Lithium Suppresses Astrogliogenesis by Neural Stem and Progenitor Cells by Inhibiting STAT3 Pathway Independently of Glycogen Synthase Kinase 3 Beta

Transplanted neural stem and progenitor cells (NSCs) produce mostly astrocytes in injured spinal cords. Lithium stimulates neurogenesis by inhibiting GSK3b (glycogen synthetase kinase 3-beta) and increasing WNT/beta catenin. Lithium suppresses astrogliogenesis but the mechanisms were unclear. We cultured NSCs from subventricular zone of neonatal rats and showed that lithium reduced NSC production of astrocytes as well as proliferation of glia restricted progenitor (GRP) cells. Lithium strongly inhibited STAT3 (signal transducer and activator of transcription 3) activation, a messenger system known to promote astrogliogenesis and cancer. Lithium abolished STAT3 activation and astrogliogenesis induced by a STAT3 agonist AICAR (5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside), suggesting that lithium suppresses astrogliogenesis by inhibiting STAT3. GSK3β inhibition either by a specific GSK3β inhibitor SB216763 or overexpression of GID5-6 (GSK3β Interaction Domain aa380 to 404) did not suppress astrogliogenesis and GRP proliferation. GSK3β inhibition also did not suppress STAT3 activation. Together, these results indicate that lithium inhibits astrogliogenesis through non-GSK3β-mediated inhibition of STAT. Lithium may increase efficacy of NSC transplants by increasing neurogenesis and reducing astrogliogenesis. Our results also may explain the strong safety record of lithium treatment of manic depression. Millions of people take high-dose (>1 gram/day) lithium carbonate for a lifetime. GSK3b inhibition increases WNT/beta catenin, associated with colon and other cancers. STAT3 inhibition may reduce risk for cancer

Depletion of Cell Adhesion Molecule L1 from Microglia and Macrophages Reduces Recovery After Spinal Cord Injury

The young mammalian central nervous system regenerates after spinal cord injury and recovers locomotion, whereas adult mice only show limited recovery that depends on the injury severity, genetic background, and physical therapy. At the molecular level, key regulators that contribute to recovery are cell adhesion molecules, such as L1CAM (L1). At the cell surface, L1 functions as a homotypic receptor that signal-transduces crucial functions in neuronal migration and survival, neurite outgrowth, myelination, formation of synapses, and synaptic plasticity. In the adult central nervous system, L1 is expressed only by neurons. We now show that L1 is unexpectedly also expressed by 26% microglia, freshly isolated from a 7-day-old mouse brain. At postnatal day 21, only 3% of microglia are L1-positive. Using a mouse mutant in which L1 is deleted specifically in monocytes of 10- to 14-week-old mice, functional recovery was reduced up to 4 weeks after injury at lower thoracic spinal levels. Also, NF200-immunoreactive and 5-HT-immunoreactive fibers were found decreased below the injury site as compared to wild-type mice. In conclusion, microglial cells that express L1 stimulate neurite outgrowth in vitro, improve functional recovery after spinal cord injury in adult mice, and increase fiber densities caudal to the lesion site

Quantitative Analysis of SSEA3+ Cells from Human Umbilical Cord after Magnetic Sorting

Multilineage-differentiating stress-enduring (Muse) cells are a population of pluripotent stage-specific embryonic antigen 3 (SSEA3)+ mesenchymal stem cells first described by Mari Dezawa in 2010. Although some investigators have reported SSEA3+ mesenchymal cells in umbilical cord tissues, none have quantitatively compared SSEA3+ cells isolated from Wharton’s jelly (WJ) and the cord lining (CL) of human umbilical cords (HUCs). We separated WJ and the CL from HUCs, cultured mesenchymal stromal cells (MSCs) isolated from these two tissues with collagenase, and quantified the percentage of SSEA3+ cells over three passages. The first passage had 5.0% ± 4.3% and 5.3% ± 5.1% SSEA3+ cells from WJ and the CL, respectively, but the percentage of SSEA3+ cells decreased significantly ( P &lt; 0.05) between P0 and P2 in the CL group and between P0 and P1 in the WJ group. Magnetic-activated cell sorting (MACS) markedly enriched SSEA3+ cells to 91.4% ± 3.2%. Upon culture of the sorted population, we found that the SSEA3+ percentage ranged from 62.5% to 76.0% in P2–P5 and then declined to 42.0%–54.7% between P6 and P9. At P10, the cultures contained 37.4% SSEA3+ cells. After P10, we resorted the cells and achieved 89.4% SSEA3+ cells in culture. The procedure for MACS-based enrichment of SSEA3+ cells, followed by expansion in culture and a re-enrichment step, allows the isolation of many millions of SSEA3+ cells in relatively pure culture. When cultured, the sorted SSEA3+ cells differentiated into embryoid spheres and survived 4 weeks after transplant into a contused Sprague-Dawley rat spinal cord. The transplanted SSEA3+ cells migrated into the injury area from four injection points around the contusion site and did not produce any tumors. The umbilical cord is an excellent source of fetal Muse cells, and our method allows the practical and efficient isolation and expansion of relatively pure populations of SSEA3+ Muse cells that can be matched by human leukocyte antigen for transplantation in human trials. </jats:p

Supplementary Methods from MIF Produced by Bone Marrow–Derived Macrophages Contributes to Teratoma Progression after Embryonic Stem Cell Transplantation

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