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US-12616779-B1 - Piezoelectric nerve guidance and regeneration

US12616779B1US 12616779 B1US12616779 B1US 12616779B1US-12616779-B1

Abstract

A method of activating a piezoelectric neuroconduit guide scaffold including a plurality of aligned piezoelectric polymer nanofibers, the method including mechanically stimulating the piezoelectric neuroconduit guide scaffold with hydro-acoustic waves or shockwaves to remotely activate a piezoelectric effect of the nanofibrous scaffolds that induces a mechano-electrical stimulus on neural cells cultured on the scaffold, wherein the mechano-electrical stimulus promotes nerve fiber outgrowth from the neuronal cells. Some aspects relate to seeding individual components of neural tissues on the piezoelectric neuroconduit guide scaffold, wherein the hydro-acoustic stimulation induces neural tissue formation. In other aspects, the piezoelectric neuroconduit guide scaffold is implanted in a damaged neural tissue, wherein stimulating the piezoelectric neuroconduit guide scaffold by the application of shockwaves promotes nerve fiber outgrowth that bridges a nerve gap to induce nerve regeneration or reinnervation of the damaged neural tissue.

Inventors

  • Jin NAM
  • Hyle B. Park
  • Karen Low
  • Gerardo Rene Ico

Assignees

  • THE REGENTS OF THE UNIVERSITY OF CALIFORNIA

Dates

Publication Date
20260505
Application Date
20220120

Claims (20)

  1. 1 . A method of activating a piezoelectric neuroconduit guide scaffold comprising a plurality of aligned piezoelectric polymer nanofibers, the method comprising mechanically stimulating the piezoelectric neuroconduit guide scaffold with hydro-acoustic waves or shockwaves to remotely activate a piezoelectric effect of the nanofibrous scaffolds that induces a mechano-electrical stimulus on neural cells cultured on the scaffold, wherein the mechano-electrical stimulus promotes nerve fiber outgrowth from the neuronal cells.
  2. 2 . The method of claim 1 , wherein the piezoelectric scaffold is mechanically stimulated in a non-contact manner in vitro using a cell culture chamber with a vertical actuator.
  3. 3 . The method according to claim 2 , comprising applying a mechanical strain having a strain of 0.02% to 0.04% with hydro-acoustic waves.
  4. 4 . The method of claim 1 , wherein the piezoelectric neuroconduit guide scaffold is mechanically stimulated in a non-contact manner in vivo using extracorporeal shockwave therapy (ESWT).
  5. 5 . The method according to claim 4 , comprising applying a sonic pulse of mechanical energy having a positive peak within about 10 ns, followed by a negative peak up to about −10 MPa, with a total life cycle of about 10 μs.
  6. 6 . The method of claim 1 , wherein the hydro-acoustic waves or shockwaves generate a peak-to-peak voltage from the piezoelectric scaffolds of about 200 mVp-p, by simultaneously controlling individual fiber diameter and fiber mat thickness.
  7. 7 . The method of claim 1 , wherein the neuronal cells are selected from the group consisting of neurons, Schwann cells and neural stem cells.
  8. 8 . The method of claim 1 , wherein the nanofibers have an average diameter of from 100-1000 nm.
  9. 9 . The method of claim 1 , wherein the piezoelectric neuroconduit guide scaffold comprises a fiber mat thickness of 40 to 400 μm.
  10. 10 . The method of claim 1 , wherein the nanofibers are all aligned within 200 of the neutral axis.
  11. 11 . The method of claim 1 , wherein the nanofibers are heat-treated.
  12. 12 . The method of claim 1 , wherein the piezoelectric polymer is poly(vinylidene fluoride) (PVDF) or a derivative thereof.
  13. 13 . The method of claim 12 , wherein said derivative of PVDF is P(VDF-trifluoroethanol) (PVDF-TrFE).
  14. 14 . The method of claim 1 comprising seeding individual components of neural tissues including neuron and Schwann cells, or neural stem cells on the piezoelectric neuroconduit guide scaffold, wherein the hydro-acoustic stimulation of the piezoelectric neuroconduit guide scaffold and the neural tissues induces neural tissue formation.
  15. 15 . The method claim 14 , wherein the neural tissue formation is in vitro.
  16. 16 . The method of claim 1 , wherein the piezoelectric neuroconduit guide scaffold is implanted in a damaged neural tissue, wherein the piezoelectric neuroconduit guide scaffold is positioned to bridge a nerve gap in the damaged neural tissue, and wherein stimulating the piezoelectric neuroconduit guide scaffold by the application of shockwaves promotes nerve fiber outgrowth, and wherein the implanted scaffold and neurite outgrowth bridges the nerve gap to induce nerve regeneration or reinnervation of the damaged neural tissue.
  17. 17 . The method of claim 16 , wherein the neural tissue is in vivo.
  18. 18 . The method of claim 16 , wherein the nerve gap is larger than 30 mm.
  19. 19 . The method of claim 16 , wherein cellular activities of Schwann cells, or myelinating oligodendrocytes and extracellular matrix-producing astrocytes promote nerve regeneration within a PNS or CNS injury, respectively.
  20. 20 . The method of claim 16 , wherein the damaged neural tissue is in the peripheral nervous system (PNS).

Description

FIELD OF THE INVENTION Piezoelectric neuroconduit guide scaffolds, including a plurality of aligned piezoelectric polymer nanofibers, for supporting axon regeneration in neural tissues. The scaffolds can be safely activated in vivo to promote nerve fiber outgrowth. REFERENCE TO SEQUENCE LISTING A Sequence Listing submitted as an ASCII text file via EFS-Web is hereby incorporated by reference in accordance with 35 U.S.C. § 1.52(e). The name of the ASCII text file for the Sequence Listing is 54948146_1.TXT, the date of creation of the ASCII text file is Jan. 20, 2022, and the size of the ASCII text file is 8.39 KB. BACKGROUND OF THE INVENTION Severe injuries to the peripheral and central nervous system present a significant clinical problem due to limited or lack of treatment for fully functional recovery. When the nerve is damaged by injuries/diseases, such as peripheral nerve transection, spinal cord injury, and diabetic neuropathy, a cascade of cellular events occurs to the affected and neighboring cells, extracellular matrix (ECM) of the injury site, and the nerve tissue. Functional regeneration of damaged nerves from the central nervous system (CNS) is very limited due to rapid glial scar tissue formation. Although the peripheral nervous system (PNS) is more capable of nerve regeneration than the CNS, appropriate clinical solutions for nerve damage with large gaps have yet to be found. Recently, various nerve regeneration strategies, such as using nerve guidance conduits, hydrogels, cell-based therapies, and electrical stimulation, have been explored to enhance nerve repair by promoting a regeneration-permissive environment or inhibiting factors that prevent regrowth from occurring. Although the PNS possesses a certain degree of regenerative capabilities, the regeneration of nerve injuries with large gaps is limited by the rate of axonal elongation. Native Schwann cells eventually advance ahead of the regenerating axons, no longer providing a sufficient environment for axon growth (Son Y-J, Trachtenberg J T, Thompson WJ. Schwann cells induce and guide sprouting and reinnervation of neuromuscular junctions. Trends in neurosciences. 1996; 19(7):280-5). Another issue with injuries of large nerve gaps is that the disorganization of axon extensions from the growth cone continues to increase as the length of the nerve gap increases (Menorca R M, Fussell T S, Elfar J C. Peripheral nerve trauma: mechanisms of injury and recovery. Hand clinics. 2013; 29(3):317; Ertürk A, Hellal F, Enes J, Bradke F. Disorganized microtubules underlie the formation of retraction bulbs and the failure of axonal regeneration. Journal of Neuroscience. 2007; 27(34):9169-80). Therefore, efforts have focused on enhancing the outcome of peripheral nerve regeneration through the use of neuroconduits to guide and provide a supportive environment for successful axon regeneration. The current gold standard to repair transected nerve is autologous nerve grafting. This method provides the structural support to guide axon regeneration, preventing the formation of neuromas (Millesi H. Bridging defects: autologous nerve grafts. How to improve the results of peripheral nerve surgery. 2007:37-8). Because the autograft is surgically removed from the patient's own body, most commonly taken from the sural nerve of the calf region, it acts as an immunogenically inert scaffold, providing viable Schwann cells and appropriate neurotrophic factors for axon regeneration (Dahlin L, Lundborg G. Use of tubes in peripheral nerve repair. Neurosurgery Clinics of North America. 2001; 12(2):341-52). However, this technique possesses many limitations, including the necessity of multiple surgeries, the induction of a functionally impaired region where the graft was taken from, and disproportion of graft to nerve tissue in size and structure. Furthermore, the patient is at high risk of neuroma formation in the transplanted area. Alternative clinical options include cadaver allografts (Kim B S, Yoo J J, Atala A. Peripheral nerve regeneration using acellular nerve grafts. Journal of biomedical materials research Part A. 2004; 68(2):201-9), veins and arteries as grafts (Battiston B, Geuna S, Ferrero M, Tos P. Nerve repair by means of tubulization: literature review and personal clinical experience comparing biological and synthetic conduits for sensory nerve repair. Microsurgery. 2005; 25(4):258-67), and natural/synthetic conduits, but each of these possess their own disadvantages. When using allografts, patients require systemic immunosuppression, putting them at risk of associated morbidity from immunomodulatory therapy (Udina E, Verdn E, Navarro X. Effects of the immunophilin ligand FK506 on nerve regeneration in collagen guides seeded with Schwann cells in rats. Neuroscience letters. 2004; 357(2):99-102); vein and artery grafts is structurally inferior to nerve tissue therefore the walls may collapse and it cannot bridge nerve gaps greater than 30 mm (Karabekmez F E,