Neuroprotective Effects of Genome-Edited Human iPS Cell-Derived Neural Stem/Progenitor Cells on Traumatic Brain Injury

Human induced pluripotent stem cell-derived therapies for regeneration after central nervous system injury

In recent years, the progression of stem cell therapies has shown great promise in advancing the nascent field of regenerative medicine. Considering the non-regenerative nature of the mature central nervous system, the concept that "blank" cells could be reprogrammed and functionally integrated into host neural networks remained intriguing. Previous work has also demonstrated the ability of such cells to stimulate intrinsic growth programs in post-mitotic cells, such as neurons. While embryonic stem cells demonstrated great potential in treating central nervous system pathologies, ethical and technical concerns remained. These barriers, along with the clear necessity for this type of treatment, ultimately prompted the advent of induced pluripotent stem cells. The advantage of pluripotent cells in central nervous system regeneration is multifaceted, permitting differentiation into neural stem cells, neural progenitor cells, glia, and various neuronal subpopulations. The precise spatiotemporal application of extrinsic growth factors in vitro, in addition to microenvironmental signaling in vivo, influences the efficiency of this directed differentiation. While the pluri- or multipotency of these cells is appealing, it also poses the risk of unregulated differentiation and teratoma formation. Cells of the neuroectodermal lineage, such as neuronal subpopulations and glia, have been explored with varying degrees of success. Although the risk of cancer or teratoma formation is greatly reduced, each subpopulation varies in effectiveness and is influenced by a myriad of factors, such as the timing of the transplant, pathology type, and the ratio of accompanying progenitor cells. Furthermore, successful transplantation requires innovative approaches to develop delivery vectors that can mitigate cell death and support integration. Lastly, host immune responses to allogeneic grafts must be thoroughly characterized and further developed to reduce the need for immunosuppression. Translation to a clinical setting will involve careful consideration when assessing both physiologic and functional outcomes. This review will highlight both successes and challenges faced when using human induced pluripotent stem cell-derived cell transplantation therapies to promote endogenous regeneration.

Implantation of MSC spheroid-derived 3D decellularized ECM enriched with the MSC secretome ameliorates traumatic brain injury and promotes brain repair

Traumatic brain injury (TBI) presents substantial clinical challenges, as existing treatments are unable to reverse damage or effectively promote brain tissue regeneration. Although implantable biomaterials have been proposed to support tissue repair by mitigating the adverse microenvironment in injured brains, many fail to replicate the complex composition and architecture of the native extracellular matrix (ECM), resulting in only limited therapeutic outcomes. This study introduces an innovative approach by developing a mesenchymal stem cell (MSC) spheroid-derived three-dimensional (3D) decellularized ECM (dECM) that is enriched with the MSC-derived matrisome and secretome, offering a promising solution for TBI treatment and brain tissue regeneration. Proteomic and cytokine array analyses revealed that 3D dECM retained a diverse array of MSC spheroid-derived matrisome proteins and secretome components, which are crucial for replicating the complexity of native ECM and the therapeutic capabilities of MSCs. These molecules were found to underlie the observed effects of 3D dECM on immunomodulation, proneuritogenesis, and proangiogenesis in our in vitro functional assays. Implantation of 3D dECM into TBI model mice effectively mitigated postinjury tissue damage and promoted brain repair, as evidenced by a reduced brain lesion volume, decreased cell apoptosis, alleviated neuroinflammation, reduced glial scar formation, and increased of neuroblast recruitment to the lesion site. These outcomes culminated in improved motor function recovery in animals, highlighting the multifaceted therapeutic potential of 3D dECM for TBI. In summary, our study elucidates the transformative potential of MSC spheroid-derived bioactive 3D dECM as an implantable biomaterial for effectively mitigating post-TBI neurological damage, paving the way for its broader therapeutic application.

Blood-brain barrier disruption: a pervasive driver and mechanistic link between traumatic brain injury and Alzheimer's disease

Traumatic brain injury (TBI) has emerged as a significant risk factor for Alzheimer's disease (AD), a complex and devastating neurodegenerative disorder characterized by progressive cognitive decline and memory loss. Both conditions share a common feature: blood‒brain barrier (BBB) dysfunction, which is believed to play a pivotal role in linking TBI to the development of AD. This review delves into the intricate relationship between TBI and AD, with a focus on BBB dysfunction and its critical role in disease mechanisms and therapeutic development. We first present recent evidence from epidemiological studies highlighting the increased incidence of AD among individuals with a history of TBI, as well as pathological and animal model studies that demonstrate how TBI can accelerate AD-like pathology. Next, we explore the mechanisms by which BBB dysfunction may mediate TBI-induced AD pathology. Finally, we investigate the shared molecular pathways associated with BBB dysfunction in both TBI and AD conditions and discuss the latest findings on how targeting these pathways and employing regenerative approaches, such as stem cell therapy and pharmacological interventions, can enhance BBB function and mitigate neurodegeneration.

PLGA scaffold combined with MSCs transplantation improved neural function and brain tissue structure in rats with traumatic brain injury

Poly (lactic-co-glycolic acid) (PLGA) is an important biomaterial for tissue defect repair, but its application in replacing missing brain tissue needs improvement. Mesenchymal stem cells (MSCs) have been used to treat various neurological diseases, but they face challenges when filling large tissue defects. The purpose of this study was to investigate the effects of PLGA combined with MSCs transplantation on brain structure and neural function in rats with traumatic brain injury (TBI), and explore its possible mechanism. The results showed that both PLGA transplantation and PLGA+MSCs transplantation could improve the brain structure and promote nerve function recovery in rats with TBI, with PLGA+MSCs transplantation being superior to PLGA transplantation. Furthermore, compared to PLGA transplantation alone, PLGA+MSCs transplantation further reduced brain injury and cell apoptosis, promoted neuron survival, and improved synaptic plasticity. Overall, the adhesion of MSCs to PLGA can enhance the therapeutic efficacy of PLGA in rats following TBI.

Research Guideline Recommendations for Research on Stem Cells, Human Embryos, and Gene Editing

Recent advances in biomedical technologies have extended the boundaries of previously established regulatory guidelines pertaining to stem cell research. These guidelines constrained the study of human pluripotent stem cells (hPSCs) and their derivatives from use under various conditions, including the introduction of hPSCs into the brains of host animals because of concerns of humanizing the brains of animal species. Other guidelines constrained the use of hPSCs in creating human-animal chimeras because of the potential contribution of human stem cells not only to the brain but also to the germline. Some regulatory guidelines forbid the growing of human embryos ex vivo beyond the stage of primitive streak development because of concerns regarding the creation of human forms of life ex vivo. At the subcellular level, there are guidelines regulating the transfer of mitochondria within human embryos. At the molecular level, there are guidelines regulating genome editing to prevent permanent genetic alterations in germline cells. These and other issues related to stem cells have been reviewed, and new research guidelines established by the International Society for Stem Cell Research (ISSCR) for its membership. Because many of the recommended changes by the ISSCR impact research being conducted by members of the American Society for Neural Therapy and Repair (ASNTR), the ASNTR established a task force to review relevant recommendations by the ISSCR to determine which new guidelines to adopt for research conducted by the ASNTR society membership. The final ASNTR recommendations are presented in this document.

20-Hydroxyeicosatetraenoic Acid Regulates the Src/EGFR/NF-κB Signaling Pathway Via GPR75 to Activate Microglia and Promote TBI in the Immature Brain

20-Hydroxyeicosatetraenoic acid (20-HETE) is associated with secondary damage in traumatic brain injury (TBI) of the immature brain. Microglial activation is pivotal in this process. However, the underlying mechanism of action remains unknown. While 20-HETE interacts with G protein-coupled receptor 75 (GPR75) in some pathological processes, their interaction in brain tissue remains uncertain. This study aimed to investigate whether 20-HETE can activate microglia by binding to GPR75 in TBI of the immature brain. Drug affinity responsive molecular target stability (DARTS) assays, cycloheximide (CHX) chase assays, and auto-dock assays were employed to analyze the interaction between 20-HETE and GPR75. The expression levels of cytochrome P450 4A (CYP4A) and GPR75 in activated microglia in an immature brain TBI model were observed by western blot and multiple immunofluorescence staining. The effects of different levels of 20-HETE expression and lentivirus-mediated GPR75 gene silencing on 20-HETE-induced inflammatory factor release from BV-2 cells were observed by enzyme-linked immunoassay (ELISA). The phosphorylation levels of the downstream Src kinase, epidermal growth factor receptor (EGFR), and nuclear factor (NF)-κB were assessed using western blot. Cell viability and apoptosis were detected by CCK-8 and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assays. 20-HETE bound to the GPR75 protein and inhibited its degradation. GPR75 gene silencing reversed the 20-HETE-induced inflammatory activation of BV-2 cells, effectively inhibiting the activation of the Src/EGFR/NF-κB pathway and the effects of 20-HETE on cell viability and the apoptosis rate. In contrast, overexpression of GPR75 had the opposite effect. In addition, after immature brain TBI, the 20-HETE and GPR75 expression levels were upregulated in microglia, with significant activation of the Src/EGFR/NF-κB pathway. Inhibition of 20-HETE synthesis with N-hydroxy-N'-(4-n-butyl-2-methylphenyl) formamidine (HET0016) produced the opposite effect. 20-HETE regulates the Src/EGFR/NF-κB signaling pathway via GPR75 to activate microglia, promoting immature brain TBI. These findings offer a novel target for promoting the brain injury effect of 20-HETE.

Human-Induced Pluripotent Stem Cell-Derived Neural Stem Cell Therapy Limits Tissue Damage and Promotes Tissue Regeneration and Functional Recovery in a Pediatric Piglet Traumatic-Brain-Injury Model

Traumatic brain injury (TBI) is a leading cause of death and disability in pediatric patients and often results in delayed neural development and altered connectivity, leading to lifelong learning, memory, behavior, and motor function deficits. Induced pluripotent stem cell-derived neural stem cells (iNSCs) may serve as a novel multimodal therapeutic as iNSCs possess neuroprotective, regenerative, and cell-replacement capabilities post-TBI. In this study, we evaluated the effects of iNSC treatment on cellular, tissue, and functional recovery in a translational controlled cortical impact TBI piglet model. Five days post-craniectomy (n = 6) or TBI (n = 18), iNSCs (n = 7) or PBS (n = 11) were injected into perilesional brain tissue. Modified Rankin Scale (mRS) neurological evaluation, magnetic resonance imaging, and immunohistochemistry were performed over the 12-week study period. At 12-weeks post-transplantation, iNSCs showed long-term engraftment and differentiation into neurons, astrocytes, and oligodendrocytes. iNSC treatment enhanced endogenous neuroprotective and regenerative activities indicated by decreasing intracerebral immune responses, preserving endogenous neurons, and increasing neuroblast formation. These cellular changes corresponded with decreased hemispheric atrophy, midline shift, and lesion volume as well as the preservation of cerebral blood flow. iNSC treatment increased piglet survival and decreased mRS scores. The results of this study in a predictive pediatric large-animal pig model demonstrate that iNSC treatment is a robust multimodal therapeutic that has significant promise in potentially treating human pediatric TBI patients.

Bioorthogonal non-canonical amino acid tagging to track transplanted human induced pluripotent stem cell-specific proteome

BACKGROUND

Human induced pluripotent stem cells (hiPSCs) and their differentiated cell types have a great potential for tissue repair and regeneration. While the primary focus of using hiPSCs has historically been to regenerate damaged tissue, emerging studies have shown a more potent effect of hiPSC-derived paracrine factors on tissue regeneration. However, the precise contents of the transplanted hiPSC-derived cell secretome are ambiguous. This is mainly due to the lack of tools to distinguish cell-specific secretome from host-derived proteins in a complex tissue microenvironment in vivo.

METHODS

In this study, we present the generation and characterization of a novel hiPSC line, L274G-hiPSC, expressing the murine mutant methionyl-tRNA synthetase, L274GMmMetRS, which can be used for tracking the cell specific proteome via biorthogonal non-canonical amino acid tagging (BONCAT). We assessed the trilineage differentiation potential of the L274G-hiPSCs in vitro and in vivo. Furthermore, we assessed the cell-specific proteome labelling in the L274G-hiPSC derived cardiomyocytes (L274G-hiPSC-CMs) in vitro following co-culture with wild type human umbilical vein derived endothelial cells and in vivo post transplantation in murine hearts.

RESULTS

We demonstrated that the L274G-hiPSCs exhibit typical hiPSC characteristics and that we can efficiently track the cell-specific proteome in their differentiated progenies belonging to the three germ lineages, including L274G-hiPSC-CMs. Finally, we demonstrated cell-specific BONCAT in transplanted L274G-hiPSC-CMs.

CONCLUSION

The novel L274G-hiPSC line can be used to study the cell-specific proteome of hiPSCs in vitro and in vivo, to delineate mechanisms underlying hiPSC-based cell therapies for a variety of regenerative medicine applications.

NSPCs-ES: mechanisms and functional impact on central nervous system diseases

Patients with central neuronal damage may suffer severe consequences, but effective therapies remain unclear. Previous research has established the transplantation of neural stem cells that generate new neurons to replace damaged ones. In a new field of scientific research, the extracellular secretion of NPSCs (NSPCs-ES) has been identified as an alternative to current chemical drugs. Many preclinical studies have shown that NSPCs-ES are effective in models of various central nervous system diseases (CNS) injuries, from maintaining functional structures at the cellular level to providing anti-inflammatory functions at the molecular level, as well as improving memory and motor functions, reducing apoptosis in neurons, and mediating multiple signaling pathways. The NSPC-ES can travel to the damaged tissue and exert a broad range of therapeutic effects by supporting and nourishing damaged neurons. However, gene editing and cell engineering techniques have recently improved therapeutic efficacy by modifying NSPCs-ES. Consequently, future research and application of NSPCs-ES may provide a novel strategy for the treatment of CNS diseases in the future. In this review, we summarize the current progress on these aspects.

Induced Pluripotent Stem Cells and Organoids in Advancing Neuropathology Research and Therapies

This review delves into the groundbreaking impact of induced pluripotent stem cells (iPSCs) and three-dimensional organoid models in propelling forward neuropathology research. With a focus on neurodegenerative diseases, neuromotor disorders, and related conditions, iPSCs provide a platform for personalized disease modeling, holding significant potential for regenerative therapy and drug discovery. The adaptability of iPSCs, along with associated methodologies, enables the generation of various types of neural cell differentiations and their integration into three-dimensional organoid models, effectively replicating complex tissue structures in vitro. Key advancements in organoid and iPSC generation protocols, alongside the careful selection of donor cell types, are emphasized as critical steps in harnessing these technologies to mitigate tumorigenic risks and other hurdles. Encouragingly, iPSCs show promising outcomes in regenerative therapies, as evidenced by their successful application in animal models.

Genetic Contributions to Recovery following Brain Trauma: A Narrative Review

Traumatic brain injury (TBI) is a frequently encountered form of injury that can have lifelong implications. Despite advances in prevention, diagnosis, monitoring, and treatment, the degree of recovery can vary widely between patients. Much of this is explained by differences in severity of impact and patient-specific comorbidities; however, even among nearly identical patients, stark disparities can arise. Researchers have looked to genetics in recent years as a means of explaining this phenomenon. It has been hypothesized that individual genetic factors can influence initial inflammatory responses, recovery mechanisms, and overall prognoses. In this review, we focus on cytokine polymorphisms, mitochondrial DNA (mtDNA) haplotypes, immune cells, and gene therapy given their associated influx of novel research and magnitude of potential. This discussion is prefaced by a thorough background on TBI pathophysiology to better understand where each mechanism fits within the disease process. Cytokine polymorphisms causing unfavorable regulation of genes encoding IL-1β, IL-RA, and TNF-α have been linked to poor TBI outcomes like disability and death. mtDNA haplotype H has been correlated with deleterious effects on TBI recovery time, whereas haplotypes K, T, and J have been depicted as protective with faster recovery times. Immune cell genetics such as microglial differentially expressed genes (DEGs), monocyte receptor genes, and regulatory factors can be both detrimental and beneficial to TBI recovery. Gene therapy in the form of gene modification, inactivation, and editing show promise in improving post-TBI memory, cognition, and neuromotor function. Limitations of this study include a large proportion of cited literature being focused on pre-clinical murine models. Nevertheless, favorable evidence on the role of genetics in TBI recovery continues to grow. We aim for this work to inform interested parties on the current landscape of research, highlight promising targets for gene therapy, and galvanize translation of findings into clinical trials.

Neural Stem Cells Transplanted into Rhesus Monkey Cortical Traumatic Brain Injury Can Survive and Differentiate into Neurons

Cortical traumatic brain injury (TBI) is a major cause of cognitive impairment accompanied by motor and behavioral deficits, and there is no effective treatment strategy in the clinic. Cell transplantation is a promising therapeutic strategy, and it is necessary to verify the survival and differentiation of cells after transplantation in large animal models like rhesus monkeys. In this study, we transplanted neural stem cells (NSCs) and simultaneously injected basic fibroblast growth factor/epidermal growth factor (bFGF/EGF) into the cortex (visual and sensory cortices) of rhesus monkeys with superficial TBI. The results showed that the transplanted NSCs did not enter the cerebrospinal fluid (CSF) and were confined to the transplantation site for at least one year. The transplanted NSCs differentiated into mature neurons that formed synaptic connections with host neurons, but glial scar formation between the graft and the host tissue did not occur. This study is the first to explore the repairing effect of transplanting NSCs into the superficial cerebral cortex of rhesus monkeys after TBI, and the results show the ability of NSCs to survive long-term and differentiate into neurons, demonstrating the potential of NSC transplantation for cortical TBI.

Uqcr11 alleviates oxidative stress and apoptosis after traumatic brain injury

Traumatic brain injury (TBI) is a major cause of death and disability that involves brain dysfunction due to external forces. Here, we found lower levels of Ubiquinol-cytochrome c reductase, complex III subunit XI (Uqcr11) expression in the cerebral cortex of TBI mice. A neuronal damage model was constructed using H2O2 or hypoxia reoxygenation (H/R) in vitro. We found that Uqcr11 overexpression attenuated the H2O2-or H/R-induced damage by preventing oxidative stress and neuronal apoptosis in HT22 cells. Moreover, up-regulated Uqcr11 contributed to the restoration of motor, learning, and memory in C57BL/6 mice after TBI, and its underlying mechanism may be associated with promoting neuron survival and inhibited oxidative stress. Collectively, our findings demonstrated that oxidative stress as well as neuronal apoptosis can be ameliorated post-TBI by Uqcr11 overexpression, which provides a potential therapeutic target for TBI.

Prospects for Nerve Regeneration and Gene Therapy in the Treatment of Traumatic Brain Injury

Traumatic brain injury (TBI) is a prevalent neurological disorder and a leading cause of death and disability worldwide. The high mortality rates result in a tremendous burden on society and families in terms of public health and economic costs. Despite advances in biomedical research, treatment options for TBI still remain limited, and there is no effective therapy to restore the structure and function of the injured brain. Regrettably, due to the excessive heterogeneity of TBI and the lack of objective and reliable efficacy evaluation indicators, no proven therapeutic drugs or drugs with clear benefits on functional outcomes have been successfully developed to date. Therefore, it is urgent to explore new therapeutic approaches to protect or regenerate the injured brain from different perspectives. In this review, we first provide a brief overview of the causes and current status of TBI and then summarize the preclinical and clinical research status of cutting-edge treatment methods, including nerve regeneration therapy and gene therapy, with the aim of providing valuable references for effective therapeutic strategies for TBI.

Reproducible generation of human retinal ganglion cells from banked retinal progenitor cells: analysis of target recognition and IGF-1-mediated axon regeneration

The selective degeneration of retinal ganglion cells (RGCs) is a common feature in glaucoma, a complex group of diseases, leading to irreversible vision loss. Stem cell-based glaucoma disease modeling, cell replacement, and axon regeneration are viable approaches to understand mechanisms underlying glaucomatous degeneration for neuroprotection, ex vivo stem cell therapy, and therapeutic regeneration. These approaches require direct and facile generation of human RGCs (hRGCs) from pluripotent stem cells. Here, we demonstrate a method for rapid generation of hRGCs from banked human pluripotent stem cell-derived retinal progenitor cells (hRPCs) by recapitulating the developmental mechanism. The resulting hRGCs are stable, functional, and transplantable and have the potential for target recognition, demonstrating their suitability for both ex vivo stem cell approaches to glaucomatous degeneration and disease modeling. Additionally, we demonstrate that hRGCs derived from banked hRPCs are capable of regenerating their axons through an evolutionarily conserved mechanism involving insulin-like growth factor 1 and the mTOR axis, demonstrating their potential to identify and characterize the underlying mechanism(s) that can be targeted for therapeutic regeneration.