Miroslaw Janowski

Intravenous route of cell delivery for treatment of neurological disorders: A meta-analysis of preclinical results

The last decade has been marked by a growing interest in an employment of intravenous cell delivery for treatment of neurological disorders. Numerous preclinical experimental studies have reported functional benefits, and have recently been followed by clinical trials. Some early clinical studies have indicated only modest positive effects, suggesting that the optimal conditions have not been defined yet. Thus, the evaluation of factors that influence outcomes, on the level of the whole population of preclinical studies by advanced statistical analysis, is warranted. PubMed search was conducted from the inception through 2006, and 60 preclinical studies were found and subjected to analysis. Categorical and continuous independent variables (IVs) were extracted. Three distinct outcomes of interest were selected as dependent variables (DVs) and named treatment effects: morphological, behavioral, and molecular, respectively. Mean outcomes, standard deviations (SDs), and animal numbers were retrieved and calculated by individual comparisons of experimental and control groups, based on the Hedges g formula, and were expressed as effect sizes (ESs) and variances. Publication bias and homogeneity were evaluated. The mainspring analyses were performed under a random effect model using Proc Mixed (SAS, version 9.2). A significant heterogeneity and publication bias were found. The ES pooling revealed large treatment effects. Univariate and multivariate meta-regression revealed that cell-related variables explained most of the heterogeneity. Cells retrieved from established lines and genetic modification of cells warrants the highest efficiency, in a dose-dependent manner. The stratified analysis of molecular effect measures revealed that apoptosis inhibition is the strongest brain tissue-positive change induced by cell therapy.

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.

Personalized nanomedicine advancements for stem cell tracking

Recent technological developments in biomedicine have facilitated the generation of data on the anatomical, physiological and molecular level for individual patients and thus introduces opportunity for therapy to be personalized in an unprecedented fashion. Generation of patient-specific stem cells exemplifies the efforts toward this new approach. Cell-based therapy is a highly promising treatment paradigm; however, due to the lack of consistent and unbiased data about the fate of stem cells in vivo, interpretation of therapeutic effects remains challenging hampering the progress in this field. The advent of nanotechnology with a wide palette of inorganic and organic nanostructures has expanded the arsenal of methods for tracking transplanted stem cells. The diversity of nanomaterials has revolutionized personalized nanomedicine and enables individualized tailoring of stem cell labeling materials for the specific needs of each patient. The successful implementation of stem cell tracking will likely be a significant driving force that will contribute to the further development of nanotheranostics. The purpose of this review is to emphasize the role of cell tracking using currently available nanoparticles.

Long-term MRI cell tracking after intraventricular delivery in a patient with global cerebral ischemia and prospects for magnetic navigation of stem cells within the CSF.

Background The purpose of the study was to evaluate the long-term clinical tracking of magnetically labeled stem cells after intracerebroventricular transplantation as well as to investigate in vitro feasibility for magnetic guidance of cell therapy within large fluid compartments. Method After approval by our Institutional Review Board, an 18-month-old patient, diagnosed as being in a vegetative state due to global cerebral ischemia, underwent cell transplantation to the frontal horn of the lateral ventricle, with umbilical cord blood-derived stem cells labeled with superparamagnetic iron oxide (SPIO) contrast agent. The patient was followed over 33 months with clinical examinations and MRI. To evaluate the forces governing the distribution of cells within the fluid compartment of the ventricular system in vivo, a gravity-driven sedimentation assay and a magnetic field-driven cell attraction assay were developed in vitro. Results Twenty-four hours post-transplantation, MR imaging (MRI) was able to detect hypointense cells in the occipital horn of the lateral ventricle. The signal gradually decreased over 4 months and became undetectable at 33 months. In vitro, no significant difference in cell sedimentation between SPIO-labeled and unlabeled cells was observed (p = NS). An external magnet was effective in attracting cells over distances comparable to the size of human lateral ventricles. Conclusions MR imaging of SPIO-labeled cells allows monitoring of cells within lateral ventricles. While the initial biodistribution is governed by gravity-driven sedimentation, an external magnetic field may possibly be applied to further direct the distribution of labeled cells within large fluid compartments such as the ventricular system.

Stem Cell–Based Tissue Replacement After Stroke: Factual Necessity or Notorious Fiction?

The increasing stroke incidence and the long-term, severe disability of survivors requiring complex nursing care over extended time periods cause an enormous social and economic burden to ageing societies. Unfortunately, all clinical trials on neuroprotectants have failed thus far.1 The only approved therapy is clot lysis (recombinant tissue-type plasminogen activator [r-tPA]), which is restricted to only 4.5 hours poststroke onset.2 Although r-tPA application is statistically justified, it can result in severe adverse events,3 complicating individual r-tPA treatment decisions. Thus, the current strategies in stroke management are focused on prevention by identification of risk factors4 and intensive rehabilitation in the chronic phase.5 However, stroke outcomes remain poor, causing a strong but unmet demand for alternative therapeutic approaches. The failure of the neuroprotective paradigm and limited eligibility for thrombolysis spawned an interest in stem cell–based neurorestoration,6 which is characterized by a wide therapeutic window and is highly convergent with rehabilitation. However, stem cell–based tissue replacement may be aggravated by pathophysiological and anatomic features, whereas the beneficial effects of (stem) cells may not necessarily result from cellular restoration. Here, we review the state of the art of cell-based stroke therapies and balance arguments supporting and challenging the concept of poststroke tissue restoration. Moreover, we discuss the respective therapeutic mechanisms related to tissue restoration versus indirect means of regenerative support including practical issues such as transplantation time windows, routes of cell administration, and potential detrimental effects. The replacement of lost brain tissue by transplanted cells has fired the imagination of researchers for decades. Studies on lesion-induced axonal sprouting of catecholamine neurons devised the fundamentals for brain-regenerating strategies. Then, the functional connections of transplanted monoamine neurons were demonstrated, whereas fetal nigral transplants were able to reverse parkinsonism in animal models and patients.7 These early proof-of-principle studies supported the …

Intracerebroventricular Transplantation of Cord Blood-Derived Neural Progenitors in a Child with Severe Global Brain Ischemic Injury:

Transplantation of neural stem/precursor cells has recently been proposed as a promising, albeit still controversial, approach to brain repair. Human umbilical cord blood could be a source of such therapeutic cells, proven beneficial in several preclinical models of stroke. Intracerebroventricular infusion of neutrally committed cord blood-derived cells allows their broad distribution in the CNS, whereas additional labeling with iron oxide nanoparticles (SPIO) enables to follow the fate of engrafted cells by MRI. A 16-month-old child at 7 months after the onset of cardiac arrest-induced global hypoxic/ischemic brain injury, resulting in a permanent vegetative state, was subjected to intracerebroventricular transplantation of the autologous neutrally committed cord blood cells. These cells obtained by 10-day culture in vitro in neurogenic conditions were tagged with SPIO nanoparticles and grafted monthly by three serial injections (12 × 10(6) cells/0.5 ml) into lateral ventricle of the brain. Neural conversion of cord blood cells and superparamagnetic labeling efficiency was confirmed by gene expression, immunocytochemistry, and phantom study. MRI examination revealed the discrete hypointense areas appearing immediately after transplantation in the vicinity of lateral ventricles wall with subsequent lowering of the signal during entire period of observation. The child was followed up for 6 months after the last transplantation and his neurological status slightly but significantly improved. No clinically significant adverse events were noted. This report indicates that intracerebroventricular transplantation of autologous, neutrally committed cord blood cells is a feasible, well tolerated, and safe procedure, at least during 6 months of our observation period. Moreover, a cell-related MRI signal persisted at a wall of lateral ventricle for more than 4 months and could be monitored in transplanted brain hemisphere.

Extracellular Vesicles in Physiology, Pathology, and Therapy of the Immune and Central Nervous System, with Focus on Extracellular Vesicles Derived from Mesenchymal Stem Cells as Therapeutic Tools

Extracellular vesicles (EVs) are membrane-surrounded structures released by most cell types. They are characterized by a specific set of proteins, lipids and nucleic acids. EVs have been recognized as potent vehicles of intercellular communication to transmit biological signals between cells. In addition, pathophysiological roles of EVs in conditions like cancer, infectious diseases and neurodegenerative disorders are well established. In recent years focus has been shifted on therapeutic use of stem cell derived-EVs. Use of stem cell derived-EVs present distinct advantage over the whole stem cells as EVs do not replicate and after intravenous administration, they are less likely to trap inside the lungs. From the therapeutic perspective, the most promising cellular sources of EVs are mesenchymal stem cells (MSCs), which are easy to obtain and maintain. Therapeutic activity of MSCs has been shown in numerous animal models and the beneficial paracrine effect of MSCs may be mediated by EVs. The various components of MSC derived-EVs such as proteins, lipids, and RNA might play a specific therapeutic role. In this review, we characterize the role of EVs in immune and central nervous system (CNS); present evidences for defective signaling of these vesicles in neurodegeneration and therapeutic role of EVs in CNS.

Structural and functional characteristic of a model for deep-seated lacunar infarct in rats

Deep-brain lacunar infarct represents a significant clinical problem as it produces severe symptoms highly resistant to rehabilitation. The limited area of necrosis may facilitate neurorepair via the action of various novel neuroprotective strategies including cell-based therapies. The lesion was induced by stereotactic injection of ouabain into adult rat brains. Subsequent behavioral testing involved beam walking task, rotarod, visual discrimination task and apomorphine rotation. For morphological and topographical analysis brain slices were stained with H-E and evaluated under light microscopy. Lesion size was measured in absolute terms and in relation to the whole brain volume. Immunohistochemical analysis for the co-localization of BrdU with specific cell-type markers (PSA-NCAM, NG2, beta-tubulin III, GFAP, ED1) have has been performed, to determine the fate of newly generated cells with emphasis on evidence of neurogenesis. The lesion involved the basal ganglia, basal forebrain nuclei, internal capsule and striatum (just 1-2% of total brain volume). Significant and relatively stable behavioral deficits were observed up to 30 days. Furthermore, large numbers of cells are seen to be newly generated in response to injury with a significant proportion of these being present on account of neurogenesis.

Survival of Neural Progenitors Allografted into the CNS of Immunocompetent Recipients is Highly Dependent on Transplantation Site

Allografts continue to be used in clinical neurotransplantation studies; hence, it is crucial to understand the mechanisms that govern allograft tolerance. We investigated the impact of transplantation site within the brain on graft survival. Mouse [Friend leukemia virus, strain B (FVB)] glial precursors, transfected with luciferase, were injected (3 × 105) into the forceps minor (FM) or striatum (STR). Immunodeficient rag2−/- and immuno-competent BALB/c mice were used as recipients. Magnetic resonance imaging (MRI) confirmed that cells were precisely deposited at the selected coordinates. The graft viability was assessed noninvasively with biolumi-nescent imaging (BLI) for a period of 16 days. Regardless of implantation site, all grafts (n = 10) deposited in immunodeficient animals revealed excellent survival. In contrast, immunocompetent animals only accepted grafts at the STR site (n = 10), whereas all the FM grafts were rejected (n = 10). To investigate the factors that led to rejection of FM grafts, with acceptance of STR grafts, another group of animals (n = 19) was sacrificed during the prerejection period, on day 5. Near-infrared fluorescence imaging with IRDye 800CW–polyethylene glycol probe displayed similar blood–brain barrier disruption at both graft locations. The morphological distribution of FM grafts was cylindrical, parallel to the needle track, whereas cells transplanted into the STR accumulated along the border between the STR and the corpus callosum. There was significantly less infiltration by both innate and adaptive immune cells in the STR grafts, especially along the calloso-striatal border. With allograft survival being dependent on the transplantation site, the anatomical coordinates of the graft target should always be taken into account as it may determine the success or failure of therapy.

MR monitoring of minimally invasive delivery of mesenchymal stem cells into the porcine intervertebral disc.

Purpose Bone marrow stem cell therapy is a new, attractive therapeutic approach for treatment of intervertebral disc (IVD) degeneration; however, leakage and backflow of transplanted cells into the structures surrounding the disc may lead to the formation of undesirable osteophytes. The purpose of this study was to develop a technique for minimally invasive and accurate delivery of stem cells. Methods Porcine mesenchymal stem cells (MSCs) were labeled with superparamagnetic iron oxide nanoparticles (SPIO, Molday ION rhodamine) and first injected into the explanted swine lumbar IVD, followed by ex vivo 3T MRI. After having determined sufficient sensitivity, IVD degeneration was then induced in swine (n=3) by laser-evaporation. 3 x 106 SPIO-labeled cells embedded within hydrogel were injected in 2 doses using a transcutaneous cannula and an epidural anesthesia catheter. T2-weighted MR images were obtained at 3T before and immediately after cell infusion. Two weeks after injection, histological examination was performed for detection of transplanted cells. Results MSCs were efficiently labeled with Molday ION rhodamine. Cells could be readily detected in the injected vertebral tissue explants as distinct hypointensities with sufficient sensitivity. MR monitoring indicated that the MSCs were successfully delivered into the IVD in vivo, which was confirmed by iron-positive Prussian Blue staining of the tissue within the IVD. Conclusion We have developed a technique for non-invasive monitoring of minimally invasive stem delivery into the IVD at 3T. By using a large animal model mimicking the anatomy of IVD in humans, the present results indicate that this procedure may be clinically feasible.