Stem Cell Therapy for Pediatric Traumatic Brain Injury

Autologous bone marrow mononuclear cells to treat severe traumatic brain injury in children

Autologous bone marrow mononuclear cells (BMMNCs) infused after severe traumatic brain injury have shown promise for treating the injury. We evaluated their impact in children, particularly their hypothesized ability to preserve the blood-brain barrier and diminish neuroinflammation, leading to structural CNS preservation with improved outcomes. We performed a randomized, double-blind, placebo-sham-controlled Bayesian dose-escalation clinical trial at two children's hospitals in Houston, TX and Phoenix, AZ, USA (NCT01851083). Patients 5-17 years of age with severe traumatic brain injury (Glasgow Coma Scale score ≤ 8) were randomized to BMMNC or placebo (3:2). Bone marrow harvest, cell isolation and infusion were completed by 48 h post-injury. A Bayesian continuous reassessment method was used with cohorts of size 3 in the BMMNC group to choose the safest between two doses. Primary end points were quantitative brain volumes using MRI and microstructural integrity of the corpus callosum (diffusivity and oedema measurements) at 6 months and 12 months. Long-term functional outcomes and ventilator days, intracranial pressure monitoring days, intensive care unit days and therapeutic intensity measures were compared between groups. Forty-seven patients were randomized, with 37 completing 1-year follow-up (23 BMMNC, 14 placebo). BMMNC treatment was associated with an almost 3-day (23%) reduction in ventilator days, 1-day (16%) reduction in intracranial pressure monitoring days and 3-day (14%) reduction in intensive care unit (ICU) days. White matter volume at 1 year in the BMMNC group was significantly preserved compared to placebo [decrease of 19 891 versus 40 491, respectively; mean difference of -20 600, 95% confidence interval (CI): -35 868 to -5332; P = 0.01], and the number of corpus callosum streamlines was reduced more in placebo than BMMNC, supporting evidence of preserved corpus callosum connectivity in the treated groups (-431 streamlines placebo versus -37 streamlines BMMNC; mean difference of -394, 95% CI: -803 to 15; P = 0.055), but this did not reach statistical significance due to high variability. We conclude that autologous BMMNC infusion in children within 48 h after severe traumatic brain injury is safe and feasible. Our data show that BMMNC infusion led to: (i) shorter intensive care duration and decreased ICU intensity; (ii) white matter structural preservation; and (iii) enhanced corpus callosum connectivity and improved microstructural metrics.

Potential injectable hydrogels as biomaterials for central nervous system injury: A narrative review

Numerous modalities exist through which the central nervous system (CNS) may sustain injury or impairment, encompassing traumatic incidents, stroke occurrences, and neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Presently available pharmacological and therapeutic interventions are incapable of restoring or regenerating damaged CNS tissue, leading to substantial unmet clinical needs among patients with CNS ailments or injuries. To address and facilitate the recovery of the impaired CNS, cell-based repair strategies encompass multiple mechanisms, such as neuronal replacement, therapeutic factor secretion, and the promotion of host brain plasticity. Despite the progression of cell-based CNS reparation as a therapeutic strategy throughout the years, substantial barriers have impeded its widespread implementation in clinical settings. The integration of cell technologies with advancements in regenerative medicine utilizing biomaterials and tissue engineering has recently facilitated the surmounting of several of these impediments. This comprehensive review presents an overview of distinct CNS conditions necessitating cell reparation, in addition to exploring potential biomaterial methodologies that enhance the efficacy of treating brain injuries.

Stem Cell Therapy in Children with Traumatic Brain Injury

Pediatric traumatic brain injury is a cause of major mortality, and resultant neurological sequelae areassociated with long-term morbidity. Increasing studies have revealed stem cell therapy to be a potential new treatment. However, much work is still required to clarify the mechanism of action of effective stem cell therapy, type of stem cell therapy, optimal timing of therapy initiation, combination of cocurrent medical treatment and patient selection criteria. This paper will focus on stem cell therapy in children with traumatic brain injury.

Loading neural stem cells on hydrogel scaffold improves cell retention rate and promotes functional recovery in traumatic brain injury

Neural stem cell (NSC) has gained considerable attention in traumatic brain injury (TBI) treatment because of their ability to replenish dysfunctional neurons and stimulate endogenous neurorestorative processes. However, their therapeutic effects are hindered by the low cell retention rate after transplantation into the dynamic brain. In this study, we found cerebrospinal fluid (CSF) flow after TBI is an important factor associated with cell loss following NSC transplantation. Recently, several studies have shown that hydrogels could serve as a beneficial carrier for stem cell transplantation, which provides a solution to prevent CSF flow-induced cell loss after TBI. For this purpose, we evaluated three different hydrogel scaffolds and found the gelatin methacrylate (GelMA)/sodium alginate (Alg) (GelMA/Alg) hydrogel scaffold showed the best capabilities for NSC adherence, growth, and differentiation. Additionally, we detected that pre-differentiated NSCs, which were loaded on the GelMA/Alg hydrogel and cultured for 7 days in neuronal differentiation medium (NSC [7d]), had the highest cell retention rate after CSF impact. Next, the neuroprotective effects of the NSC-loaded GelMA/Alg hydrogel scaffold were evaluated in a rat model of TBI. NSC [7d]-loaded GelMA/Alg markedly decreased microglial activation and neuronal death in the acute phase, reduced tissue loss, alleviated astrogliosis, promoted neurogenesis, and improved neurological recovery in the chronic phase. In summary, we demonstrated that the integration with the GelMA/Alg and modification of NSC differentiation could inhibit the influence of CSF flow on transplanted NSCs, leading to increased number of retained NSCs and improved neuroprotective effects, providing a promising alternative for TBI treatment.

Co-transplantation of novel Nano-SDF scaffold with human neural stem cells attenuates inflammatory responses and apoptosis in traumatic brain injury

Traumatic brain injury (TBI) causes long-term disability and mortality worldwide. The prime pathological players in TBI are neuroinflammation and apoptosis. These pathological changes lead to a limited capacity of regeneration after TBI. To alleviate inflammatory responses and apoptosis triggered by TBI, developing bioactive scaffolds conjoined with stem cells is a decisive approach in neural tissue engineering. The aim of this study was to fabricate a novel nano-scaffold made of RADA-16 with a bioactive motif of stromal cell-derived factor-1 α (SDF-1α) and evaluate its effects with stem cell transplantation on inflammatory pathways, reactive gliosis, and apoptosis after TBI. Co-transplantation of Nano-SDF and human neural stem cells (hNSCs) derived from fetus brain in adult rats subjected to TBI led to the improvement of motor activitycompared with the control group. The treated animals with hNSCs + Nano-SDF had a significantly lower expression of toll-like receptor 4 and nuclear factor-kappa B at the injury site than the control animals. A significant reduction in the number of reactive astrocytes was also observed in rats that received hNSCs + Nano-SDF compared with the vehicle and Nano-SDF groups. Furthermore, the TUNEL assay indicated a significant reduction in TUNEL positive cells in the hNSCs + Nano-SDF group compared with the TBI, vehicle, and Nano-SDF groups. These data demonstrated co-transplantation of hNSCs with Nano-SDF can reduce inflammatory responses and cell death after TBI via creating a more supportive microenvironment. Further research is required to establish the therapeutic efficacy of Nano-SDF with stem cells for TBI.

A new era for optic pathway glioma: A developmental brain tumor with life-long health consequences

Optic pathway and hypothalamic glioma (OPHG) are low-grade brain tumors that arise from any part of the visual pathways frequently involving the hypothalamus. The tumors grow slowly and present with features driven by their precise anatomical site, their age at presentation and the stage of growth and development of the host neural and orbital bony tissues. Up to 50% of optic pathway glioma arise in association with Neurofibromatosis type 1 (NF1), which affects 1 in 3,000 births and is a cancer predisposition syndrome. As low-grade tumors, they almost never transform to malignant glioma yet they can threaten life when they present under two years of age. The main risks are to threaten vision loss by progressive tumor damage to optic pathways; furthermore, invasion of the hypothalamus can lead to diencephalic syndrome in infancy and hypopituitarism later in life. Progressive cognitive and behavioural dysfunction can occur, as part of NF1 syndromic features and in sporadic cases where large bulky tumors compress adjacent structures and disrupt neuro-hypothalamic pathways. Persistently progressive tumors require repeated treatments to attempt to control vision loss, other focal brain injury or endocrine dysfunction. In contrast tumors presenting later in childhood can be seen to spontaneously arrest in growth and subsequently progress after periods of stability. These patterns are influenced by NF status as well as stages of growth and development of host tissues. The past two decades has seen an expansion in our understanding and knowledge of the clinical and scientific features of these tumors, their modes of presentation, the need for careful visual and endocrine assessment. This influences the decision-making surrounding clinical management with surgery, radiotherapy, chemotherapy and most recently, the potential benefit of molecularly targeted drug therapy. This article, based upon the authors' clinical and research experience and the published literature will highlight advances in approach to diagnosis, the established role of vision loss as justification of treatments and the emerging evidence of endocrine and neurological consequences that need to be incorporated into judgements for case selection for therapy or observation. Consideration is given to the current state of biological evidence justifying current trials of new therapies, the genetic studies of the NF1 gene and the potential for new approaches to OPHG detection and treatment. The outstanding health system priorities from the perspective of children, their parents and health system commissioners or insurers are discussed.

Regenerative medicine and traumatic brain injury: from stem cell to cell-free therapeutic strategies

Traumatic brain injury (TBI) is a serious health concern, yet there is a lack of standardized treatment to combat its long-lasting effects. The objective of the present study was to provide an overview of the limitation of conventional stem-cell therapy in the treatment of TBI and to discuss the application of novel acellular therapies and their advanced strategies to enhance the efficacy of stem cells derived therapies in the light of published study data. Moreover, we also discussed the factor to optimize the therapeutic efficiency of stem cell-derived acellular therapy by overcoming the challenges for its clinical translation. Hence, we concluded that acellular therapy possesses the potential to bring a breakthrough in the field of regenerative medicine to treat TBI.

Pharmacological Modulation of Neurite Outgrowth in Human Neural Progenitor Cells by Inhibiting Non-muscle Myosin II

Studies on neural development and neuronal regeneration after injury are mainly based on animal models. The establishment of pluripotent stem cell (PSC) technology, however, opened new perspectives for better understanding these processes in human models by providing unlimited cell source for hard-to-obtain human tissues. Here, we aimed at identifying the molecular factors that confine and modulate an early step of neural regeneration, the formation of neurites in human neural progenitor cells (NPCs). Enhanced green fluorescent protein (eGFP) was stably expressed in NPCs differentiated from human embryonic and induced PSC lines, and the neurite outgrowth was investigated under normal and injury-related conditions using a high-content screening system. We found that inhibitors of the non-muscle myosin II (NMII), blebbistatin and its novel, non-toxic derivatives, initiated extensive neurite outgrowth in human NPCs. The extracellular matrix components strongly influenced the rate of neurite formation but NMII inhibitors were able to override the inhibitory effect of a restrictive environment. Non-additive stimulatory effect on neurite generation was also detected by the inhibition of Rho-associated, coiled-coil-containing protein kinase 1 (ROCK1), the upstream regulator of NMII. In contrast, inhibition of c-Jun N-terminal kinases (JNKs) had only a negligible effect, suggesting that the ROCK1 signal is dominantly manifested by actomyosin activity. In addition to providing a reliable cell-based in vitro model for identifying intrinsic mechanisms and environmental factors responsible for impeded axonal regeneration in humans, our results demonstrate that NMII and ROCK1 are important pharmacological targets for the augmentation of neural regeneration at the progenitor level. These studies may open novel perspectives for development of more effective pharmacological treatments and cell therapies for various neurodegenerative disorders.

Post-traumatic Neuroinflammation: Relevance to Pediatrics

Both detrimental and beneficial effects of post-traumatic neuroinflammation have become a major research focus as they offer the potential for immediate as well as delayed targeted reparative therapies. Understanding the complex interactions of central and peripheral immunocompetent cells as well as their mediators on brain injury and recovery is complicated by the temporal, regional, and developmental differences in their response to injuries. Microglia, the brain-resident macrophages, have become central in these investigations as they serve a major surveillance function, have the ability to react swiftly to injury, recruit various cellular and chemical mediators, and monitor the reparative/degenerative processes. In this review we describe selected aspects of this burgeoning literature, describing the critical role of cytokines and chemokines, microglia, advances in neuroimaging, genetics and fractal morphology analysis, our research efforts in this area, and selected aspects of pediatric post-traumatic neuroinflammation.