In vivo electrical conductivity across critical nerve gaps using poly(3,4-ethylenedioxythiophene)-coated neural interfaces.
BACKGROUND
Bionic limbs require sensitive, durable, and physiologically relevant bidirectional control interfaces. Modern central nervous system interfacing is high risk, low fidelity, and failure prone. Peripheral nervous system interfaces will mitigate this risk and increase fidelity by greatly simplifying signal interpretation and delivery. This study evaluates in vivo relevance of a hybrid peripheral nervous system interface consisting of biological acellular muscle scaffolds made electrically conductive using poly(3,4-ethylenedioxythiophene).


METHODS
Peripheral nervous system interfaces were tested in vivo using the rat hind-limb conduction-gap model for motor (peroneal) and sensory (sural) nerves. Experimental groups included acellular muscle, iron(III) chloride-treated acellular muscle, and poly(3,4-ethylenedioxythiophene) polymerized on acellular muscle, each compared with intact nerve, autogenous nerve graft, and empty (nonreconstructed) nerve gap controls (n=5 for each). Interface lengths tested included 0, 5, 10, and 20 mm. Immediately following implantation, the interface underwent electrophysiologic characterization in vivo using nerve conduction studies, compound muscle action potentials, and antidromic sensory nerve action potentials.


RESULTS
Both efferent and afferent electrophysiology demonstrates acellular muscle-poly(3,4-ethylenedioxythiophene) interfaces conduct physiologic action potentials across nerve conduction gaps of at least 20 mm with amplitude and latency not differing from intact nerve or nerve grafts, with the exception of increased velocity in the acellular muscle-poly(3,4-ethylenedioxythiophene) interfaces.


CONCLUSIONS
Nonmetallic, biosynthetic acellular muscle-poly(3,4-ethylenedioxythiophene) peripheral nervous system interfaces both sense and stimulate physiologically relevant efferent and afferent action potentials in vivo. This demonstrates their relevance not only as a nerve-electronic coupling device capable of reaching the long-sought goal of closed-loop neural control of a prosthetic limb, but also in a multitude of other bioelectrical applications.
Egeland
Brent M
BM
Ann Arbor, Mich.; and Newark, Del. From the Department of Surgery, Section of Plastic and Reconstructive Surgery, and the Department of Materials Science and Engineering and Biomedical Engineering, University of Michigan; Biotectix, LLC; and the Department of Material Science and Engineering, University of Delaware.
Urbanchek
Melanie G
MG
Peramo
Antonio
A
Richardson-Burns
Sarah M
SM
Martin
David C
DC
Kipke
Daryl R
DR
Kuzon
William M
WM
Cederna
Paul S
PS
D000465:Algorithms; D000818:Animals; D001186:Artificial Limbs; D001701:Bionics / Q000379:methods*; D019086:Bridged Bicyclo Compounds, Heterocyclic; D020099:Coated Materials, Biocompatible; D004553:Electric Conductivity; D004576:Electromyography; D008297:Male; D008866:Microsurgery / Q000379:methods; D018482:Muscle, Skeletal; D009431:Neural Conduction / Q000502:physiology*; D010525:Peripheral Nerves / Q000502:physiology* / Q000601:surgery*; D010543:Peroneal Nerve / Q000502:physiology / Q000601:surgery; D011108:Polymers; D011474:Prosthesis Design; D051381:Rats; D011916:Rats, Inbred F344; D011930:Reaction Time / Q000502:physiology; D013497:Sural Nerve / Q000502:physiology / Q000601:surgery; D054457:Tissue Scaffolds; D014584:User-Computer Interface
D019086:Bridged Bicyclo Compounds, Heterocyclic; D020099:Coated Materials, Biocompatible; D011108:Polymers; C121383:poly(3,4-ethylene dioxythiophene)