Therapeutic time window and effect of intracarotid neural stem cells transplantation for intracerebral hemorrhage

Current Status and Progress in Stem Cell Therapy for Intracerebral Hemorrhage

Intracerebral hemorrhage is a highly prevalent and prognostically poor disease, imposing immeasurable harm on human life and health. However, the treatment options for intracerebral hemorrhage are severely limited, particularly in terms of improving the microenvironment of the lesion, promoting neuronal cell survival, and enhancing neural function. This review comprehensively discussed the application of stem cell therapy for intracerebral hemorrhage, providing a systematic summary of its developmental history, types of transplants, transplantation routes, and transplantation timing. Moreover, this review presented the latest research progress in enhancing the efficacy of stem cell transplantation, including pretransplantation preconditioning, genetic modification, combined therapy, and other diverse strategies. Furthermore, this review pioneeringly elaborated on the barriers to clinical translation for stem cell therapy. These discussions were of significant importance for promoting stem cell therapy for intracerebral hemorrhage, facilitating its clinical translation, and improving patient prognosis.

Application of stem cells and exosomes in the treatment of intracerebral hemorrhage: an update

Non-traumatic intracerebral hemorrhage is a highly destructive intracranial disease with high mortality and morbidity rates. The main risk factors for cerebral hemorrhage include hypertension, amyloidosis, vasculitis, drug abuse, coagulation dysfunction, and genetic factors. Clinically, surviving patients with intracerebral hemorrhage exhibit different degrees of neurological deficits after discharge. In recent years, with the development of regenerative medicine, an increasing number of researchers have begun to pay attention to stem cell and exosome therapy as a new method for the treatment of intracerebral hemorrhage, owing to their intrinsic potential in neuroprotection and neurorestoration. Many animal studies have shown that stem cells can directly or indirectly participate in the treatment of intracerebral hemorrhage through regeneration, differentiation, or secretion. However, considering the uncertainty of its safety and efficacy, clinical studies are still lacking. This article reviews the treatment of intracerebral hemorrhage using stem cells and exosomes from both preclinical and clinical studies and summarizes the possible mechanisms of stem cell therapy. This review aims to provide a reference for future research and new strategies for clinical treatment.

Stem Cell Therapy: A Promising Therapeutic Method for Intracerebral Hemorrhage

Spontaneous intracerebral hemorrhage (ICH) is one type of the most devastating cerebrovascular diseases worldwide, which causes high morbidity and mortality. However, efficient treatment is still lacking. Stem cell therapy has shown good neuroprotective and neurorestorative effect in ICH and is a promising treatment. In this study, our aim was to review the therapeutic effects, strategies, related mechanisms and safety issues of various types of stem cell for ICH treatment. Numerous studies had demonstrated the therapeutic effects of diverse stem cell types in ICH. The potential mechanisms include tissue repair and replacement, neurotrophy, promotion of neurogenesis and angiogenesis, anti-apoptosis, immunoregulation and anti-inflammation and so forth. The microenvironment of the central nervous system (CNS) can also influence the effects of stem cell therapy. The detailed therapeutic strategies for ICH treatment such as cell type, the number of cells, time window, and the routes of medication delivery, varied greatly among different studies and had not been determined. Moreover, the safety issues of stem cell therapy for ICH should not be ignored. Stem cell therapy showed good therapeutic effect in ICH, making it a promising treatment. However, safety should be carefully evaluated, and more clinical trials are required before stem cell therapy can be extensively applied to clinical use.

Hypoxic preconditioning enhances neural stem cell transplantation therapy after intracerebral hemorrhage in mice

Previous studies have shown that intraparenchymal transplantation of neural stem cells ameliorates neurological deficits in animals with intracerebral hemorrhage. However, hemoglobin in the host brain environment causes massive grafted cell death and reduces the effectiveness of this approach. Several studies have shown that preconditioning induced by sublethal hypoxia can markedly improve the tolerance of treated subjects to more severe insults. Therefore, we investigated whether hypoxic preconditioning enhances neural stem cell resilience to the hemorrhagic stroke environment and improves therapeutic effects in mice. To assess whether hypoxic preconditioning enhances neural stem cell survival when exposed to hemoglobin, neural stem cells were exposed to 5% hypoxia for 24 hours before exposure to hemoglobin. To study the effectiveness of hypoxic preconditioning on grafted-neural stem cell recovery, neural stem cells subjected to hypoxic preconditioning were grafted into the parenchyma 3 days after intracerebral hemorrhage. Hypoxic preconditioning significantly enhanced viability of the neural stem cells exposed to hemoglobin and increased grafted-cell survival in the intracerebral hemorrhage brain. Hypoxic preconditioning also increased neural stem cell secretion of vascular endothelial growth factor. Finally, transplanted neural stem cells with hypoxic preconditioning exhibited enhanced tissue-protective capability that accelerated behavioral recovery. Our results suggest that hypoxic preconditioning in neural stem cells improves efficacy of stem cell therapy for intracerebral hemorrhage.

Stem cell therapy in intracerebral hemorrhage rat model

Intracerebral hemorrhage (ICH) is a very complex pathology, with many different not fully elucidated etiologies and prognostics. It is the most severe subtype of stroke, with high mortality and morbidity rates. Unfortunately, despite the numerous promising preclinical assays including neuroprotective, anti-hypertensive, and anti-inflammatory drugs, to this moment only symptomatic treatments are available, motivating the search for new alternatives. In this context, stem cell therapy emerged as a promising tool. However, more than a decade has passed, and there is still much to be learned not only about stem cells, but also about ICH itself, and how these two pieces come together. To date, rats have been the most widely used animal model in this research field, and there is much more to be learned from and about them. In this review, we first summarize ICH epidemiology, risk factors, and pathophysiology. We then present different methods utilized to induce ICH in rats, and examine how accurately they represent the human disease. Next, we discuss the different types of stem cells used in previous ICH studies, also taking into account the tested transplantation sites. Finally, we summarize what has been achieved in assays with stem cells in rat models of ICH, and point out some relevant issues where attention must be given in future efforts.

Intranasal delivery of hypoxia-preconditioned bone marrow-derived mesenchymal stem cells enhanced regenerative effects after intracerebral hemorrhagic stroke in mice

Intracerebral hemorrhagic stroke (ICH) causes high mortality and morbidity with very limited treatment options. Cell-based therapy has emerged as a novel approach to replace damaged brain tissues and promote regenerative processes. In this study we tested the hypothesis that intranasally delivered hypoxia-preconditioned BMSCs could reach the brain, promote tissue repair and improve functional recovery after ICH. Hemorrhagic stroke was induced in adult C57/B6 mice by injection of collagenase IV into the striatum. Animals were randomly divided into three groups: sham group, intranasal BMSC treatment group, and vehicle treatment group. BMSCs were pre-treated with hypoxic preconditioning (HP) and pre-labeled with Hoechst before transplantation. Behavior tests, including the mNSS score, rotarod test, adhesive removal test, and locomotor function evaluation were performed at varying days, up to 21days, after ICH to evaluate the therapeutic effects of BMSC transplantation. Western blots and immunohistochemistry were performed to analyze the neurotrophic effects. Intranasally delivered HP-BMSCs were identified in peri-injury regions. NeuN+/BrdU+ co-labeled cells were markedly increased around the hematoma region, and growth factors, including BDNF, GDNF, and VEGF were significantly upregulated in the ICH brain after BMSC treatment. The BMSC treatment group showed significant improvement in behavioral performance compared with the vehicle group. Our data also showed that intranasally delivered HP-BMSCs migrated to peri-injury regions and provided growth factors to increase neurogenesis after ICH. We conclude that intranasal administration of BMSC is an effective treatment for ICH, and that it enhanced neuroregenerative effects and promoted neurological functional recovery after ICH. Overall, the investigation supports the potential therapeutic strategy for BMSC transplantation therapy against hemorrhagic stroke.

Transplantation of neural stem cells that overexpress SOD1 enhances amelioration of intracerebral hemorrhage in mice

Previous studies have shown that intraparenchymal transplantation of neural stem cells (NSCs) ameliorates neurologic deficits in animals with intracerebral hemorrhage (ICH). However, massive grafted cell death after transplantation, possibly caused by a hostile host brain environment, lessens the effectiveness of this approach. We focused on the effect of oxidative stress against grafted NSCs and hypothesized that conferring antioxidant properties to transplanted NSCs may overcome their death and enhance neuroprotection after ICH. Copper/zinc-superoxide dismutase (SOD1) is a specific antioxidant enzyme that counteracts superoxide anions. We investigated whether genetic manipulation to overexpress SOD1 enhances survival of grafted NSCs and accelerates amelioration of ICH. Neural stem cells that overexpress SOD1 were administered intracerebrally 3 days after ICH in a mouse model. Histologic and behavioral tests were examined after ICH. Copper/zinc-superoxide dismutase overexpression protected the grafted NSCs via a decrease in production of reactive oxygen species. This resulted in an increase in paracrine factors released by the NSCs, and an increase in surviving neurons in the striatum and a reduction in striatal atrophy. In addition, SOD1 overexpression showed progressive improvement in behavioral recovery. Our results suggest that enhanced antioxidative activity in NSCs improves efficacy of stem cell therapy for ICH.

Cell size and velocity of injection are major determinants of the safety of intracarotid stem cell transplantation

Intracarotid transplantation has shown potential for efficient stem cell delivery to the brain. However, reported complications, such as compromised cerebral blood flow (CBF), prompted us to perform further safety studies. Glial-restricted precursors (GRPs) and mesenchymal stem cells (MSCs) were transplanted into the internal carotid artery of rats (n=99), using a microcatheter. Magnetic resonance imaging was used to detect post-transplantation complications, including the development of stroke, for the following experimental variables: cell size, cell dose, cell infusion velocity, delay between artery occlusion and cell infusion, discordant versus concordant xenografting, and intracarotid transplantation with preserved versus compromised blood flow. Immunocompatibility and delayed infusion did not affect the number of complications. An infusion velocity over 1 mL/minute often resulted in stroke (27 out of 44 animals), even with an infusion of vehicle, whereas a lower velocity (0.2 mL/minute) was safe for the infusion of both vehicle and smaller cells (GRPs, diameter=15 μm). Infusion of larger cells (MSCs, diameter=25 μm) resulted in a profound decrease (75±17%) in CBF. Stroke lesions occurred frequently (12 out of 15 animals) when injecting 2 × 10(6) MSCs, but not after lowering the dose to 1 × 10(6) cells. The present results show that cell size and infusion velocity are critical factors in developing safe protocols for intracarotid stem cell transplantation.

Therapeutic effect of mesenchymal stem cells in rats with intracerebral hemorrhage: reduced apoptosis and enhanced neuroprotection

Stem cell transplantation has been used to improve neural function in intracerebral hemorrhage (ICH). However, reports on bone marrow-derived mesenchymal stem cell (MSC) transplantation in ICH are limited. We aimed to explore the therapeutic effect and related mechanisms by transplantation of MSCs in rats with ICH. An experimental rat ICH model was established by intrastriatal administration of collagenase. The rats were randomly divided to receive either rat MSCs or PBS solution intravenously. In addition, behavioral tests using the modified neurological severity score (mNSS) were performed following ICH. Immunohistochemistry was performed to detect the Brdu-labeled MSCs and the protein expression of caspase 2, NF200 and GFAP in neural tissues. Western blotting and ELISA were performed to measure the protein expression of Akt and bcl-2 or the protein content of G-CSF and BDNF. The MSC-transplanted group demonstrated better neural function on the mNSS test following ICH compared with the control group (P<0.05). The MSC-transplanted group also showed reduced hemorrhage volume at 24 and 72 h following ICH. In the perihematomal regions of rat brain with ICH, a substantial number of Brdu-labeled MSCs were observed, and a high protein expression of caspase 3, NF200 and GFAP was found in the MSC-transplanted group. The protein content of Akt, Bcl-2, G-CSF and BDNF were all elevated by MSC transplantation. Intravenously transplanted MSCs are capable of improving functional recovery and restoring neurological deficits in experimental ICH. The mechanisms are associated with enhanced survival and differentiation of neural cells, and increased expression of anti-apoptotic proteins and trophic factors.

Effects of duplicate administration of human neural stem cell after focal cerebral ischemia in the rat

We investigated the functional and histological recovery of middle cerebral artery occluded (MCAo) rats after of duplicate intravenous (i.v.) injection of human neural stem cells (hNSCs). Rats received i.v. injections of hNSCs (HB1.F3, 4 × 10(6) cells) on day 1 (1C), day 7 (7C), or both days 1 and 7 (1/7C) following MCAo. Functional recovery of rats was evaluated 1 day before MCAo and 1, 7, 14, 21, and 28 days following MCAo, using the modified neurological severity score (mNSS), and cylinder test. Nissl staining and anti-human nuclear matrix antigen /NeuN or GFAP were used to measure infarct size and investigate the migration and differentiation of injected cells. Treatment with hNSCs did not significantly affect infarct size of ischemic animals. Behavior evaluation using mNSS showed that functional deficits in the 1C group were reduced faster than in the 7C and 1/7C groups, and functional recovery in 1/7C rats was significantly more pronounced than that in the 7C group (day 21). Injected cells were identified at the boundary of lesions, where they had differentiated into neurons and astrocytes. Our study suggests that duplicate i.v. administration of hNSCs after stroke offers no advantages over single administration, 1 day following an ischemic event.

Cell replacement therapy for intracerebral hemorrhage

✓ Intracerebral hemorrhage (ICH), for which no effective treatment strategy is currently available, constitutes one of the most devastating forms of stroke. As a result, developing therapeutic options for ICH is of great interest to the medical community. The 3 potential therapies that have the most promise are cell replacement therapy, enhancing endogenous repair mechanisms, and utilizing various neuroprotective drugs. Replacement of damaged cells and restoration of function can be accomplished by transplantation of cells derived from different sources, such as embryonic or somatic stem cells, umbilical cord blood, and genetically modified cell lines. Early experimental data showing the benefits of cell transplantation on functional recovery after ICH have been promising. Nevertheless, several studies have focused on another therapeutic avenue, investigating novel ways to activate and direct endogenous repair mechanisms in the central nervous system, through exposure to specific neuronal growth factors or by inactivating inhibitory molecules. Lastly, neuroprotective drugs may offer an additional tool for improving neuronal survival in the perihematomal area. However, a number of scientific issues must be addressed before these experimental techniques can be translated into clinical therapy. In this review, the authors outline the recent advances in the basic science of treatment strategies for ICH.