Stem Cell Therapy

Stromal/stem cell implant improves motor function in patients with history of TBI

Stromal/stem cell implant improves motor function in patients with history of TBI

Patients with previous traumatic brain injury experienced significant improvement in motor functioning after implantation of mesenchymal stromal/stem cells, according to interim data from the STEMTRA phase 2 trial published in Neurology.

“Mesenchymal stromal/stem cell (MSC) implantation is a promising strategy for the treatment of TBI,” MasahitoKawabori,MD, PhD, of the department of neurosurgery at Hokkaido University Hospital in Sapporo, Japan, and colleagues wrote. “Allogeneic modified bone marrow-derived MSCs (SB623 cells, SanBio, Inc.) are in clinical development for chronic TBI and stroke without concomitant immunosuppressants which were determined to be unnecessary based on the prior Phase 1/2a clinical study and preclinical studies submitted to the FDA

Kawabori and colleagues conducted a 1-year, multicenter, double-blind, randomized, surgical sham-controlled trial of 61 patients (mean age, 34.4 years; men, 70.5%; median time since injury, 68.9 months) who were at least 12 months past the initial TBI. Patients had Glasgow Outcome Scale-Extended scores of 3 to 6 and focal cerebral injuries that were visible on MRI that correlated with chronic motor deficits. The mean Fugl-Meyer Motor Scale (FMMS) score at baseline was 52.2 in patients who received the SB623 implant and 52.3 in controls.

Researchers randomly assigned patients to receive either the SB623 implant (n = 46) or sham surgery (n = 15). The treatment group was further randomly assigned to 2.5x10⁶ (n = 15), 5x10⁶ (n = 15) or 10x10⁶ (n = 16). They wrote that SB623 cells “are produced by the transient transfection of MSCs with a plasmid containing the human Notch-1 intracellular domain” and “increases [cells’] ability to secrete trophic factors, chemotactic factors and deposit extracellular matrix proteins which may support damaged neural cells.” The proprietary formulation is also being developed for other indications including spinal cord injury, according to SanBio.

Significant improvement of FMMS scores from baseline at 6 months served as the study’s primary endpoint. Researchers selected FMMS score, which is “well-established as a measure of motor impairment” and often used as a measurement of chronic stroke recovery, as the primary endpoint “because of its reliability and validity in measuring changes in patients with persistent motor deficits.”

FMSS scores improved more in patients treated with SB623 compared with controls at 6 months (least square [LS] mean, +8.3 vs. +2.3); the LS mean difference between scores was 6 (95% CI, 0.3-11.8). Patients in the 5.0x10⁶ group saw the greatest FMMS score improvements at 6 months (+10.9 vs. +2.4 point improvement; P = .002) and had the highest percentage of patients whose FMMS scores improved by 10 or more points (53.3%).

No dose-limiting toxicities or deaths occurred. Treatment-emergent adverse events occurred in 100% of patients treated with SB623 compared with 93.3% of controls, though this difference was not statistically significant. Headache of mild or moderate severity was the most common treatment-emergent adverse event in both the SB623 pooled group (50%) and the control group (26.7%).

“In this interim analysis of a first double-blind, randomized, controlled clinical trial of cell therapy for chronic motor deficits secondary to TBI, treatment with SB623 cells appeared to be safe and was associated with statistically significant improvement of the Fugl-Meyer Motor Scale at 6 months,” the researchers wrote. “The favorable safety and efficacy outcomes reported here demonstrate the need for functional imaging studies and confirmatory Phase 3 clinical trials of SB623 cells for the treatment of chronic motor deficits secondary to TBI

Strategies for CNS repair following TBI - PubMed

Both MSC and human umbilical cord blood cells have been reported to transdifferentiate into neural andglial cell lineages. MSC transdifferentiation into neural cells was first shown in 2000 after proliferation in vitro (Woodbury et al., 2000). This study was followed shortly by reports of MSC transdifferentiation into astrocytes and neurons in vivo (Lu et al., 2001). Reports of spontaneous migration of transplanted bone marrow cell into the brain of animals and humans have also been published. Thevast majority of these cells were noted to differentiate into non-neuronal cells, but some of the cells found in

hippocampus and cortex displayed markers of neuronal lineage (Mezey et al., 2000; Mezey et al., 2003). However, it has been argued that these results are due to cell fusion of marrow cells with a recipient cell in the brain (Terada et al., 2002). Subsequent studies cast doubt on in vivodifferentiation of MSC into neuronal elements. One such paper did so by demonstrating that cell labels such as bromdeoxyuridine and benzamide may transfer from graft cells to host cells after elimination by the an immune mediated response (Coyne et al., 2006). In light of results showing minimal engraftment in addition to rare or even questionable transdifferentiation, neural replacement has been posited to have limited ability as a current therapeutic mechanism by some authors (Walker, 2010). While direct neuronal cell replacement with progenitor cell therapies remains audacious, other avenues remain for improving neuronal function following TBI. Axonal sprouting and cortical rewiring has been found in animal models following stroke and TBI. Evidence from animal models of TBI and stroke demonstrate that this process may be amplified by treatment with intraparenchymal transplantation of MSC (Liu et al., 2008; Mahmood et al., 2013). MSC transplantation appears to have some limited ability to promote axonal regeneration across lesions and provide neuroprotection to neurons that have undergone axotomy in a model of spinal cord injury (Novikova et al., 2011). These histopathologic changes following treatment appear to arise with associated changes in function. In an animal model of TBI, the degree to which corticospinal tract axonal sprouting occurs within the spinal cord has been shown to have a correlation with improvement in of motor function (Mahmood et al., 2013). The central nervous system is known to have a limited ability for both axonal sprouting from uninjured neurons and regeneration from damaged neurons when compared to the peripheral nervous system. One of the reasons for this dichotomy is the differences in local environment and presence of myelin associated inhibitors such as Nogo-A, MAG & OMgp (Geoffroy and Zheng, 2014). In vitroMSC have been demonstrated to mitigate these effects through multiple mechanisms mechanisms: stimulation of neurite growth by soluble factors and contact mediated reductions in the effect of these inhibitors (Wright et al., 2007b). In the case of MSC transplantation with collagen scaffolds following TBI, there is evidence of decreased Nogo-A synthesis by oligodendrocytes. This same study showed a decrease Nogo-A levels with MSC transplantation alone, but not to the same degree as those transplanted with the collagen scaffold (Mahmood et al., 2014). An increase in axonal sprouting with anti Nogo-A antibodies has also been shown in a stroke model. Furthermore, this increase in axonal sprouting from the contralateral corticospinal tract occurs in concert with reorganization of the undamaged motor cortex (Lindau et al., 2013). The use of scaffolds with cell therapies, which has shown improvement in cell engraftment, may also aid in functional neurorestoration by way of axonal sprouting in major white matter tracts such as the corpus callosum and corticospinal tracts (Mahmood et al., 2013; Xiong et al., 2009). This ability to produce signs of therapeutic effect diffusely throughout the CNS is promising and may be necessary for functional recovery in severe TBI due to the high incidence of DAI.Further experimentation is necessary thought todetermine if these locoregional effects are scalable to larger primates. In vitroanalysis of the effect of MSC derived factors on NSC have been able to show evidence of increased neurite outgrowth even independent of glial interaction, which could be beneficial for repair of neuronal circuitry (Croft and Przyborski, 2009). Increased axonal sprouting has also been reported following intravenous administration of MSC in rodents following middle cerebral artery occlusion (Liu et al., 2010). However, no current study appears to have investigated whether or not systemically administered progenitor cell therapy isable to mediate the axonal sprouting or regeneration in TBI. Alternatively, replacement/repair at the site of injured brain parenchyma may be possible without the need of cell transplantation. Modulation of the constitutive cell populations at the site of injury is currently being investigated for treatment of central nervous system injuries. Neuronal replacement may be achievable by cellular reprogramming of glial or neural progenitor cells in the brain. One pathway that has been targeted with gene transfer via viral transfection is the Notch-Hes1 signaling pathway. Stereotactical infusion of Hes1 short interfering RNA prior to lateral fluid percussion injury has been shown to result increased differentiation of hippocampal neural progenitor cells into NeuN+ neurons and is associated with improvements in spatial memory following injury (Zhang et al., 2014). Downregulation of Hes1 is also known to result in an inverse relationship to neurogenesis and cell proliferation (Baek et

Furthermore, this downregulation may be a natural response to injury asit has been observed to occur spontaneously following TBI in rodent models to a limited degree (Yang et al., 2009). Areas without a ready supply of neural progenitor cells may benefit from reprogramming of local glial cells. Conversion of astrocytes in the striatum and cortex has been reported in vivo. This has been achieved by viral transfection with the transcription factor SOX2 in uninjured animals resulting in doublcortin + neuroblasts, but few mature neurons as shown by staining for NeuN. Replication of this effect with SOX2 transfection is also observable in vivo following a stab wound model of TBI. In this model, no differentiation of astrocytes was noted on the non lesioned hemisphere. However, the authors in this study reported the development of action potentials and synapse formation (Heinrich et al., 2014). A similar process has also been seen with animal models of spinal cord injury. Transfection of astrocytes with SOX2 containing lentiviruses following spinal cord hemisection resulted in induction to form neuroblasts as shown by staining for doublecortin. This transformation was observable at 4 weeks following injury and mature neurons appeared later around 8 weeks following injury. Additionally, this method of neural replacement also resulted in synaptic formation with preexisting motor neurons (Su et al., 2014). Further increases in cell survival and maturation toward neuronal lineages has been achieved following SOX2 transfection with the use of histone deacteylase inhibitors or transfection to express noggin/BDNF or Asc11 (Heinrich et al., 2014; Niu et al., 2013; Su et al., 2014

with intra-arterial but not with intravenous administration (Kamiya et al., 2008). Alternatively, other studies comparing intra-arterial with intravenous administration of BM-MNC have shown no difference in behavioral/functional or structural outcomes in several animal models (Vasconcelos-dos-Santos et al., 2012; Yang et al., 2013). In addition, intravenous administration was found to cause potentially beneficial attenuation of cytokines with greater decreases in IL-1β and increases in IL-10 when compared to intra-arterial administration (Yang et al., 2013). No current studiesreport differences in behavioral, motor or structural outcomes with intravenous versus intra-arterial administration of stem cellsin animal TBI models. Ultimately, the need for intra-arterial administration will likely depend on the degree to which functional outcomes are dependent on loco-regional versus systemic therapeutic mechanisms. Supporting this idea is data from intravenous administration of the secretome produced by MSC on culture media. This secretome has been found to result in decreased perilesional neuronal apoptosis as well as lesion volume and possibly increase neurogenesis as shown by increased numbers of BrdU/NeuN/DAPI staining neurons at the lesion site (Chang et al., 2013). This provides some evidence that engraftment and differentiation may not be necessary to achieve neuroprotection or repair with progenitor cell therapies. Pathways that have been implicated in the protective effects of treatment with progenitor cells and MSC in particular include paracrine mediated activation of the MAPK/Erk 1, 2 and PI3-K/Akt. In vitro analysis has demonstrated that secretory factors from MSC are able to illicit enhanced phosphorylation of MAPK/Erk 1, 2 in neurons and leads to decreased neuronal apoptosis. This decrease in apoptosis is prevented with the addition of inhibitors of MEK1 thus preventing MAPK/Erk 1, 2 activation and inhibition of PI3-K (Isele et al., 2007). These two pathways have also been shown to be protective toward astrocytes (Gao et al., 2005). Activation of the PI3-K/Akt pathway following treatment with MSC also appears to result in increased axonal outgrowth. The activation of this pathway using cells in a transwell co-culture provides further evidence that this outcome is secondary to yet undiscovered secretory factories or paracrine effects (Liu et al., 2013).Clinical InvestigationIn review of the available literature, there is one published case series where direct autologous MSC transplantation was performed in humans following TBI. In this report, 7 patients (ages 6-55) underwent bone marrow harvest with subsequent isolation and expansion of their MSC population. The cells were then administered locally and later intravenously. No serious adverse effects were reported during a 6 month follow up period (Zhang et al., 2008). Intrathecal administration of MSC has also been performed in humans. In a series of 97 patients Tian and associates were able to demonstrate that they could safely harvest and administer autologous MSC using as much as 5 mL (1 x 106cells/mL) via lumbar puncture in patients with persistent vegetative state or other deficits 1 month after injury. In this series of patients, the greatest improvements were seen in younger patients who underwent treatment closer to the time of injury (Tian et al., 2013). The use of allogenic, umbilical cord MSC was evaluated in patients with chronic deficits following TBI. Twenty of the forty enrolled patients underwent 4 injections of 1 x 107cells (2 mL) over a period of 5-7 days. As a result of the intervention, 20% of the displayed symptoms of low intracranial pressure but no other events were reported. The investigators reported statistically significant improvements in functional assessments 6 months out from treatment which was not seen in controls (Wang et al., 2013b

Neurorestorative Treatments for Traumatic Brain Injury

Although human embryonic stem cells (hESCs) or fetal tissues are suitable sources for cell-based therapies, their clinical application is limited by both ethical considerations and other practical challenges including tumorigenicity, cell viability and antigenic compatibility. Reprogramming differentiated cells generates induced pluripotent stem cells (iPSCs) that resemble embryonic stem cells (Yamanaka, 2007). These iPSCs avoid the ethical issues and remove the major roadblock of immune rejection associated with the clinical use of hESCs, as well as potentially generate patient-specific cells for cell-replacement therapy. However, the safety and therapeutic applications of iPSCs and iPSC-derived cells must be rigorously tested in appropriate animal models before advancing to any clinical trial. The most important issue with iPSCs is potential tumorigenicity. Even with improvements in the virus-free and transgene-free reprogramming technologies, the cancer-causing possibility of the derived “safe” iPSCs/derivatives still needs to be evaluated in animal models before their clinical application for regenerative treatment.

Bone marrow stromal cells (MSCs) are a mixed cell population, including stem and progenitor cells, and are a promising source of cell-based therapy for TBI, since they can be easily isolated from many tissues and expanded in culture from patients without ethical and immune rejection problems (Chopp and Li, 2002). When grafted into the lateral ventricles of neonatal mouse brains, mouse MSCs migrated and differentiated into olfactory bulb granule cells and periventricular astrocytes (Deng et al., 2006). Systematically infused rat MSCs migrated into injured rat brains and survived (Lu et al., 2001). Some of the implanted MSCs expressed cell markers for neurons and astrocytes. Expression of the chemokine stromal-cell-derived factor-1 was significantly increased in the lesion boundary zone after brain injury induced by ischemia (Shen et al., 2007). The stromal-cell-derived factor-1 receptor, CXC-chemokine receptor-4, was expressed in MSCs both in vitro and in vivo (Shen et al., 2007). The interaction of stromal-cell-derived factor-1 with CXC-chemokine receptor-4 may contribute to the trafficking of transplanted MSCs into the injured brain (Itoh et al., 2009; Shen et al., 2007). Direct implantation (6 h post injury) of MSCs enhances neuroprotection via activation of resident NSC nuclear factor κB activity leading to an increase in interleukin-6 production and decrease in apoptosis (Walker et al., 2010). The delayed administration (24 h or 1 week following injury) of MSCs also significantly improved functional outcome in rodents following TBI (Chopp and Li, 2002; Chopp et al., 2009; Lu et al., 2001; Mahmood et al., 2004b; Mahmood et al., 2005; Mahmood et al., 2006).

MSCs secrete various growth factors, including brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF) and bFGF (basic fibroblast growth factor), and increase the levels of these factors in the brain (Chopp and Li, 2002; Mahmood et al., 2004a). MSCs also induce intrinsic parenchymal cells to produce these growth factors (Mahmood et al., 2004a). After MSC transplantation, these neurotrophic/growth factors enhance angiogenesis and vascular stabilization in the lesion boundary zone where the majority of MSCs that survive in the brain are located (Mahmood et al., 2006). These growth factors also promote neurogenesis in vitro and in vivo (Jin et al., 2002; Lee et al., 2002; Yoshimura et al., 2003). In rodent TBI models, MSCs not only increased vascular density in the lesion boundary zone and hippocampus (Qu et al., 2008), but also enhanced neurogenesis in the SGZ and SVZ (Mahmood et al., 2004b). Delayed (4 days after TBI) treatment with MSCs alone did not reduce lesion volume, whereas MSCs seeded in collagen scaffolds significantly reduced lesion volume, enhanced the migration of MSCs into the lesion boundary zone, and significantly improved spatial learning and sensorimotor function (Lu et al., 2007a). Even more delayed (7 days post injury) transplantation of MSCs or MSCs seeded in scaffolds improved spatial learning and sensorimotor function, enhanced angiogenesis in the injured cortex and the ipsilateral hippocampus and increased transcallosal neural fibers in the injured cortex (Xiong et al., 2009). The significant therapeutic benefits of MSCs are not attributed to the few MSCs that differentiate into neural cells (Lu et al., 2001). However, MSCs appear to act as neurotrophic/growth factor generators and inducers to promote brain functional recovery via angiogenesis, neurogenesis, synaptogenesis and axonal remodeling (Chopp and Li, 2002; Chopp and Li, 2006). MSCs (or neural stem/precursor cells)-seeded scaffolds may be a new and effective strategy for treatment of TBI.

The safety and feasibility of treatment with autologous MSCs were assessed in seven patients with TBI (Zhang et al., 2008). In this trial, no toxicity related to the cell therapy was observed within the 6-month follow-up period. A safety study of autologous stem cell treatment in children with TBI has also been completed (ClinicalTrials.gov, Identifier: NCT00254722); however, no data are available. This study should determine if bone marrow harvest and re-infusion is safe in children after severe TBI

Traumatic Brain Injury and Stem Cells: An Overview of Clinical Trials, the Current Treatments and Future Therapeutic Approaches

Currently, interventions to improve the lives of people with TBI in use—including drug treatments, surgeries, and rehabilitation therapy—provide poor outcomes [11]. The use of SCs in the treatment of TBI has recently entered the clinic as a possible therapeutic application [23,24]. SCs therapy is used in regenerative medicine to restore damaged neurons. SCs are cells that showed the multipotent capacity to differentiate toward different cell types and possess the capacity to renew themselves [25]. In different preclinical studies, conducted on TBI animal models, stem cell transplantation has promoted the improvement of several neurological parameters [12]. Specifically, NSCs and MSCs—such as BM-MSCs, AD-MSCs, and UC-MSCs—appear capable of regenerating damaged nerve tissue, as demonstrated in several in vivo studies, using animal models of TBI.

NSCs derived from the lateral ventricle, the dentate gyrus of the hippocampus [26]. Moreover, NSCs are a type of cell capable of self-renewal, they can differentiate into neurons, oligodendrocytes, and astrocytes. Additionally, NSCs are able to release cytokines and neurotrophic factors such as brain-derived neurotrophic factor (BDNF), glial cell-derived neurotrophic factor (GDNF), and insulin growth-factors-1 (IGF-1). Several studies suggest that transplanted NSCs can potentially repair and integrate neurons and glial cells at the injury site, due to their ability to release crucial molecules to maintain structural and functional plasticity [27]. NSCs, when administered in an experimental model of TBI, may be an effective, long-term treatment for neurological recovery after brain injury [28].

The MSCs are multipotent stromal cells that can be easily harvested from a variety of tissue sources such as bone marrow, umbilical cord, adipose tissue, placenta, and oral cavity [29]. Also, MSCs are potentially capable of differentiating into a variety of cell types including osteogenic, adipogenic, chondrogenic, and neural lineages [30]. Moreover, MSCs according to the definition of MSCs of must be positive for CD73, CD90, and CD105 surface markers. On the contrary, MSCs must be negative for CD45, CD34, CD14, CD11b, CD79a, and CD19 and for the major histocompatibility complex class II surface molecules [31]. MSCs promote the regeneration of damaged tissues through reducing inflammation response, recruiting local progenitor cells to replace lost cells and releasing trophic factors including BDNF, GDNF, vascular endothelial growth factors (VEGF), and nerve growth factor (NGF) [32]. Therefore, thanks to their proprieties, MSCs therapy can potentially be useful to repair damage following TBI [33]. Indeed, it was demonstrated that MSCs are able to electively migrate to the lesioned nervous tissue of the TBI rat and following differentiate towards neurons and astrocytes, in order to repair the damaged area, with consequent enhancement the motor activity after TBI [34].

The BM-MSCs derive from the bone marrow and showed the ability to differentiate into several cell lineage including neurons and glial cells [35]. It was demonstrated that BM-MSCs transplantation promotes neuroplasticity and neuronal regeneration through several mechanisms [36]. BM-MSCs showed anti-inflammatory effects by promoting the differentiation of lymphocytes. Additionally, BM-MSCs are able to release growth factors such as VEGF, BDNF, GDNF, NGF, epidermal growth factor (EGF), fibroblast growth factor (FGF), and neurotrophin-3 (NT-3), in this way leading on the repair of the lesioned area [37]. Several preclinical studies showed that BM-MSCs release trophic factors into the damaged sites, that inhibit apoptosis, promote angiogenesis and stimulate host progenitor cells to differentiate toward neurons and astrocytes. In this way, BM-MSCs showed the ability to repair the lesioned tissue and recovered function in animal models of TBI [38,39].

The UC-MSCs are obtained easily by treating the umbilical cord or the cord blood. The UM-MSCs compared to other stem cells showed several advantages such as a low immunogenicity power, less risk of rejection after transplantation, easy harvesting, and no ethical controversy [40]. These cells secreted neutrophil activator, NT-3, BDNF, VEGF, and FGF in order to induce neuronal regeneration and neuronal vascularization in the damaged area. It was demonstrated that UM-MSCs confer trophic support in the injured, induce the microglia/macrophage to remodel of the brain, leading to significant improvement of neurological functions [41].

The AD-MSCs are easily isolated from adipose tissue [42]. These cells have the ability to differentiate into cell types including neurons, endothelial-derived cells, and Schwann cells [43]. Additionally, AD-MSCs exhibit immunomodulatory properties thanks to the release of several cytokines including IL-10 and transforming growth factor-beta (TGF-β) [44]. Likewise, thanks also to the release of neurotrophic factors such as BDNF and GDNF, they showed neuroprotective properties [45]. It was demonstrated the AD-MSCs transplantation improvement motor activity in an animal model of TBI, suggesting that these cells might be considered for patients with TBI [46].

To date, studies report that the principally used stem cell routes of administration are the intravenous route and local administration by stereotactic injections [47]. The intravenous route has the advantage of being a non-invasive strategy, but it shows the limit that the percentage of infused cells that reaches the lesion site is very small. In addition, intravenous administration of stem cells implicates that these cells are retained by the pulmonary capillaries, thus compromising their therapeutic potential [48]. Hence, this route of administration results not very effective due to the large dispersion of cells between the different organs of the body, which requires the administration of a large number of stem cells. Compared to intravenous administration, local infusion of stem cells by stereotaxic injections is invasive but allows to inject stem cells directly into the injury site [49]. Therefore, this route of administration shows the advantage of reducing the number of stem cells used. However, the best route of administration has not yet been established, as each route shows its advantages and disadvantages

TBI is a very complex disease. Nowadays, there are no effective treatments able to reduce the effects of the primary injury, but only therapies capable of blocking their progression. In recent decades, NSCs and MSCs (BM-MSCs, AT-MSCs and UC-MSCs), have demonstrated to be a useful tool that can reduce the effects of post-traumatic brain injury. In several of the clinical studies described, BM-MSCs administrated via intravenous and via lumbar puncture, shown improvement in damaged brain areas. The same results were obtained using the UC-MSCs transplantation; however, the number of studies is fewer. Therefore, the available results encourage the use of both SCs and therapies described as useful for the treatment of TBI

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2721253

adult CNS neurons are able to grow extensively after injury if offered a permissive peripheral nerve transplant (Richardson *et al.*, 1980; David and Aguayo, 1981; Aguayo *et al.*, 1991; Xie and Zheng, 2008). These experiments not only helped to overcome the dogma that injured adult CNS axons have lost their axonal growth capability but also induced a shift in focus towards the micro-environment of injured axons, giving rise to the question, ‘What makes the CNS micro-environment so hostile for regrowth of injured fibers?’ One of the first to answer this question was Martin Berry who postulated that breakdown products of the CNS myelin are responsible for the failure of injured CNS fibres to regrow. Martin Schwab and colleagues soon discovered the differences between CNS myelin and that of the peripheral nervous system where regeneration of injured nerve fibres is known to occur (Berry, 1982; Schwab and Thoenen, 1985; Schwab and Bartholdi, 1996; Xie and Zheng, 2008). The inhibitory activity of CNS myelin was overcome in a seminal rat spinal cord injury experiment conducted by Schnell and Schwab. They showed that intraventricular injection of hybridoma cells, producing a monoclonal antibody directed against inhibitory proteins of the CNS myelin, later called NOGO A, enhanced regenerative growth of injured corticospinal tract fibres across the spinal lesion site and improved functional recovery (Schnell and Schwab, 1990). Since these pioneering studies, we have learned that, besides CNS myelin, glial scar tissue forming at the lesion site in the spinal cord or brain also impedes fibre growth. Some of its molecular constituents will be discussed later in more detail (Silver and Miller, 2004; Mueller *et al.*, 2005). Based on experiments with antagonists of myelin-associated inhibitors or glial scar-associated inhibitors or pharmacological modifiers of the neuronal growth response, performed primarily in animals with spinal injury, several mechanisms have been described to account for drug-induced axon growth or rearrangement-induced functional improvement. A recent classification distinguishes regeneration from sprouting and plasticity based on the inciting event, the timing of axonal growth and rearrangement and distance of axonal regrowth (Cafferty *et al.*, 2008). The term regeneration is used to describe the growth of injured or damaged axons over longer distances and over longer periods of time, whereas sprouting refers to growth from injured or damaged fibres or from intact fibres over moderate distances. Plasticity, in a narrow sense, describes changes in the underlying network induced by damaged fibres and correlated functional loss (Cafferty *et al.*, 2008). The most time-consuming of these is the process of regeneration which takes weeks to months to bring about functional improvements, whereas sprouting and plasticity occur at a faster rate, that is, within days or even hours of the damaging event (Cafferty *et al.*, 2008). Most of these different mechanisms have been identified in animals with spinal cord injury and another important insight gained from these experiments was that, despite their often meandering course within the spinal cord tissue, regrowing fibres are able to synapse with their proper target neurons. Just how they are guided to their synaptic partners is not actually known but re-expression of many classes of developmentally active attractive and repulsive axon guidance molecules at the site of lesion or damage might be an explanation for the proper pathfinding and paucity of aberrant connections formed. This constitutes a very encouraging sign for the development of axonal growth therapeutics and several neuroregenerative drug candidates are currently being evaluated in clinical trials with spinal cord injury patients (Baptiste and Fehlings, 2008; Gonzenbach and Schwab, 2008). Table 1 provides a summary of potential axonal growth therapeutics including their proposed mode of action and investigational status in spinal cord injury. If successful, it is envisioned that these regenerative drug approaches will be extended to other CNS injuries such as traumatic brain injury (TBI

Regenerative strategies under evaluation for spinal cord injury treatment (Therapeutic agent, Proposed mechanism of action, trial Status as of 2009

Rho inhibitor (Cethrin®)

Anti-Nogo A antibodies

Neutralization of growth inhibitory myelin protein phase I/IIa

Chondroitinase ABC

Anti-NgR antibodies or antagonists

LINGO-1 antagonist

Anti-RGM A antibodies

Rho kinase (ROCK) inhibitors (Fasudil)

Sema3A inhibitor (SM-216289)

Neurotrophins (BDNF, CNTF, GDNF)

Largely not considered credible or teneable yet. Revisit

(Help rewrite changes to DNA?)

What we certainly dont have at the moment is targeted stem cell therapy, so the devil is in the details I reckon. Just sating "stem cell" therapy is far too broad a spectrum..

can reactivate ebv hhv ( I think I read somewhere there is a risk of herpes reactivation from stem cells transplant(Correct me if I am wrong, I am not an expert) and she did get reactivated shingles after and then went down with ME months later).

on positive testimony

"Mesenchymal stem cells (MSCs) are now known to display not only stem cell multipotency, but also robust antiinflammatory and regenerative properties. After widespread in-vitro and in-vivo preclinical testing, autologous and allogeneic MSCs have been applied in a range of immune mediated conditions, including graft versus host disease, Crohn's disease, multiple sclerosis, refractory systemic lupus erythematosus and systemic sclerosis. Current data suggests that MSCs may not only replace diseased tissues, but also exert several trophic, regenerative and antiinflammatory effects.

Cells home to areas of inflamation when reintroduced systemically either intravenously or otherwise, typically most will go to the lungs, but many also go to the gut, and some to the brain, this has been proved in research. Also once extracted from fat they are separated, primed, chemically potentiated, only then reintroduced to the system. Mesemchycal stem cells extracted from fat have been shown to repair thyroid, diabetes, help with conditions like chrons.

Also my own testimony is my lymphocytes have returned to normal range for the first time in 7 years just months following a stem cell procedure, they were well below refference range every single time before this without fail. Im pretty sure this is not a placebo effect. I am noticing little shifts, but it is a process."