In Vitro Effects of Methylprednisolone over Oligodendroglial Cells: Foresight to Future Cell Therapies.

The implantation of oligodendrocyte precursor cells may be a useful therapeutic strategy for targeting remyelination. However, it is yet to be established how these cells behave after implantation and whether they retain the capacity to proliferate or differentiate into myelin-forming oligodendrocytes. One essential issue is the creation of administration protocols and determining which factors need to be well established. There is controversy around whether these cells may be implanted simultaneously with corticosteroid treatment, which is widely used in many clinical situations. This study assesses the influence of corticosteroids on the capacity for proliferation and differentiation and the survival of human oligodendroglioma cells. Our findings show that corticosteroids reduce the capacity of these cells to proliferate and to differentiate into oligodendrocytes and decrease cell survival. Thus, their effect does not favour remyelination; this is consistent with the results of studies with rodent cells. In conclusion, protocols for the administration of oligodendrocyte lineage cells with the aim of repopulating oligodendroglial niches or repairing demyelinated axons should not include corticosteroids, given the evidence that the effects of these drugs may undermine the objectives of cell transplantation.

Mesenchymal Stem Cell-Based Therapies in the Post-Acute Neurological COVID Syndrome: Current Landscape and Opportunities.

One of the main concerns related to SARS-CoV-2 infection is the symptoms that could be developed by survivors, known as long COVID, a syndrome characterized by persistent symptoms beyond the acute phase of the infection. This syndrome has emerged as a complex and debilitating condition with a diverse range of manifestations affecting multiple organ systems. It is increasingly recognized for affecting the Central Nervous System, in which one of the most prevalent manifestations is cognitive impairment. The search for effective therapeutic interventions has led to growing interest in Mesenchymal Stem Cell (MSC)-based therapies due to their immunomodulatory, anti-inflammatory, and tissue regenerative properties. This review provides a comprehensive analysis of the current understanding and potential applications of MSC-based interventions in the context of post-acute neurological COVID-19 syndrome, exploring the underlying mechanisms by which MSCs exert their effects on neuroinflammation, neuroprotection, and neural tissue repair. Moreover, we discuss the challenges and considerations specific to employing MSC-based therapies, including optimal delivery methods, and functional treatment enhancements.

Chitosan-Hydroxycinnamic Acids Conjugates: Emerging Biomaterials with Rising Applications in Biomedicine.

Over the past thirty years, research has shown the huge potential of chitosan in biomedical applications such as drug delivery, tissue engineering and regeneration, cancer therapy, and antimicrobial treatments, among others. One of the major advantages of this interesting polysaccharide is its modifiability, which facilitates its use in tailor-made applications. In this way, the molecular structure of chitosan has been conjugated with multiple molecules to modify its mechanical, biological, or chemical properties. Here, we review the conjugation of chitosan with some bioactive molecules: hydroxycinnamic acids (HCAs); since these derivatives have been probed to enhance some of the biological effects of chitosan and to fine-tune its characteristics for its application in the biomedical field. First, the main characteristics of chitosan and HCAs are presented; then, the currently employed conjugation strategies between chitosan and HCAs are described; and, finally, the studied biomedical applications of these derivatives are discussed to present their limitations and advantages, which could lead to proximal therapeutic uses.

The Integration of Cell Therapy and Biomaterials as Treatment Strategies for Remyelination.

Multiple sclerosis (MS) is a chronic degenerative autoimmune disease of the central nervous system that causes inflammation, demyelinating lesions, and axonal damage and is associated with a high rate of early-onset disability. Disease-modifying therapies are used to mitigate the inflammatory process in MS but do not promote regeneration or remyelination; cell therapy may play an important role in these processes, modulating inflammation and promoting the repopulation of oligodendrocytes, which are responsible for myelin repair. The development of genetic engineering has led to the emergence of stable, biocompatible biomaterials that may promote a favorable environment for exogenous cells. This review summarizes the available evidence about the effects of transplantation of different types of stem cells reported in studies with several animal models of MS and clinical trials in human patients. We also address the advantages of combining cell therapy with biomaterials.

Intranasal Administration of Undifferentiated Oligodendrocyte Lineage Cells as a Potential Approach to Deliver Oligodendrocyte Precursor Cells into Brain.

Oligodendrocyte precursor cell (OPC) migration is a mechanism involved in remyelination; these cells migrate from niches in the adult CNS. However, age and disease reduce the pool of OPCs; as a result, the remyelination capacity of the CNS decreases over time. Several experimental studies have introduced OPCs to the brain via direct injection or intrathecal administration. In this study, we used the nose-to brain pathway to deliver oligodendrocyte lineage cells (human oligodendroglioma (HOG) cells), which behave similarly to OPCs in vitro. To this end, we administered GFP-labelled HOG cells intranasally to experimental animals, which were subsequently euthanised at 30 or 60 days. Our results show that the intranasal route is a viable route to the CNS and that HOG cells administered intranasally migrate preferentially to niches of OPCs (clusters created during embryonic development and adult life). Our study provides evidence, albeit limited, that HOG cells either form clusters or adhere to clusters of OPCs in the brains of experimental animals.

Experimental Models for the Study of Central Nervous System Infection by SARS-CoV-2.

INTRODUCTION: The response to the SARS-CoV-2 coronavirus epidemic requires increased research efforts to expand our knowledge of the disease. Questions related to infection rates and mechanisms, the possibility of reinfection, and potential therapeutic approaches require us not only to use the experimental models previously employed for the SARS-CoV and MERS-CoV coronaviruses but also to generate new models to respond to urgent questions. DEVELOPMENT: We reviewed the different experimental models used in the study of central nervous system (CNS) involvement in COVID-19 both in different cell lines that have enabled identification of the virus' action mechanisms and in animal models (mice, rats, hamsters, ferrets, and primates) inoculated with the virus. Specifically, we reviewed models used to assess the presence and effects of SARS-CoV-2 on the CNS, including neural cell lines, animal models such as mouse hepatitis virus CoV (especially the 59 strain), and the use of brain organoids. CONCLUSION: Given the clear need to increase our understanding of SARS-CoV-2, as well as its potential effects on the CNS, we must endeavor to obtain new information with cellular or animal models, with an appropriate resemblance between models and human patients.

Variants of genes encoding TNF receptors and ligands and proteins regulating TNF activation in familial multiple sclerosis.

INTRODUCTION: Numerous genetic variants have been associated with susceptibility to multiple sclerosis (MS). Variants located in genes involved in specific pathways, such as those affecting TNF-α, can contribute to the risk of MS. The purpose of this study was to determine whether variants of these genes are associated with greater risk of MS. METHODS: We used whole-exome sequencing to study genes coding for TNF-α receptors and ligands, and proteins promoting TNF-α expression in 116 individuals from 19 families including at least two MS patients. We compared patients with MS, patients with other autoimmune diseases, and healthy individuals. RESULTS: Greater polymorphism was observed in several genes in families with familial MS compared to the general population; this may reflect greater susceptibility to autoimmune diseases. Pedigree analysis also revealed that LT-α variants rs1041981 and rs2229094 and LT-ß variant rs4647197 were associated with MS and that LT-ß variant rs4647183 was associated with other autoimmune diseases. The association between autoimmune disease and TNFAIP2 variant rs1132339 is particularly noteworthy, as is the fact that TNFAIP6 variant rs1046668 appears to follow a recessive inheritance pattern. CONCLUSIONS: Our findings support the idea that the risk of familial MS is associated with variants of signaling pathways, including those involving TNF-α.

Evaluation of the Safety and Efficacy of the Therapeutic Potential of Adipose-Derived Stem Cells Injected in the Cerebral Ischemic Penumbra.

INTRODUCTION: Stroke represents an attractive target for cell therapy. Although different types of cells have been employed in animal models with variable results, the human adipose-derived stem cells (hASCs) have demonstrated favorable characteristics in the treatment of diseases with inflammatory substrate, but experience in their intracerebral administration is lacking. The purpose of this study is to evaluate the effect and safety of the intracerebral application of hASCs in a stroke model. METHODS: A first group of Athymic Nude mice after stroke received a stereotactic injection of hASCs at a concentration of 4 × 104/µL at the penumbra area, a second group without stroke received the same cell concentration, and a third group had only stroke and no cells. After 7, 15, and 30 days, the animals underwent fluorodeoxyglucose-positron emission tomography and magnetic resonance imaging; subsequently, they were sacrificed for histological evaluation (HuNu, GFAP, IBA-1, Ki67, DCX) of the penumbra area and ipsilateral subventricular zone (iSVZ). RESULTS: The in vitro studies found no alterations in the molecular karyotype, clonogenic capacity, and expression of 62 kDa transcription factor and telomerase. Animals implanted with cells showed no adverse events. The implanted cells showed no evidence of proliferation or differentiation. However, there was an increase of capillaries, less astrocytes and microglia, and increased bromodeoxyuridine and doublecortin-positive cells in the iSVZ and in the vicinity of ischemic injury. CONCLUSIONS: These results suggest that hASCs in the implanted dose modulate inflammation, promote endogenous neurogenesis, and do not proliferate or migrate in the brain. These data confirm the safety of cell therapy with hASCs.

Inhibition of neurogenesis in a case of Marburg variant multiple sclerosis.

INTRODUCTION: Neural stem cells (NSC) are located essentially in the subventricular zone (SVZ), subgranular zone (SGZ), and along the central canal of the spinal cord. These cells can proliferate in vitro and differentiate into neurons, oligodendrocytes, and astroglia, thus contributing to repair in multiple sclerosis (MS). We conducted a pathological study to analyse neurogenic response in a patient with Marburg variant MS. METHODS: We present the case of a 27-year-old immunocompetent patient with Marburg variant MS, a fulminant form of the disease. The condition lasted 20 days. Diagnosis was based on clinical symptoms and MRI showed demyelinating lesions located in subependymal areas and histopathological findings. Neurogenic niches (SVZ and dentate gyrus) were analysed by confocal microscopy using markers of proliferation (Ki-67, PCNA), neuroblasts (PSA-NCAM, DCX, Tuj1), stem cells (Nestin, GFAPδ, SOX2, PAX6, Musashi), astrocytes (GFAP, AQ4), oligodendrocytes (NG2, Olig), microglia and cell infiltrates (IBA-1, CD68, MHCII), and cell death (TUNEL). RESULTS: Expression of the markers GFAPδ, SOX2, and PAX6 in NSC was found to be very low. Likewise, markers of proliferation (Ki-67) and intermediate precursors (NG2) were also reduced. This lack of markers of the first stages of cell differentiation means that neurogenesis is inhibited even in very early stages of the disease. CONCLUSION: Inhibition of neurogenesis in our patient, which cannot be explained by the fulminant nature of his symptoms, may be related to inflammation and immune response. This finding may further our knowledge of repair mechanisms in MS.

Amyloid PET in pseudotumoral multiple sclerosis.

BACKGROUND: Pseudotumoral multiple sclerosis is a rare form of demyelinating disease of the central nervous system. Positron emission tomography (PET) using amyloid-tracers has also been suggested as a marker of damage in white matter lesions in multiple sclerosis due to the nonspecific uptake of these tracers in white matter. METHOD: We present the case of a 59 year-old woman with a pathological-confirmed pseudotumoral multiple sclerosis, who was studied with the amyloid tracer 18F-florbetaben. The patient had developed word-finding difficulties and right hemianopia twelve years ago. In that time, MRI showed a lesion on the left hemisphere with an infiltrating aspect in frontotemporal lobes. Brain biopsy showed demyelinating areas and inflammation. During the following years, two new clinical relapses occurred. RESULTS: 18F-florbetaben PET showed lower uptake in the white matter lesion visualized in the CT and MRI images. Decreased tracer uptake was also observed in a larger area of the left hemisphere beyond the lesions observed on MRI or CT. White matter lesion volume on FLAIR was 44.2mL, and tracer uptake change between damaged white matter and normal appearing white matter was - 40.5%. Standardized uptake value was inferior in the pseudotumoral lesion than in the other white matter lesions. CONCLUSION: We report the findings of amyloid PET in a patient with pseudotumoral multiple sclerosis. This case provides further evidence on the role of amyloid PET in the assessment of white matter and demyelinating diseases.

Mechanical endovascular treatment of acute stroke due to cardiac myxoma.

BACKGROUND: Myxomas are rare cardiac tumors which often present with stroke caused by tumorous or thrombotic emboli. Treatment with intravenous recombinant tissue plasminogen activator (rtPA) and intra-arterial thrombolysis has been described previously but mechanical thrombectomy has not yet been reported, and treatment of myxoma-related ischemic stroke remains a clinical and technical challenge. METHODS: Two patients with ischemic stroke due to cardiac myxoma in which mechanical thrombectomy was performed are presented. RESULTS: Endovascular thrombectomy after intravenous rtPA (bridging therapy) was safely achieved in both cases, although with different clinical outcomes and degrees of recanalization. CONCLUSIONS: In stroke secondary to cardiac myxoma, mechanical thrombectomy might represent a safe and effective treatment option. The authors suggest the use of histological examination of the clot for diagnosis as its composition may explain the differences in treatment outcome.

Endovascular treatment of distal internal carotid artery occlusions with retrievable stents.

BACKGROUND: Acute stroke due to distal intracranial internal carotid artery (ICA) occlusion has a poor natural history. Outcome in patients who receive intravenous tissue plasminogen activator (tPA) is also unsatisfactory. The objective of this study is to evaluate the effectiveness and safety of endovascular treatment with retrievable stents in these patients. METHODS: Data from a prospective register of patients with acute stroke treated with an endovascular procedure in a single centre were analysed. RESULTS: A total of 20 patients with distal ICA occlusion were collected. Mean baseline National Institutes of Health Stroke Scale score was 18. Eight cases (40%) had received previous intravenous tPA. Mean time from stroke to recanalization was 393 min. Retrievable stents with proximal occlusion and aspiration were used in all cases. In 3 patients, 2 retrievable stents were used simultaneously. Complete recanalization (thrombolysis in cerebral infarction 2b/3) was accomplished in 85% of cases. A favourable clinical outcome (modified Rankin Scale score 0-2) was achieved in 13 patients (65%). Mortality occurred in 2 cases (10%). CONCLUSIONS: Endovascular treatment of patients with distal ICA occlusion seems safe and effective. Retrievable stents may be the treatment of choice, although randomized clinical trials are necessary. The use of 2 retrievable stents at the same time could be an alternative technique useful in thrombi of larger size.

Peroneal palsy after bariatric surgery; is nerve decompresion always necessary?

We present two patients who underwent successful bariatric surgery and developed peroneal nerve palsy six months after the procedure. This is an unusual complication which determines a significant functional limitation, mainly because of foot drop, and its presence may be a hallmark of excessive and rapid weight loss. We discuss possible pathogenic mechanisms and therapeutic options, and we emphasize the important role of an adequate nutritional management, in order to avoid the need for a surgical nerve decompression.

Se presentan dos pacientes sometidos a cirugía bariátrica que desarrollaron una neuropatía del nervio peroneo común seis meses después de la intervención. Se trata de una complicación poco frecuente que supone una importante limitación funcional, y su aparición puede ser indicativa de una pérdida de peso demasiado rápida y excesiva. Se discute la patogenia y las posibles alternativas terapéuticas, y se destaca el papel esencial del correcto manejo nutricional, con el fin de evitar la necesidad de descompresión quirúrgica nerviosa.

Early endovascular treatment of subarachnoid hemorrhage.

Subarachnoid hemorrhage is an important cause of morbidity and mortality. Rebleeding is one of its major complications, which occurs mainly within the first 24 h and worsens the clinical outcome in a very dramatic way. It may be prevented by aneurysm treatment: surgical clipping or endovascular coiling. We review the evidence of and recent advances in endovascular treatment and timing of the intervention. Data supporting the benefit of early (<72 h) and ultra-early (<24 h) treatment is based on observational studies. An earlier approach may be relevant for the prevention of rebleeding and improvement of clinical outcome, but several disadvantages should be considered, such as an increased rate of periprocedural complications. Hence, a well-designed randomized controlled trial deems necessary to be able to define the optimal time of treatment. The possibility of treatment concomitant with the initial angiography should also be taken into account in this trial. This fact might represent a benefit favoring coiling over clipping in the prevention of rebleeding, and thus avoiding the inevitable delay necessary for the preparation for surgery.