Potential use of stem cells in neuroreplacement therapies for neurodegenerative diseases

Construction of "Coral" SERS sensor for ultrasensitive and rapid detection of harmful component macrophage migration inhibitory factor in Platelet-rich Plasma

Macrophage migration inhibitory factor (MIF) is a pro-inflammatory factor produced by residual red blood cell lysis, which can significantly influence the curative effect of Platelet-rich plasma (PRP) therapy used for osteoarthritis (OA) treatment. In this study, we proposed a novel approach for detecting the concentration of MIF in PRP using a dopamine-coated antibody-Au (core)-Ag (shell)-SERS sensor, which enables ultrasensitive and rapid detection of MIF. The best experimental conditions have a detection limit of only 90.05 pg/mL and a good linear relationship between 1-5000 ng/mL. In 40 PRP samples collected from actual clinical patients, we detected MIF concentrations ranging from 2.0-3.6 ng/mL. This indicated that the Coral SERS sensor not only allows for results highly consistent with the traditional ELISA method, but also costs less ($0.40-$0.70), needs shorter testing time (integration time is only 10s), and consumes less PRP that can greatly improve the sample quality and maximize the curative effect in clinical applications for OA treatment with PRP.

Co-administration of TiO2-nanowired dl-3-n-butylphthalide (dl-NBP) and mesenchymal stem cells enhanced neuroprotection in Parkinson's disease exacerbated by concussive head injury

dl-3-n-butylphthalide (dl-NBP) is a powerful antioxidant compound with profound neuroprotective effects in stroke and brain injury. However, its role in Parkinson's disease (PD) is not well known. Traumatic brain injury (TBI) is one of the key factors in precipitating PD like symptoms in civilians and particularly in military personnel. Thus, it would be interesting to explore the possible neuroprotective effects of NBP in PD following concussive head injury (CHI). In this chapter effect of nanowired delivery of NBP together with mesenchymal stem cells (MSCs) in PD with CHI is discussed based on our own investigations. It appears that CHI exacerbates PD pathophysiology in terms of p-tau, α-synuclein (ASNC) levels in the cerebrospinal fluid (CSF) and the loss of TH immunoreactivity in substantia niagra pars compacta (SNpc) and striatum (STr) along with dopamine (DA), dopamine decarboxylase (DOPAC). And homovanillic acid (HVA). Our observations are the first to show that a combination of NBP with MSCs when delivered using nanowired technology induces superior neuroprotective effects in PD brain pathology exacerbated by CHI, not reported earlier.

Epiregulin promotes osteogenic differentiation and inhibits neurogenic trans-differentiation of adipose-derived mesenchymal stem cells via MAPKs pathway

Mesenchymal stem cells (MSCs) exists low efficiency to trans-differentiate into other germinal layer cell types. One key issue is to discover the effect of important factor on MSCs differentiation abiltiy. In this study, we investigated the role and mechanism of epiregulin (EREG) on the osteogenic differentiation and neurogenic trans-differentiation in adipose-derived stem cells (ADSCs). We discovered that the depletion of EREG inhibited the osteogenic differentiation in vitro. And 25 ng/mL recombinant human epiregulin protein (rhEREG) effectively improved the osteogenic differentiation of EREG-depleted-ADSCs. Depletion of EREG promoted the formation of neural spheres, and increased the expressions of nestin, βIII-tubulin, NeuroD, NCAM, TH, and NEF in ADSCs. Then, 25 ng/mL rhEREG significantly inhibited these neurogenic differentiation indicators. Inhibition of p38 MAPK, JNK, or Erk1/2 signaling pathway separately, blocked the rhEREG-enhanced osteogenic differentiation ability and the rhEREG-inhibited neurogenic trans-differentiation ability of ADSCs. In conclusions, EREG promoted the osteogenic differentiation and inhibited the neurogenic trans-differentiation potentials of ADSCs via MAPK signaling pathways.

Assessing clinical implications and perspectives of the pathophysiological effects of erythrocytes and plasma free hemoglobin in autologous biologics for use in musculoskeletal regenerative medicine therapies. A review

Autologous biologics, defined as platelet-rich plasma (PRP) and bone marrow aspirate concentrate (BMC), are cell-based therapy treatment options in regenerative medicine practices, and have been increasingly used in orthopedics, sports medicine, and spinal disorders. These biological products are produced at point-of-care; thereby, avoiding expensive and cumbersome culturing and expansion techniques.

Numerous commercial PRP and BMC systems are available but reports and knowledge of bio-cellular formulations produced by these systems are limited. This limited information hinders evaluating clinical and research outcomes and thus making conclusions about their biological effectiveness. Some of their important cellular and protein properties have not been characterized, which is critical for understanding the mechanisms of actions involved in tissue regenerative processes. The presence and role of red blood cells (RBCs) in any biologic has not been addressed extensively. Furthermore, some of the pathophysiological effects and phenomena related to RBCs have not been studied. A lack of a complete understanding of all of the biological components and their functional consequences hampers the development of clinical standards for any biological preparation.

This paper aims to review the clinical implications and pathophysiological effects of RBCs in PRP and BMC; emphasizes hemolysis, eryptosis, and the release of macrophage inhibitory factor; and explains several effects on the microenvironment, such as inflammation, oxidative stress, vasoconstriction, and impaired cell metabolism.

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Different biological formulations optimize disease specific regenerative treatment protocols.

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Disintegrated RBC's release harmful components to regenerative therapy treatment vials.

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The effectiveness of MSC injection depends on the quality of the bone marrow aspiration procedure.

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PRP and BMC should contain minimal to no erythrocytes.

Stem Cell Tracing Through MR Molecular Imaging

Stem cell therapy opens a new window in medicine to overcome several diseases that remain incurable. It appears such diseases as cardiovascular disorders, brain injury, multiple sclerosis, urinary system diseases, cartilage lesions and diabetes are curable with stem cell transplantation. However, some questions related to stem cell therapy have remained unanswered. Stem cell imaging allows approval of appropriated strategies such as selection of the type and dose of stem cell, and also mode of cell delivery before being tested in clinical trials. MRI as a non-invasive imaging modality provides proper conditions for this aim. So far, different contrast agents such as superparamagnetic or paramagnetic nanoparticles, ultrasmall superparamagnetic nanoparticles, fluorine, gadolinium and some types of reporter genes have been used for imaging of stem cells. The core subject of these studies is to investigate the survival and differentiation of stem cells, contrast agent's toxicity and long term following of transplanted cells. The promising results of in vivo and some clinical trial studies may raise hope for clinical stem cells imaging with MRI.

Schwann Cell Transplantation Improves Reticulospinal Axon Growth and Forelimb Strength after Severe Cervical Spinal Cord Contusion

Schwann cell (SC) implantation alone has been shown to promote the growth of propriospinal and sensory axons, but not long-tract descending axons, after thoracic spinal cord injury (SCI). In the current study, we examined if an axotomy close to the cell body of origin (so as to enhance the intrinsic growth response) could permit supraspinal axons to grow onto SC grafts. Adult female Fischer rats received a severe (C5) cervical contusion (1.1 mm displacement, 3 KDyn). At 1 week postinjury, 2 million SCs ex vivo transduced with lentiviral vector encoding enhanced green fluorescent protein (EGFP) were implanted within media into the injury epicenter; injury-only animals served as controls. Animals were tested weekly using the BBB score for 7 weeks postimplantation and received at end point tests for upper body strength: self-supported forelimb hanging, forearm grip force, and the incline plane. Following behavioral assessment, animals were anterogradely traced bilaterally from the reticular formation using BDA-Texas Red. Stereological quantification revealed a twofold increase in the numbers of preserved NeuN+ neurons rostral and caudal to the injury/graft site in SC implanted animals, corroborating previous reports of their neuroprotective efficacy. Examination of labeled reticulospinal axon growth revealed that while rarely an axon was present within the lesion site of injury-only controls, numerous reticulospinal axons had penetrated the SC implant/lesion milieu. This has not been observed following implantation of SCs alone into the injured thoracic spinal cord. Significant behavioral improvements over injury-only controls in upper limb strength, including an enhanced grip strength (a 296% increase) and an increased self-supported forelimb hanging, accompanied SC-mediated neuroprotection and reticulospinal axon growth. The current study further supports the neuroprotective efficacy of SC implants after SCI and demonstrates that SCs alone are capable of supporting modest supraspinal axon growth when the site of axon injury is closer to the cell body of the axotomized neuron.

Adult Mesenchymal Stem Cells in Dental Research: A New Approach for Tissue Engineering

Many adult tissues contain a population of stem cells that have the ability to regenerate after trauma, disease or aging. Recently, there has been great interest in mesenchymal stem cells and their roles in maintaining the physiological structure of tissues. The studies on stem cells are thought to be very important and, in fact, it has been shown that this cell population can be expanded ex vivo to regenerate tissues not only of the mesenchymal lineage, such as intervertebral disc cartilage, bone and tooth-associated tissues, but also other types of tissues. Several studies have focused on the identification of odontogenic progenitors from oral tissues, and it has been shown that the mesenchymal stem cells obtained from periodontal ligament and dental pulp could have similar morphological and phenotypical features of the bone marrow mesenchymal cells. In fact a population of homogeneous human mesenchymal stem cells derived from periodontal ligament and dental pulp, and proliferating in culture with a well-spread morphology, can be recovered and characterized. Since these cells are considered as candidates for regenerative medicine, the knowledge of the cell differentiation mechanisms is imperative for the development of predictable techniques in implant dentistry, oral surgery and maxillo-facial reconstruction. Thus, future research efforts might be focused on the potential use of this cell population in tissue engineering. Further studies will be carried out to elucidate the molecular mechanisms involved in their maintenance and differentiation in vitro and in vivo.

Facilitated Neural Differentiation of Adipose Tissue–Derived Stem Cells by Electrical Stimulation and Nurr-1 Gene Transduction

Neuron-like cells derived from adipose tissue-derived stem cells (ADSCs) have been considered one of the most promising cells for the treatment of neurodegenerative diseases and neurotrauma in the central nervous system (CNS). Thus far, extensive efforts have been made to facilitate neuronal differentiation of ADSCs, but limited progress has been achieved. In the present study, we tested the possibility of using a combination of electrical stimulation (ES) with Nurr-1 gene transduction to promote neuronal differentiation of ADSCs. The tolerance of ADSCs to ES was first examined by a cell apoptosis assay. The proliferation of cells was characterized using a CCK-8 assay. The morphology of cells was examined by scanning electron microscopy (SEM). The differentiation of ADSCs into neuron-like cells was examined by immunocytochemistry (ICC)–immunofluorescence staining, quantitative real-time polymerase chain reaction (qRT-PCR), Western blotting, and enzyme linked immunosorbent assay (ELISA). The gene expression of microtubule-associated protein 2 (MAP-2), β-tubulin, neurofilament 200 (NF-200), octamer binding transcription factor 4 (OCT-4), and glial fibrillary acidic protein (GFAP) after stimulation was examined by qRT-PCR. We found that the optimal intensity of ES for neuronal differentiation of ADSCs was 1 V/cm. In addition, ES combined with Nurr-1 gene transduction increased the neuronal differentiation rate of ADSCs, the length of neurite-like processes, and the secretion of dopamine. Further studies showed that a combination of ES with Nurr-1 gene transduction was capable of promoting the expression of MAP-2, β-tubulin, and NF-200 but decreased the expression of OCT-4 and GFAP. All of these findings indicate that a combination of ES with Nurr-1 gene transduction could facilitate neuronal differentiation of ADSCs, which raises the possibility of its application in the treatment of neurodegenerative diseases and neurotrauma in the CNS.

Ultrasound guided neural stem cell transplantation through the lateral ventricle for treatment of cerebral palsy in children

A total of 24 children with cerebral palsy were enrolled in this study and underwent ultrasound guided transplantation of neural stem cells through the lateral ventricle. Neural stem cells (3.8 × 10⁶–7.3 × 10⁷) were injected into the lateral ventricles. Mild injury of lateral ventricular blood vessels occurred in only two cases (8.3%). Seven cases (29.2%) experienced a fever. Clinical manifestations were improved to varying degrees in eight cases (28.0%) within 3 months after transplantation. Patient condition did not worsen, and no patient experienced severe adverse reactions.

Mesenchymal stem cells as a potent cell source for articular cartilage regeneration

Since articular cartilage possesses only a weak capacity for repair, its regeneration potential is considered one of the most important challenges for orthopedic surgeons. The treatment options, such as marrow stimulation techniques, fail to induce a repair tissue with the same functional and mechanical properties of native hyaline cartilage. Osteochondral transplantation is considered an effective treatment option but is associated with some disadvantages, including donor-site morbidity, tissue supply limitation, unsuitable mechanical properties and thickness of the obtained tissue. Although autologous chondrocyte implantation results in reasonable repair, it requires a two-step surgical procedure. Moreover, chondrocytes expanded in culture gradually undergo dedifferentiation, so lose morphological features and specialized functions. In the search for alternative cells, scientists have found mesenchymal stem cells (MSCs) to be an appropriate cellular material for articular cartilage repair. These cells were originally isolated from bone marrow samples and further investigations have revealed the presence of the cells in many other tissues. Furthermore, chondrogenic differentiation is an inherent property of MSCs noticed at the time of the cell discovery. MSCs are known to exhibit homing potential to the damaged site at which they differentiate into the tissue cells or secrete a wide spectrum of bioactive factors with regenerative properties. Moreover, these cells possess a considerable immunomodulatory potential that make them the general donor for therapeutic applications. All of these topics will be discussed in this review.

Skeletal muscle tissue engineering: which cell to use?

Tissue-engineered skeletal muscle is urgently required to treat a wide array of devastating congenital and acquired conditions. Selection of the appropriate cell type requires consideration of several factors which amongst others include, accessibility of the cell source, in vitro myogenicity at high efficiency with the ability to maintain differentiation over extended periods of time, susceptibility to genetic manipulation, a suitable mode of delivery and finally in vivo differentiation giving rise to restoration of structural morphology and function. Potential stem-progenitor cell sources include and are not limited to satellite cells, myoblasts, mesoangioblasts, pericytes, muscle side-population cells, CD133(+) cells, in addition to embryonic stem cells, mesenchymal stem cells, amniotic fluid stem cells and induced pluripotent stem (iPS) cells. The relative merits and inherent limitations of these cell types within the field of tissue-engineering are discussed in the light of current research. Recent advances in the field of iPS cells should bear the fruits for some exciting developments within the field in the forthcoming years.

Therapeutic implications of mesenchymal stem cells in liver injury

Mesenchymal stem cells (MSCs), represent an attractive tool for the establishment of a successful stem-cell-based therapy of liver diseases. A number of different mechanisms contribute to the therapeutic effects exerted by MSCs, since these cells can differentiate into functional hepatic cells and can also produce a series of growth factors and cytokines able to suppress inflammatory responses, reduce hepatocyte apoptosis, regress liver fibrosis, and enhance hepatocyte functionality. To date, the infusion of MSCs or MSC-conditioned medium has shown encouraging results in the treatment of fulminant hepatic failure and in end-stage liver disease in experimental settings. However, some issues under debate hamper the use of MSCs in clinical trials. This paper summarizes the biological relevance of MSCs and the potential benefits and risks that can result from translating the MSC research to the treatment of liver diseases.

Therapeutic implications of mesenchymal stem cells in liver injury

Mesenchymal stem cells (MSCs), represent an attractive tool for the establishment of a successful stem-cell-based therapy of liver diseases. A number of different mechanisms contribute to the therapeutic effects exerted by MSCs, since these cells can differentiate into functional hepatic cells and can also produce a series of growth factors and cytokines able to suppress inflammatory responses, reduce hepatocyte apoptosis, regress liver fibrosis, and enhance hepatocyte functionality. To date, the infusion of MSCs or MSC-conditioned medium has shown encouraging results in the treatment of fulminant hepatic failure and in end-stage liver disease in experimental settings. However, some issues under debate hamper the use of MSCs in clinical trials. This paper summarizes the biological relevance of MSCs and the potential benefits and risks that can result from translating the MSC research to the treatment of liver diseases.

Remestemcel-L: human mesenchymal stem cells as an emerging therapy for Crohn's disease

INTRODUCTION

Human mesenchymal stem cells (Prochymal brand of remestemcel-L) have been developed for experimental use in Crohn's disease and other conditions. Mesenchymal stems cells (MSCs) have been shown to inhibit inflammatory responses of innate and adaptive immune cells as well as have reparative effects on inflamed tissues. Promising preliminary therapeutic results of MSCs on gastrointestinal graft-versus-host disease have lead to Phase III trials for active Crohn's disease.

AREAS COVERED

This review examines the discovery and characterization of mesenchymal stem cells, their immune effects, their use in animal models of disease, the production and administration of remestemcel-L and the published results of trials of remestemcel-L and alternative MSCs in Crohn's disease.

EXPERT OPINION

The Prochymal brand of remestemcel-L represents the successful pharmaceutical development of mesenchymal stem cells for potential therapy in human disease. While preliminary results show promise of this therapy in terms of efficacy and safety, robust trials confirming efficacy results, explanation of the mechanism of response and estimates of effect compared to other biologics and immunosuppressants will be needed before this is an approved and widely accepted therapy.

Mesenchymal stem cells engraftment in the injured intestine of mice

AIM: To investigate the engraftment of murine bone marrow mesenchymal stem cells (MSCs) in the irradiated intestine of mice to provide some clues about the mechanism of intestine epithelium healing and lay an experimental foundation for treatment of intestine diseases by intravenous transplantation of MSCs.

METHODS: MSCs from male mice were isolated, expanded, identified, suspended in sterile normal saline (1 × 10⁶ cells/mL), and slowly infused into irradiated female mice via the tail vein. Meanwhile, a group of irradiated female mice receiving an equal volume of sterile normal saline were used as controls. For tracing male MSC residence in the intestine after intravenous transplantation, in situ hybridization (ISH) was used to detect the Sry gene on the Y chromosome.

RESULTS: In the transplantation group, ISH analysis revealed the presence of male donor MSCs in the submucosa of the intestine of female mice, but not in the mucosal epithelium. At week 1 after cell transplantation, Sry-positive cells were scattered around the crypt, with a percentage of 19.48% ± 5.01%. At week 2, this percentage rose to 30.86% ± 12.14%, significantly higher than that at week 1 (P < 0.05). However, there was no significant difference in the percentage of Sry-positive cells between at week 2 and week 4 (week 4: 35.95% ± 11.98%, P > 0.05). In the control group, no Sry-positive cells were found.

CONCLUSION: After MSCs were transplanted into mice, they were attracted to and retained in the irradiated intestine and colonized in the intestinal submucosa.

ES, iPS, MSC, and AFS cells. Stem cells exploitation for Pediatric Surgery: current research and perspective

Despite the advancements that have been made in treating infants with congenital malformations, these still represent a major cause of disease and death during the first years of life and childhood. Regeneration of natural tissue from living cells to restore damaged tissues and organs is the main purpose of regenerative medicine. This relatively new field has emerged by the combination of tissue engineering and stem cell transplantation as a possible strategy for the replacement of damaged organs or tissues. This review would like to offer an insight on the latest evolution of stem cells with a glance at their possible application for regenerative medicine, particularly in the Paediatric Surgery field.

Mesenchymal stem cells as immunomodulators after liver transplantation

Mesenchymal stem cells (MSCs) are promising candidate cells for immunomodulation therapy that are currently being tested in the preclinical and clinical setting. MSCs suppress the immune response in a variety of in vitro and disease models and may thus be of benefit for patients suffering from autoimmune disorders or transplant rejection. The mechanism by which MSCs modulate the immune response is still under thorough investigation, but it most likely involves expression of local factors such as indoleamine 2,3-dioxygenase, inducible nitric oxide synthase, and others as well as interactions with dendritic or antigen-presenting cells. Although MSCs have been evaluated in clinical phase I and II studies for graft-versus-host disease and heart, kidney, and bone disease, their introduction into solid organ transplantation is still eagerly awaited. In this short review, we summarize the current understanding of immunomodulation achieved by MSC therapies and introduce a possible outline for a clinical study that will use MSCs in the context of a calcineurin inhibitor-free induction protocol after liver transplantation.

Nitric oxide production during the osteogenic differentiation of human periodontal ligament mesenchymal stem cells

The critical tissues that require regeneration in the periodontium are of mesenchymal origin; therefore, the ability to identify, characterize and manipulate mesenchymal stem cells within the periodontium is of considerable clinical significance. In particular, recent findings suggest that periodontal ligament cells may possess many osteoblast-like properties. In the present study, periodontal ligament mesenchymal stem cells obtained from healthy volunteers were maintained in culture until confluence and then induced to osteogenic differentiation. Intracellular calcium ([Ca2+](i)) concentration and nitric oxide, important signalling molecules in the bone, were measured along with cell differentiation. Alkaline phosphatase activity was assayed and bone nodule-like structures were evaluated by means of morphological and histochemical analysis. Our results showed that the periodontal ligament mesenchymal stem cells underwent an in vitro osteogenic differentiation, resulting in the appearance of active osteoblast-like cells together with the formation of calcified deposits. Differentiating cells were also characterized by an increase of [Ca2+](i) and nitric oxide production. In conclusion, our data show a link between nitric oxide and the osteogenic differentiation of human periodontal ligament mesenchymal stem cells, thus suggesting that local reimplantation of expanded cells in conjugation with a nitric oxide donor could represent a promising method for treatment of periodontal defects.

Potential Role of Culture Mediums for Successful Isolation and Neuronal Differentiation of Amniotic Fluid Stem Cells

In recent years, the use of stem cells has generated increasing interest in regenerative medicine and cancer therapies. The most potent stem cells derive from the inner cell mass during embryonic development and their use yields serious ethical and methodological problems. Recently, a number of reports suggests that another suitable source of multipotent stem cells may be the amniotic fluid. Amniotic fluid mesenchymal stem cells (AFMSCs) are capable of extensive self-renewal, able to differentiate in specialized cells representative of all three germ layers, do not show ethical restriction, and display minimal risks of teratomas and a very low immunogenity. For all these reasons, amniotic fluid appears as a promising alternative source for stem cell therapy. Their recent discovery implies a lack of knowledge of their specific features as well as the existence of a protocol universally recognized as the most suitable for their isolation, growth and long-term conservation. In this study, we isolated stem cells from six amniotic fluids; these cells were cultured with three different culture mediums [Mesenchymal Stem Cell Medium (MSCGM), PC-1 and RPMI-1640], characterized by cytofluorimetric analysis, and then either frozen or induced to neuronal differentiation. Even if the immunophenotype seemed not to be influenced by culture medium (all six samples cultured in the above-mentioned mediums expressed surface antigens commonly found on stem cells), cells showed different abilities to differentiate into neuron-like cells and to re-start the culture after short-long-term storage. Cells isolated and cultured in MSCGM showed the highest proliferation rate, and formed neuron-like cells when sub-plated with neuronal differentiation medium. Cells from PC-1, on the contrary, displayed an increased ability to re-start culture after short-long term storage. Finally, cells from RPMI-1640, even if expressing stem cells markers, were not able to differentiate in neuron-like cells. Further studies are still needed in order to assess the effective role of culture medium for a successful isolation, growth, differentiation and storage of AFMSCs, but our data underline the importance of finding a universally accepted protocol for the use of these cells.

The performance of human periodontal ligament mesenchymal stem cells on xenogenic biomaterials

Mesenchymal stem cells from periodontal ligament (PDL-MSCs) hold great promise for bone regeneration. Most studies regarding the osteogenic differentiation of stem cells from periodontal tissue suggest that PDL cells may have many osteoblast-like properties, including the ability to form calcified nodules in vitro. This study investigated the morphological and histochemistry aspects of human PDL-MSCs, induced for osteogenic differentiation and seeded on a xenogenic porcine bone substitute in vitro, at different times of incubation. This biomaterial seems physically identical to human bone, and it has been reported to be osteoconductive. Our results indicated that the cells had a high affinity for the three-dimensional biomaterials; in fact, cellular proliferation and colonization was evident, and after 21 days the adherent cells started to detach themselves from the substrate, and at 30 days of incubation in differentiation medium, the cells completely lost the adhesion to the Petri's disk, englobing all bioparticles. In conclusion, the in vitro behaviour of PDL-MSCs and their relationship with three-dimensional scaffold biomaterials encourage in vivo investigations for their use in dental tissue regeneration.

Biologic characteristics of mesenchymal stromal cells and their clinical applications in pediatric patients

In the past few years, intensive research in the understanding of the biologic characteristics of the mesenchymal stromal cells has already led to some early clinical applications. The aim of this review is to summarize the latest information from basic science advances and the outcome of their use in clinical practice with a particular focus in pediatric patients. The minimum criteria required to identify mesenchymal stromal cells, their immunosuppressive-nonimmunogenic properties and their attribution in the treatment of graft-versus-host disease, in the acceleration of hematopoietic recovery, in tissue repair/tissue engineering and in the treatment of selected inherited disorders are discussed. Appropriate preclinical models, completion of ongoing and development of new clinical trials will establish the role of these cells in the treatment of both adult and pediatric patients.

GMP-grade preparation of biomimetic scaffolds with osteo-differentiated autologous mesenchymal stromal cells for the treatment of alveolar bone resorption in periodontal disease

BACKGROUND

Periodontal disease is a degenerative illness that leads to resorption of the alveolar bone. Mesenchymal stromal cells (MSC) represent a novel tool for the production of biologic constructs for the treatment of degenerative bone diseases. The preparation of MSC differentiated into osteogenic lineage for clinical use requires the fulfillment of strict good manufacturing practice (GMP) procedures.

METHODS

MSC were isolated from BM samples and then cultured under GMP conditions. MSC were characterized phenotypically and for their differentiative potential. Cells were seeded onto collagen scaffolds (Gingistat) and induced to differentiate into osteogenic lineages using clinical grade drugs compared with standard osteogenic supplements. Alizarin Red S stain was used to test the deposition of the mineral matrix. Standard microbiologic analysis was performed to verify the product sterility.

RESULTS

The resulting MSC were negative for CD33, CD34 and HLA-DR but showed high expression of CD90, CD105 and HLA-ABC (average expressions of 94.3%, 75.8% and 94.2%, respectively). Chondrogenic, osteogenic and adipogenic differentiation potential was demonstrated. The MSC retained their ability to differentiate into osteogenic lineage when seeded onto collagen scaffolds after exposure to a clinical grade medium. Cell numbers and cell viability were adequate for clinical use, and microbiologic assays demonstrated the absence of any contamination.

DISCUSSION

In the specific context of a degenerative bone disease with limited involvement of skeletal tissue, the combined use of MSC, exposed to an osteogenic clinical grade medium, and biomimetic biodegradable scaffolds offers the possibility of producing adequate numbers of biologic tissue-engineered cell-based constructs for use in clinical trials.

Immunomodulation by mesenchymal stem cells and clinical experience

Mesenchymal stem cells (MSCs) from adult marrow can differentiate in vitro and in vivo into various cell types, such as bone, fat and cartilage. MSCs preferentially home to damaged tissue and may have therapeutic potential. In vitro data suggest that MSCs have low inherent immunogenicity as they induce little, if any, proliferation of allogeneic lymphocytes. Instead, MSCs appear to be immunosuppressive in vitro. They inhibit T-cell proliferation to alloantigens and mitogens and prevent the development of cytotoxic T-cells. In vivo, MSCs prolong skin allograft survival and have several immunomodulatory effects, which are presented and discussed in the present study. Possible clinical applications include therapy-resistant severe acute graft-versus-host disease, tissue repair, treatment of rejection of organ allografts and autoimmune disorders.

Expression of Thy 1.2 surface antigen increases significantly during the murine mesenchymal stem cells cultivation period

This study sought to investigate the absence or expression of some surface antigens on murine mesenchymal stem cells (mMSCs) during the cultivation period of primary culture to passage 3 (equivalent to about 15 or 16 population doubling number). For this purpose, bone marrow cells from 6-8-week-old mice (either NMRI or Balb/c) were cultivated in 75-cm(2) culture flask for three successive passages, in each of which the culture was examined for the expression of CD135, CD44, CD31, Thy1.2, CD11b, CD45, CD34, Vcam1, Sca-1, and c-Kit antigens, using flow cytometry. Passage-3 cells from each strain can easily be differentiated into bone and fat, which was indicative of their mesenchymal nature. Our results demonstrated that for each given antigen, the percentages of the cells expressing that antigen had been changed by subcultures. The statistical analysis showed that nearly all differences between the passages were statistically significant. In this term, the expressional changes of Thy 1.2 seemed to be very significant in such a way that the expression increased to about half of the whole population in passage 3. In conclusion, it seems that this antigen could be considered as an enriching antigen for mMSCs population from bone marrow adherent cell culture.

Exogenous mesenchymal stem cells localize to the kidney by means of CD44 following acute tubular injury

Mesenchymal stem cells (MSC) were recently shown to migrate to injured tissues when transplanted systemically. The mechanisms underlying the migration and homing of these cells is, however, unclear. In this study, we examine the role of CD44 and its major ligand, hyaluronic acid, in the trafficking of intravenously injected MSC in the glycerol-induced mouse model of acute renal failure (ARF). In vitro, hyaluronic acid promoted a dose-dependent migration of the stem cells that was inhibited by an anti-CD44 blocking monoclonal antibody. In vivo, stem cells injected into mice with ARF migrated to the injured kidney where hyaluronic acid expression was increased. Their presence correlated with morphological and functional recovery. Renal localization of the MSC was blocked by pre-incubation with the CD44 blocking antibody or by soluble hyaluronic acid. Stem cells derived from CD44 knockout mice did not localize to the injured kidney and did not accelerate morphological or functional recovery. Reconstitution by transfection of CD44 knockout stem cells with cDNA encoding wild-type CD44, but not a loss of function CD44 unable to bind hyaluronic acid, restored in vitro migration and in vivo localization of the cells to injured kidneys. We suggest that CD44 and hyaluronic acid interactions recruit exogenous MSC to injured renal tissue and enhance renal regeneration.

Mesenchymal progenitors able to differentiate into osteogenic, chondrogenic, and/or adipogenic cells in vitro are present in most primary fibroblast-like cell populations

MSCs and mesenchymal progenitor cells (MPCs) are studied for their potential in regenerative medicine. MSCs in particular have great potential, because various reports have shown that they can differentiate into many different cell types. However, the difference between mesenchymal stem/progenitor cells and so-called fibroblasts is unclear. In this study, we found that most of the distinct populations of primary fibroblast-like cells derived from various human tissues, including lung, skin, umbilical cord, and amniotic membrane, contained cells that were able to differentiate into at least one mesenchymal lineage, including osteoblasts, chondrocytes, and adipocytes. We therefore propose that primary fibroblast-like cell populations obtained from various human tissues do not comprise solely fibroblasts, but rather that they also include at least MPCs and possibly MSCs, to some extent. Disclosure of potential conflicts of interest is found at the end of this article.

Murine mesenchymal stem cells isolated by low density primary culture system

Murine mesenchymal stem cells (mMSC) and the difficult task of isolation and purification of them have been the subject of rather extensive investigation. The present study sought to isolate these cells from two different mouse strains, one outbred and the other inbred, primarily through a relatively simple but novel approach, the most important feature of which was the low density primary culture of bone marrow cells. For this purpose, mononuclear cells from either NMRI or BALB/c bone marrow were plated at about 500 cells per well of 24-well plates and incubated for 7 days. At this point, the fibroblastic clones that had emerged were pooled together and expanded through several subcultures. To investigate the mesenchymal nature, we differentiated the cells into the osteoblastic, chondrocytic and adipocytic lineages in different subcultures up to passage 10. According to the results, 1 week after culture initiation, several clones each comprising several fibroblastic cells appeared in each plate. The cells from different passages were capable of differentiating into corresponding skeletal tissues. In the present investigation, the best culture condition for maximum proliferation and also the expression of certain surface marker on isolated cells were examined. In this term the two murine strains showed some differences.

The satellite cell as a companion in skeletal muscle plasticity: currency, conveyance, clue, connector and colander

Satellite cells are companions to voluntary muscle fibres, and are named for their intimate positional or ;satellite' relationship, as if revolving around fibres, like a satellite moon around the earth. Studies on the nature of at least some satellite cells, including their capabilities for self-renewal and for giving rise to multiple lineages in a stem cell-like function, are exploring the molecular basis of phenotypes described by markers of specialized function and gene expression in normal development, neuromuscular disease and aging. In adult skeletal muscle, the self-renewing capacity of satellite cells contributes to muscle growth, adaptation and regeneration. Muscle remodeling, such as demonstrated by changes in myofibre cross-sectional area and length, nerve and tendon junctions, and fibre-type distribution, occur in the absence of injury and provide broad functional and structural diversity among skeletal muscles. Those contributions to plasticity involve the satellite cell in at least five distinct roles, here described using metaphors for behaviour or the investigator's perspective. Satellite cells are the 'currency' of muscle; have a 'conveyance' role in adaptation by domains of cytoplasm along a myofibre; serve researchers, through a marker role, as 'clues' to various activities of muscle; are 'connectors' that physically, and through signalling and cell-fibre communications, bridge myofibres to the intra- and extra-muscular environment; and are equipped as metabolic and genetic filters or 'colanders' that can rectify or modulate particular signals. While all these roles are still under exploration, each contributes to the plasticity of skeletal muscle and thence to the overall biology and function of an organism. The use of metaphor for describing these roles helps to clarify and scrutinize the definitions that form the basis of our understanding of satellite cell biology: the metaphors provide the construct for various approaches to detect or test the nature of satellite cell functions in skeletal muscle plasticity.

Treatment of neurodegenerative diseases using adult bone marrow stromal cell-derived neurons

Many neurodegenerative diseases are attributed to the degeneration of neurons with subsequent functional loss. Cell transplantation is a strategy with potential for treating such diseases, and many kinds of cells are considered candidates for transplantation therapy. Bone marrow stromal cells (MSCs) have great potential as therapeutic agents, as they are easy to isolate and expand from patients without serious ethical and technical problems. The authors have found a method for the highly efficient, exclusive and specific induction of functional postmitotic neuronal cells from both rat and human MSCs. Gene transfer of Notch intracellular domain (NICD) followed by the administration of certain trophic factors induced mature neurons expressing neuronal markers, some of which showed action potentials. Induced neurons were transplanted to animal models of neurodegenerative disorders, including Parkinson's disease and ischaemic brain injury, resulting in the successful integration of transplanted cells and improvement in function of the transplanted animals. This review summarises the respective potentials, benefits and drawbacks of MSC-derived neurons, and discusses the possibility of their clinical application in neurodegenerative diseases.

Mesenchymal stem cells spontaneously express neural proteins in culture and are neurogenic after transplantation

Reports of neural transdifferentiation of mesenchymal stem cells (MSCs) suggest the possibility that these cells may serve as a source for stem cell-based regenerative medicine to treat neurological disorders. However, some recent studies controvert previous reports of MSC neurogenecity. In the current study, we evaluate the neural differentiation potential of mouse bone marrow-derived MSCs. Surprisingly, we found that MSCs spontaneously express certain neuronal phenotype markers in culture, in the absence of specialized induction reagents. A previously published neural induction protocol that elevates cytoplasmic cyclic AMP does not upregulate neuron-specific protein expression significantly in MSCs but does significantly increase expression of the astrocyte-specific glial fibrillary acidic protein. Finally, when grafted into the lateral ventricles of neonatal mouse brain, MSCs migrate extensively and differentiate into olfactory bulb granule cells and periventricular astrocytes, without evidence of cell fusion. These results indicate that MSCs may be "primed" toward a neural fate by the constitutive expression of neuronal antigens and that they seem to respond with an appropriate neural pattern of differentiation when exposed to the environment of the developing brain.

Adult mesenchymal stem cells: characterization, differentiation, and application in cell and gene therapy

A considerable amount of retrospective data is available that describes putative mesenchymal stem cells (MSCs). However, there is still very little knowledge available that documents the properties of a MSC in its native environment. Although the precise identity of MSCs remains a challenge, further understanding of their biological properties will be greatly advanced by analyzing the mechanisms that govern their self-renewal and differentiation potential. This review begins with the current state of knowledge on the biology of MSCs, specifically with respect to their existence in the adult organism and postulation of their biological niche. While MSCs are considered suitable candidates for cell-based strategies owing to their intrinsic capacity to self-renew and differentiate, there is currently little information available regarding the molecular mechanisms that govern their stem cell potential. We propose here a model for the regulation of MSC differentiation, and recent findings regarding the regulation of MSC differentiation are discussed. Current research efforts focused on elucidating the mechanisms regulating MSC differentiation should facilitate the design of optimal in vitro culture conditions to enhance their clinical utility cell and gene therapy.

Morphological and cytofluorimetric analysis of adult mesenchymal stem cells expanded ex vivo from periodontal ligament

Many adult tissues contain a population of stem cells that have the ability of regeneration after trauma, disease or aging. Recently, there has been great interest in mesenchymal stem cells and their roles in maintaining the physiological structure of tissues, and their studies have been considered very important and intriguing, after having shown that this cell population can be expanded ex vivo to regenerate tissues not only of the mesenchymal lineage, such as intervertebral disc cartilage, bone, tooth-associated tissue, cardiomyocytes, but also to differentiate into cells derived from other embryonic layers, including neurons. Currently, different efforts have been focused on the identification of odontogenic progenitors from oral tissues. In this study we isolated and characterized a population of homogeneous human mesenchymal stem cells proliferating in culture with an attached well-spread morphology derived from periodontal ligament, a tissue of ectomesenchymal origin, with the ability to form a specialized joint between alveolar bone and tooth. The adherent cells were harvested and expanded ex vivo under specific conditions and analysed by FACScan flow cytometer and morphological analysis was carried out by light, scanning and transmission electron microscopy. Our results displayed highly evident cells with a fibroblast-like morphology and a secretory apparatus, probably indicating that the enhanced function of the secretory apparatus of the mesenchymal stem cells may be associated with the secretion of molecules that are required to survive and proliferate. Moreover, the presence in periodontal ligament of CD90, CD29, CD44,CD166, CD 105, CD13 positive cells, antigens that are also identified as stromal precursors of the bone marrow, indicate that the periodontal ligament may turn out to be a new efficient source of the cells with intrinsic capacity to self-renewal, high ability to proliferate and differentiate, that can be utilized for a new approach to regenerative medicine and tissue engineering.

Regeneration of human auditory nerve. In vitro/in video demonstration of neural progenitor cells in adult human and guinea pig spiral ganglion

Time lapse video recordings of cultured adult human and guinea pig spiral ganglion (hSG and gpSG) show that mitogen responsive progenitor/stem cells develop in the form of spheres that proliferate and differentiate into mature neurons and glia cells. Neurospheres, cultured with EGF and bFGF showed expression of nestin and incorporation of 5'-Bromo-2-deoxyuridine (BrdU). Newly formed BrdU labelled cells were positive for beta-tubulin, and also for GFAP demonstrating that neuronal cells were derived from a dividing population of progenitor cells. Dissociated spheres cultured either with glia cell line-derived neurotrophic factor (GDNF) or brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3), induced differentiation of the progenitor cells. Video microscopy showed that neurons develop from subcultured spheres maintained for up to four weeks. Neurons showed fasciculation and migration with a speed of 10-30 microm/h, and some cells had up to 6 mm long neurites coexpressing TrkB and TrkC receptors. Precise dissection suggests that the neurons formed are cochlea-specific. The results suggest that the mammalian auditory nerve has the capability for self-renewal and replacement. Transplantation of progenitor cells together with established means to induce neural differentiation and fiber growth may facilitate strategies for better repair and treatment of auditory neuronal damage.

Induction of endogenous neural precursors in mouse models of spinal cord injury and disease

Adult neural precursor cells (NPCs) in the mammalian central nervous system (CNS) have been demonstrated to be responsive to conditions of injury and disease. Here we investigated the response of NPCs in mouse models of spinal cord disease [motor neuron disease (MND)] with and without sciatic nerve axotomy, and spinal cord injury (SCI). We found that neither axotomy, nor MND alone brought about a response by Nestin-positive NPCs. However, the combination of the two resulted in mobilization of NPCs in the spinal cord. We also found that there was an increase in the number of NPCs following SCI which was further enhanced by systemic administration of the neuregulatory cytokine, leukaemia inhibitory factor (LIF). NPCs were demonstrated to differentiate into astrocytes in axotomized MND mice. However, significant differentiation into the various neural cell phenotypes was not demonstrated at 1 or 2 weeks following SCI. These data suggest that factors inherent to injury mechanisms are required for induction of an NPC response in the mammalian spinal cord.