an overview of biological characteristics of MSCs, experimental animal studies and early clinical trials with MSCs. In addition, we discuss the routes of cell delivery, cell tracking experiments and current knowledge of the mechanistic underpinnings of their action.