Distribution of Mesenchymal Stem Cells and Effects on Neuronal Survival and Axon Regeneration after Optic Nerve Crush and Cell Therapy

Bone marrow-derived cells have been used in different animal models of neurological diseases. We investigated the therapeutic potential of mesenchymal stem cells (MSC) injected into the vitreous body in a model of optic nerve injury. Adult (3–5 months old) Lister Hooded rats underwent unilateral optic nerve crush followed by injection of MSC or the vehicle into the vitreous body. Before they were injected, MSC were labeled with a fluorescent dye or with superparamagnetic iron oxide nanoparticles, which allowed us to track the cells in vivo by magnetic resonance imaging. Sixteen and 28 days after injury, the survival of retinal ganglion cells was evaluated by assessing the number of Tuj1- or Brn3a-positive cells in flat-mounted retinas, and optic nerve regeneration was investigated after anterograde labeling of the optic axons with cholera toxin B conjugated to Alexa 488. Transplanted MSC remained in the vitreous body and were found in the eye for several weeks. Cell therapy significantly increased the number of Tuj1- and Brn3a-positive cells in the retina and the number of axons distal to the crush site at 16 and 28 days after optic nerve crush, although the RGC number decreased over time. MSC therapy was associated with an increase in the FGF-2 expression in the retinal ganglion cells layer, suggesting a beneficial outcome mediated by trophic factors. Interleukin-1β expression was also increased by MSC transplantation. In summary, MSC protected RGC and stimulated axon regeneration after optic nerve crush. The long period when the transplanted cells remained in the eye may account for the effect observed. However, further studies are needed to overcome eventually undesirable consequences of MSC transplantation and to potentiate the beneficial ones in order to sustain the neuroprotective effect overtime.     

Superparamagnetic iron oxide nanoparticles as a tool to track mouse neural stem cells in vivo

Cell transplantation offers a promising approach in many neurological disorders. Neural stem (NS) cells are potential candidates for cell therapy. The ability to track the grafted cells in the host tissue will refine this therapy. Superparamagnetic iron oxide nanoparticles (SPION) have been suggested as a feasible method, but there is no consensus about its safety. Here we investigated the feasibility of label NS cells with SPION and track by MRI after transplantation into mouse striatum with SPION cells and its therapeutic effects by grafting the cells into mouse striatum. We demonstrated that SPION-labeled NS cells display normal patterns of cellular processes including proliferation, migration, differentiation and neurosphere formation. Transmission electron microscopy reveals SPION in the cytoplasm of the cells, which was confirmed by microanalysis. Neurons and astrocytes generated from SPION-labeled NS cells were able to carry nanoparticles after 7 days under differentiation. SPION-labeled NS cells transplanted into striatum of mice were detected by magnetic resonance imaging (MRI) and microscopy 51 days later. In agreement with others reports, we demonstrated that NS cells are able to incorporate SPION in vitro without altering the stemness, and can survive and be tracked by MRI after they have been grafted into mice striatum.

     

Bone-marrow cell therapy induces differentiation of radial glia-like cells and rescues the number of oligodendrocyte progenitors in the subventricular zone after global cerebral ischemia

The subventricular zone (SVZ) is recognized as one of the neurogenic regions in the adult mammalian central nervous system and the presence of cells that share similar characteristics with developmental radial glia, the radial glia-like cells (RGLCs) has been demonstrated in this region. In this study, we investigated whether and how SVZ cells respond to global ischemia and/or to the intravenous transplant of bone-marrow mononuclear cells (BMMCs). Adult rats were subjected to bilateral common carotid ligation (BCCL) and after 1 day 2 × 10⁷ BMMCs or saline injection. The BMMC transplant stimulated a transitory increase in the proliferation of SVZ cells in the BCCL group. We observed a significant increase in the number of RGLCs 3 days after ischemia, in both BCCL and BCCL + BMMC groups. However, this increase persisted in the subsequent days only in BCCL animals that received the transplant. BMMC transplantation also inhibits the reduction of NG2-positive oligodendrocyte progenitors in the SVZ observed in the BCCL group. Interestingly, brain-derived neurotrophic factor (BDNF) expression was up-regulated in the SVZ in the treated animals, but not in the other groups. These data thus suggest that BMMC transplantation modulates the phenotype of RGLCs/progenitors in the SVZ and could have a protective role after ischemia.