Neurons Generated by Mouse ESCs with Hippocampal or Cortical Identity Display Distinct Projection Patterns When Co-transplanted in the Adult Brain

The capability of generating neural precursor cells with distinct types of regional identity in vitro has recently opened new opportunities for cell replacement in animal models of neurodegenerative diseases. By manipulating Wnt and BMP signaling, we steered the differentiation of mouse embryonic stem cells (ESCs) toward isocortical or hippocampal molecular identity. These two types of cells showed different degrees of axonal outgrowth and targeted different regions when co-transplanted in healthy or lesioned isocortex or in hippocampus. In hippocampus, only precursor cells with hippocampal molecular identity were able to extend projections, contacting CA3. Conversely, isocortical-like cells were capable of extending long-range axonal projections only when transplanted in motor cortex, sending fibers toward both intra- and extra-cortical targets. Ischemic damage induced by photothrombosis greatly enhanced the capability of isocortical-like cells to extend far-reaching projections. Our results indicate that neural precursors generated by ESCs carry intrinsic signals specifying axonal extension in different environments. In this article, Terrigno and colleagues show that Wnt and BMB signaling control the differentiation of mouse ESCs toward isocortical or hippocampal identity in vitro. The two types of cells contact different regions when transplanted in adult brain. Photothrombotic lesion favors neurite elongation of cortical transplanted cells, which can improve the motor performance after ischemic damage of motor cortex.