Engraftment of freshly isolated or cultured human umbilical cord blood cells and the effect of cyclosporin A on the outcome

Exosomes derived from highly scalable and regenerative human progenitor cells promote functional improvement in a rat model of ischemic stroke

Globally, there are 15 million stroke patients each year who have significant neurological deficits. Today, there are no treatments that directly address these deficits. With demographics shifting to an older population, the problem is worsening. Therefore, it is crucial to develop feasible therapeutic treatments for stroke. In this study, we tested exosomes derived from embryonic endothelial progenitor cells (eEPC) to assess their therapeutic efficacy in a rat model of ischemic stroke. Importantly, we have developed purification methods aimed at producing robust and scalable exosomes suitable for manufacturing clinical grade therapeutic exosomes. We characterized exosome cargos including RNA-seq, miRNAs targets, and proteomic mass spectrometry analysis, and we found that eEPC-exosomes were enhanced with angiogenic miRNAs (i.e., miR-126), anti-inflammatory miRNA (i.e., miR-146), and anti-apoptotic miRNAs (i.e., miR-21). The angiogenic activity of diverse eEPC-exosomes sourced from a panel of eEPC production lines was assessed in vitro by live-cell vascular tube formation and scratch wound assays, showing that several eEPC-exosomes promoted the proliferation, tube formation, and migration in endothelial cells. We further applied the exosomes systemically in a rat middle cerebral artery occlusion (MCAO) model of stroke and tested for neurological recovery (mNSS) after injury in ischemic animals. The mNSS scores revealed that recovery of sensorimotor functioning in ischemic MCAO rats increased significantly after intravenous administration of eEPC-exosomes and outpaced recovery obtained through treatment with umbilical cord stem cells. Finally, we investigated the potential mechanism of eEPC-exosomes in mitigating ischemic stroke injury and inflammation by the expression of neuronal, endothelial, and inflammatory markers. Taken together, these data support the finding that eEPCs provide a valuable source of exosomes for developing scalable therapeutic products and therapies for stroke and other ischemic diseases.

Human umbilical cord blood mononuclear cells ameliorate ischemic brain injury via promoting microglia/macrophages M2 polarization in MCAO Rats

Cerebral infarction is one of the most prevalent cerebrovascular disorders. Microglia and infiltrating macrophages play a key role in regulating the inflammatory response after ischemic stroke. Regulation of microglia/macrophages polarization contributes to the recovery of neurological function in cerebral infarction. In recent decades, human umbilical cord blood mononuclear cells (hUCBMNCs) have been considered a potential therapeutic alternative. However, the mechanism of action is yet unclear. Our study aimed to explore whether hUCBMNCs treatment for cerebral infarction is via regulation of microglia/macrophages polarization. Adult male Sprague-Dawley rats were subjected to middle cerebral artery occlusion (MCAO) and were treated by intravenous routine with or without hUCBMNCs at 24 h following MCAO. We evaluated the therapeutic effects of hUCBMNCs on cerebral infarction by measuring animal behavior and infarct volume, and further explored the possible mechanisms of hUCBMNCs for cerebral infarction by measuring inflammatory factors and microglia/macrophages markers using Elisa and immunofluorescence staining, respectively. We found that administration with hUCBMNCs improved behavioral functions and reduced infarct volume. Rats treated with hUCBMNCs showed a significant reduction in the level of IL-6, and TNF-α and increased the level of IL-4 and IL-10 compared to those treated without hUCBMNCs. Furthermore, hUCBMNCs inhibited M1 polarization and promoted M2 polarization of microglia/macrophages after MCAO. We conclude that hUCBMNCs could ameliorate cerebral brain injury by promoting microglia/macrophages M2 polarization in MCAO Rats. This experiment provides evidence that hUCBMNCs represent a promising therapeutic option for ischemic stroke.

Timing of Cord Blood Treatment after Experimental Stroke Determines Therapeutic Efficacy

Embolic stroke is thought to cause irreparable damage in the brain immediately adjacent to the region of reduced blood perfusion. Therefore, much of the current research focuses on treatments such as anti-inflammatory, neuroprotective, and cell replacement strategies to minimize behavioral and physiological consequences. In the present study, intravenous delivery of human umbilical cord blood cells (HUCBC) 48 h after a middle cerebral artery occlusion (MCAo) in a rat resulted in both behavioral and physiological recovery. Nissl and TUNEL staining demonstrated that many of the neurons in the core were rescued, indicating that while both necrotic and apoptotic cell death occur in ischemia, it is clear that apoptosis plays a larger role than first anticipated. Further, immunohistochemical and histochemical analysis showed a diminished and/or lack of granulocyte and monocyte infiltration and astrocytic and microglial activation in the parenchyma in animals treated with HUCBC 48 h poststroke. Successful treatment at this time point should offer encouragement to clinicians that a therapy with a broader window of efficacy may soon be available to treat stroke.

Amelioration of Ischemic Brain Injury in Rats With Human Umbilical Cord Blood Stem Cells: Mechanisms of Action

Despite the high prevalence and devastating outcome, there remain a few options for treatment of ischemic stroke. Currently available treatments are limited by a short time window for treatment and marginal efficacy when used. We have tested a human umbilical cord blood-derived stem cell line that has been shown to result in a significant reduction in stroke infarct volume as well as improved functional recovery following stroke in the rat. In the present study we address the mechanism of action and compared the therapeutic efficacy of high- versus low-passage nonhematopoietic umbilical cord blood stem cells (nh-UCBSCs). Using the middle cerebral arterial occlusion (MCAo) model of stroke in Sprague-Dawley rats, we administered nh-UCBSC by intravenous (IV) injection 2 days following stroke induction. These human cells were injected into rats without any immune suppression, and no adverse reactions were detected. Both behavioral and histological analyses have shown that the administration of these cells reduces the infarct volume by 50% as well as improves the functional outcome of these rats following stroke for both high- and low-passaged nh-UCBSCs. Flow cytometry analysis of immune cells present in the brains of normal rats, rats with ischemic brain injury, and ischemic animals with nh-UCBSC treatment confirmed infiltration of macrophages and T cells consequent to ischemia and reduction to normal levels with nh-UCBSC treatment. Flow cytometry also revealed a restoration of normal levels of microglia in the brain following treatment. These data suggest that nh-UCBSCs may act by inhibiting immune cell migration into the brain from the periphery and possibly by inhibition of immune cell activation within the brain. nh-UCBSCs exhibit great potential for treatment of stroke, including the fact that they are associated with an increased therapeutic time window, no known ill-effects, and that they can be expanded to high numbers for, and stored for, treatment.

Intravenous administration of human umbilical cord blood-mononuclear cells dose-dependently relieve neurologic deficits in rat intracerebral hemorrhage model

Human umbilical cord blood (HUCB) is now considered as a valuable source for stem cell-based therapies. Previous studies showed that intravascular injection of the HUCB significantly improves neurological functional recovery in a model of intracerebral hemorrhage (ICH). To extend these findings, we examined the behavioral recovery and injured volume in the presence of increasing doses of human umbilical cord blood derived mononuclear cells (HUC-MCs) after intracerebral hemorrhage in rats. The experimental ICH was induced by intrastriatal administration of bacterial collagenase IV in adult rats. One day after the surgery, the rats were randomly divided into 4 groups to receive intravenously either BrdU positive human UC-MCs (4 × 10(6), 8 × 10(6) and 16 × 10(6) cells in 1 ml saline, n=10, respectively) as treated groups or the same amount of saline as lesion group (n=10). There was also one group (control n=10) that received only the vehicle solution of collagenase. The animals were evaluated for 14 days with modified limb placing and corner turn tests. The transplanted human UC-MCs were also detected by immunohistochemistry with labeling of BrdU. Two weeks after infusion, there was a significant recovery in the behavioral performance when 4 × 10(6) or more UC-MCs were delivered (P<0.05-0.001). Injured volume measurements disclosed an inverse relationship between UC-MCs dose and damage reaching significance at the higher UC-MCs doses. Moreover, human UC-MCs were localized by immunohistochemistry only in the injured area. Intravenously transplanted UC-MCs can accelerate the neurological function recovery of ICH rat and diminish the striatum lesion size by demonstrating a dose relationship between them.

MHC mismatch inhibits neurogenesis and neuron maturation in stem cell allografts

Background

The role of histocompatibility and immune recognition in stem cell transplant therapy has been controversial, with many reports arguing that undifferentiated stem cells are protected from immune recognition due to the absence of major histocompatibility complex (MHC) markers. This argument is even more persuasive in transplantation into the central nervous system (CNS) where the graft rejection response is minimal.

Methodology/Principal Findings

In this study, we evaluate graft survival and neuron production in perfectly matched vs. strongly mismatched neural stem cells transplanted into the hippocampus in mice. Although allogeneic cells survive, we observe that MHC-mismatch decreases surviving cell numbers and strongly inhibits the differentiation and retention of graft-derived as well as endogenously produced new neurons. Immune suppression with cyclosporine-A did not improve outcome but non-steroidal anti-inflammatory drugs, indomethacin or rosiglitazone, were able to restore allogeneic neuron production, integration and retention to the level of syngeneic grafts.

Conclusions/Significance

These results suggest an important but unsuspected role for innate, rather than adaptive, immunity in the survival and function of MHC-mismatched cellular grafts in the CNS.

Cellular environment directs differentiation of human umbilical cord blood-derived neural stem cells in vitro

Cord blood-derived neural stem cells (NSCs) are proposed as an alternative cell source to repair brain damage upon transplantation. However, there is a lack of data showing how these cells are driven to generate desired phenotypes by recipient nervous tissue. Previous research indicates that local environment provides signals driving the fate of stem cells. To investigate the impact of these local cues interaction, the authors used a model of cord blood-derived NSCs co-cultured with different rat brain-specific primary cultures, creating the neural-like microenvironment conditions in vitro. Neuronal and astro-, oligo-, and microglia cell cultures were obtained by the previously described methods. The CMFDA-labeled neural stem cells originated from, non-transformed human umbilical cord blood cell line (HUCB-NSCs) established in a laboratory. The authors show that the close vicinity of astrocytes and oligodendrocytes promotes neuronal differentiation of HUCB-NSCs, whereas postmitotic neurons induce oligodendrogliogenesis of these cells. In turn, microglia or endothelial cells do not favor any phenotypes of their neural commitment. Studies have confirmed that HUCB-NSCs can read cues from the neurogenic microenvironment, attaining features of neurons, astrocytes, or oligodendrocytes. The specific responses of neurally committed cord blood-derived cells, reported in this work, are very much similar to those described previously for NSCs derived from other "more typical" sources. This further proves their genuine neural nature. Apart from having a better insight into the neurogenesis in the adult brain, these findings might be important when predicting cord blood cell derivative behavior after their transplantation for neurological disorders.

Intravenous human umbilical cord blood transplantation for stroke: impact on infarct volume and caspase-3-dependent cell death in spontaneously hypertensive rats

Transplantation of human umbilical cord blood cells (HUCBC) produces reliable behavioral and morphological improvements in animal models of stroke. However, the mechanisms of action still have not been fully elucidated. The aim of the present study is the evaluation of potential neuroprotective effects produced by HUCBC in terms of reduced infarct volume and caspase-3-dependent cell death. Permanent middle cerebral artery occlusion was induced in 90 spontaneously hypertensive rats. The animals were randomly assigned to the control group (n=49) or the verum group (n=41). The cell suspension (8 × 10(6) HUCBC per kilogram bodyweight) or vehicle solution was intravenously administered 24h after stroke onset. Fifty subjects (n=25/25) were sacrificed after 25, 48, 72 and 96h, and brain specimens were removed for immunohistochemistry for MAP2, cleaved caspase-3 (casp3) and GFAP. Another 42 animals (n=26/16) were sacrificed after 0, 6, 24, 36 and 48h and their brains processed for quantitative PCR for casp3 and survivin. The infarct volume remained stable over the entire experimental period. However, cleaved casp3 activity increased significantly in the infarct border zone within the same time frame. Numerous cleaved casp3-positive cells were colocalized with the astrocytic marker GFAP, whereas cleavage of neuronal casp3 was observed rarely. Neither the infarct volume nor casp3 activity was significantly affected by cell transplantation. Delayed systemic transplantation of HUCBC failed to produce neuroprotective effects in a permanent stroke model using premorbid subjects.

Systemic neurotransplantation--a problem-oriented systematic review

Systemic neurotransplantation (SNT) was introduced in the laboratory in 2000 and currently it is being widely examined in animal models of neurological disorders. The aim of this systematic review was to evaluate the current state of knowledge in the field of experimental SNT and the premise for the introduction of clinical trials. PubMed was searched and 60 articles utilizing an SNT approach were found and subjected to analysis. The time window for cell transplantation was addressed in only two studies, with contradictory results. Immunosuppression was applied in 25% of studies. No study addressed the justification for immunosuppression. Bone marrow was the most frequent source of grafted cells, followed by cord blood and then by cells of embryonic origin. Studies investigating dose-dependency revealed no satisfactory results with transplantation of less than 10(6) cells/animal; the efficient dose most frequently ranged from 10(6)-10(7) cells/animal (mice and rats). The behavioral effects of cell transplantation were assessed in 75% of all studies; significant improvement was achieved in 95% of them. Morphological effect was evaluated in half of the studies; significant positive effect was achieved in 73% of them. Experimental attempts to elucidate the mechanisms mediating cell-dependent effect were not undertaken in half of the studies. In the other half, the most frequent mechanisms were growth factors, neurogenesis and immunomodulation. SNT still seems to be at the very initial stage of development. Many critical factors have not been sufficiently addressed in laboratory studies and they must be clarified before the introduction of clinical trials.

Human umbilical cord blood-derived mesenchymal stem cells do not differentiate into neural cell types or integrate into the retina after intravitreal grafting in neonatal rats

This study investigated the ability of mesenchymal stem cells (MSCs) derived from full-term human umbilical cord blood to survive, integrate and differentiate after intravitreal grafting to the degenerating neonatal rat retina following intracranial optic tract lesion. MSCs survived for 1 week in the absence of immunosuppression. When host animals were treated with cyclosporin A and dexamethasone to suppress inflammatory and immune responses, donor cells survived for at least 3 weeks, and were able to spread and cover the entire vitreal surface of the host retina. However, MSCs did not significantly integrate into or migrate through the retina. They also maintained their human antigenicity, and no indication of neural differentiation was observed in retinas where retinal ganglion cells either underwent severe degeneration or were lost. These results have provided the first in vivo evidence that MSCs derived from human umbilical cord blood can survive for a significant period of time when the host rat response is suppressed even for a short period. These results, together with the observation of a lack of neuronal differentiation and integration of MSCs after intravitreal grafting, has raised an important question as to the potential use of MSCs for neural repair through the replacement of lost neurons in the mammalian retina and central nervous system.

Routes of stem cell administration in the adult rodent

Stem cell transplantation to replace damaged tissue or correct metabolic disease holds the promise of helping a myriad of human afflictions. Although a great deal of attention has focused on pluripotent stem cells derived from embryos, adult stem cells have been described in a variety of tissues, and they likely will prove to be as beneficial as embryonic stem cells in cell replacement therapy and control of inbred errors of metabolism. We describe methods by which stem cells can be introduced into the nervous system, although the techniques are applicable to any portion of the body to be targeted or any cell that may be used for cell therapy. The first and most straight-forward method is introduction of stem cells directly into the brain parenchyma. The second, which in our hands has proven to be superior in some instances, is introduction of the stem cells into the circulatory system.

Transplantation of a novel human cord blood-derived neural-like stem cell line in a rat model of cortical infarct

Umbilical cord blood can be a rich source of stem/progenitor cells, not only for hematopoetic but also for other tissue-specific lineages. Recently, we have developed a novel, self-renewed neural-like stem cell line named HUCB-NSC from human cord blood. To test if HUCB-NSCs can supply brain in need of regeneration, we injected these cells into immunosuppressed intact rat forebrain and to animals suffering from a photothrombotic cortical lesion at 48 h after injury. The survival, migration, and differentiation of the transplanted HUCB-NSCs were measured at 7 and 30 days post-transplantation by immunohistochemical methods. Results show survival and extensive migration of transplanted neural-like progenitors into damaged brain cortex during the first week of post-stroke recovery. The donor cells accumulated mainly in peri-infarct area and then differentiated showing a strong co-expression of neuronal (NF-200) but only moderate of astrocytic (GFAP) cell markers. However, the paucity of HUCB-NSCs detected within post-ischemic rat brain at the end of a 1 month period, as well as acute rejection of grafted cells by intact, yet cyclosporin A (CsA) immunosuppressed, rat brain tissue, suggests development of a severe adverse host reaction to the presence of alien donor cells and an urgent need for further study of the immunological response evoked by xenotransplantations of human cord blood-derived cells in animal experimental models.

Umbilical cord blood transfusions for prevention of progressive brain injury and induction of neural recovery: an immunological perspective

One of the most promising treatments for neurodegenerative diseases appears to be human umbilical cord blood cell transplantation. A variety of studies demonstrate some benefit of this method of treatment in a number of different animal models and case studies. However, before the methodologies and results of these animal studies and case studies can be translated into successful widespread treatments, aspects relating to the immunological properties of the transplanted cells must be considered. In this perspective, we discuss the benefit of the cellular immaturity of these cells with respect to the immune response, and compare cord blood transplantation to blood transfusions, as well as discussing what future studies should entail.

Cord blood mesenchymal stem cells: Potential use in neurological disorders

Our previous studies demonstrate enhanced neural protective effects of cord blood (CB) cells in comparison to stem cells from adult marrow. To determine further whether mesenchymal stem cells (MSCs) derived from human umbilical cord blood (hUCB) possess optimal characteristics for neural therapy, we isolated populations of plastic-adherent CB MSCs. These cells generated CD34-, CD45-, CD11b-, CD3-, CD19- cells in culture and failed to produce CFU-M, CFU-GEMM, or CFU-GM hematopoietic colonies in methylcellulose. However, cultured CB MSCs possessed a remarkable ability to support proliferation as well as differentiation of hematopoietic cells in vitro. In addition, supernatants from cultured CB MSCs promoted survival of NT2 N neural cells and peripheral blood mononuclear cells (MNCs) cultured under conditions designed to induce cell stress and limit protein synthesis. After incubation in neural differentiation medium, CB MSCs expressed the neural cell-surface antigen A2B5, the neurofilament polypeptide NF200, the oligodendrocyte precursor marker 04, intermediate filament proteins characteristic of neural differentiation (nestin and vimentin), as well as the astrocyte marker glial fibrillary acidic protein (GFAP) and the neural progenitor marker TUJ-1. We examined the immunomodulatory effects of the CB MSCs after co-culture with murine splenocytes. Whereas spleen cells from normal C57Bl/6 mice exhibited a prominent immunoglobulin M (IgM) response after immunization with the T cell-dependent antigen sheep red blood cells, this response was significantly decreased after incubation with CB MSCs. These data indicate that CB MSCs possess multiple utilities that may contribute to their therapeutic potency in the treatment of neurological disorders.