Molecular Bioelectronics for Neural Interfacing and Repair
Mario I. Romero-Ortega
Bioengineering, University of Texas in Arlington and U.T. Southwestern Medical Center
UTARI March 20, 2014
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Peripheral Nerve Injury
Neurapaxia Axonotmesis Neurotmesis
Amputation
Aba and Cavalli, 2008
The Grow/No Grow Dilemma in PNI
Transection Nerve Injury:- Paralysis- Anesthesia- Allodynia- Can be permanent
Neuroma- Excruciating pain- Responsive to thermal,
barometric, and other stimuli.
- Can lead to phantom limb perception
GROW NO-GROW
. Fot
o: O
tto
Boc
k/M
icha
el A
ppel
t
DIRECTED GROWTH
Peripheral Neural Interfaces- Control growth to MEAs- Modality specificity- Avoid pain or aesthesias- Prevent neuromas
Peripheral Nerve Gap Injury
• Autografts remains the gold standard for bridging gap defects
• Limitations:– Available quantity of donor nerve– Scarring– Painful neuroma at donor site
– Graft thickness limited by revascularization
– Only 10% of axons after a nerve transection and ‘‘best’’ surgical apposition reach target organs (Witzel et al., 2005).
Peripheral nerve injuries that induce gaps larger than 2 cm require bridging strategies for repair
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FDA Approved Biosynthetic Nerve Conduits
Schlosshauer et al., 2006.
NeuraGen. Integra Neuroscience (collagen).
Neurolac.
(PL-caprolactone)
Neurotube.Synovis Micro (polyglocolide)
• Limited to the repair of short digital sensory nerve gaps (≤3cm) in humans.
• No luminar fillers or growth factors
Biomimetic Nerve Implant: BNI
Biodegradable conduit
Agarose
Collagen +
Agarose
Collagen + growth factors
7Tansey et al., 2011
BNI Short Nerve Gap Repair (10 mm)
Tansey et al., 2011
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BNI: EM Morphometry and Behavioral Recovery
Tansey et al., 2011Tansey et al., 2011
Long Gap Nerve Repair ( >30 mm)
Luminar saline Luminar ECM Muliluminal ECM Multiluminar ECM with growth facors
Complexity/Efficacy
CTR
GDNF
BSA GDNF_MP
PLGA Microparticle Growth Factor Release
Synergetic effects of pleiotrophic and neurotrophic factors on axonal growth in vitro.
Control
Combination A
Combination B
12Romero et al., Unpublished
Biodegradable conduit
Agarose
Collagen +
Agarose
Collagen
Growth Factor MP
Combination A
Control
GF-MP BNI: 30 mm Rabbit Peroneal Nerve
Romero et al., In preparation
Normalside
Injured side: No regeneration
Normalside
Injured side: Regeneration
4 weeks 6 weeks
GF-MP BNI: 30 mm Motor Recovery
Romero et al., In preparation
14Romero et al., Unpublished
Biodegradable conduit
Agarose
Collagen +
Agarose
Collagen
Growth Factor MP
GF-MP BNI: 30 mm Rabbit Peroneal Nerve
Alsmadi et al., submitted
Deployment of GF Coiled Microfibers in Microchannels
Alsmadi et al., Submitted
Deployment of GF Coiled Microfibers in Microchannels
Alsmadi et al., Submitted
Cheng-Jen Choung
Deployment of GF Coiled Microfibers in Microchannels
Alsmadi et al., Submitted
Bidirectional Molecular Guidance
Alsmadi et al., Submitted
More than 1.6 million Americans are amputees, and 185,000 more are expected to loss their limbs each year.
Ziegler-Graham et al., 2008
Modular Prosthetic Limb: JHAPL
Neural Control of Robotic Prosthesis
Kuiken et al., 2007
http://armdynamics.com/pages/tmr
Cortical Neuro-Electrode Interfaces
BMI- 3D Neural Control of Robotic ProsthesisCollinger, Andrew Schwartz, Univ Pittsburgh 2013
Current Challenges in PNS Neurointerfacing
- Tissue damage/Inflammation– limited functionality (weeks to months)
due to continued signal deterioration
- Current injection– Tissue damage due to metal dissolution
or water electrolysis.
- Motor decoding/Sensory encoding capability. – Sensitive neural recording from low
voltage (µV) signals.
– Accurate and efficient stimulation of specific neuron subtypes Luke Skywalker's Bionic Arm, "The Empire
Strikes Back (1980)
TMR(Targeted Muscle Reinnervation)-Prothese. Foto: Otto Bock/Michael Appelt
SynTouch BioTacG. Loeb, USC
Kinea Tactor: Johns Hopkins APL
Advanced Limb Prosthetics: Sensory Feedback
Selective Function and Neural Encoding
Motor Axon
20 distinct sensory modalities
Flat ElectrodeD. Durand, D. Tyler; CWRU
TIME ElectrodeS Micera; EPFL
Four weeks recording and efficacy of sensory stimulation decayed after 10 days” Rossini et al., 2010
Pierpaolo Petruzziello, 2010
K. Horch, 2004
K. Warnick, 2004
Motor Decoding/Sensory encoding
15 d 30 d 60 d
Regenerative Multielectrode Interface: REMI
Garde et al., 2009
Recording/Stimulation Free-Moving Animals
Garde et al., 2009
Kinematic Analysis during Bipedal Locomotion
Gait
Cineplex
Rats are also video tracked using Cineplex software (Plexon Inc.) to track angle between the joints.
Rats are trained on a robot treadmill (Robomedica, Inc.) for gait analysis to monitor recovery after peripheral nerve injury.
Firing Pattern of Single Unit Spikes recorded from Tibial Nerve
• Robot assisted standing on hind limbs – No Rhythmic Walking
Single Unit on Ch 2
45 Days Post Implant
Tonic Unit seen only on Ch 2, while Ch1 and 3 did not have Single Unit activity
Ch 1
Ch 2
Ch 3
Ch 2
Raster Plot
50 sec interval
1400 μsec
148 μV
Tonic to Bursting during Walking
• Robot assisted Bipedal Locomotion – Rhythmic Walking
Bursting Units elicited while walking as seen on Ch1, 2, 3
Channel 1 Channel 2 Channel 3
Ch 1
Ch 2
Ch 3
50 sec interval
1400 μsec
184 μV
1400 μsec
828 μV
1400 μsec
296 μV
Sensory Specific Evoked Neural Activity
Perievent Histogram bin = 500ms
Freq
uenc
y (s
pike
s/se
c)
Ch
ann
el
AC
han
ne
l B
0- 55 CFr
eque
ncy
(spi
kes/
sec)
Ch
ann
el
AC
han
ne
l B
0-50 gr
REMI: Mix Modality Interfacing
The rat sciatic nerve consist of 3 fascicles containing about 8,100 motor axons and 17,000 unmylinated axons (Castro et al., 2008)
Motor and SensoryModalities
ChAT
Badia et al. 2009
Badia et al. 2009
Axon Composition in PNS
Targeting Sensory Type Regeneration In Vivo
Directed Axonal Growth by NGF and NT-3
Unmyelinated Fibers
Myelinated Fibers
Both DRGs and ventral motor neurons grow towards A/B targets
Surrogate Targets
Muscle
Skin
Nerve
Nerve
Single Growth Factors
Multiple Growth Factors
BDNF/GDNFNT-3
PTN
BSA
BSA
BSA
NGF
NT-3
BDNF/GDNF
BDNF/GDNF
NT-3/NGF
BDNF/GDNF
BDNF/GDNF
BDNF/GDNF
PTN/NGF/NT-3
PTN/NGF
BSA
PTN
Anand et al., In Preparation
Painful Neuromas Occur in up to 80% of limb amputations
Sehirlioglu et al., 2009Healthy Nerve Neuroma
Granja et al., In Preparation
BNI- Nerve Block: Discouraging Nerve Growth
BNI
BNI-NB
Granja et al., In Preparation
BNI-NBBNI
BNI- Nerve Block: Discouraging Nerve Growth
Granja et al., In Preparation
Healthy Nerve
Guided Inhibition
r= .175mmX3channelsA= 0.29 sq.mm
r= 4.5 mmA= 25.4 sq.mm
Healthy Nerve
Uncontrolled Regeneration
Hollow tube
r= 4.5 mmA= 25.4 sq.mm
r= 9 mmA= 254 sq.mm
Simple Tubularization vs BNI-Nerve Block
Granja et al., In Preparation
BNI-NB Prevents Mechanoceptive Pain
Granja et al., In Preparation
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Grow-No Grow Strategies
Increasing Gap Length • Contact guidance: Agarose microchannels filled with collagen
• Growth Factors: Linear GFR Promote neuronal and functional recovery in 3 cm gaps
• Longer Gaps might be repair with GF-Gradient Multi-luminal implants.
Growth: Long Gap Repair
No Growth: Neuroma
• Amputated nerves: Differential growth of modality-specific axons
• Axon growth can be GF-directed separate Y-shaped compartments
Conditional Growth: Interfaces
• Surgical placement: Bone, Muscle
• Capped Tubularization: Silicon tubes, epineurium cap.
• BNI-NB can be used to prevent neuroma
Interfacing Amputated Nerves
Block Growth
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Bioelectronic Medicines
Nano-scale devices connect to groups of individual nerve fibres and change patterns of electrical signals to restore health to organs and biological functions
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Soft, Conformal Electrodes for Small Nerves and Inoperable Plexi
Walter Voit
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UTARI Michrochannel Multielectrode Array
Muthu Wijesundara Young-tae Kim
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UTARI MMEA: Fabrication
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UTARI MMEA: Recording/Stimulation
AcknowledgmentsUTA Students
Sanjay Anand
Nesreen Alsmadi
Benjamin Johnston
Vidhi Desai
Rafael Granja, MD
Aswini Kanneganti
Parisa Lotfi
Lokesh Patil
Srikanth Vasudevan
UTA/UTSW facultyYoung-tae KimJonathan ChengCheng-Jen ChuongJennifer Seifert
Plexon Inc.Edward KeeferHarvey Wiggins
Grant Sources:NIH NINDS Scottish Rite Hospital for ChildrenTexas Higher Education Coordinating BoardCrowley-Carter FoundationTexas Star Plus FundTissue Gen CorporationDefense Advanced Research Projects Agency (DARPA)
Microsystems Technology Office (MTO), Naval Warfare Systems Command (SPAWAR) Systems Center (SSC) Pacific grants No. N66001-11-1-4408 and No. N66001-11-C-4168.
UoW AustraliaGordon Wallace
UTARIMuthu WijesundarCaleb NothnagleEileen ClementsRet. Gral. Rick Lynch