Myelin-Independent Therapeutic Potential of Canine Glial-Restricted Progenitors Transplanted in Mouse Model of Dysmyelinating Disease.

BACKGROUND: Dysfunction of glia contributes to the deterioration of the central nervous system in a wide array of neurological disorders, thus global replacement of glia is very attractive. Human glial-restricted precursors (hGRPs) transplanted intraventricularly into neonatal mice extensively migrated and rescued the lifespan in half of the studied mice, whereas mouse GRPs (mGRPs) presented no therapeutic benefit. We studied in the same experimental setting canine GRPs (cGRP) to determine whether their therapeutic potential falls between hGRPs and mGRPs. Additional motivation for the selection of cGRPs was a potential for use in veterinary medicine. METHODS: cGRPs were extracted from the brain of dog fetuses. The cells were transplanted into the anterior or posterior aspect of the lateral ventricle (LV) of neonatal, immunodeficient, dysmyelinated mice (Mbpshi, Rag2 KO; shiv/rag2). Outcome measures included early cell biodistribution, animal survival and myelination assessed with MRI, immunohistochemistry and electron microscopy. RESULTS: Grafting of cGRP into posterior LV significantly extended animal survival, whereas no benefit was observed after anterior LV transplantation. In contrast, myelination of the corpus callosum was more prominent in anteriorly transplanted animals. CONCLUSIONS: The extended survival of animals after transplantation of cGRPs could be explained by the vicinity of the transplant near the brain stem.

In Vitro Assessment of Fluorine Nanoemulsion-Labeled Hyaluronan-Based Hydrogels for Precise Intrathecal Transplantation of Glial-Restricted Precursors.

PURPOSE: We studied the feasibility of labeling hydrogel scaffolds with a fluorine nanoemulsion for 19F- magnetic resonance imaging (MRI) to enable non-invasive visualization of their precise placement and potential degradation. PROCEDURE: Hyaluronan-based hydrogels (activated hyaluronan, HA) with increasing concentrations of fluorine nanoemulsion (V-sense) were prepared to measure the gelation time and oscillatory stress at 1 h and 7 days after the beginning of gelation. All biomechanical measurements were conducted with an ARES 2 rheometer. Diffusion of fluorine from the hydrogel: Three hydrogels in various Vs to HA volumetric ratios (1:50, 1:10, and 1:5) were prepared in duplicate. Hydrogels were incubated at 37 °C. To induce diffusion, three hydrogels were agitated at 1000 rpm. 1H and 19F MRI scans were acquired at 1, 3, 7 days and 2 months after gel preparation on a Bruker Ascend 750 scanner. To quantify fluorine content, scans were analyzed using Voxel Tracker 2.0. Assessment of cell viability in vitro and in vivo: Luciferase-positive mouse glial-restricted progenitors (GRPs) were embedded in 0:1, 1:50, 1:10, and 1:5 Vs:HA mixtures (final cell concentration  =1 × 107/ml). For the in vitro assay, mixtures were placed in 96-wells plate in triplicate and bioluminescence was measured after 1, 3, 7, 14, 21, and 28 days. For in vivo experiments, Vs/HA mixtures containing GRPs were injected subcutaneously in SCID mice and BLI was acquired at 1, 3, 7, and 14 days post-injection. RESULTS: Mixing of V-sense at increasing ratios of 1:50, 1:10, and 1:5 v/v of fluorine/activated hyaluronan (HA) hydrogel gradually elongated the gelation time from 194 s for non-fluorinated controls to 304 s for 1:5 V-sense:HA hydrogels, while their elastic properties slightly decreased. There was no release of V-sense from hydrogels maintained in stationary conditions over 2 months. The addition of V-sense positively affected in vitro survival of scaffolded GRPs in a dose-dependent manner. CONCLUSIONS: These results show that hydrogel fluorination does not impair its beneficial properties for scaffolded cells, which may be used to visualize scaffolded GRP transplants with 19F MRI.

The role of mesenchymal stromal cells in spinal cord injury, regenerative medicine and possible clinical applications.

Diseases of the central nervous system still remain among the most challenging pathologies known to mankind, having no or limited therapeutic possibilities and a very pessimistic prognosis. Advances in stem cell biology in the last decade have shown that stem cells might provide an inexhaustible source of neurons and glia as well as exerting a neuroprotective effect on the host tissue, thus opening new horizons for tissue engineering and regenerative medicine. Here, we discuss the progress made in the cell-based therapy of spinal cord injury. An emphasis has been placed on the application of adult mesenchymal stromal cells (MSCs). We then review the latest and most significant results from in vitro and in vivo research focusing on the regenerative/neuroprotective properties of MSCs. We also attempt to correlate the effect of MSCs with the pathological events that are taking place in the nervous tissue after SCI. Finally, we discuss the results from preclinical and clinical trials involving different routes of MSC application into patients with neurological disorders of the spinal cord.