Figure 8. Neuronal and glial cell invasion into the ECM hydrogel.

A. While most of the migrating neural progenitors (doublecortin, DCX) were seen at the host-biomaterial interface, a small number of DCX+ cells could be seen inside the material (4 mg/mL shown). B. Immunostaining with beta III-tubulin (Tuj) neuron marker revealed further differentiation of these progenitors inside, as well as in between the remnant of ECM hydrogel. Occasionally GFAP+ astrocytes were adjacent to these neurons, but often these neurons were not paired with astrocytes. C. To verify if mature neurons were being generated in this de novo tissue, NeuN staining was performed to target post-mitotic neurons that typically extend processes for tissue integration. Fewer of these were evident, mostly in between ECM hydrogel patches, rather than within the scaffold per se. D. Occasional clusters containing NeuN+ cells in between ECM hydrogel were also found, potentially illustrating different stages of development within newly forming tissue. E. Neuron and tissue maturation were evident at 90 days with some neurons extending neurofilament (NF) containing axons. F. Glia lineage cells also invaded the ECM hydrogel. There were surprisingly fewer astrocytes inside the hydrogel, whereas oligodendrocytes efficiently colonized the weaker 3 and 4 mg/mL scaffolds by 90 days post-injection.