Current methods for bioprinting functional tissue lack appropriate biofabrication techniques to build complex 3D microarchitectures essential for guiding cell growth and promoting tissue maturation1. 3D printing of central nervous system (CNS) structures has not been accomplished, possibly owing to the complexity of CNS architecture. Here, we report the use of a microscale continuous projection printing method (μCPP) to create a complex CNS structure for regenerative medicine applications in the spinal cord. μCPP can print 3D biomimetic hydrogel scaffolds tailored to the dimensions of the rodent spinal cord in 1.6 s and is scalable to human spinal cord sizes and lesion geometries. We tested the ability of µCPP 3D-printed scaffolds loaded with neural progenitor cells (NPCs) to support axon regeneration and form new ‘neural relays’ across sites of complete spinal cord injury in vivo in rodents1,2. We find that injured host axons regenerate into 3D biomimetic scaffolds and synapse onto NPCs implanted into the device and that implanted NPCs in turn extend axons out of the scaffold and into the host spinal cord below the injury to restore synaptic transmission and significantly improve functional outcomes. Thus, 3D biomimetic scaffolds offer a means of enhancing CNS regeneration through precision medicine.
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Data supporting the findings of this study are available from firstname.lastname@example.org on reasonable request. All requests for materials and data are promptly reviewed by the Office of Innovation and Commercialization—University of California San Diego to verify whether the request is subject to any intellectual property or confidentiality obligations. Any materials and data that can be shared will be released via a Material Transfer Agreement.
Kadoya, K., et al. Spinal cord reconstitution with homologous neural grafts enables robust corticospinal regeneration. Nat. Med. 22, 479–487 (2016).
Lu, P. et al. Long-distance growth and connectivity of neural stem cells after severe spinal cord injury. Cell 150, 1264–1273 (2012).
NSCISC Annual Statistical Report - Model Systems Public Version (National Spinal Cord Injury Statistical Center, University of Alabama at Birmingham, 2014).
Murphy, S. V. & Atala, A. 3D bioprinting of tissues and organs. Nat. Biotechnol. 32, 773–785 (2014).
Soman, P., Chung, P. H., Zhang, A. P. & Chen, S. Digital microfabrication of user-defined 3D microstructures in cell-laden hydrogels. Biotechnol. Bioeng. 110, 3038–3047 (2013).
Dalton, P. D., Flynn, L. & Shoichet, M. S. Manufacture of poly(2-hydroxyethyl methacrylate-co-methyl methacrylate) hydrogel tubes for use as nerve guidance channels. Biomaterials 23, 3843–3851 (2002).
Hung, T. K., Chang, G. L., Lin, H. S., Walter, F. R. & Bunegin, L. Stress-strain relationship of the spinal cord of anesthetized cats. J. Biomech. 14, 269–276 (1981).
Tsai, E. C., Dalton, P. D., Shoichet, M. S. & Tator, C. H. Synthetic hydrogel guidance channels facilitate regeneration of adult rat brainstem motor axons after complete spinal cord transection. J. Neurotrauma 21, 789–804 (2004).
Koffler, J., Samara, R. F. & Rosenzweig, E. S. Using templated agarose scaffolds to promote axon regeneration through sites of spinal cord injury. Methods Mol. Biol. 1162, 157–165 (2014).
Gao, M. et al. Templated agarose scaffolds for the support of motor axon regeneration into sites of complete spinal cord transection. Biomaterials 34, 1529–1536 (2013).
Gros, T., Sakamoto, J. S., Blesch, A., Havton, L. A. & Tuszynski, M. H. Regeneration of long-tract axons through sites of spinal cord injury using templated agarose scaffolds. Biomaterials 31, 6719–6729 (2010).
Stokols, S. et al. Templated agarose scaffolds support linear axonal regeneration. Tiss. Eng. 12, 2777–2787 (2006).
Stokols, S. & Tuszynski, M. H. The fabrication and characterization of linearly oriented nerve guidance scaffolds for spinal cord injury. Biomaterials 25, 5839–5846 (2004).
Stokols, S. & Tuszynski, M. H. Freeze-dried agarose scaffolds with uniaxial channels stimulate and guide linear axonal growth following spinal cord injury. Biomaterials 27, 443–451 (2006).
Lu, P. et al. Prolonged human neural stem cell maturation supports recovery in injured rodent CNS. J. Clin. Invest. 127, 3287–3299 (2017).
Lu, P. et al. Long-distance axonal growth from human induced pluripotent stem cells after spinal cord injury. Neuron 83, 789–796 (2014).
Li, J. & Lepski, G. Cell transplantation for spinal cord injury: a systematic review. Biomed. Res. Int. 2013, 786475 (2013).
Park, S. S. et al. Comparison of canine umbilical cord blood-derived mesenchymal stem cell transplantation times: involvement of astrogliosis, inflammation, intracellular actin cytoskeleton pathways, and neurotrophin-3. Cell Transplant. 20, 1867–1880 (2011).
Peron, S. et al. A delay between motor cortex lesions and neuronal transplantation enhances graft integration and improves repair and recovery. J. Neurosc. 37, 1820–1834 (2017).
Wang, L. et al. Early administration of tumor necrosis factor-alpha antagonist promotes survival of transplanted neural stem cells and axon myelination after spinal cord injury in rats. Brain Res. 1575, 87–100 (2014).
Yu, D. et al. Blockade of peroxynitrite-induced neural stem cell death in the acutely injured spinal cord by drug-releasing polymer. Stem Cells 27, 1212–1222 (2009).
Karimi-Abdolrezaee, S., Eftekharpour, E., Wang, J., Morshead, C. M. & Fehlings, M. G. Delayed transplantation of adult neural precursor cells promotes remyelination and functional neurological recovery after spinal cord injury. J. Neurosci. 26, 3377–3389 (2006).
Zhu, Y., Uezono, N., Yasui, T. & Nakashima, K. Neural stem cell therapy aiming at better functional recovery after spinal cord injury. Dev. Dyn. 247, 75–84 (2018).
Fehlings, M. G., Sekhon, L. H. & Tator, C. The role and timing of decompression in acute spinal cord injury: what do we know? What should we do? Spine 26, S101–S110 (2001).
Tator, C. H., Fehlings, M. G., Thorpe, K. & Taylor, W. Current use and timing of spinal surgery for management of acute spinal surgery for management of acute spinal cord injury in North America: results of a retrospective multicenter study. J. Neurosurg. 91, 12–18 (1999).
Okada, S. The pathophysiological role of acute inflammation after spinal cord injury. Inflamm. Regen. 36, 20 (2016).
Ciranna, L. Serotonin as a modulator of glutamate- and GABA-mediated neurotransmission: implications in physiological functions and in pathology. Curr. Neuropharmacol. 4, 101–114 (2006).
Harris, K. M. & Weinberg, R. J. Ultrastructure of synapses in the mammalian brain. Cold Spring Harb. Perspect. Biol. 4, a005587 (2012).
Scannevin, R. H. & Huganir, R. L. Postsynaptic organization and regulation of excitatory synapses. Nat. Rev. Neurosci. 1, 133–141 (2000).
Armulik, A. et al. Pericytes regulate the blood–brain barrier. Nature 468, 557–561 (2010).
Weiss, N., Miller, F., Cazaubon, S. & Couraud, P. O. The blood–brain barrier in brain homeostasis and neurological diseases. Biochim. Biophys. Acta 1788, 842–857 (2009).
Basso, D. M., Beattie, M. S. & Bresnahan, J. C. Graded histological and locomotor outcomes after spinal cord contusion using the NYU weight-drop device versus transection. Exp. Neurol. 139, 244–256 (1996).
Iyer, S., Maybhate, A., Presacco, A. & All, A. H. Multi-limb acquisition of motor evoked potentials and its application in spinal cord injury. J. Neurosci. Methods 193, 210–216 (2010).
van Gorp, S. et al. Amelioration of motor/sensory dysfunction and spasticity in a rat model of acute lumbar spinal cord injury by human neural stem cell transplantation. Stem Cell Res. Ther. 4, 57 (2013).
Olson, H. E. et al. Neural stem cell- and Schwann cell-loaded biodegradable polymer scaffolds support axonal regeneration in the transected spinal cord. Tissue. Eng. A 15, 1797–1805 (2009).
Pawar, K. et al. Biomaterial bridges enable regeneration and re-entry of corticospinal tract axons into the caudal spinal cord after SCI: Association with recovery of forelimb function. Biomaterials 65, 1–12 (2015).
Wong, D. Y. et al. Macro-architectures in spinal cord scaffold implants influence regeneration. J. Neurotrauma 25, 1027–1037 (2008).
Anderson, M. A. et al. Astrocyte scar formation aids central nervous system axon regeneration. Nature 532, 195–200 (2016).
Filous, A. R. & Silver, J. Targeting astrocytes in CNS injury and disease: a translational research approach. Prog. Neurobiol. 144, 173–187 (2016).
Fairbanks, B. D., Schwartz, M. P., Bowman, C. N. & Anseth, K. S. Photoinitiated polymerization of PEG-diacrylate with lithium phenyl-2,4,6-trimethylbenzoylphosphinate: polymerization rate and cytocompatibility. Biomaterials 30, 6702–6707 (2009).
Yu, C. G., Joshi, A. & Geddes, J. W. Intraspinal MDL28170 microinjection improves functional and pathological outcome following spinal cord injury. J. Neurotrauma 25, 833–840 (2008).
Grill, R., Murai, K., Blesch, A., Gage, F. H. & Tuszynski, M. H. Cellular delivery of neurotrophin-3 promotes corticospinal axonal growth and partial functional recovery after spinal cord injury. J. Neurosci. 17, 5560–5572 (1997).
We thank J. Liu for materials synthesis, J. Li, D. Xue and S. You for helpful discussion and CAD design, and R. Anderson for assistance in scanning electron microscopy. This work was supported in part by the NIH (R01EB021857, R21HD090662), the NSF (1547005, 1644967), the California Institute for Regenerative Medicine (RT3–07899) and the Dr. Miriam and Sheldon G. Adelson Medical Research Foundation. The electron micrographs were taken in the Cellular and Molecular Medicine Electron microscopy core facility, which is supported in part by National Institutes of Health Award number S10OD023527.
The authors declare no competing interests.
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Koffler, J., Zhu, W., Qu, X. et al. Biomimetic 3D-printed scaffolds for spinal cord injury repair. Nat Med 25, 263–269 (2019). https://doi.org/10.1038/s41591-018-0296-z
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