(2008). Guidelines for the use and interpretation of assays for monitoring autophagy in higher eukaryotes. Autophagy: Vol. 4, No. 2, pp. 151-175.

Various types of induced pluripotent stem (iPS) cells have been established by different methods, and each type exhibits different biological properties. Before iPS cell-based clinical applications can be initiated, detailed evaluations of the cells, including their differentiation potentials and tumorigenic activities in different contexts, should be investigated to establish their safety and effectiveness for cell transplantation therapies. Here we show the directed neural differentiation of murine iPS cells and examine their therapeutic potential in a mouse spinal cord injury (SCI) model. “Safe” iPS-derived neurospheres, which had been pre-evaluated as nontumorigenic by their transplantation into nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mouse brain, produced electrophysiologically functional neurons, astrocytes, and oligodendrocytes in vitro. Furthermore, when the safe iPS-derived neurospheres were transplanted into the spinal cord 9 d after contusive injury, they differentiated into all three neural lineages without forming teratomas or other tumors. They also participated in remyelination and induced the axonal regrowth of host 5HT ⁺ serotonergic fibers, promoting locomotor function recovery. However, the transplantation of iPS-derived neurospheres pre-evaluated as “unsafe” showed robust teratoma formation and sudden locomotor functional loss after functional recovery in the SCI model. These findings suggest that pre-evaluated safe iPS clone-derived neural stem/progenitor cells may be a promising cell source for transplantation therapy for SCI.

The concentration of cytoplasmic free calcium (Ca ²⁺ ) increases in various stimulated cells in a wave (Ca ²⁺ wave) and in periodic transients (Ca ²⁺ oscillations). These phenomena are explained by inositol 1,4,5-trisphosphate (IP ₃ )-induced Ca ²⁺ release (IICR) and Ca ²⁺ -induced Ca ²⁺ release (CICR) from separate intracellular stores, but decisive evidence is lacking. A monoclonal antibody to the IP ₃ receptor inhibited both IICR and CICR upon injection of IP ₃ and Ca ²⁺ into hamster eggs, respectively. The antibody completely blocked sperm-induced Ca ²⁺ waves and Ca ²⁺ oscillations. The results indicate that Ca ²⁺ release in fertilized hamster eggs is mediated solely by the IP ₃ receptor, and Ca ²⁺ -sensitized IICR, but not CICR, generates Ca ²⁺ waves and Ca ²⁺ oscillations.

Orphan No More: The glutamate receptor δ2 (GluD2), another member of the ionotropic glutamate receptor family, has long been considered to be an orphan receptor because there are no known endogenous ligands. Nevertheless, GluD2 is essential for the normal development of cerebellar circuits. Using immunocytochemistry, binding assays, electrophysiology, and freeze-fracture electron microscopy, Matsuda et al. (p. 363 ) found that Cbln1, a soluble protein secreted from cerebellar granule cells, binds to the extracellular N terminus of GluD2 on Purkinje cells. Binding has two independent consequences: First, it leads to presynaptic differentiation and second, it causes postsynaptic clustering of several important synapse-specific molecules. Both events are needed for synapse formation between granule cells and Purkinje cells.