Mesenchymal stem cells in treating autism: Novel insights

The promise of autologous and allogeneic cellular therapies in the clinical trials of autism spectrum disorder

Autism spectrum disorder (ASD) is a consortium of developmental conditions. As scientists have not yet identified the exact underlying cause for these disorders, it is not easy to narrow down a singular therapy to propose a reliable cure. The preponderance of research suggests that stem-cell therapy improves aspects of outcome measure scales in patients with ASD; therefore, future studies should give us more confidence in the results. This overview considers the data that have emerged from the small set of published trials conducted using different approaches in stem-cell therapy for ASD, evaluates their results and proposes additional steps that could be taken if this field of endeavor is to be pursued further.

Possible Effect of the use of Mesenchymal Stromal Cells in the Treatment of Autism Spectrum Disorders: A Review

Autism spectrum disorder (ASD) represents a set of heterogeneous neurodevelopmental conditions defined by impaired social interactions and repetitive behaviors. The number of reported cases has increased over the past decades, and ASD is now a major public health burden. So far, only treatments to alleviate symptoms are available, with still unmet need for an effective disease treatment to reduce ASD core symptoms. Genetic predisposition alone can only explain a small fraction of the ASD cases. It has been reported that environmental factors interacting with specific inter-individual genetic background may induce immune dysfunctions and contribute to the incidence of ASD. Such dysfunctions can be observed at the central level, with increased microglial cells and activation in ASD brains or in the peripheral blood, as reflected by high circulating levels of pro-inflammatory cytokines, abnormal activation of T-cell subsets, presence of auto-antibodies and of dysregulated microbiota profiles. Altogether, the dysfunction of immune processes may result from immunogenetically-determined inefficient immune responses against a given challenge followed by chronic inflammation and autoimmunity. In this context, immunomodulatory therapies might offer a valid therapeutic option. Mesenchymal stromal cells (MSC) immunoregulatory and immunosuppressive properties constitute a strong rationale for their use to improve ASD clinical symptoms. In vitro studies and pre-clinical models have shown that MSC can induce synapse formation and enhance synaptic function with consequent improvement of ASD-like symptoms in mice. In addition, two preliminary human trials based on the infusion of cord blood-derived MSC showed the safety and tolerability of the procedure in children with ASD and reported promising clinical improvement of core symptoms. We review herein the immune dysfunctions associated with ASD provided, the rationale for using MSC to treat patients with ASD and summarize the current available studies addressing this subject.

Intrathecal autologous bone marrow stem cell therapy in children with autism: A randomized controlled trial

INTRODUCTION

This study aimed to determine the safety and efficacy of treatment with autologous bone marrow mesenchymal stem cell (BMMSCs) compared with the routine treatment in children with autism spectrum disorder (ASD).

METHODS

In this ethically approved randomized controlled trial, 32 ASD children aged 5-15 years were randomly assigned to receive either autologous BMMSC plus rehabilitation therapy and risperidone (intervention group) or rehabilitation therapy and risperidone (control group). Autologous BMMSCs were intrathecally injected in the intervention group twice in 4 weeks. Patients were assessed using childhood autism rating scale (CARS), Gilliam autism rating scale-second edition (GARS-II), and clinical global impression (CGI) at the baseline, as well as 6 and 12 months after intervention.

RESULTS

Overall, 32 patients in two groups of intervention (n = 14) and control (n = 18) completed the study, of which 27 (84.4%) were male. Mean age was 9.50 ± 2.14 years. The improvements in CARS total score, GARS-II autism index, and CGI global improvement showed no significant differences between the groups over 12 months. However, the main effect for time*group interaction was significant regarding the CGI-severity of illness, showing a significantly more pronounced improvement in the intervention group (F = 6.719; P = .002).

DISCUSSION

Intrathecal injection of autologous BMMSCs seems to be safe and feasible, but has limited clinical efficacy in treatment of children with ASD.

Stem Cells for Improving the Treatment of Neurodevelopmental Disorders

Treatment options for neurodevelopmental disorders such as schizophrenia and autism are currently limited. Antipsychotics used to treat schizophrenia are not effective for all patients, do not target all symptoms of the disease, and have serious adverse side effects. There are currently no FDA-approved drugs to treat the core symptoms of autism. In an effort to develop new and more effective treatment strategies, stem cell technologies have been used to reprogram adult somatic cells into induced pluripotent stem cells, which can be differentiated into neuronal cells and even three-dimensional brain organoids. This new technology has the potential to elucidate the complex mechanisms that underlie neurodevelopmental disorders, offer more relevant platforms for drug discovery and personalized medicine, and may even be used to treat the disease.

Stem Cell-Derived Exosomes in Autism Spectrum Disorder

Neurodevelopmental lifelong pathologies defined by problems with social interaction, communication capacity and presence of repetitive/stereotyped clusters of behavior and interests are grouped under the definition of autism spectrum disorder (ASD). ASD prevalence is still increasing, indicating the need to identify specific biomarkers and novel pharmacotherapies. Neuroinflammation and neuro-immune cross-talk dysregulation are specific hallmarks of ASD, offering the possibility of treating these disorders by stem cell therapy. Indeed, cellular strategies have been postulated, proposed and applied to ASD. However, less is known about the molecular action mechanisms of stem cells. As a possibility, the positive and restorative effects mediated by stem cells could be due to their paracrine activity, by which stem cells produce and release several ameliorative and anti-inflammatory molecules. Among the secreted complex tools, exosomes are sub-organelles, enriched by RNA and proteins, that provide cell-to-cell communication. Exosomes could be the mediators of many stem cell-associated therapeutic activities. This review article describes the potential role of exosomes in alleviating ASD symptoms.

Cell Therapy Targets for Autism Spectrum Disorders: Hopes, Challenges and Future Directions

Autism spectrum disorders as a group of pediatric neurodevelopmental diseases is a crucial part of the worldwide disabilities which have influence in communication skills, social interactions, and ability to understand the concepts. The precise pathophysiology of autism spectrum disorders due to the abundance of involved mechanisms is unknown. Some of these involved mechanisms are related to genetic factors, chronic neuro inflammation, mitochondrial dysfunction, oxidative stress, immune dysregulation, hormonal imbalance, and environmental factors. Current main treatments for autisms are behavioral, nutritional and medical therapies, however there is not definitive treatment approach. Therein, more novel therapies are still required to improve the symptoms. Several preclinical and clinical evidence were shown that stem cell therapy is a potential treatment option for autism spectrum disorders individuals. Considering the significant factors which can affect the outcome of stem cell therapeutic effects including stem cell types, route and dosage of administration, and mechanism of activity along with selecting best animal models can be very important in performing clinical trials.

Allogeneic Human Umbilical Cord Mesenchymal Stem Cells for the Treatment of Autism Spectrum Disorder in Children: Safety Profile and Effect on Cytokine Levels

Individuals with autism spectrum disorder (ASD) suffer from developmental disabilities that impact communication, behavior, and social interaction. Immune dysregulation and inflammation have been linked to children with ASD, the latter manifesting in serum levels of macrophage‐derived chemokine (MDC) and thymus, and activation‐regulated chemokine (TARC). Mesenchymal stem cells derived from umbilical cord tissue (UC‐MSCs) have immune‐modulatory and anti‐inflammatory properties, and have been safely used to treat a variety of conditions. This study investigated the safety and efficacy of UC‐MSCs administered to children diagnosed with ASD. Efficacy was evaluated with the Autism Treatment Evaluation Checklist (ATEC) and the Childhood Autism Rating Scale (CARS), and with measurements of MDC and TARC serum levels. Twenty subjects received a dose of 36 million intravenous UC‐MSCs every 12 weeks (four times over a 9‐month period), and were followed up at 3 and 12 months after treatment completion. Adverse events related to treatment were mild or moderate and short in duration. The CARS and ATEC scores of eight subjects decreased over the course of treatment, placing them in a lower ASD symptom category when compared with baseline. MDC and TARC inflammatory cytokine levels also decreased for five of these eight subjects. The mean MDC, TARC, ATEC, and CARS values attained their lowest levels 3 months after the last administration. UC‐MSC administration in children with ASD was therefore determined to be safe. Although some signals of efficacy were observed in a small group of children, possible links between inflammation levels and ASD symptoms should be further investigated. stem cells translational medicine2019;8:1008–1016

Stem cell therapy in autism: recent insights

Autism spectrum disorders (ASDs) are characterized by core domains: persistent deficits in social communication and interaction; restricted, repetitive patterns of behavior, interests, or activities. ASDs comprise heterogeneous and complex neurodevelopmental pathologies with well-defined inflammatory conditions and immune system dysfunction. Due to neurobiologic changes underlying ASD development, cell-based therapies have been proposed and applied to ASDs. Indeed, stem cells show specific immunologic properties, which make them promising candidates in ASD treatment. This comprehensive up-to-date review focuses on ASD cellular/molecular abnormalities, potentially useful stem cell types, animal models, and current clinical trials on the use of stem cells in treating autism. Limitations are also discussed.

Embryonic stem cell transplants as a therapeutic strategy in a rodent model of autism

Autism is a neurodevelopmental disorder characterized by disruptions in three core behavioral domains: deficits in social interaction, impairments in communication, and repetitive and stereotyped patterns of behavior or thought. There are currently no drugs available for the treatment of the core symptoms of ASD and drugs that target comorbid symptoms often have serious adverse side effects, suggesting an urgent need for new therapeutic strategies. The neurobiology of autism is complex, but converging evidence suggests that ASD involves disruptions in the inhibitory GABAergic neurotransmitter system. Specifically, people with autism have a reduction in parvalbumin (PV)-containing interneurons in the PFC, leading to the suggestion that restoring interneuron function in this region may be a novel therapeutic approach for ASD. Here we used a dual-reporter embryonic stem cell line to generate enriched populations of PV-positive interneurons, which were transplanted into the medial prefrontal cortex (mPFC) of the Poly I:C rodent model of autism. PV interneuron transplants were able to decrease pyramidal cell firing in the mPFC and alleviated deficits in social interaction and cognitive flexibility. Our results suggest that restoring PV interneuron function in the mPFC may be a novel and effective treatment strategy to reduce the core symptoms of autism.

Long term beneficial effect of neurotrophic factors-secreting mesenchymal stem cells transplantation in the BTBR mouse model of autism

Autism spectrum disorders (ASD) are neurodevelopmental disabilities characterized by severe impairment in social communication skills and restricted, repetitive behaviors. We have previously shown that a single transplantation of mesenchymal stem cells (MSC) into the cerebral lateral ventricles of BTBR autistic-like mice resulted in an improvement across all diagnostic criteria of ASD. We suggested that brain-derived neurotrophic factor (BDNF), a protein which supports the survival and regeneration of neurons secreted by MSC, largely contributed to the beneficial behavioral effect. In this study, we investigated the behavioral effects of transplanted MSC induced to secrete higher amounts of neurotrophic factors (NurOwn^®), on various ASD-related behavioral domains using the BTBR mouse model of ASD. We demonstrate that NurOwn^® transplantation had significant advantages over MSC transplantation in terms of improving communication skills, one and six months following treatment, as compared to sham-treated BTBR mice. Furthermore, NurOwn^® transplantation resulted in reduced stereotypic behavior for as long as six months post treatment, compared to the one month improvement observed in the MSC treated mice. Notably, NurOwn^® treatment resulted in improved cognitive flexibility, an improvement that was not observed by MSC treatment. Both MSC and NurOwn^® transplantation induced an improvement in social behavior that lasted for six months. In conclusion, the present study demonstrates that a single transplantation of MSC or NurOwn^® have long-lasting benefits, while NurOwn^® may be superior to MSC treatment.

Immunomodulatory oligonucleotide IMT504: Effects on mesenchymal stem cells as a first-in-class immunoprotective/immunoregenerative therapy

The immune responses of humans and animals to insults (i.e., infections, traumas, tumoral transformation and radiation) are based on an intricate network of cells and chemical messengers. Abnormally high inflammation immediately after insult or abnormally prolonged pro-inflammatory stimuli bringing about chronic inflammation can lead to life-threatening or severely debilitating diseases. Mesenchymal stem cell (MSC) transplant has proved to be an effective therapy in preclinical studies which evaluated a vast diversity of inflammatory conditions. MSCs lead to resolution of inflammation, preparation for regeneration and actual regeneration, and then ultimate return to normal baseline or homeostasis. However, in clinical trials of transplanted MSCs, the expectations of great medical benefit have not yet been fulfilled. As a practical alternative to MSC transplant, a synthetic drug with the capacity to boost endogenous MSC expansion and/or activation may also be effective. Regarding this, IMT504, the prototype of a major class of immunomodulatory oligonucleotides, induces in vivo expansion of MSCs, resulting in a marked improvement in preclinical models of neuropathic pain, osteoporosis, diabetes and sepsis. IMT504 is easily manufactured and has an excellent preclinical safety record. In the small number of patients studied thus far, IMT504 has been well-tolerated, even at very high dosage. Further clinical investigation is necessary to demonstrate the utility of IMT504 for resolution of inflammation and regeneration in a broad array of human diseases that would likely benefit from an immunoprotective/immunoregenerative therapy.

Human Embryonic Stem Cells in the Treatment of Autism: A Case Series

Background: Autism spectrum disorder is a neurodevelopmental disorder accompanied by weak immune system and neuroinflammation. Multiple factors contribute to etiology of autism spectrum disorder including genetic disorders, environmental substances/toxins, imbalanced immune system, encephalitis, and viral infections. Autism spectrum disorder is an incurable disease; however, it can be managed by educational and medical interventions. Human embryonic stem cell therapy has been shown to improve blood perfusion in the brain; thus, this therapy may be effective in improving motor skills, social skills, and cognition in patients with autism spectrum disorder. Method: Three pediatric patients with autism spectrum disorder were administered human embryonic stem cell therapy. Their treatment plan comprised 3 to 4 therapy sessions (T1, T2, T3, T4) that were 4 to 6 weeks in length, with 4- to 8-month gap phases separating each therapy session. Results: The patients showed improvements in eye coordination, writing, balancing, cognition, and speech and showed reduced hypersensitivity to noises and smells. Conclusion: The use of human embryonic stem cell therapy may be a safe and effective treatment for patients with autism spectrum disorder. Studies with larger sample sizes are needed to support the use of human embryonic stem cell therapy in this patient population.

Human adipose-derived stem cells ameliorate repetitive behavior, social deficit and anxiety in a VPA-induced autism mouse model. Behav Brain Res. 2017;317:479-484. [PMID: 27717813 DOI: 10.1016/j.bbr.2016.10.004]

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder characterized by impairments in social interaction and communication, and patients often display co-occurring repetitive behaviors. Although the global prevalence of ASD has increased over time, the etiology and treatments for ASD are poorly understood. Recently, some researchers have suggested that stem cells have therapeutic potential for ASD. Thus, in the present study, we investigated the therapeutic effects of human adipose-derived stem cells (hASCs), a kind of autologous mesenchymal stem cells (MSCs) isolated from adipose tissue, on valproic acid (VPA)-induced autism model mice. Human ASCs were injected into the neonatal pups (P2 or P3) intraventricularly and then we evaluated major behavior symptoms of ASD. VPA-treated mice showed increased repetitive behaviors, decreased social interactions and increased anxiety but these autistic behaviors were ameliorated through transplantation of hASCs. In addition, hASCs transplantation restored the alteration of phosphatase and tensin homolog (PTEN) expression and p-AKT/AKT ratio in the brains of VPA-induced ASD model mice. The decreased level of vascular endothelial growth factor (VEGF) and interleukin 10 (IL-10) by VPA were rescued in the brains of the hASC-injected VPA mice. With these results, we experimentally found hASCs' therapeutic effects on autistic phenotypes in a ASD model mice for the first time. This animal model system can be used to elucidate further mechanisms of therapeutic effects of hASCs in ASD.

Mesenchymal stem cells in autism spectrum and neurodevelopmental disorders: pitfalls and potential promises

OBJECTIVES

In this conceptual review, the authors discuss the promises and pitfalls in the use of mesenchymal stem cells as a potential experimental therapeutic for autism spectrum and other neurodevelopmental disorders.

METHODS

The relevant literature in autism spectrum disorders and other neurodevelopmental disorders regarding immune dysregulation and neuroinflammation and relevant therapeutics with mesenchymal stem cell infusion is reviewed. The relevant literature pertaining to mesenchymal stem cells and their clinical applications is also reviewed.

RESULTS

It is proposed that immune dysregulation and neuroinflammation play a role in the aetiology of autism spectrum disorders. Mesenchymal stem cells have been shown to have immune-modulating capabilities and are neuroprotective. There are three international studies that have utilized mesenchymal stem cell infusions as a treatment for children with autism spectrum disorders, all of which demonstrated improvement in autism rating scale scores, although each study has limitations which are described.

CONCLUSIONS

Mesenchymal stem cell transplantation for the treatment of autism spectrum disorders is a novel approach that deserves further investigation, however substantial methodological and theoretical challenges and pitfalls remain before this can be considered a viable therapeutic option.

Mesenchymal Stem Cell Transplantation Promotes Neurogenesis and Ameliorates Autism Related Behaviors in BTBR Mice

Autism spectrum disorders (ASD) are characterized by social communication deficits, cognitive rigidity, and repetitive stereotyped behaviors. Mesenchymal stem cells (MSC) have a paracrine regenerative effect, and were speculated to be a potential therapy for ASD. The BTBR inbred mouse strain is a commonly used model of ASD as it demonstrates robust behavioral deficits consistent with the diagnostic criteria for ASD. BTBR mice also exhibit decreased brain-derived neurotrophic factor (BDNF) signaling and reduced hippocampal neurogenesis. In the current study, we evaluated the behavioral and molecular effects of intracerebroventricular MSC transplantation in BTBR mice. Transplantation of MSC resulted in a reduction of stereotypical behaviors, a decrease in cognitive rigidity and an improvement in social behavior. Tissue analysis revealed elevated BDNF protein levels in the hippocampus accompanied by increased hippocampal neurogenesis in the MSC-transplanted mice compared with sham treated mice. This might indicate a possible mechanism underpinning the behavioral improvement. Our study suggests a novel therapeutic approach which may be translatable to ASD patients in the future.

Rising interdisciplinary collaborations refine our understanding of autisms and give hope to more personalized solutions

Autism is heterogeneous, complex and arguably a condition of many conditions. Both the number of researchers and the number of research collaborations in the field of autism have been growing at unprecedented rates. Interdisciplinary collaborations have increased more than eightfold since the year 2000. In fact, most - if not all - areas of autism research are starting to converge, and these convergences are leading not only to a richer research network but also to a causal network for autism. This network can, and likely will, decode the many forms of autism into its various subcomponents, enabling increasingly more personalized approaches for both the detection and treatment of those different forms of autism.

Therapeutic potential of human adipose-derived stem cells in neurological disorders

Stem cell therapy has been noted as a novel strategy to various diseases including neurological disorders such as Alzheimer's disease, Parkinson's disease, stroke, amyotrophic lateral sclerosis, and Huntington's disease that have no effective treatment available to date. The adipose-derived stem cells (ASCs), mesenchymal stem cells (MSCs) isolated from adipose tissue, are well known for their pluripotency with the ability to differentiate into various types of cells and immuno-modulatory property. These biological features make ASCs a promising source for regenerative cell therapy in neurological disorders. Here we discuss the recent progress of regenerative therapies in various neurological disorders utilizing ASCs.