Rotary jet-spun porous microfibers as scaffolds for stem cells delivery to central nervous system injury.

Stem cell transplantation is a promising strategy to treat brain injuries. However, cell-based therapies are limited because poor local cell engraftment. Here, we present a polylactic acid (PLA) scaffold to support mesenchymal stem cells (MSCs) delivery in stroke. We isolated bone marrow MSCs from adult C57/Bl6 mice, cultured them on PLA polymeric rough microfibrous (PRM) scaffolds obtained by rotary jet spinning, and transplanted over the brains of adult C57/Bl6 mice, carrying thermocoagulation-induced cortical stroke. No inflammatory response to PRM was found. MSCs transplantation significantly reduced the area of the lesion and PRM delivery increased MSCs retention at the injury site. In addition, PRM upregulated α6-integrin and CXCL12 production, which may be the cause for greater cell retention at the lesion site and may provide additional benefit to MSCs transplantation procedures. We conclude that PRM scaffolds offer a promising new system to deliver stem cells to injured areas of the brain.

Chondroitin Sulfate Impairs Neural Stem Cell Migration Through ROCK Activation.

Brain injuries such as trauma and stroke lead to glial scar formation by reactive astrocytes which produce and secret axonal outgrowth inhibitors. Chondroitin sulfate proteoglycans (CSPG) constitute a well-known class of extracellular matrix molecules produced at the glial scar and cause growth cone collapse. The CSPG glycosaminoglycan side chains composed of chondroitin sulfate (CS) are responsible for its inhibitory activity on neurite outgrowth and are dependent on RhoA activation. Here, we hypothesize that CSPG also impairs neural stem cell migration inhibiting their penetration into an injury site. We show that DCX+ neuroblasts do not penetrate a CSPG-rich injured area probably due to Nogo receptor activation and RhoA/ROCK signaling pathway as we demonstrate in vitro with neural stem cells cultured as neurospheres and pull-down for RhoA. Furthermore, CS-impaired cell migration in vitro induced the formation of large mature adhesions and altered cell protrusion dynamics. ROCK inhibition restored migration in vitro as well as decreased adhesion size.

Medial Ganglionic Eminence Cells Freshly Obtained or Expanded as Neurospheres Show Distinct Cellular and Molecular Properties in Reducing Epileptic Seizures.

AIMS: Medial ganglionic eminence (MGE) progenitors give rise to inhibitory interneurons and may serve as an alternative cell source for large-scale cell transplantation for epilepsy after in vitro expansion. We investigated whether modifications in the culture medium of MGE neurospheres affect neuronal differentiation and expression of MGE-specific genes. In vivo, we compared anticonvulsant effects and cell differentiation pattern among neurospheres grown in different culture media and compared them with freshly harvested MGE cells. METHODS: We used four variations of cell culture: standard, containing growth factors (EGF/FGF-2) (GF); addition of retinoic acid (GF-RA); withdrawal of EGF/FGF-2 (WD); and addition of retinoic acid and withdrawal of EGF/FGF-2 (WD-RA). Based on in vitro results neurosphere-grown (WD-RA or GF conditions) or fresh MGE cells were transplanted into the hippocampus. RESULTS: In vitro WD-RA showed increased neuronal population and higher expression of Dlx1, Nkx2.1, and Lhx6 genes in comparison with GF culture condition. After transplantation, fresh MGE cells and neurospheres (GF) showed anticonvulsant effects. However, fresh MGE cells differentiated preferentially into inhibitory neurons, while GF gave rise to glial cells. CONCLUSION: We conclude that freshly isolated and neurosphere-grown MGE cells reduced seizures by different mechanisms (inhibitory interneurons vs. astrocytes). Fresh MGE cells appear more appropriate for cell therapies targeting inhibitory interneurons for conferring anticonvulsant outcomes.

CXCL12 N-terminal end is sufficient to induce chemotaxis and proliferation of neural stem/progenitor cells.

Neural stem/progenitor cells (NSC) respond to injury after brain injuries secreting IL-1, IL-6, TNF-α, IL-4 and IL-10, as well as chemokine members of the CC and CXC ligand families. CXCL12 is one of the chemokines secreted at an injury site and is known to attract NSC-derived neuroblasts, cells that express CXCL12 receptor, CXCR4. Activation of CXCR4 by CXCL12 depends on two domains located at the N-terminal of the chemokine. In the present work we aimed to investigate if the N-terminal end of CXCL12, where CXCR4 binding and activation domains are located, was sufficient to induce NSC-derived neuroblast chemotaxis. Our data show that a synthetic peptide analogous to the first 21 amino acids of the N-terminal end of CXCL12, named PepC-C (KPVSLSYRCPCRFFESHIARA), is able to promote chemotaxis of neuroblasts in vivo, and stimulate chemotaxis and proliferation of CXCR4+ cells in vitro, without affecting NSC fate. We also show that PepC-C upregulates CXCL12 expression in vivo and in vitro. We suggest the N-terminal end of CXCL12 is responsible for a positive feedback loop to maintain a gradient of CXCL12 that attracts neuroblasts from the subventricular zone into an injury site.

Mesenchymal stem cell therapy modulates the inflammatory response in experimental traumatic brain injury.

Therapy with mesenchymal stem cells (MSCs) has showed to be promising due to its immunomodulatory function. Traumatic brain injury (TBI) triggers immune response and release of inflammatory mediators, mainly cytokines, by glial cells creating a hostile microenvironment for endogenous neural stem cells (NSCs). We investigated the effects of factors secreted by MSCs on NSC in vitro and analyzed cytokines expression in vitro in a TBI model. Our in vitro results show that MSC-secreted factors increase NSC proliferation and induce higher expression of GFAP, indicating a tendency toward differentiation into astrocytes. In vivo experiments showed that MSC injection at an acute model of brain injury diminishes a broad profile of cytokines in the tissue, suggesting that MSC-secreted factors may modulate the inflammation at the injury site, which may be of interest to the development of a favorable microenvironment for endogenous NSC and consequently to repair the injured tissue.