Synaptic development in the injured spinal cord cavity following co-transplantation of fetal spinal cord cells and autologous activated Schwann cells

Transplantation of activated transgenic Schwann cells or a fetal spinal cord cell suspension has been widely used to treat spinal cord injury. However, little is known regarding the effects of co-transplantation. In the present study, autologous Schwann cells in combination with a fetal spinal cord cell suspension were transplanted into adult Wistar rats with spinal cord injury, and newly generated axonal connections were observed ultrastructurally. Transmission electron microscopic observations showed that the neuroblast first presented cytoplasmic processes, followed by pre- and postsynaptic membranes with low electron density forming a dense projection. The number and types of synaptic vesicles were increased. Synaptic connections developed from single cell body-dendritic synapses into multiple cell body-dendritic and dendrite-dendritic synapses. In addition, the cell organs of the transplanted neuroblast, oligodendroblast and astroblast matured gradually. The blood-brain barrier appeared subsequently. Moreover, neurofilament, histamine, calcitonin-gene-related peptides, and glial fibrillary acidic protein positive fibers were observed in the transplant region. These findings demonstrate that fetal spinal cord cells in the presence of autologous activated Schwann cells can develop into mature synapses in the cavity of injured spinal cords, suggesting the possibility of information exchange through the reconstructed synapse between fetal spinal cord cells and the host.

Inventory Management with Trade Policy Uncertainty

This paper develops a theoretical model to describe how exporting firms manage their inventory stocks in response to an exogenous trade policy uncertainty shock.Using firm-level data from China Industrial Enterprise Database and China Customs Database on inventory and exports over the period around China's WTO accession,we show that a reduction in trade policy uncertainty significantly increased exporting firms'inventory holdings.The result wasrobust tovarious robustness checks.This effect was found to be stronger for private and foreign firms than state-owned enterprises and mainly driven by firms from the coastal region.We also found that the reduction in trade policy uncertainty increased the frequency and the average volume of export transactions,and that this was the mechanism behind the effect.This paper helps to understand exporting firms'optimal inventory problem arising from tradepolicyuncertaintyand shocks.