P2X7 Receptor Triggers Lysosomal Leakage Through Calcium Mobilization in a Mechanism Dependent on Pannexin-1 Hemichannels.

The P2X7 receptor is a critical purinergic receptor in immune cells. Its activation was associated with cathepsin release into macrophage cytosol, suggesting its involvement in lysosomal membrane permeabilization (LMP) and leakage. Nevertheless, the mechanisms by which P2X7 receptor activation induces LMP and leakage are unclear. This study investigated cellular mechanisms associated with endosomal and lysosomal leakage triggered by P2X7 receptor activation. We found that ATP at 500 µM and 5 mM (but not 50 µM) induced LMP in non-stimulated peritoneal macrophages. This effect was not observed in P2X7-deficient or A740003-pretreated macrophages. We found that the P2X7 receptor and pannexin-1 channels mediate calcium influx that might be important for activating specific ion channels (TRPM2 and two-pore channels) on the membranes of late endosomes and lysosomes leading to LMP leakage and consequent cathepsin release. These findings suggest the critical role of the P2X7 receptor in inflammatory and infectious diseases via lysosomal dysfunction.

GD3 synthase deletion alters retinal structure and impairs visual function in mice.

Gangliosides are glycosphingolipids abundantly expressed in the vertebrate nervous system, and are classified into a-, b-, or c-series according to the number of sialic acid residues. The enzyme GD3 synthase converts GM3 (an a-series ganglioside) into GD3, a b-series ganglioside highly expressed in the developing and adult retina. The present study evaluated the visual system of GD3 synthase knockout mice (GD3s-/- ), morphologically and functionally. The absence of b- series gangliosides in the retinas of knockout animals was confirmed by mass spectrometry imaging, which also indicated an accumulation of a-series gangliosides, such as GM3. Retinal ganglion cell (RGC) density was significantly reduced in GD3s-/- mice, with a similar reduction in the number of axons in the optic nerve. Knockout animals also showed a 15% reduction in the number of photoreceptor nuclei, but no difference in the bipolar cells. The area occupied by GFAP-positive glial cells was smaller in GD3s-/- retinas, but the number of microglial cells/macrophages did not change. In addition to the morphological alterations, a 30% reduction in light responsiveness was detected through quantification of pS6-expressing RGC, an indicator of neural activity. Furthermore, electroretinography (ERG) indicated a significant reduction in RGC and photoreceptor electrical activity in GD3s-/- mice, as indicated by scotopic ERG and pattern ERG (PERG) amplitudes. Finally, evaluation of the optomotor response demonstrated that GD3s-/- mice have reduced visual acuity and contrast sensitivity. These results suggest that b-series gangliosides play a critical role in regulating the structure and function of the mouse visual system.

Human mesenchymal stem cell therapy promotes retinal ganglion cell survival and target reconnection after optic nerve crush in adult rats.

BACKGROUND: Optic-nerve injury results in impaired transmission of visual signals to central targets and leads to the death of retinal ganglion cells (RGCs) and irreversible vision loss. Therapies with mesenchymal stem cells (MSCs) from different sources have been used experimentally to increase survival and regeneration of RGCs. METHODS: We investigated the efficacy of human umbilical Wharton's jelly-derived MSCs (hWJ-MSCs) and their extracellular vesicles (EVs) in a rat model of optic nerve crush. RESULTS: hWJ-MSCs had a sustained neuroprotective effect on RGCs for 14, 60, and 120 days after optic nerve crush. The same effect was obtained using serum-deprived hWJ-MSCs, whereas transplantation of EVs obtained from those cells was ineffective. Treatment with hWJ-MSCs also promoted axonal regeneration along the optic nerve and reinnervation of visual targets 120 days after crush. CONCLUSIONS: The observations showed that this treatment with human-derived MSCs promoted sustained neuroprotection and regeneration of RGCs after optic nerve injury. These findings highlight the possibility to use cell therapy to preserve neurons and to promote axon regeneration, using a reliable source of human MSCs.

Erratum to "Preconditioning of Rat Bone Marrow-Derived Mesenchymal Stromal Cells with Toll-Like Receptor Agonists".

[This corrects the article DOI: 10.1155/2019/7692973.].

Neuroprotection from optic nerve injury and modulation of oxidative metabolism by transplantation of active mitochondria to the retina.

Mitochondrial dysfunctions are linked to a series of neurodegenerative human conditions, including Parkinson's disease, schizophrenia, optic neuropathies, and glaucoma. Recently, a series of studies have pointed mitotherapy - exogenous mitochondria transplant - as a promising way to attenuate the progression of neurologic disorders; however, the neuroprotective and pro-regenerative potentials of isolated mitochondria in vivo have not yet been elucidated. In this present work, we tested the effects of transplants of active (as well-coupled organelles were named), liver-isolated mitochondria on the survival of retinal ganglion cells and axonal outgrowth after optic nerve crush. Our data show that intravitreally transplanted, full active mitochondria incorporate into the retina, improve its oxidative metabolism and electrophysiological activity at 1 day after transplantation. Moreover, mitotherapy increases cell survival in the ganglion cell layer at 14 days, and leads to a higher number of axons extending beyond the injury site at 28 days; effects that are dependent on the organelles' structural integrity. Together, our findings support mitotherapy as a promising approach for future therapeutic interventions upon central nervous system damage.

Effects of a combinatorial treatment with gene and cell therapy on retinal ganglion cell survival and axonal outgrowth after optic nerve injury.

After an injury, axons in the central nervous system do not regenerate over large distances and permanently lose their connections to the brain. Two promising approaches to correct this condition are cell and gene therapies. In the present work, we evaluated the neuroprotective and neuroregenerative potential of pigment epithelium-derived factor (PEDF) gene therapy alone and combined with human mesenchymal stem cell (hMSC) therapy after optic nerve injury by analysis of retinal ganglion cell survival and axonal outgrowth. Overexpression of PEDF by intravitreal delivery of AAV2 vector significantly increased Tuj1-positive cells survival and modulated FGF-2, IL-1ß, Iba-1, and GFAP immunostaining in the ganglion cell layer (GCL) at 4 weeks after optic nerve crush, although it could not promote axonal outgrowth. The combination of AAV2.PEDF and hMSC therapy showed a higher number of Tuj1-positive cells and a pronounced axonal outgrowth than unimodal therapy after optic nerve crush. In summary, our results highlight a synergistic effect of combined gene and cell therapy relevant for future therapeutic interventions regarding optic nerve injury.

Preconditioning of Rat Bone Marrow-Derived Mesenchymal Stromal Cells with Toll-Like Receptor Agonists.

Bone marrow-derived mesenchymal stromal cells (BM-MSCs) are dynamic cells that can sense the environment, adapting their regulatory functions to different conditions. Accordingly, the therapeutic potential of BM-MSCs can be modulated by preconditioning strategies aimed at modifying their paracrine action. Although rat BM-MSCs (rBM-MSCs) have been widely tested in preclinical research, most preconditioning studies have employed human and mouse BM-MSCs. Herein, we investigated whether rBM-MSCs modify their phenotype and paracrine functions in response to Toll-like receptor (TLR) agonists. The data showed that rBM-MSCs expressed TLR3, TLR4, and MDA5 mRNA and were able to internalize polyinosinic-polycytidylic acid (Poly(I:C)), a TLR3/MDA5 agonist. rBM-MSCs were then stimulated with Poly(I:C) or with lipopolysaccharide (LPS, a TLR4 agonist) for 1 h and were grown under normal culture conditions. LPS or Poly(I:C) stimulation did not affect the viability or the morphology of rBM-MSCs and did not modify the expression pattern of key cell surface markers. Poly(I:C) did not induce statistically significant changes in the release of several inflammatory mediators and VEGF by rBM-MSCs, although it tended to increase IL-6 and MCP-1 secretion, whereas LPS increased the release of IL-6, MCP-1, and VEGF, three factors that were constitutively secreted by unstimulated cells. The neurotrophic activity of the conditioned medium from unstimulated and LPS-preconditioned rBM-MSCs was investigated using dorsal root ganglion explants, showing that soluble factors produced by unstimulated and LPS-preconditioned rBM-MSCs can stimulate neurite outgrowth similarly, in a VEGF-dependent manner. LPS-preconditioned cells, however, were slightly more efficient in increasing the number of regrowing axons in a model of sciatic nerve transection in rats. In conclusion, LPS preconditioning boosted the production of constitutively secreted factors by rBM-MSCs, without changing their mesenchymal identity, an effect that requires further investigation in exploratory preclinical studies.

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 2×10(7) 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 3days 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.

Effects of protein restriction during gestation and lactation on cell proliferation in the hippocampus and subventricular zone: functional implications. Protein restriction alters hippocampal/SVZ cell proliferation.

There is no consensus about the effects of protein restriction on neurogenesis and behavior. Here, for the first time, we evaluated the effects of protein restriction during gestation and lactation, on the two major neurogenic regions of the adult brain, the subgranular zone (SGZ) of the hippocampal dentate gyrus and the subventricular zone (SVZ), simultaneously. We also assessed different types of behavior relevant to each region. After mating, pregnant Wistar rats were divided into a control group (CG) that received a normal diet (20% protein); and a protein-restriction group (PRG) that received a low-protein diet (8% protein). After birth, the same diets were provided to the mother and pups until weaning, when some rats were analyzed and others received a normal-protein diet until adulthood. Different sets of rats were used for cellular and behavioral studies in juvenile or adult age. Brains were processed for immunohistochemistry anti-BrdU, anti-Ki67, or anti-pHisH3. Juvenile and adult rats from distinct litters also underwent several behavioral tests. Our data show that early protein restriction results in a reduction of hippocampal progenitors and deficits in object recognition during adult life. Moreover, longer periods of immobility in the tail suspension and in the forced swimming tests revealed that PRG rats show a depressive behavior at 21 days of age (P21) and in adulthood. Furthermore, we suggest that despite the reduced number/proliferation of neural stem cells (B and/or E cells) in SVZ there is a compensatory mechanism in which the progenitors (types C and A cells) proliferate in a higher rate, without affecting olfactory ability in adulthood.

Neuroprotective effects and magnetic resonance imaging of mesenchymal stem cells labeled with SPION in a rat model of Huntington's disease.

Bone marrow mesenchymal stem cells (MSC) have been tested and proven effective in some neurodegenerative diseases, but their tracking after transplantation may be challenging. Our group has previously demonstrated the feasibility and biosafety of rat MSC labeling with iron oxide superparamagnetic nanoparticles (SPION). In this study, we investigated the therapeutic potential of SPION-labeled MSC in a rat model of Huntington's disease, a genetic degenerative disease with characteristic deletion of striatal GABAergic neurons. MSC labeled with SPION were injected into the striatum 1h after quinolinic acid injection. FJ-C analysis demonstrated that MSC transplantation significantly decreased the number of degenerating neurons in the damaged striatum 7 days after lesion. In this period, MSC transplantation enhanced the striatal expression of FGF-2 but did not affect subventricular zone proliferation, as demonstrated by Ki67 proliferation assay. In addition, MSC transplantation significantly reduced the ventriculomegaly in the lesioned brain. MRI and histological techniques detected the presence of the SPION-labeled cells at the lesion site. SPION-labeled MSC produced magnetic resonance imaging (MRI) signals that were visible for at least 60 days after transplantation. Our data highlight the potential of adult MSC to reduce brain damage under neurodegenerative diseases and indicate the use of nanoparticles in cell tracking, supporting their potential as valuable tools for cell therapy.

Response of osteoblastic cells to titanium submitted to three different surface treatments.

In the complex process of bone formation at the implant-tissue interface, surface properties are relevant factors modulating osteoblastic function. In this study, commercially pure titanium (cp Ti) samples were prepared with different surface characteristics using chemical attack with a sulfuric acid/hydrochloric acid based solution (treatment A); chemical attack plus anodic oxidation using phosphoric acid (treatment B); and chemical attack plus thermal oxidation followed by immersion in a sodium fluoride solution (treatment C). The samples were characterized by scanning electron microscopy (SEM), contact profilometry and contact angle. The biological performance of the prepared surfaces was evaluated using mice osteoblastic cell cultures for up to 21 days. Cells seeded on the different titanium samples showed similar behavior during cell attachment and spreading. However, cellular proliferation and differentiation were higher for samples submitted to treatments A and C (p < or = 0.05; n = 3), which were less rough and showed surface free energy with smaller polar components.

Response of osteoblastic cells to titanium submitted to three different surface treatments / Resposta de células osteoblásticas ao titânio submetido a três diferentes tratamentos de superfície

No complexo processo de formação óssea na interface implante-osso, as propriedades de superfície são um importante fator modulador da função osteoblástica. No presente estudo, foram preparadas amostras de titânio comercialmente puro (cp Ti) com diferentes propriedades de superfície por meio de ataque químico com solução à base de ácido sulfúrico/clorídrico (tratamento A); ataque químico seguido de oxidação anódica com ácido fosfórico (tratamento B); e ataque químico seguido de oxidação térmica e imersão em fluoreto de sódio (tratamento C). As chapas foram caracterizadas por meio de microscopia eletrônica de varredura (MEV), perfilometria e ângulo de contato. O comportamento de células osteoblásticas de camundongo foi acompanhado por três semanas. As células cultivadas sobre os diferentes substratos de titânio apresentaram um modelo de comportamento similar durante as etapas de adesão e espalhamento. No entanto, a proliferação e a diferenciação celulares foram maiores nas amostras submetidas aos tratamentos A e C, que se apresentaram menos rugosas e com energia livre de superfície com menores componentes polares.