Spinal cord injury in rat: treatment with bone marrow stromal cell transplantation

Oligonucleotide IMT504 reduces neuropathic pain after peripheral nerve injury

We have recently shown that the administration of bone marrow stromal cells (MSCs) prevents the development of mechanical and thermal allodynia in animals subjected to a sciatic nerve injury. Furthermore, exogenously administered MSCs have been shown to participate in the repair and regeneration of damaged tissues in a variety of animal models. However, some limitations of this therapeutic approach, basically related to the ex vivo cell manipulation procedure, have arisen. IMT504, the prototype of the PyNTTTTGT class of immunostimulatory oligonucleotides, stimulates MSC expansion both in vitro and in vivo. In this study, we evaluated the effect of IMT504 systemic administration on the development of mechanical and thermal allodynia in rats subjected to a sciatic nerve crush. Animals were treated with IMT504, MSCs or saline either immediately after performing the lesion or 4 days after it, and were evaluated using the von Frey and Choi tests at different times after injury. Control animals developed both mechanical and thermal allodynia. Animals receiving either IMT504 or MSCs immediately after injury did not develop mechanical allodynia and presented a significantly lower number of nociceptive responses to cold stimulation as compared to controls. Moreover, injury-induced allodynia was significantly reduced after IMT504 delayed treatment. Our results show that the administration of IMT504 reduces neuropathic pain-associated behaviors, suggesting that IMT504 could represent a possible therapeutic approach for the treatment of neuropathic pain.

Transplanted bone marrow stromal cells migrate, differentiate and improve motor function in rats with experimentally induced cerebral stroke

Bone marrow stromal cells are multipotential cells that can be induced to differentiate into osteoblasts, chondrocytes, myocytes and adipocytes in different microenvironments. Recent studies revealed that bone marrow stromal cells could improve neurological deficits of various damages or diseases of the central nervous system such as Parkinson's disease, brain trauma, spinal cord injury and multiple sclerosis, and promote glia-axonal remodeling in animal brain subjected to an experimentally induced stroke. In the present study, bone marrow stromal cells were intracerebrally transplanted into the cerebrum following a transient middle cerebral artery occlusion. Our aim was to find out whether the bone marrow stromal cells could survive and express neural phenotypic proteins and, in addition, whether they could restore the behavioral and functional deficits of the cerebral ischemic rats. Our results demonstrated that transplanted bone marrow stromal cells survived and migrated to areas around the lesion site. Some of them exhibited marker proteins of astrocytes and oligodendrocytes. Bone marrow stromal cell implantation significantly reduced the transient middle cerebral artery occlusion-induced cortical loss and thinning of the white matter and enhanced cortical beta-III-tubulin immunoreactivity. Rats implanted with bone marrow stromal cells showed significant improvement in their performance of elevated body swing test and forelimb footprint analysis and only transient recovery of the adhesive-removal test. Our data support bone marrow stromal cells as a valuable source of autologous or allogenic donor cells for transplantation to improve the outcome following cerebral ischemia.

Bone marrow-derived mesenchymal stem cell transplantation does not improve quality of muscle reinnervation or recovery of motor function after facial nerve transection in rats

Recently, we devised and validated a novel strategy in rats to improve the outcome of facial nerve reconstruction by daily manual stimulation of the target muscles. The treatment resulted in full recovery of facial movements (whisking), which was achieved by reducing the proportion of pathologically polyinnervated motor endplates. Here, we posed whether manual stimulation could also be beneficial after a surgical procedure potentially useful for treatment of large peripheral nerve defects, i.e., entubulation of the transected facial nerve in a conduit filled with suspension of isogeneic bone marrow-derived mesenchymal stem cells (BM-MSCs) in collagen. Compared to control treatment with collagen only, entubulation with BM-MSCs failed to decrease the extent of collateral axonal branching at the lesion site and did not improve functional recovery. Post-operative manual stimulation of vibrissal muscles also failed to promote a better recovery following entubulation with BM-MSCs. We suggest that BM-MSCs promote excessive trophic support for regenerating axons which, in turn, results in excessive collateral branching at the lesion site and extensive polyinnervation of the motor endplates. Furthermore, such deleterious effects cannot be overridden by manual stimulation. We conclude that entubulation with BM-MSCs is not beneficial for facial nerve repair.

Stem and progenitor cell therapies: recent progress for spinal cord injury repair

Mechanical trauma to the spinal cord is often accompanied by irreversible tissue damage, limited endogenous repair and permanent loss of motor, sensory and autonomic function. The implantation of exogenous cells or the stimulation of endogenous cells, to repopulate and replace or to provide a conducive environment for repair, offers a promising therapeutic direction for overcoming the multitude of obstacles facing successful recovery from spinal cord injury. Although relatively new to the scene of cell based therapies for reparative medicine, stem cells and their progenitors have been labeled as the 'cell of the future' for revolutionizing the treatment of CNS injury and neurodegenerative disorders. The following review examines the different types of stem cells and their progenitors, their utility in experimental models of spinal cord injury and explores the outstanding issues that still need to be addressed before they move towards clinical implementation.

Mannitol enhances delivery of marrow stromal cells to the brain after experimental intracerebral hemorrhage

Previous studies show that intravascular injection of human bone marrow stromal cells (hBMSCs) significantly improves neurological functional recovery in a rat model of intracerebral hemorrhage (ICH). In the present study, we tested the hypothesis that mannitol improves the efficiency of intraarterial MSC delivery (i.e., fewer injected cells required for therapeutic efficacy) after ICH. There were four post-ICH groups (N=9): group 1, negative control with only intraarterial injection of 1 million human fibroblasts in phosphate-buffered saline (PBS); group 2, intravenous injection of mannitol alone in PBS (1.5 g/kg); group 3, intraarterial injection of 1 million hBMSCs alone in PBS; and group 4, intravenous injection of mannitol (1.5 g/kg) in PBS followed by intraarterial injection of 1 million hBMSCs in PBS. Group 4 exhibited significantly improved neurological functional outcome as assessed by neurological severity score (NSS) and corner test scores. Immunohistochemical staining of group 4 suggested increased synaptogenesis, proliferating immature neurons, and neuronal migration. The number of hBMSCs recruited to the injured region increased strikingly in group 4. Tissue loss was notably reduced in group 4. In summary, the beneficial effects of intraarterial infusion of MSCs are amplified with intravenous injection of mannitol. Preadministration of mannitol significantly increases the number of hBMSCs located in the ICH region, improves histochemical parameters of neural regeneration, and reduces the anatomical and pathological consequences of ICH.

Effects of co-grafts mesenchymal stem cells and nerve growth factor suspension in the repair of spinal cord injury

To investigate effect of the transplantation of mesenchymal stem cells (MSCs) in combination with nerve growth factor (NGF) on the repair of spinal cord injury (SCI) in adult rats, spinal cord of adult rats (n= 32) was injured by using the modified Allen's method. One week after the injury, the injured cords were injected with Dubecco-modified Eagles medium (DMEM, Group I), MSCs (Group II), NGF (Group III), and MSCs plus NGF (Group IV). One month and two months after the injury, rats were sacrificed and their injured cord tissues were sectioned for the identification of the transplanted cells. The axonal regeneration and the differentiation of MSCs were examined by immunocytochemical staining. At the same time, rats were subjected to behavioral tests by using the open-field BBB scoring system. Immunocytochemical staining showed that axonal regeneration and the transplanted cells partially expressed neuron-specific nuclear protein (NeuN) and glial fibrillary acidic protein (GFAP). At the same time, significant improvement in BBB locomotor rating scale (P<0. 05) were observed in the treatment group. More importantly, further functional improvement were noted in the combined treatment group. MSCs could differentiate into neurons and astrocytes. MSCs and NGF can promote axonal regeneration and improve functional recovery. There might exist a synergistic effect between MSCs and NGF.

Systematic neuronal and muscle induction systems in bone marrow stromal cells: the potential for tissue reconstruction in neurodegenerative and muscle degenerative diseases

Because bone marrow stromal cells (MSCs) are easily accessible from both healthy donors and patients and can be expanded on a therapeutic scale, they have attracted attention for cell-based therapy. Benefits of MSCs have been discussed mainly from two aspects: one is their tissue protective and immunomodulatory effects, and the other is their capability under specific manipulations to differentiate into various cell types. In this review, their differentiation into functional neural and muscle cell lineages is the focus, and their potential to the application for tissue reconstruction in neurodegenerative and muscle degenerative diseases is discussed.

Transplantation of human bone marrow-derived stromal cells into the contused spinal cord of nude rats

OBJECT

Human bone marrow stromal cells (hMSCs) constitute a potential source of pluripotent stem cells. In the present study, hMSCs were transplanted into an area of spinal cord contusion in nude rats to determine their survival, differentiation, potential for neuroprotection, and influence on axonal growth and functional recovery.

METHODS

Twenty-nine animals received 6 x 10(5) hMSCs in 6 microl medium 1 week after a contusion, while 14 control animals received an injection of 6 microl medium alone. Basso-Beattie-Bresnahan (BBB) tests were performed weekly. The spinal cords were collected at 6 weeks posttransplantation for histological analysis and assessment of tissue injury.

RESULTS

Immunostaining with anti-human mitochondria antibody and pretransplantation labeling with green fluorescent protein demonstrated that the grafted hMSCs survived and were capable of achieving a flattened appearance in the grafted area; however, none of the transplanted cells stained positively for human-specific neuronal, anti-neurofilament H or glial fibrillary acidic protein within the sites of engraftment. While neuronal or astrocytic differentiation was not seen, cells lining blood vessels in the vicinity of the transplant stained positively for anti-human endothelium CD105 antibody. Staining for anti-neurofilament H antibody demonstrated abundant axonlike structures around the transplanted area in the hMSC group. Tissue sparing analysis showed that animals with grafted hMSCs had a smaller area of contusion cyst compared with controls, but there was no significant difference between the two groups in BBB scores.

CONCLUSIONS

The grafted hMSCs survived for > or = 6 weeks posttransplantation, although they did not differentiate into neural or glial cells. Cells with human endothelial characteristics were observed. Spinal cord-injured rats grafted with hMSCs had smaller contusion cavities, which did not have a significant influence on functional recovery.

Application of autologous bone marrow stem cells in the therapy of spinal cord injury patients

We studied the safety and efficiency of transplantation of autologous bone marrow cells in complex therapy of patients with spinal cord injury in the late period of the disease. In control group patients, meningomyeloradiculolis was performed, while in the main group surgical treatment was supplemented by transplantation of autologous bone marrow cells. Transplantation of BM stem cells into the cyst cavity and intravenously was well tolerated, did not cause allergic or inflammatory reactions in the early and delayed periods after surgery, and did not induce the formation of ossification foci in the nervous tissue. Analysis of the neurological status by ASIA, Bartel, and Ashworth scales showed that in the main group the positive clinical dynamics was more often observed than in the control. The decrease in neurological deficit included improvement of sensory and motor activity and conducting sensory function. Thus, transplantation of autologous bone marrow cells can be a novel safe strategy for the treatment of patients in the late period after spinal trauma.

Therapeutic benefits by human mesenchymal stem cells (hMSCs) and Ang-1 gene-modified hMSCs after cerebral ischemia

Transplantation of human mesenchymal stem cells (hMSCs) prepared from adult bone marrow has been reported to ameliorate functional deficits after cerebral artery occlusion in rats. Although several hypotheses to account for these therapeutic effects have been suggested, current thinking is that both neuroprotection and angiogenesis are primarily responsible. In this study, we compared the effects of hMSCs and angiopoietin-1 gene-modified hMSCs (Ang-hMSCs) intravenously infused into rats 6 h after permanent middle cerebral artery occlusion. Magnetic resonance imaging and histologic analyses revealed that rats receiving hMSCs or Ang-hMSCs exhibited comparable reduction in gross lesion volume as compared with the control group. Although both cell types indeed improved angiogenesis near the border of the ischemic lesions, neovascularization and regional cerebral blood flow were greater in some border areas in Ang-hMSC group. Both hMSC- and Ang-hMSC-treated rats showed greater improved functional recovery in the treadmill stress test than did control rats, but the Ang-hMSC group was greater. These results indicate the intravenous administration of genetically modified hMSCs to express angiopoietin has a similar effect on reducing lesion volume as hMSCs, but the Ang-hMSC group showed enhanced regions of increased angiogenesis at the lesion border, and modest additional improvement in functional outcome.

Disparate host response and donor survival after the transplantation of mesenchymal or neuroectodermal cells to the intact rodent brain

BACKGROUND

To circumvent ethical and legal complications associated with embryonic cell sources, investigators have proposed the use of nonneural donor sources for use in neural transplantation strategies. Leading candidate sources include autologous marrow stromal cells (MSCs) and fibroblasts, which are mesodermal derivatives. However, we recently reported that MSCs transplanted to the adult brain are rapidly rejected by an inflammatory response. Whether extrinsic variables or intrinsic mesenchymal traits stimulated inflammation and rejection is unknown. To determine the future utility of these cells in neural transplantation, we have now performed a systematic analysis of MSC transplantation to the brain.

METHODS

To examine the effects of extrinsic variables on transplantation, green fluorescent protein (GFP)-expressing rat MSCs, cultured under distinct conditions, were transplanted stereotactically to the normal adult rat striatum, and donor survival and the host response was compared. To examine whether intrinsic donor traits promoted rejection, 50,000 GFP-expressing rat MSCs, fibroblasts, or astrocytes were transplanted stereotactically to the adult rat striatum and graft survival and the host response was compared.

RESULTS

Irrespective of preoperative culture conditions, MSCs elicited an inflammatory response and were rejected by 14 days, indicating acute rejection was not mediated by culture conditions. Comparison of MSC, fibroblast, or astrocyte grafts revealed that mesenchymal derivatives, MSCs and fibroblasts, elicited an inflammatory response and were rapidly rejected, whereas neuroectodermal astrocytes demonstrated robust survival in the absence of inflammation.

CONCLUSIONS

Our findings suggest that intrinsic characteristics of mesenchymal cells may stimulate host inflammation, and thus may not represent an ideal donor source for transplantation to the adult brain.

Isolation and culture of bone marrow-derived human multipotent stromal cells (hMSCs)

We have developed protocols whereby a total of 30-90 x 10(6) hMSCs with an average viability greater than 90% can be produced in a single multilevel Cell Factory from a relatively small (1-3 mL) bone marrow aspirate in 14-20 d. It is possible to generate as many as 5 x 10(8) multipotent stromal cells (MSCs) from a single sample, depending on the number of Cell Factories seeded from the initial isolated hMSCs. Briefly, mononuclear cells are collected from a bone marrow aspirate by density gradient centrifugation. The cells are cultured overnight and the adherent cells are allowed to attach to the flask. Nonadherent cells are removed and the culture expanded for 7-10 d with periodic feeding of the cells. The cells are then harvested and seeded at low density (60-100 cells/cm2) into Nunc Cell Factories. The cells are allowed to expand for an additional 7-10 d, and are then harvested.

Preparation of neural progenitors from bone marrow and umbilical cord blood

The bone marrow is clearly much more than a reservoir of stem cells that repopulates blood cell lineages throughout life. The marrow also contains nonhematopoietic stem cells, which are much more versatile than previously appreciated. These nonhematopoietic stem/progenitor cells are found in the bone marrow stromal cell (BMSC) population. BMSCs also are known as colony-forming unit fibroblasts and mesenchymal stem cells (MSCs). MSCs also can be generated from umbilical cord blood and other tissues. MSCs have been shown to express properties of neuroectodermal cells in vitro by many researchers and in vivo after transplantation into the brain and spinal cord. Many investigators have developed variations on the original method described 6 years ago for the preparation of neural progenitors from BMSCs. We bring up to date the materials and procedures used to prepare BMSCs from bone marrow and from human umbilical cord blood for the induction of neural progenitor cells and subsequent differentiation into neurons and glia.

Human mesenchymal stromal cells ameliorate the phenotype of SOD1-G93A ALS mice

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a progressive, lethal, neurodegenerative disease, currently without any effective therapy. Multiple advantages make mesenchymal stromal cells (MSC) a good candidate for cellular therapy in many intractable diseases such as stroke and brain injury. Until now, no irrefutable evidence exists regarding the outcome of MSC transplantation in the mouse model of ALS. The present study was designed to investigate the therapeutic potential of human MSC (hMSC) in the mouse model of ALS (SOD1-G93A mice).

METHODS

hMSC were isolated from iliac crest aspirates from healthy donors and kept in cell cultures. hMSC of the fifth passage were delivered intravenously into irradiated pre-symptomatic SOD1-G93A mice. Therapeutic effects were analyzed by survival analysis, rotarod test, motor neuron count in spinal cord and electrophysiology. The engraftment and in vivo differentiation of hMSC were examined in the brain and spinal cord of hMSC-transplanted mice.

RESULTS

After intravenous injection into irradiated pre-symptomatic SOD1-G93A mice, hMSC survived more than 20 weeks in recipient mice, migrated into the parenchyma of brain and spinal cord and showed neuroglia differentiation. Moreover, hMSC-transplanted mice showed significantly delayed disease onset (14 days), increased lifespan (18 days) and delayed disease progression compared with untreated mice.

DISCUSSION

Our data document the positive effects of hMSC transplantation in the mouse model of ALS. It may signify the potential use of hMSC in treatment of ALS.

Human mesenchymal stem cells home specifically to radiation-injured tissues in a non-obese diabetes/severe combined immunodeficiency mouse model

The therapeutic potential of bone marrow-derived human mesenchymal stem cells (hMSC) has recently been brought into the spotlights of many fields of research. One possible application of the approach is the repair of tissue injuries related to side effects of radiotherapy. The first challenge in cell therapy is to assess the quality of the cell and the ability to retain their differentiation potential during the expansion process. Efficient delivery to the sites of intended action is also necessary. We addressed both challenges using hMSC cultured and then infused to non-obese diabetes/severe combined immunodeficiency (NOD/SCID) mice submitted to total body irradiation. Furthermore, we tested the impact of additional abdominal irradiation superimposed to total body irradiation (TBI), as a model of local therapeutic irradiation. Our results showed that the hMSC used for transplant have been expanded without significant loss in their differentiation capacities. After transplantation into adult unconditioned mice, hMSC not only migrate in bone marrow but also into other tissues. Total body irradiation increased hMSC implantation in bone marrow and muscle and further led to engraftment in brain, heart and liver. Local irradiation in addition to TBI, increased homing of injected cells to the injured tissues and to other tissues outside the local irradiation field. Morphological recovery of irradiated tissues after MSC transplantation and/or differentiation of MSC into specific organ cell types needs to be investigated. This study suggests that using the potential of hMSC to home to various organs in response to tissue injuries might be a strategy to repair the radiation-induced damages.

Human stem cells for CNS repair

Although most peripheral tissues have at least a limited ability for self-repair, the central nervous system (CNS) has long been known to be relatively resistant to regeneration. Small numbers of stem cells have been found in the adult brain but do not appear to be able to affect any significant recovery following disease or insult. In the last few decades, the idea of being able to repair the brain by introducing new cells to repair damaged areas has become an accepted potential treatment for neurodegenerative diseases. This review focuses on the suitability of various human stem cell sources for such treatments of both slowly progressing conditions, such as Parkinson's disease, Huntington's disease and multiple sclerosis, and acute insult, such as stroke and spinal cord injury. Despite stem cell transplantation having now moved a step closer to the clinic with the first trials of autologous mesenchymal stem cells, the effects shown are moderate and are not yet at the stage of development that can fulfil the hopes that have been placed on stem cells as a means to replace degenerating cells in the CNS. Success will depend on careful investigation in experimental models to enable us to understand not just the practicalities of stem cell use, but also the underlying biological principles.

Intrathecal injection of bone marrow stromal cells attenuates neurologic injury after spinal cord ischemia

BACKGROUND

It has been shown that transplantation of bone marrow stromal cells (MSCs) into the ischemic brain improves functional outcome. We sought to investigate whether intrathecal injection of MSCs can attenuate neurologic injury of spinal cord ischemia.

METHODS

Rabbit MSCs were expanded in vitro and were pre-labeled with bromodeoxyuridine. Spinal cord ischemia was induced in rabbits by infrarenal aortic occlusion. Group A and control A were subjected to a 20-minute ischemia and the ischemic duration was extended to 30 minutes in group B and control B. Two days before spinal cord ischemia, 1 x 10(8) MSCs were intrathecally injected into groups A and B, whereas vehicle alone was injected into the control groups. Hind-limb motor function was assessed during a 14-day recovery period with Tarlov criteria, and then histologic examination was performed.

RESULTS

Marrow stromal cells survived and engrafted into the spinal cord 2 days after transplantation, and more MSCs were found in the lumbar spinal cord (ischemic segment) than in the thoracic spinal cord (nonischemic segment) at 14 days. Compared with their respective control groups, Tarlov scores were significantly higher in both groups A and B (p < 0.05, group A vs control A, at 2, 7, and 14 days; p < 0.05, group B vs control B, at 1, 2, 7, and 14 days, respectively). The number of intact motor neurons was much higher in the two experimental groups (p < 0.01 vs the corresponding control groups, respectively).

CONCLUSIONS

Intrathecal injection of MSCs attenuates ischemic injury of spinal cord.

Adenovirus vector-mediated ex vivo gene transfer of brain-derived neurotrophic factor to bone marrow stromal cells promotes axonal regeneration after transplantation in completely transected adult rat spinal cord

The aim of this study was to evaluate the efficacy in adult rat completely transected spinal cord of adenovirus vector-mediated brain-derived neurotrophic factor (BDNF) ex vivo gene transfer to bone marrow stromal cells (BMSC). BMSC were infected with adenovirus vectors carrying beta-galactosidase (AxCALacZ) or BDNF (AxCABDNF) genes. The T8 segment of spinal cord was removed and replaced by graft containing Matrigel alone (MG group) or Matrigel and BMSC infected by AxCALacZ (BMSC-LacZ group) or AxCABDNF (BMSC-BDNF group). Axons in the graft were evaluated by immunohistochemistry and functional recovery was assessed with BBB locomotor scale. In the BMSC-BDNF group, the number of fibers positive for growth associated protein-43, tyrosine hydroxylase, and calcitonin gene-related peptide was significantly larger than numbers found for the MG and BMSC-LacZ groups. Rats from BMSC-BDNF and BMSC-LacZ groups showed significant recovery of hind limb function compared with MG rats; however, there was no significant difference between groups in degree of functional recovery. These findings demonstrate that adenovirus vector-mediated ex vivo gene transfer of BDNF enhances the capacity of BMSC to promote axonal regeneration in this completely transected spinal cord model; however, BDNF failed to enhance hind limb functional recovery. Further investigation is needed to establish an optimal combination of cell therapy and neurotrophin gene transfer for cases of spinal cord injury.

Therapeutic applications of mesenchymal stromal cells

Mesenchymal stromal cells (MSC) are multipotent cells that can be derived from many different organs and tissues. They have been demonstrated to play a role in tissue repair and regeneration in both preclinical and clinical studies. They also have remarkable immunosuppressive properties. We describe their application in settings that include the cardiovascular, central nervous, gastrointestinal, renal, orthopaedic and haematopoietic systems. Manufacturing of MSC for clinical trials is also discussed. Since tissue matching between MSC donor and recipient does not appear to be required, MSC may be the first cell type able to be used as an "off-the-shelf" therapeutic product.

Neurotrophic and growth factor gene expression profiling of mouse bone marrow stromal cells induced by ischemic brain extracts

Treatment of rodents after stroke with bone marrow stromal cells (BMSCs) improves functional outcome. However, the mechanisms underlying this benefit have not been ascertained. This study focused on the contribution of neurotrophic and growth factors produced by BMSCs to therapeutic benefit. Rats were subjected to middle cerebral artery occlusion and the ischemic brain extract supernatant was collected to prepare the conditioned medium. The counterpart normal brain extract from non-ischemic rats was employed as the experimental control. Using microarray assay, we measured the changes of the neurotrophin associated gene expression profile in BMSCs cultured in different media. Furthermore, real-time RT-PCR and fluorescent immunocytochemistry were utilized to validate the gene changes. The morphology of BMSCs, cultured in the ischemic brain-conditioned medium for 12 h, was dramatically altered from a polygonal and flat appearance to a fibroblast-like long and thin cell appearance, compared to those in the normal brain-conditioned medium and the serum replacement medium. Forty-four neurotrophin-associated genes in BMSCs were identified by microarray assay under all three culture media. Twelve out of the 44 genes (7 neurotrophic and growth factor genes, 5 receptor genes) increased in BMSCs cultured in the ischemic brain-conditioned medium compared to the normal brain-conditioned medium. Real time RT-PCR and immunocytochemistry validated that the ischemic brain-conditioned medium significantly increased 6/7 neurotrophic and growth factor genes, compared with the normal brain-conditioned medium. These six genes consisted of fibroblast growth factor 2, insulin-like growth factor 1, vascular endothelial growth factor A, nerve growth factor beta, brain-derived neurotrophic factor and epidermal growth factor. Our results indicate that transplanted BMSCs may work as 'small molecular factories' by secreting neurotrophins, growth factors and other supportive substances after stroke, which may produce therapeutic benefits in the ischemic brain.

Design Strategies of Tissue Engineering Scaffolds with Controlled Fiber Orientation

Tissue engineering is an emerging area of applied research with a goal of repairing or regenerating the functions of damaged tissue that fails to heal spontaneously by using cells and synthetic functional components called scaffolds. Scaffolds made of nanofibers (herein called "nano-fibrous scaffolds") play a key role in the success of tissue engineering by providing a structural support for the cells to accommodate and guiding their growth in the three-dimensional space into a specific tissue. The orientation of these fibers is considered as one of the important features of a perfect tissue scaffold, because the fiber orientation greatly influences cell growth and related functions. Therefore, engineering scaffolds with a control over fiber orientation is essential and a prerequisite for controlling cell orientation and tissue growth. Recent advances in electrospinning have made it possible to create nano-featured scaffolds with controlled fiber orientation. Electrospinning is a straightforward, cost-effective, and versatile method, which is recently applied in engineering well-defined nano-fibrous scaffolds that hold promise in serving as a synthetic extra-cellular matrix (ECM). This article reviews the current trends in electrospinning nano-fibrous scaffolds with fiber orientation. A detailed mechanism involved in the spinning process is discussed, followed by experimental examples that show how the fiber orientation influences cellular growth behavior. This review is expected to be useful for readers to gain knowledge on the state-of-the-art of scaffold engineering by electrospinning.

Autologous bone marrow stem cells--properties and advantages

The properties of self-renewal and multi-lineage differentiation make stem cells attractive candidates for use in cellular reparative therapy, particularly in neurological diseases where there is a paucity of treatment options. However, clinical trials using foetal material in Parkinson's disease have been disappointing and highlighted problems associated with the use of embryonic stem cells, including ethical issues and practical concerns regarding teratoma formation. Understandably, this has led investigators to explore alternative sources of stem cells for transplantation. The expression of neuroectodermal markers by cells of bone marrow origin focused attention on these adult stem cells. Although early enthusiasm has been tempered by dispute regarding the validity of reports of in vitro (trans)differentiation, the demonstration of functional benefit in animal models of neurological disease is encouraging. Here we will review some of the required properties of stem cells for use in transplantation therapy with specific reference to the development of bone marrow-derived cells as a source of cells for repair in demyelination.

Potential therapeutic clue of skin-derived progenitor cells following cytokine-mediated signal overexpressed in injured spinal cord

Recent evidence indicates that neural progenitor cell characters can be found in the population of adult skin-derived progenitor cells (SPCs). They have the ability to proliferate actively in vitro as spheres in suspension and they contain neural stem cells and several chemokines. Spheres derived from adult skin tissues have a higher capacity to differentiate into neurons in vitro. We report here that intravenous infusion of SPCs from adult skin ameliorated spinal cord lesions and improved motor function in laboratory mice with a spinal cord injury (SCI). After 4-5 weeks, transplanted SPCs survived and migrated into the injured region of the SCI very efficiently, and migrated cells were partially differentiated into neurons and glial cells. Behavioral and ultrastructural tissue analysis revealed that locomotor functions and remyelinated tissue lesions of SPCs engrafted onto SCI mice were restored significantly compared to those of the control group. Efficient migration of SPCs into SCI lesions suggests that SCI-induced chemotaxic factors facilitate the migration of SPCs. Also, we verified that SCI-induced chemotaxic factors play an important role in proliferation, migration, and differentiation of engrafted SPCs. In transplantation paradigms, the interaction between the SCI microenvironment and engrafted cells will be very important in promoting host injury repair through the induction of cell migration, proliferation, and differentiation. Finally, adult SPCs can behave as a multipotent population, suggesting potential clinical applications for SCI therapy.

The Use of Stem Cells’ Hematopoietic Stimulating Factors Therapy Following Spinal Cord Injury

Spinal cord injury (SCI) remains one of the most devastating conditions in medicine, particularly due to the loss of productive life years and the high economic burden it places on our society. There are limited therapeutic options available to reduce the morbidity and mortality related to SCI. However, recent work with stem cells in repairing SCI appears to be promising, making this one of the most exciting frontiers in medicine. A brief review of the mechanisms of SCI is presented. Stem cells from a variety of sources have shown effectiveness in improving motor function after SCI in animals. The pre-clinical use of stem cells in SCI and methods of delivery are discussed. The potential use of granulocyte-colony stimulating factor (G-CSF) to increase the number of stem cells engrafting at the site of injury in order to improve neurological and motor function recovery following SCI is introduced. G-CSF, through stimulation of lymphohemopoietic stem cells in peripheral blood, can potentially cause repopulation of the SCI region with neural progenitor cells. This allows for improved functional outcomes. More pre-clinical and translational research exploring this possibility is required.

Bone marrow-derived mesenchymal stromal cells for the repair of central nervous system injury

Transplantation of bone marrow-derived mesenchymal stromal cells (MSCs) into the injured brain or spinal cord may provide therapeutic benefit. Several models of central nervous system (CNS) injury have been examined, including that of ischemic stroke, traumatic brain injury and traumatic spinal cord injury in rodent, primate and, more recently, human trials. Although it has been suggested that differentiation of MSCs into cells of neural lineage may occur both in vitro and in vivo, this is unlikely to be a major factor in functional recovery after brain or spinal cord injury. Other mechanisms of recovery that may play a role include neuroprotection, creation of a favorable environment for regeneration, expression of growth factors or cytokines, vascular effects or remyelination. These mechanisms are not mutually exclusive, and it is likely that more than one contribute to functional recovery. In light of the uncertainty surrounding the fate and mechanism of action of MSCs transplanted into the CNS, further preclinical studies with appropriate animal models are urgently needed to better inform the design of new clinical trials.

Bone marrow stromal cells promoting corticospinal axon growth through the release of humoral factors in organotypic cocultures in neonatal rats

OBJECT

The transplantation of bone marrow stromal cells (BMSCs) is considered to be an alternative treatment to promote central nervous system regeneration, but the precise mechanisms of this regeneration after transplantation of BMSCs have not been clarified. In the present study, the authors assessed the effects of BMSC transplantation on corticospinal axon growth quantitatively, and they analyzed the mechanism of central nervous system regeneration in the injured and BMSC-treated spinal cord using the organotypic coculture system.

METHODS

Bone marrow stromal cells derived from green fluorescent protein-expressing transgenic Sprague-Dawley rats were transplanted to the organotypic coculture system in which brain cortex and spinal cord specimens obtained in neonatal Sprague-Dawley rats were used. The axon growth from the cortex to the spinal cord was assessed quantitatively, using anterograde tracing with 1,1 '-ioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate. To identify the differentiation of transplanted BMSCs, immunohistochemical examinations were performed. In addition, BMSCs were analyzed using reverse transcriptase polymerase chain reaction (RT-PCR) for mRNA expression of the growth factors. The transplantation of BMSCs beneath the membrane, where the transplanted cells did not come into direct contact with the cultured tissue, promoted corticospinal axon growth to the same extent as transplantation of BMSCs on the tissues. The RT-PCR showed that the transplanted BMSCs expressed the mRNA of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF). Con

CONCLUSIONS

ese findings strongly suggest that humoral factors expressed by BMSCs, including BDNF and VEGF, participate in regeneration of the central nervous system after transplantation of these cells.

Autologous bone marrow transplantation in patients with subacute and chronic spinal cord injury

Stem cell transplants into spinal cord lesions may help to improve regeneration and spinal cord function. Clinical studies are necessary for transferring preclinical findings from animal experiments to humans. We investigated the transplantation of unmanipulated autologous bone marrow in patients with transversal spinal cord injury (SCI) with respect to safety, therapeutic time window, implantation strategy, method of administration, and functional improvement. We report data from 20 patients with complete SCI who received transplants 10 to 467 days postinjury. The follow-up examinations were done at 3, 6, and 12 months after implantation by two independent neurologists using standard neurological classification of SCI, including the ASIA protocol, the Frankel score, the recording of motor and somatosensory evoked potentials, and MRI evaluation of lesion size. We compared intra-arterial (via catheterization of a. vertebralis) versus intravenous administration of all mononuclear cells in groups of acute (10-30 days post-SCI, n=7) and chronic patients (2-17 months postinjury, n=13). Improvement in motor and/or sensory functions was observed within 3 months in 5 of 6 patients with intra-arterial application, in 5 of 7 acute, and in 1 of 13 chronic patients. Our case study shows that the implantation of autologous bone marrow cells appears to be safe, as there have been no complications following implantation to date (11 patients followed up for more than 2 years), but longer follow-ups are required to determine that implantation is definitively safe. Also, we cannot yet confirm that the observed beneficial effects were due to the cell therapy. However, the outcomes following transplantation in acute patients, and in one chronic patient who was in stable condition for several months prior to cell implantation, are promising. It is evident that transplantation within a therapeutic window of 3-4 weeks following injury will play an important role in any type of stem cell SCI treatment. Trials involving a larger population of patients and different cell types are needed before further conclusions can be drawn.

Neuronal repair and replacement in spinal cord injury

Spinal cord injury (SCI) often induces loss of motor and/or sensory function below the level of injury. While deficits persist in complete lesions, partial lesions of the spinal cord can be followed by spontaneous functional recovery. In this review we address the mechanisms underlying spontaneous recovery in the adult CNS. We argue that the adult brain and spinal cord are able to spontaneously respond to SCI, and do so by (i) anatomically reorganizing axonal connections and (ii) generating new precursor cells. Knowledge of the endogenous recovery strategies should also provide the basis for the development of new therapeutic strategies for spinal cord injury. In this review we describe the processes of endogenous axonal repair and cell replacement in the injured spinal cord and discuss how transplantation of stem/progenitor cells could enhance these endogenous repair strategies.

Fat tissue: views on reconstruction and exploitation

Transplantation of autologous fat as pedicle or transposition flaps has been a classical method in plastic surgery for tissue reconstruction. The injection of fat for soft tissue reconstruction is also an old innovation. This approach has some significant drawbacks such as resorption of the fat transplant. To regenerate additional and self-regenerating adipose tissue for reconstructive purposes, a thorough understanding of adipose tissue (mesodermal stem cells, adipoblasts, pre-adipocytes, mature, lipid-synthesizing, and lipid-storing white or brown adipocytes) on cellular and molecular levels is required. Several transcription factors that play a central role in the control of adipogenesis have been identified. Among these are the CCAAT/enhancer binding protein gene family and peroxisome proliferator-activated receptor-gamma. Hormones and growth factors, such as insulin and insulin-like growth factor (IGF), transfer external signals to differentiating adipocytes. In an attempt to improve the quality of tissue-engineered fat by culture-expanded adipocytes, various pre-adipocyte and stem cell culture conditions and expansion methods have been developed. In the presence of fetal calf serum, spontaneous differentiation of pre-adipocytes into fat cell clusters occurs to some degree. This in vitro differentiation can be enhanced by addition of inducing agents such as dexamethasone, isobutylmethylxantine, and insulin into the culture medium. Recent work has shown the multipotency of pre-adipocytes, which are fibroblast-like precursors of adipocytes. With use of specific culture conditions, human adipose tissue-derived stem cells can be induced to express markers of adipocyte, osteoblast, and myocyte cell lineages. The multipotent characteristics of adipose tissue-derived stem cells, as well as their abundance and accessibility in the human body, make them a potential cell source for tissue engineering applications.

Localization of bone marrow stromal cells in injured spinal cord treated by intravenous route depends on the hemorrhagic lesions in traumatized spinal tissues

OBJECTIVES

Bone marrow stromal cells (BMSCs) have been reported to improve movement deficit in adult rats with spinal cord injury (SCI). The purpose of this study is to determine the distribution of BMSCs in the spinal cord lesion of the contusion model of SCI.

METHODS

Laminectomy was carried out at L1 vertebra level and SCI was carried out using the weight drop method. BMSCs were isolated from adult rats, labeled with bromodeoxyuridine (BrdU) and administered intravenously to the rats 1 week after SCI, which were killed after 4 weeks. The non-treated animals were used as negative control, which showed cavitations of the spinal cord after 5 weeks of SCI. Rats in another group were killed immediately and used to study the hemorrhagic lesions. The volume densities (Vv) of the hemorrhage and cavitation were the highest at the site of direct trauma.

RESULTS

The numerical densities of the transmigrated cells per area (Nat) were as follows: 0.3 +/- 0.2, 3.9 +/- 0.4, 5.4 +/- 0.4, 8.4 +/- 0.5, 5.5 +/- 0.3, 3.6 +/- 0.3 and 0.4 +/- 0.2 at the end and the middle of the thoracic vertebra 13 (T13), the region between T13 and the first lumbar vertebra, the middle of L1, the region between L1 and L2, and the middle and the end of L2 vertebra, respectively. The distribution of Nat at the above regions was a Gaussian model. The volume densities of hemorrhage in the spinal cord taken from the above regions showed that hemorrhage with the highest volume density occurred at the impact site and the volume density declined as the samples taken were more distant from the impact site.

DISCUSSION

The migration of BMSCs in the injured region depends on the amount of the hemorrhage and damage to blood vessels of the spinal cord.

Mesenchymal stem cells derived from peripheral blood protects against ischemia

Intravenous delivery of mesenchymal stem cells (MSCs) prepared from bone marrow (BMSCs) reduces infarction volume and ameliorates functional deficits in a rat cerebral ischemia model. MSC-like multipotent precursor cells (PMSCs) have also been suggested to exist in peripheral blood. To test the hypothesis that treatment with PMSCs may have a therapeutic benefit in stroke, we compared the efficacy of systemic delivery of BMSCs and PMSCs. A permanent middle cerebral artery occlusion (MCAO) in rat was induced by intraluminal vascular occlusion with a microfilament. Rat BMSCs and PMSCs were prepared in culture and intravenously injected into the rats 6 h after MCAO. Lesion size was assessed at 6 h, and 1, 3, and 7 days using MR imaging and histology. The hemodynamic change of cerebral blood perfusion on stroke was assessed the same times using perfusion-weighted image (PWI). Functional outcome was assessed using the treadmill stress test. Both BMSCs and PMSCs treated groups had reduced lesion volume, improved regional cerebral blood flow, and functional improvement compared to the control group. The therapeutic benefits of both MSC-treated groups were similar. These data suggest that PMSCs derived from peripheral blood could be an important cell source of cell therapy for stroke.

BDNF, NT-3, and NGF released from transplanted neural progenitor cells promote corticospinal axon growth in organotypic cocultures

STUDY DESIGN

Experimental study of spinal cord injury using an organotypic slice culture.

OBJECTIVE

To clarify the mechanism of corticospinal axon regeneration following transplantation of neural progenitor cells (NPCs) in the injured spinal cord.

SUMMARY OF BACKGROUND DATA

Several mechanisms underlying central nervous system regeneration after transplantation of NPCs have been proposed; however, the precise mechanism has not been clarified. Previously, we demonstrated that transplanted NPCs secreted humoral factors that in turn promoted corticospinal axon growth using the unique organotypic coculture system involving brain cortex and spinal cord from neonatal rats.

METHODS

Cultured NPCs were immunostained with antibodies against neurotrophic factors including brain-derived neurotrophic factor (BDNF), neurotrophin (NT)-3, nerve growth factor (NGF), and ciliary neurotrophic factor (CNTF) both before and after differentiation. To evaluate corticospinal axon growth quantitatively, we used the organotypic coculture system. The dissected brain cortex and spinal cord obtained from neonatal rats were aligned next to each other and cultured on a membrane. NPCs were transplanted onto the cocultures. Furthermore, neutralizing antibodies against BDNF, NT-3, NGF, or CNTF were added to the cocultures. Axon growth from the brain cortex into the spinal cord was assessed quantitatively using anterograde axon tracing with DiI.

RESULTS

The cultured NPCs were positively immunostained by antibodies against BDNF, NT3, NGF, and CTNF both before and after differentiation. Transplantation of NPCs promoted axon growth from the brain cortex into the spinal cord. The axon growth promoted by NPCs was significantly suppressed by the addition of neutralizing antibodies against BDNF, NT-3, and NGF but not CNTF.

CONCLUSION

The neurotrophic factors, BDNF, NT-3, and NGF, secreted by transplanted NPCs, were involved in the promotion of corticospinal axon growth after transplantation of NPCs.

Therapeutic potential of bone marrow-derived mesenchymal stem cells on experimental liver fibrosis

OBJECTIVE

To study the effect of mesenchymal stem cells (MSC) on experimental liver fibrosis in rats.

DESIGN AND METHOD

MSC were derived from bone marrow obtained from femoral and tibial bones of male albino rats. MSC were separated, grown, and propagated in culture for 4 weeks and were characterized morphologically and by detection of CD29 by RT-PCR. They were then infused into the tail vein of female rats that received CCl4 injection to induce liver fibrosis. Rats were divided into 4 groups: control, CCl4, CCl4 plus MSC, and MSC. Liver tissue was examined histopathologically and liver functions (ALT and serum albumin) were estimated for all groups. Y-chromosome gene (sry) was assessed by PCR in liver tissue of the female rats to confirm uptake of the male stem cells. Hydroxyproline content in liver tissue was assessed by chemical methods and expression of the collagen gene (type I) was detected as a marker for liver fibrosis. Results of the present study showed that MSC have a significant antifibrotic effect as evidenced by the significant decrease in liver collagen gene expression as well as the decrease in hydroxyproline content in the CCl4/MSC group (p<0.001) compared to the CCl4 group. The Y-chromosome gene (sry) was detected by RT-PCR in the CCl4/MSC group, but was not detected in control group and other groups. The CD29 gene was expressed in MSC culture, and this confirmed the efficiency of isolation and propagation of MSC in culture. With regard to liver function, there was also a significant improvement and elevation of serum albumin in the CCl4/MSC group compared to the CCl4 group (p<0.05). As regard to the liver enzyme ALT, there was a decrease of its level in the CCl4/MSC group compared to the CCl4 group. However, this was statistically nonsignificant (p>0.05). In conclusion, MSC have a potential therapeutic effect against the fibrotic process through their effect in minimizing collagen deposition in addition to their capacity to differentiate into hepatocytes.

Complete spinal cord injury treatment using autologous bone marrow cell transplantation and bone marrow stimulation with granulocyte macrophage-colony stimulating factor: Phase I/II clinical trial

To assess the safety and therapeutic efficacy of autologous human bone marrow cell (BMC) transplantation and the administration of granulocyte macrophage-colony stimulating factor (GM-CSF), a phase I/II open-label and nonrandomized study was conducted on 35 complete spinal cord injury patients. The BMCs were transplanted by injection into the surrounding area of the spinal cord injury site within 14 injury days (n = 17), between 14 days and 8 weeks (n = 6), and at more than 8 weeks (n = 12) after injury. In the control group, all patients (n = 13) were treated only with conventional decompression and fusion surgery without BMC transplantation. The patients underwent preoperative and follow-up neurological assessment using the American Spinal Injury Association Impairment Scale (AIS), electrophysiological monitoring, and magnetic resonance imaging (MRI). The mean follow-up period was 10.4 months after injury. At 4 months, the MRI analysis showed the enlargement of spinal cords and the small enhancement of the cell implantation sites, which were not any adverse lesions such as malignant transformation, hemorrhage, new cysts, or infections. Furthermore, the BMC transplantation and GM-CSF administration were not associated with any serious adverse clinical events increasing morbidities. The AIS grade increased in 30.4% of the acute and subacute treated patients (AIS A to B or C), whereas no significant improvement was observed in the chronic treatment group. Increasing neuropathic pain during the treatment and tumor formation at the site of transplantation are still remaining to be investigated. Long-term and large scale multicenter clinical study is required to determine its precise therapeutic effect. Disclosure of potential conflicts of interest is found at the end of this article.

2', 3'-Cyclic nucleotide 3'-phosphodiesterase cells derived from transplanted marrow stromal cells and host tissue contribute to perineurial compartment formation in injured rat spinal cord

Transdifferentiation of transplanted marrow stromal cells (MSCs) and reactive changes of glial cells in a completely transected rat spinal cord were examined. Marrow stromal cells exhibited 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) at the plasma membrane and this has allowed their identification after transplantation by immunoelectron microscopy. In the control rats, the lesion site showed activated microglia/neural macrophages and some elongated cells, whose cytoplasm was immunoreactive for CNP. Cells designated as CNP1 and apparently host-derived expressed CXCR4. In experimental rats receiving MSCs transplantation, CNP1 cells were increased noticeably. This was coupled with the occurrence of a different subset of CNP cells whose plasma membrane was CNP-immunoreactive and expressed CXCR4. These cells, designated as CNP2, enclosed both myelinated and unmyelinated neurites thus assuming a spatial configuration resembling that of Schwann cells. A remarkable feature was the extensive ramifications of CNP1 cells with long filopodia processes delineating the CNP2 cells and their associated neurites, forming many perineurial-like compartments. Present results have shown that CNP2 cells considered to be MSCs-derived can transform into cells resembling Schwann cells based on their spatial relation with the regenerating nerve fibers, whereas the CNP1 glial cells participate in formation of perineurial compartments, probably serving as conduits to guide the nerve fiber growth. The chemotactic migration of CNP cells either derived from host tissue or MSCs bearing CXCR4 may be attracted by stromal derived factor-1alpha (SDF-1alpha) produced locally. The coordinated cellular interaction between transplanted MSCs and local glial cells may promote the growth of nerve fibers through the lesion site.

Mesenchymal stem cells increase self-renewal of small intestinal epithelium and accelerate structural recovery after radiation injury

Patients who undergo pelvic or abdominal radiotherapy may develop side effects that can be life threatening. Tissue complications caused by radiation-induced stem cell depletion may result in structural and functional alterations of the gastrointestinal (GI) tract. Stem cell therapy using mesenchymal stem cells (MSC) is a promising approach for replenishment of the depleted stem cell compartment during radiotherapy. There is little information on the therapeutic potential of MSC in injured-GI tract following radiation exposure. In this study, we addressed the ability of MSC to support the structural regeneration of the small intestine after abdominal irradiation. We isolated MSC from human bone marrow and human mesenchymal stem cells (hMSC) were transplanted into immunotolerent NOD/SCID mice with a dose of 5.10(6) cells via the systemic route. Using a model of radiation-induced intestinal injury, we studied the link between damage, hMSC engraftment and the capacity of hMSC to sustain structural recovery. Tissue injury was assessed by histological analysis. hMSC engraftment in tissues was quantified by PCR assay. Following abdominal irradiation, the histological analysis of small intestinal structure confirms the presence of partial and transient (three days) mucosal atrophy. PCR analysis evidences a low but significant hMSC implantation in small intestine (0.17%) but also at all the sites of local irradiation (kidney, stomach and spleen). Finally, in presence of hMSC, the small intestinal structure is already recovered at three days after abdominal radiation exposure. We show a structural recovery accompanied by an increase of small intestinal villus height, three and fifteen days following abdominal radiation exposure. In this study, we show that radiation-induced small intestinal injury may play a role in the recruitment of MSC for the improvement of tissue recovery. This work supports, the use of MSC infusion to repair damaged GI tract in patients subjected to radiotherapy. MSC therapy to avoid extended intestinal crypt sterilization is a promising approach to diminish healthy tissue alterations during the course of pelvic radiotherapy.

Strategies for achieving and monitoring myelin repair

A number of factors more or less unique to multiple sclerosis have suggested that this disease may be particularly amenable to cell-based reparative therapies. The relatively focussed damage to oligodendrocytes and myelin at least in early disease implies that only a single population of cells need be replaced-and that the daunting problem of re-establishing connectivity does not apply. The presence of significant though partial spontaneous myelin repair in multiple sclerosis proves there to be no insurmountable barrier to remyelination intrinsic to the CNS: the therapeutic challenge becomes that of supplementing this spontaneous process, rather than creating repair de novo. Finally, the large body of available knowledge concerning the biology of oligodendrocytes, and the success of experimental myelin repair, have allowed cautious optimism that future prospects for such therapies are not unrealistic. Nonetheless, particular and significant problems are not hard to list: the occurrence of innumerable lesions scattered throughout the CNS, axon loss, astrocytosis, and a continuing inflammatory process, to name but a few. Here we review the progress and the areas where difficulties have yet to be resolved in efforts to develop remyelinating therapies for multiple sclerosis.

Bone marrow stromal cells induce changes in pain behavior after sciatic nerve constriction

Peripheral nerve injury, i.e. a single ligature nerve constriction (SLNC), triggers neuropathic pain. Bone marrow stromal cells (MSCs) have been observed to migrate to the injured tissues and mediate functional recovery following brain, spinal cord and peripheral nerve lesions. We have recently shown MSC selective migration to the ipsilateral lumbar (L3-6) dorsal root ganglia (DRGs) after a sciatic nerve SLNC. In this study, we have analyzed the thermal and mechanical sensitivities of animals subjected to a SLNC of the sciatic nerve and an ipsilateral intraganglionic MSC injection, using the von Frey and Choi tests. Control animals were subjected to the nerve lesion either alone or followed by the administration of phosphate-buffered saline (PBS) or bone marrow non-adherent mononuclear cells (BNMCs). All the animals were tested both before surgery and after 1, 3, 7, 14, 21, 28 and 56 days. Animals subjected to the sciatic nerve constriction developed ipsilateral mechanical and thermal allodynia already 3 days after the lesion. The allodynic responses were maintained even after 56 days. MSC administration prevented the generation of mechanical allodynia and reduced the number of allodynic responses to cold stimuli. On the contrary, the injection of either PBS or BNMCs could not counteract allodynia. These results suggest that MSCs may modulate pain generation after sciatic nerve constriction. The underlying mechanisms by which MSCs exert their actions on pain behavior need to be clarified.

Bone marrow stromal cells stimulate neurite outgrowth over neural proteoglycans (CSPG), myelin associated glycoprotein and Nogo-A

In animal models, transplantation of bone marrow stromal cells (MSC) into the spinal cord following injury enhances axonal regeneration and promotes functional recovery. How these improvements come about is currently unclear. We have examined the interaction of MSC with neurons, using an established in vitro model of nerve growth, in the presence of substrate-bound extracellular molecules that are thought to inhibit axonal regeneration, i.e., neural proteoglycans (CSPG), myelin associated glycoprotein (MAG) and Nogo-A. Each of these molecules repelled neurite outgrowth from dorsal root ganglia (DRG) in a concentration-dependent manner. However, these nerve-inhibitory effects were much reduced in MSC/DRG co-cultures. Video microscopy demonstrated that MSC acted as "cellular bridges" and also "towed" neurites over the nerve-inhibitory substrates. Whereas conditioned medium from MSC cultures stimulated DRG neurite outgrowth over type I collagen, it did not promote outgrowth over CSPG, MAG or Nogo-A. These findings suggest that MSC transplantation may promote axonal regeneration both by stimulating nerve growth via secreted factors and also by reducing the nerve-inhibitory effects of the extracellular molecules present.

Granulocyte colony-stimulating factor (G-CSF) mobilizes bone marrow-derived cells into injured spinal cord and promotes functional recovery after compression-induced spinal cord injury in mice

The aim of the present study was to elucidate the effects of granulocyte colony-stimulating factor (G-CSF)-mediated mobilization of bone marrow-derived stem cells on the injured spinal cord. Bone marrow cells of green fluorescent protein (GFP) transgenic mice were transplanted into lethally irradiated C57BL/6 mice. Four weeks after bone marrow transplantation, spinal cord injury was produced by a static load (20 g, 5 min) at T8 level. G-CSF (200 microg/kg/day) was injected subcutaneously for 5 days. Immunohistochemistry for GFP and cell lineage markers was performed to evaluate G-CSF-mediated mobilization of bone marrow-derived cells into injured spinal cord. Hind limb locomotor recovery was assessed for 6 weeks. Immunohistochemistry revealed that G-CSF increased the number of GFP-positive cells in injured spinal cord, indicating that bone marrow-derived cells were mobilized and migrated into injured spinal cord. The numbers of double positive cells for GFP and glial markers were larger in the G-CSF treated mice than in the control mice. Luxol Fast Blue staining revealed that G-CSF promoted white matter sparing. G-CSF treated mice showed significant recovery of hind limb function compared to that of the control mice. In conclusion, G-CSF showed efficacy for spinal cord injury treatment through mobilization of bone marrow-derived cells.

Neurotrophin-directed differentiation of human adult marrow stromal cells to dopaminergic-like neurons

Marrow-isolated adult multilineage inducible (MIAMI) cells were differentiated in vitro to neuronal cells in a neurotrophin-dependent fashion. After induction, the cells revealed electrophysiological features similar to those observed in mature neurons. Primary early passage human MIAMI cells without any type of co-cultures with other cell types were used. The developmental program involved a multi-step process requiring the concerted action of brain-derived neurotrophic factor, nerve growth factor and depended on neurotrophin-3, after basic fibroblast growth factor withdrawal. MIAMI-derived neuron-like cells sequentially expressed the neuronal markers, developed a complex neurite outgrowth and arborization, and acquired electrophysiological characteristics similar to those observed in mature neurons. The young and old MIAMI-derived neuronal cells developed both inward and outward currents upon depolarization, similar to those observed in normal neurons. These results represent the earliest evidence that neurotrophin-3 can direct the differentiation of non-neural stem cells from human adult bone marrow stroma to neuron-like cells in vitro. Supplementing the aforementioned multi-step process with sonic hedgehog, fibroblast growth factor 8, and retinoic acid increased the expression of molecules involved in dopaminergic differentiation and of tyrosine hydroxylase, the rate limiting enzyme of dopamine synthesis. MIAMI cells from young and old individuals represent autologous human cell populations for the treatment of disorders of the skeletal and nervous systems and for applications in cell therapy and reparative medicine approaches.

Bone marrow stromal cell transplantation preserves gammaaminobutyric acid receptor function in the injured spinal cord

A surprising shortage of information surrounds the mechanisms by which bone marrow stromal cells (BMSC) restore lost neurologic functions when transplanted into the damaged central nervous system. In the present study, we sought to elucidate whether BMSCs express the neuron-specific gamma-aminobutyric acid (GABA) receptor when transplanted into injured spinal cord. To examine this, we harvested and cultured rat femoral BMSCs. We then subjected Sprague-Dawley rats to thoracic spinal cord injury (SCI) with a pneumatic impact device. Fluorescence-labeled BMSCs (n = 7) were transplanted stereotactically or the vehicle in which these cells were cultured (n = 4) was introduced stereotactically into the rostral site of SCI at 7 days after injury. We evaluated GABA receptor function by measuring the binding potential for 125I-iomazenil (125I-IMZ) through in vitro autoradiography at 4 weeks after BMSC transplantation and simultaneously examined the fate of the transplanted BMSCs by immunocytochemistry. We found that the transplanted BMSC migrated toward the core of the injury and were densely distributed in the marginal region at 4 weeks after transplantation. BMSC transplantation significantly increased the binding potential for 125I-IMZ (p = 0.0376) and increased the number of GABA receptor-positive cells (p = 0.0077) in the marginal region of the injury site. Some of the transplanted BMSCs were positive for microtubule-associated protein-2 and the alpha1 subunit of GABA(A) receptor in the region of injury. These findings suggest that BMSCs have the potential to support the survival of neurons in the marginal region of SCI and can partly differentiate into neurons, regenerating spinal cord tissue at the site of injury.

Bone marrow-derived stem cells in neurological diseases: stones or masons?

In spite of the commonly held belief that ‘the brain does not regenerate’, it is now accepted that postnatal neurogenesis does occur. Thus, one wonders whether cellular-replacement therapy might be used to heal the brain in diseases caused by neuronal cell loss. The existence of neural stem cells has been demonstrated by many scientists and is now generally accepted. The exact role of these cells, how their numbers are regulated and how they participate in CNS and spinal cord regeneration in postnatal life are still not well known. There are many reviews summarizing work on these cells; consequently, I will focus instead on other cells that may participate in postnatal neurogenesis: bone marrow-derived stem cells. The possibility that bone marrow-derived stem cells populate the CNS and differentiate into various neural elements is certainly not universally accepted.

Potentiality of Mesenchymal Stem Cells in Regeneration of Sweat Glands

Sweat glands play some key roles in homeostasis maintenance and body temperature regulation. In full-thickness burn wounds, sweat glands cannot regenerate to form their three-dimensional organization via the division and terminal differentiation of sweat gland cells. However, the plasticity of mesenchymal stem cells (MSCs) may offer the hope and potentiality to regenerate sweat glands after severe burn injury.

Transplantation of bone marrow stem cells as well as mobilization by granulocyte-colony stimulating factor promotes recovery after spinal cord injury in rats

Emerging clinical studies of treating brain and spinal cord injury (SCI) with autologous adult stem cells led us to compare the effect of an intravenous injection of mesenchymal stem cells (MSCs), an injection of a freshly prepared mononuclear fraction of bone marrow cells (BMCs) or bone marrow cell mobilization induced by granulocyte colony stimulating factor (G-CSF) in rats with a balloon- induced spinal cord compression lesion. MSCs were isolated from rat bone marrow by their adherence to plastic, labeled with iron-oxide nanoparticles and expanded in vitro. Seven days after injury, rats received an intravenous injection of MSCs or BMCs or a subcutaneous injection of GCSF (from day 7 to 11 post-injury). Functional status was assessed weekly for 5 weeks after SCI, using the Basso-Beattie-Bresnehan (BBB) locomotor rating score and the plantar test. Animals with SCI treated with MSCs, BMCs, or G-CSF had higher BBB scores and better recovery of hind limb sensitivity than controls injected with saline. Morphometric measurements showed an increase in the spared white matter. MR images of the spinal cords were taken ex vivo 5 weeks after SCI using a Bruker 4.7-T spectrometer. The lesions populated by grafted MSCs appeared as dark hypointense areas. Histology confirmed a large number of iron-containing and PKH 26-positive cells in the lesion site. We conclude that treatment with three different bone marrow cell populations had a positive effect on behavioral outcome and histopathological assessment after SCI, which was most pronounced after MSC injection.