Impaired motor unit recovery and maintenance in a knock-in mouse model of ALS-associated Kif5a variant.

Kinesin family member 5A (KIF5A) is an essential, neuron-specific microtubule-associated motor protein responsible for the anterograde axonal transport of various cellular cargos. Loss of function variants in the N-terminal, microtubule-binding domain are associated with hereditary spastic paraplegia and hereditary motor neuropathy. These variants result in a loss of the ability of the mutant protein to process along microtubules. Contrastingly, gain of function splice-site variants in the C-terminal, cargo-binding domain of KIF5A are associated with amyotrophic lateral sclerosis (ALS), a neurodegenerative disease involving death of upper and lower motor neurons, ultimately leading to degradation of the motor unit (MU; an alpha motor neuron and all the myofibers it innervates) and death. These ALS-associated variants result in loss of autoinhibition, increased procession of the mutant protein along microtubules, and altered cargo binding. To study the molecular and cellular consequences of ALS-associated variants in vivo, we introduced the murine homolog of an ALS-associated KIF5A variant into C57BL/6 mice using CRISPR-Cas9 gene editing which produced mutant Kif5a mRNA and protein in neuronal tissues of heterozygous (Kif5a+/c.3005+1G>A; HET) and homozygous (Kif5ac.3005+1G>A/c.3005+1G>A; HOM) mice. HET and HOM mice appeared normal in behavioral and electrophysiological (compound muscle action potential [CMAP] and MU number estimation [MUNE]) outcome measures at one year of age. When subjected to sciatic nerve injury, HET and HOM mice have delayed and incomplete recovery of the MUNE compared to wildtype (WT) mice suggesting an impairment in MU repair. Moreover, aged mutant Kif5a mice (aged two years) had reduced MUNE independent of injury, and exacerbation of the delayed and incomplete recovery after injury compared to aged WT mice. These data suggest that ALS-associated variants may result in an impairment of the MU to respond to biological challenges such as injury and aging, leading to a failure of MU repair and maintenance. In this report, we present the behavioral, electrophysiological and pathological characterization of mice harboring an ALS-associated Kif5a variant to understand the functional consequences of KIF5A C-terminal variants in vivo.

AAV1.NT-3 gene therapy increases muscle fiber diameter through activation of mTOR pathway and metabolic remodeling in a CMT mouse model.

Neurotrophin 3 (NT-3) has well-recognized effects on peripheral nerve and Schwann cells, promoting axonal regeneration and associated myelination. In this study, we assessed the effects of AAV.NT-3 gene therapy on the oxidative state of the neurogenic muscle from the TremblerJ (Tr J ) mice at 16 weeks post-gene injection and found that the muscle fiber size increase was associated with a change in the oxidative state of muscle fibers towards normalization of the fiber type ratio seen in the wild type. NT-3-induced fiber size increase was most prominent for the fast twitch glycolytic fiber population. These changes in the Tr J muscle were accompanied by increased phosphorylation levels of 4E-BP1 and S6 proteins as evidence of mTORC1 activation. In parallel, the expression levels of the mitochondrial biogenesis regulator PGC1α, and the markers of glycolysis (HK1 and PK1) increased in the TrJ muscle. In vitro studies showed that recombinant NT-3 can directly induce Akt/mTOR pathway activation in the TrkC expressing myotubes but not in myoblasts. In addition, myogenin expression levels were increased in myotubes while p75 NTR expression was downregulated compared to myoblasts, indicating that NT-3 induced myoblast differentiation is associated with mTORC1 activation. These studies for the first time have shown that NT-3 increases muscle fiber diameter in the neurogenic muscle through direct activation of mTOR pathway and that the fiber size increase is more prominent for fast twitch glycolytic fibers.

VIP-expressing dendritic cells protect against spontaneous autoimmune peripheral polyneuropathy.

The spontaneous autoimmune peripheral polyneuropathy (SAPP) model in B7-2 knockout nonobese diabetic mice mimics a progressive and unremitting course of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). In this study, bone marrow-derived dendritic cells (DCs) were transduced to express vasoactive intestinal polypeptide (VIP) using a lentiviral vector (LV-VIP). These transduced DCs (LV-VIP-DCs) were then injected intravenously (i.v.) into 16-week-old (before disease onset) and 21-week-old (after disease onset) SAPP mice in order to prevent or attenuate the disease. Outcome measures included behavioral tests, clinical and histological scoring, electrophysiology, real-time PCR, flow cytometry analyses, and enzyme-linked immunosorbent assay. LV-VIP-DCs were recruited to the inflamed sciatic nerve and reduced the expression of inflammatory cytokines. A single injection of LV-VIP-DC delayed the onset of disease, stabilized, and attenuated clinical signs correlating with ameliorated behavioral functions, reduced nerve demyelination, and improved nerve conduction. This proof-of-principle study is an important step potentially leading to a clinical translational study using DCs expressing VIP in cases of CIDP refractory to standard immunosuppressive therapy.

Differentiation and neuro-protective properties of immortalized human tooth germ stem cells.

Stem cells are considered to be promising therapeutic options in many neuro-degenerative diseases and injuries to the central nervous system, including brain ischemia and spinal cord trauma. Apart from the gold standard embryonic and mesenchymal origin, human tooth germ stem cells (hTGSCs) have also been shown to enjoy the characteristics of mesenchymal stem cells (MSCs) and the ability to differentiate into adipo-, chondro-, osteo- and neuro-genic cells, suggesting that they might serve as potential alternatives in the cellular therapy of various maladies. Immortalization of stem cells may be useful to avoid senescence of stem cells and to increase their proliferation potential without altering their natural characteristics. This study evaluated the expression of stem cell markers, surface antigens, differentiation capacity, and karyotype of hTGSCs that have been immortalized by human telomerase reverse transcriptase (hTERT) or simian vacuolating virus 40 (SV40) large T antigen. These undying cells were also evaluated for their neuro-protective potential using an in vitro SH-SY5Y neuro-blastoma model treated with hydrogen-peroxide or doxo-rubicin. Although hTGSC-SV40 showed abnormal karyotypes, our results suggest that hTGSC-hTERT preserve their MSC characteristics, differentiation capacity and normal karyotype, and they also possess high proliferation rate and neuro-protective effects even at great passage numbers. These peculiars indicate that hTGSC-hTERT could be used as a viable model for studying adipo-, osteo-, odonto- and neuro-genesis, as well as neuro-protection of MSCs, which may serve as a springboard for potentially utilizing dental waste material in cellular therapy.

Adapting CRISPR/Cas9 System for Targeting Mitochondrial Genome.

Gene editing of the mitochondrial genome using the CRISPR-Cas9 system is highly challenging mainly due to sub-efficient delivery of guide RNA and Cas9 enzyme complexes into the mitochondria. In this study, we were able to perform gene editing in the mitochondrial DNA by appending an NADH-ubiquinone oxidoreductase chain 4 (ND4) targeting guide RNA to an RNA transport-derived stem loop element (RP-loop) and expressing the Cas9 enzyme with a preceding mitochondrial localization sequence. We observe mitochondrial colocalization of RP-loop gRNA and a marked reduction of ND4 expression in the cells carrying a 11205G variant in their ND4 sequence coincidently decreasing the mtDNA levels. This proof-of-concept study suggests that a stem-loop element added sgRNA can be transported to the mitochondria and functionally interact with Cas9 to mediate sequence-specific mtDNA cleavage. Using this novel approach to target the mtDNA, our results provide further evidence that CRISPR-Cas9-mediated gene editing might potentially be used to treat mitochondrial-related diseases.

Systemic delivery of AAVrh74.tMCK.hCAPN3 rescues the phenotype in a mouse model for LGMD2A/R1.

Limb girdle muscular dystrophy (LGMD) 2A/R1, caused by mutations in the CAPN3 gene and CAPN3 loss of function, is known to play a role in disease pathogenicity. In this study, AAVrh74.tMCK.CAPN3 was delivered systemically to two different age groups of CAPN3 knockout (KO) mice; each group included two treatment cohorts receiving low (1.17 × 1014 vg/kg) and high (2.35 × 1014 vg/kg) doses of the vector and untreated controls. Treatment efficacy was tested 20 weeks after gene delivery using functional (treadmill), physiological (in vivo muscle contractility assay), and histopathological outcomes. AAV.CAPN3 gene therapy resulted in significant, robust improvements in functional outcomes and muscle physiology at low and high doses in both age groups. Histological analyses of skeletal muscle showed remodeling of muscle, a switch to fatigue-resistant oxidative fibers in females, and fiber size increases in both sexes. Safety studies revealed no organ tissue abnormalities; specifically, there was no histopathological evidence of cardiotoxicity. These results show that CAPN3 gene replacement therapy improved the phenotype in the CAPN3 KO mouse model at both doses independent of age at the time of vector administration. The improvements were supported by an absence of cardiotoxicity, showing the efficacy and safety of the AAV.CAPN3 vector as a potential gene therapy for LGMDR1.

Comparison and optimisation of transfection of human dental follicle cells, a novel source of stem cells, with different chemical methods and electro-poration.

INTRODUCTION: Human dental follicle cells (HDFCs) derived from human impacted third molars (wisdom teeth) have been shown to be a significant source of adult stem cells. Generation of mesenchymal stem cell-like cells from dental follicles causes minimal surgical stress. In vitro and in vivo reports showed that HDFCs can be utilized in gene and cell therapy applications which make them an attractive alternative source for different gene-cell therapy applications. However, there are currently no systematic comparative studies on transfection potential of HDFC cells using different chemical and electro-poration techniques. METHODS: Stem cells from impacted third tooth molars were isolated, and analyzed for expression of surface markers. Transfection efficiencies of four commercially available transfection reagents (Transfast, Escort V, Superfect and FuGene HD) and electro-poration on isolated stem cells were compared. RESULTS: Isolated HDFCs were stained positive for CD105, CD90, CD73, CD166, and negative for CD34, CD45, and CD133. Among the chemical transfection reagents used in this study, FuGene HD was the most efficient in transfecting HDFCs, even in the presence of 10% serum. CONCLUSION: Electro-poration of HDFCs yield relatively high transfection rates and cell viability when compared to chemical transfection techniques. Our observations might be useful for developing gene and cell therapy applications using dental follicle stem cells.

PUMILIO hyperactivity drives premature aging of Norad-deficient mice.

Although numerous long noncoding RNAs (lncRNAs) have been identified, our understanding of their roles in mammalian physiology remains limited. Here, we investigated the physiologic function of the conserved lncRNA Norad in vivo. Deletion of Norad in mice results in genomic instability and mitochondrial dysfunction, leading to a dramatic multi-system degenerative phenotype resembling premature aging. Loss of tissue homeostasis in Norad-deficient animals is attributable to augmented activity of PUMILIO proteins, which act as post-transcriptional repressors of target mRNAs to which they bind. Norad is the preferred RNA target of PUMILIO2 (PUM2) in mouse tissues and, upon loss of Norad, PUM2 hyperactively represses key genes required for mitosis and mitochondrial function. Accordingly, enforced Pum2 expression fully phenocopies Norad deletion, resulting in rapid-onset aging-associated phenotypes. These findings provide new insights and open new lines of investigation into the roles of noncoding RNAs and RNA binding proteins in normal physiology and aging.

Efficacy of exogenous pyruvate in TremblerJ mouse model of Charcot-Marie-Tooth neuropathy.

INTRODUCTION: Classic Charcot-Marie-Tooth (CMT) neuropathies including those with Schwann cell genetic defects exhibit a length-dependent process affecting the distal axon. Energy deprivation in the distal axon has been the proposed mechanism accounting for length-dependent distal axonal degeneration. We hypothesized that pyruvate, an intermediate glycolytic product, could restore nerve function, supplying lost energy to the distal axon. METHODS: To test this possibility, we supplied pyruvate to the drinking water of the Trembler-J (TrJ ) mouse and assessed efficacy based on histology, electrophysiology, and functional outcomes. Pyruvate outcomes were compared with untreated TrJ controls alone or adeno-associated virus mediated NT-3 gene therapy (AAV1.NT-3)/pyruvate combinatorial approach. RESULTS: Pyruvate supplementation resulted increased myelinated fiber (MF) densities and myelin thickness in sciatic nerves. Combining pyruvate with proven efficacy from AAV1.tMCK.NT-3 gene therapy provided additional benefits showing improved compound muscle action potential amplitudes and nerve conduction velocities compared to pyruvate alone cohort. The end point motor performance of both the pyruvate and the combinatorial therapy cohorts was better than untreated TrJ controls. In a unilateral sciatic nerve crush paradigm, pyruvate supplementation improved myelin-based outcomes in both regenerating and the contralateral uncrushed nerves. CONCLUSIONS: This proof of principle study demonstrates that exogenous pyruvate alone or as adjunct therapy in TrJ may have clinical implications and is a candidate therapy for CMT neuropathies without known treatment.

A novel p.T139M mutation in HSPB1 highlighting the phenotypic spectrum in a family.

INTRODUCTION: Mutations in the HSPB1 gene encoding the small heat shock protein B1 are associated with an autosomal dominant, axonal form of Charcot-Marie-Tooth disease 2F (CMT2F) and distal hereditary motor neuropathy. Recently, distal myopathy had been described in a patient carrying HSPB1 mutation adding to the complexity of phenotypes resulting from HSPB1 mutations. METHODS: Five patients in a family with concerns of hereditary neuropathy were included. Detailed clinical examinations, including assessments of motor and sensory function, and electrophysiological data were obtained. Genetic analysis was requested through a commercial laboratory. In vitro studies were carried out to assess the pathogenicity of the novel mutation found in this family studies. RESULTS: All patients carried a novel mutation, c.146 C>T (p.T139M), substitution in the α-crystallin domain of HSPB1 causing a clinical phenotype with hyperreflexia and intrafamilial variability, from muscle cramps as the only presenting symptom to a classic CMT phenotype. In vitro studies showed that cells expressing HSPB1-T139M displayed decreased cell viability with increased expression of apoptosis markers. Moreover, overexpression of the mutant, not the wild-type HSPB1, caused formation of congophilic aggregates. CONCLUSIONS: In vitro findings strongly support the pathogenicity of this novel mutation. We propose that Congo red histochemical stain may serve as a simple screening tool for investigating if the aggregates in mutant cells have misfolded ß-pleated sheet secondary structures.

Impaired regeneration in calpain-3 null muscle is associated with perturbations in mTORC1 signaling and defective mitochondrial biogenesis.

BACKGROUND: Previous studies in patients with limb-girdle muscular dystrophy type 2A (LGMD2A) have suggested that calpain-3 (CAPN3) mutations result in aberrant regeneration in muscle. METHODS: To gain insight into pathogenesis of aberrant muscle regeneration in LGMD2A, we used a paradigm of cardiotoxin (CTX)-induced cycles of muscle necrosis and regeneration in the CAPN3-KO mice to simulate the early features of the dystrophic process in LGMD2A. The temporal evolution of the regeneration process was followed by assessing the oxidative state, size, and the number of metabolic fiber types at 4 and 12 weeks after last CTX injection. Muscles isolated at these time points were further investigated for the key regulators of the pathways involved in various cellular processes such as protein synthesis, cellular energy status, metabolism, and cell stress to include Akt/mTORC1 signaling, mitochondrial biogenesis, and AMPK signaling. TGF-ß and microRNA (miR-1, miR-206, miR-133a) regulation were also assessed. Additional studies included in vitro assays for quantifying fusion index of myoblasts from CAPN3-KO mice and development of an in vivo gene therapy paradigm for restoration of impaired regeneration using the adeno-associated virus vector carrying CAPN3 gene in the muscle. RESULTS: At 4 and 12 weeks after last CTX injection, we found impaired regeneration in CAPN3-KO muscle characterized by excessive numbers of small lobulated fibers belonging to oxidative metabolic type (slow twitch) and increased connective tissue. TGF-ß transcription levels in the regenerating CAPN3-KO muscles were significantly increased along with microRNA dysregulation compared to wild type (WT), and the attenuated radial growth of muscle fibers was accompanied by perturbed Akt/mTORC1 signaling, uncoupled from protein synthesis, through activation of AMPK pathway, thought to be triggered by energy shortage in the CAPN3-KO muscle. This was associated with failure to increase mitochondria content, PGC-1α, and ATP5D transcripts in the regenerating CAPN3-KO muscles compared to WT. In vitro studies showed defective myotube fusion in CAPN3-KO myoblast cultures. Replacement of CAPN3 by gene therapy in vivo increased the fiber size and decreased the number of small oxidative fibers. CONCLUSION: Our findings provide insights into understanding of the impaired radial growth phase of regeneration in calpainopathy.

Differentiation of human stem cells is promoted by amphiphilic pluronic block copolymers.

Stem cell usage provides novel avenues of tissue regeneration and therapeutics across disciplines. Apart from ethical considerations, the selection and amplification of donor stem cells remain a challenge. Various biopolymers with a wide range of properties have been used extensively to deliver biomolecules such as drugs, growth factors and nucleic acids, as well as to provide biomimetic surface for cellular adhesion. Using human tooth germ stem cells with high proliferation and transformation capacity, we have investigated a range of biopolymers to assess their potential for tissue engineering. Tolerability, toxicity, and their ability to direct differentiation were evaluated. The majority of pluronics, consisting of both hydrophilic and hydrophobic poly(ethylene oxide) chains, either exerted cytotoxicity or had no significant effect on human tooth germ stem cells; whereas F68 increased the multi-potency of stem cells, and efficiently transformed them into osteogenic, chondrogenic, and adipogenic tissues. The data suggest that differentiation and maturation of stem cells can be promoted by selecting the appropriate mechanical and chemical properties of polymers. It has been shown for the first time that F68, with its unique molecular characteristics, has a great potential to increase the differentiation of cells, which may lead to the development of new tissue engineering strategies in regenerative medicine.

RNA interference and amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a debilitating neuro-degenerative disorder characterized by progressive loss of motor neurons. The etiology and molecular pathogenesis of cell death in most sub-types of the disease are largely unknown. The best documented cause of moto-neuron degeneration is the mutation in the superoxide dismutase-1 (SOD1) gene, which occurs in 10% of the familial forms of ALS. Discovery of RNA interference (RNAi), which plays an important role in the regulation of gene expression, has proven to be a powerful tool to study the pathogenesis and to develop innovative treatment options for hereditary diseases, including familial variants of ALS. This review summarizes current research advances in RNAi in relation to ALS.

Genetically modified human umbilical cord blood cells expressing vascular endothelial growth factor and fibroblast growth factor 2 differentiate into glial cells after transplantation into amyotrophic lateral sclerosis transgenic mice.

Current therapy of a number of neuropsychiatric maladies has only symptomatic modality. Effective treatment of these neuro-degenerative diseases, including amyotrophic lateral sclerosis (ALS), may benefit from combined gene/stem-cell approaches. In this report, mononuclear fraction of human umbilical cord blood cells (hUCBCs) were transfected by electroporation with dual plasmid constructs, simultaneously expressing vascular endothelial growth factor 165 (VEGF(165)) and human fibroblast growth factor 2 (FGF(2)) (pBud-VEGF-FGF(2)). These genetically modified hUCBCs were injected retro-orbitally into presymptomatic ALS transgenic animal models ((G)93(A) mice). Lumbar spinal cords of rodents were processed for immunofluoresent staining with antibodies against human nuclear antigen (HNA), oligodendrocyte-specific protein, S100, iba1, neuronal ß(3)-tubulin and CD34. Co-localization of HNA and S100 was found in the spinal cord of mice after transplantation of genetically modified hUCBCs over-expressing VEGF-FGF(2). Double staining in control animals treated with unmodified hUCBCs, however, revealed HNA+ cells expressing iba1 and CD34. Neuron-specific ß(3)-tubulin or oligodendrocyte-specific protein were not expressed in hUCBCs in either control or experimental mice. These results demonstrate that genetically naïve hUCBCs may differentiate into endothelial (CD34+) and microglial (iba1+) cells; however when over-expressing VEGF-FGF(2), hUCBCs transform into astrocytes (S100+). Autocrine regulation of VEGF and FGF(2) on hUCBCs, signal molecules from dying motor neurons in spinal cord, as well as self-differentiating potential may provide a unique microenvironment for the transformation of hUCBCs into astrocytes that eventually serve as a source of growth factors to enhance the survive potential of surrounding cells in the diseased regions.

Interaction and self-organization of human mesenchymal stem cells and neuro-blastoma SH-SY5Y cells under co-culture conditions: A novel system for modeling cancer cell micro-environment.

The common drawback of many in vitro cell culture systems is the absence of appropriate micro-environment, which is formed by the combination of factors such as cell-cell contacts, extracellular matrix and paracrine regulation. Micro-environmental factors in a tumor tissue can influence physiological status of the cancer cells and their susceptibility to anticancer therapies. Interaction of cancer cells with their micro-environment and regional stem cells, therefore, is of particular interest. Development of in vitro systems which allow more accurate modeling of complex relations occurring in real tumor environments can increase efficiency of preclinical assays for screening anticancer drugs. The aim of this work was to study interactions between human mesenchymal stem cells (MSCs) and neuro-blastoma cancer SH-SY5Y cells under co-culture conditions on different coated surfaces to determine the effect of co-existence of cancer and stem cells on each cellular population under various stress conditions. We developed an efficient in vitro system for studying individual cancer and stem cell populations during co-culture using differential live fluorescent membrane labeling, and demonstrated self-organization of cancer and stem cells during co-culture on various coated surfaces. Our findings support the evidence that cancer and stem cell interactions play important roles in cellular behavior of cancer cells. These properties can be used in different fields of cancer research, tissue engineering and biotechnology.

Human tooth germ stem cells preserve neuro-protective effects after long-term cryo-preservation.

The use of mesenchymal stem cells (MSCs) has been shown to be promising in chronic disorders such as diabetes, Alzheimer's dementia, Parkinson's disease, spinal cord injury and brain ischemia. Recent studies revealed that human tooth germs (hTG) contain MSCs which can be easily isolated, expanded and cryo-preserved. In this report, we isolated human tooth germ stem cells (hTGSCs) with MSC characteristics from third molar tooth germs, cryo-preserved them at -80( degrees )C for 6 months, and evaluated for their surface antigens, expression of pluri-potency associated genes, differentiation capacity, karyotype, and proliferation rate. These characteristics were compared to their non-frozen counterparts. In addition, neuro-protective effects of cryo-preserved cells on neuro-blastoma SH-SY5Y cells were also assessed after exposure to stress conditions induced by hydrogen-peroxide (oxidative stress) and paclitaxel (microtubule stabilizing mitotic inhibitor). After long term cryo-preservation hTGSCs expressed surface antigens CD29, CD73, CD90, CD105, and CD166, but not CD34, CD45 or CD133, which was typical for non-frozen hTGSCs. Cryo-preserved hTGSCs were able to differentiate into osteo-, adipo- and neuro-genic cells. They also showed normal karyotype after high number of population doublings and unchanged proliferation rate. On the other hand, cryo-preserved cells demonstrated a tendency for lower level of pluri-potency associated gene expression (nanog, oct4, sox2, klf4, c-myc) than non-frozen hTGSCs. hTGSCs conditioned media increased survival of SH-SY5Y cells exposed to oxidative stress or paclitaxel. These findings confirm that hTGSCs preserve their major characteristics and exert neuro-protection after long-term cryo-preservation, suggesting that hTGSCs, harvested from young individuals and stored for possible use later as they grow old, might be employed in cellular therapy of age-related degenerative disorders.

Coronary artery bypass surgery provokes Alzheimer's disease-like changes in the cerebrospinal fluid.

Several biomarkers are used in confirming the diagnosis of cognitive disorders. This study evaluates whether the level of these markers after heart surgery correlates with the development of cognitive dysfunction, which is a frequent complication of cardiac interventions. Concentrations of amyloid-ß peptide, tau, and S100ß in the cerebro-spinal fluid were assessed, as well as cognitive functions were evaluated before and after coronary artery bypass grafting, utilizing immuno-assays and psychometric tests, respectively. A drastic rise in the level of S100ß was observed one week after the surgery, a mark of a severe generalized cerebral injury. The level of amyloid-ß peptide significantly decreased, whereas the concentration of tau markedly increased six months postoperatively. Gradual cognitive decline was also present. These findings clearly demonstrate post-surgical cognitive impairment associated with changes in biomarkers similar to that seen in Alzheimer's disease, suggesting a unifying pathognomic factor between the two disorders. A holistic approach to coronary heart disease and Alzheimer's type dementia is proposed.

Potential role of dental stem cells in the cellular therapy of cerebral ischemia.

Stem cell based therapies for cerebral ischemia (CI) utilize different cell sources including embryonic stem cells (ESCs), neural stem cells (NSCs), umbilical cord blood cells (UCBCs), mesenchymal stem cells (MSCs), and some immortalized cell lines. To date, experimental studies showed that all of these cell sources have been successful to some extent in attenuating the ischemic damage and improving functional recovery after brain injury. Bone marrow derived MSCs seem to be the most widely used and well characterized cell source, which can be also employed for autologous transplantation. Currently, there are two main theories behind the therapeutic effect of stem cell transplantation for treating CIs. The first concept is cell replacement theory in which transplanted stem cells differentiate into progenitor and specialized somatic cells to supersede dying cells. The other hypothesis is based on immuno-modulatory, neuro-protective and neuro-trophic abilities of stem cells which help reducing stroke size and increasing the recovery of behavioral functions. Recent studies focusing on alternative stem cell sources have revealed that dental stem cells (DSCs), including dental pulp stem cells (DPSCs) and dental follicle cells (DFCs) possess properties of MSCs and NSCs. They differentiate into neural linage cells and some other cell types such as osteocytes, adipocytes, chondrocytes, muscle cells and hepatocytes. This review is intended to examine stem cell therapy approaches for CI and emphasize potential use of DSCs as an alternative cell source for the treatment of brain ischemia.