Developmentally engineered bio-assemblies releasing neurotrophic exosomes guide in situ neuroplasticity following spinal cord injury.

The emerging tissue-engineered bio-assemblies are revolutionizing the regenerative medicine, and provide a potential program to guarantee predictive performance of stem-cell-derived treatments and hence support their clinical translation. Mesenchymal stem cell (MSC) showed the attractive potential for the therapy of nervous system injuries, especially spinal cord injury (SCI), and yet failed to make an impact on clinical outcomes. Herein, under the guidance of the embryonic development theory that appropriate cellular coarctations or clustering are pivotal initiators for the formation of geometric and functional tissue structures, a developmentally engineered strategy was established to assemble DPMSCs into a bio-assembly termed Spinor through a three-level sequential induction programme including reductant, energy and mechanical force stimulation. Spinor exhibited similar geometric construction with spinal cord tissue and attain autonomy to released exosome with the optimized quantity and quality for suppressing cicatrization and inflammation and promoting axonal regeneration. As a spinal cord fascia and exosome mothership, Spinor guided the neuroplasticity of spinal cord , and caused the significant motor improvement, sensory recovery, and faster urinary reflex restoration in rats following SCI, while maintaining a highly favorable biosafety profile. Collectively, Spinor not only is a potentially clinical therapeutic paradigm as a living "exosome mothership" for revisiting Prometheus' Myth in SCI, but can be viewed allowing developmentally engineered manufacturing of biomimetic bio-assemblies with complex topology features and inbuilt biofunction attributes towards the regeneration of complex tissues including nervous system.