Fig. 5.

Micro-tissue engineered neural networks (Micro-TENNs) consisting of aligned axons and/or glia for CNS repair. We have developed “micro-TENNs”, which are miniature, living, preformed constructs grown in vitro that consist of discrete neuronal population(s) spanned by long axonal tracts. These living micro-TENNs reconstitute the neuroanatomy of brain pathways, and therefore may be used to physically reconstruct lost or dysfunctional neural circuits. (A-D) Confocal reconstructions of micro-TENNs labeled via immunocytochemistry to denote neuronal somata/axons (β-tubulin III; green), cell nuclei (Hoechst; blue), and glial somata/processes (glial-fibrillary acidic protein; red) at 7 days in vitro. (A) Axons projected longitudinally into the construct core, (B) while both neuronal and glial (when present) somata remained in a dense cluster on the end. (C) When glial processes were present, they also presented aligned 3-D growth, but did not project as far as the axons. (D) Overlay (scale bar = 100 um). (E) These miniature living scaffolds are designed for minimally invasive injection into the brain to simultaneously replace neurons and reconstruct long-distance axonal connections lost due to trauma, stroke, or neurodegenerative disease. Note that while (A-D) illustrates a unidirectional micro-TENN, (E) depicts the implantation of a bi-directional micro-TENN. Adapted with permission from [72].