AMERICAN PHYSIOLOGICAL SOCIETY AMERICAN PHYSIOLOGICAL SOCIETY EDUCATION COMMITTEEEDUCATION COMMITTEE

Refresher Course, 2002: Recent Advances In Refresher Course, 2002: Recent Advances In NeuroscienceNeuroscience

Recent Advances in Recent Advances in

Spinal Cord Injury Regeneration Spinal Cord Injury Regeneration and Repairand Repair

Claire E. Hulsebosch, Ph.D.Claire E. Hulsebosch, Ph.D.Program Dir., UTMB Spinal Cord Injury ProgramProgram Dir., UTMB Spinal Cord Injury Program

Spinal Cord InjurySpinal Cord Injury

Incidence: 11,000 people a year in the USA

Prevalence: Between 183,000 to 230,000 in USA

Gender: Males four times as often as females

Age: Most frequently to those from 16 to 30 years of age

Etiology: Most commonly a result of vehicular accident, usually involving alcohol

Etiology

Falls

Pedestrians

Medical/Surgical

Sports

Vehicular

Violence

Other

Unknown

Total

0-30 yrs.

11.7

1.5

1.1

23.6

46.7

6.1

6.4

2.9

100

31-60 yrs.

21

0.7

4.3

7.5

49.3

4.6

9.9

2.7

100

61+ yrs.

36

21.2

23.7

0

3.1

.5

15.5

0

100

Age at Injury %Age at Injury %

• Spinal cord 16 years after injury. Three spinal segments are telescoped into the space of one. The center of the scar is connective tissue which is invaded by regenerating fibers from the dorsal roots.

• Cervical spinal cord above a complete transverse traumatic lesion showing ascending degeneration in the dorsal (posterior) columns and spinal cerebellar and spinothalamic tracts.

Left: Dorsal view of spinal cord with fracture-dislocation at the T12-L1 junction which crushed the lumbar cord.

Top Right: Longitudinal section showing site of direct cord trauma and rostral and caudal hemorrhagic extension.

Bottom Right: Twelve transverse sections through the cervical and thoracic cord. The third rows from the left show almost complete hemorrhagic necrosis. Hemorrhages can be seen in the grey matter in other blocks for several centimeters.

• Post-traumatic syringomyelia occurs in up to 20% of all SCI patients and in a subset of these, continues to progress over time. Shown on the top left is a section from T2 stained for myelin from an injury centered on T11.

• The bottom left shows a higher magnification of a different section from the same syrinx demonstrating the thick astrocytic lining of the cavity (H and E stain).

Increased Life Expectancy with Spinal Cord Increased Life Expectancy with Spinal Cord Injury due to Improved Patient ManagementInjury due to Improved Patient Management

World War II: 3 months

1958: 3 years

1966: 20 years

1980: 21 years

Current: 27 +

Cause of Death: In the past-renal failure; Current-cardiac failure, pneumonia, pulmonary emboli and septicemia.

Therefore, we can turn our attention to therapeutic opportunities to increase function after SCI.

Quality of Life Issues Targeted by Patients Quality of Life Issues Targeted by Patients of Spinal Cord Injuryof Spinal Cord Injury

1. Bowel and bladder control

2. Pain management

3. Hand use if limited

4. Improved locomotor function

Restorative treatments will be incremental; thus, both basic and clinical measures need to be refined to be able to detect the interventions that are successful.

Number of SCI Animal Studies Published

Year published

1965

1966

1967

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

1982

1983

1984

1985

1986

1987

1988

1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

Num

ber

of a

rtic

les

0

50

100

150

200

250

300

350

*

+

* - Christopher Reeve's injury

+ - 1/01/02 through 3/20/02

Number of American SCI Number of American SCI CentersCenters

Mission Connect, Mission Connect, TexasTexasSCI Program, SCI Program, U of Texas Med. Br.U of Texas Med. Br.The Miami Project, The Miami Project, U MiamiU MiamiEPVA Center, EPVA Center, YaleYaleCRPF Consortium CRPF Consortium CORD, CORD, U British ColumbiaU British ColumbiaReeve-Irvine Center, Reeve-Irvine Center, UC IrvineUC IrvineBrain Institute, Brain Institute, U FloridaU FloridaThe SCI Project-Keck Ctr., The SCI Project-Keck Ctr., RutgersRutgersSpinal Cord Res. Ctr., Spinal Cord Res. Ctr., ManitobaManitobaSCI Program, SCI Program, Wash UWash USCoBIRC,SCoBIRC, U KentuckyU KentuckyKentucky SCI Research Center, Kentucky SCI Research Center, U U Louisville Louisville Center for Paralysis Res.,Center for Paralysis Res., PurduePurdue

Ohio State UOhio State UGeorgetown UGeorgetown U

MCP Hahnemann UMCP Hahnemann UU TorontoU Toronto

State Funds: State Funds: FL, KY, TX, NY, FL, KY, TX, NY, NJ, CA, VA, IL, NJ, CA, VA, IL, MD, OR, CT, BCMD, OR, CT, BC

MASCIS SPINAL IMPACTOR

Tissue Loss after SCI

1 Hour Post Injury 60 Days Post Injury

Recovery Mechanism

Resolution of acute injury events

Resolution of secondary injury processes

Regrowth or regeneration

Time after Injury

Minutes to 7d

2 h to 4 wk

24 h to years

Window of Opportunity for Neurological Window of Opportunity for Neurological Recovery after Spinal Cord InjuryRecovery after Spinal Cord Injury

Neuropathology of Spinal Cord InjuryNeuropathology of Spinal Cord Injury

ACUTE: Mechanical/ischemic cell damage , hemorrhage, edema, compression, loss of vascular autoreg., systemic hypotension, injury discharge

SECONDARY: Ischemic cell damage, apoptosis, electrolytic shifts, [EAA]o inc., [Ca]i inc., inflammatory casade (cytokine/chemokine), lipid peroxidation, free radical production, neutrophils-lymphocytes, reactive gliosis, edema

CHRONIC: Apoptosis, receptor changes, demyelination and conduction deficits, cyst formation, regeneration/sprouting of neurites for 1 mm, neural circuit changes, central sensitization, chronic pain

Key Targets of Intervention for Key Targets of Intervention for Spinal Cord InjurySpinal Cord Injury

PRIMARY (ACUTE): Cessation of bleeding, relief of compression, increased blood pressure

SECONDARY: Rescue of cells at risk of cell death in secondary events, stop development of inhibitory barriers to regeneration (ex. reactive gliosis, proteoglycans)

CHRONIC: Repair conduction deficits, create bridges to fill the gap, promote neurite growth, replace lost cells (glial, neuronal, or engineered cell lines), aggressive physical therapy, functional electrical stimulation

McDonald, J. W. and Sadowsky, C. Lancet 359:417-425,2002

Phospholipase A2

O2.-

.ONOO.

NO.

.OH

Trauma, Ischemia

Glutamate release

Cell membrane NMDA-receptors Membrane phospholipids

Ca2+

Activation of enzymes

Lipid peroxidationProtein oxidation

DNA/RNA oxidation

Free Arachidonic acid

COX-2(neurons, glia, microglia

endothelium)

Prostaglandins

+ H+

ONOOH

+ NO2

OXIDATIVE CELL DEATH INFLAMMATION

endoperoxidaseseicosanoids

Selectiveinhibition of

COX-2 (NS 398) will decrease oxidative cell injury, inhibit inflammation

Inhibition of glutamate receptors will block

increases in [Ca]i

Metabotropic Glutamate Group I Receptor Antagonist - AIDA (0.1 nmol)

-10

0

10

20

30

40

50

60VehicleAIDA

Time After Injury (minutes)

Asp

arta

te (m

M)

-5

0

5

10

15

20

-15 15 60 120 180 240-30 90 150 21045300-15 15 60 120 180 240-30 90 150 21045300

* VehicleAIDA

*

Glu

tam

ate

(μM

)

Asp

arta

te (

μM

)

Time After Injury (minutes)

2.4 mm Rostral Epicenter 2.4 mm Caudal

 

  

Vehicle

AIDA

LY 367385

MPEP

Mills, C.D., Johnson, K.M. and Hulsebosch, C.E. , J. Neurotrauma 19:23-42,2002.

COX-2 Inhibition by NS-398

VIABLE SPINAL CORD TISSUE POST-SCI RECOVERY

Hains, B.C., Yucra, J.A. and Hulsebosch, C.E. J. Neurotrauma 18:409-423, 2001.

5-H

T

BD

NF

RN46A-V1 RN46A-B14

TRANSPLANTATION FOR CHRONIC PAIN: RN46A-B14/V1 CELLS TRANSPLANTATION FOR CHRONIC PAIN: RN46A-B14/V1 CELLS

150 m

100

75

50

25

00 50 100 150 200 250

100

75

50

25

00 50 100 150 200 250

100

75

50

25

00 50 100 150 200 250

100

75

50

25

00 50 100 150 200 250

100

75

50

25

00 50 100 150 200 250

100

75

50

25

00 50 100 150 200 250

100

75

50

25

00 50 100 150 200 250

100

75

50

25

00 50 100 150 200 250

100

75

50

25

00 50 100 150 200 250

100

75

50

25

00 50 100 150 200 250

100

75

50

25

00 50 100 150 200 250

100

75

50

25

00 50 100 150 200 250

CONTROL SHAM XPL RN46A-V1 XPL RN46A-B14 XPL

RA

TE

(sp

ikes

/bin

)HEMISECTED

TIME (sec)

LT

WDR

HT

BR PR PI 3.84 9.96 204 47oC

EVOKED ACTIVITY – CUTANEOUS STIMULI EVOKED ACTIVITY – CUTANEOUS STIMULI

Hains, B.C., Johnson, K.M., Eaton, M.J., McAdoo, D.J., Willis, W.D. and Hulsebosch, C.E. Behavior: Exp. Neurol., 171:361-378, 2001; Electrophysiology: Neuroscience, submitted, 2002.

BR PR PI 3.84 9.96 204 47oC BR PR PI 3.84 9.96 204 47oC BR PR PI 3.84 9.96 204 47oC

TREATMENT STRATEGIES FOR SPINAL CORD INJURY

Problem1) Edema, Free radical

production, Activation of arachidonic acid pathway

2) High extracellular Glut & Asp, High intracellular Ca++

3) Inflammation

4) Secondary neuronal cell death (Apoptosis)

Treatment• Methylprednisolone+ (30 mg/kg bolus,

IV over 1 hr, followed by 5, 4 mg/kg/hr for 23 hr) within 8 hrs after injury

• Tirilazad mesylate * - inhibits lipid peroxidation

• EAA receptor antagonists (NMDA, AMPA/kainate, metabotropic Glut receptors)

• IL-10, LIF (anti-inflammatory cytokines), COX-2 inhibitors, CM101 (antiangiogenic drug used in cancer treatment), activated T-cells*

• Neurotrophins (nerve/nutrition) -NGF, BDNF, NT-3, GDNF, CNTF

Problem 5) Demyelination and conduction

deficits

6) Neurite growth is only 1 mm

7) Missing circuitry, missing factors

8) Chondroitin sulfate proteoglycans and glial scarring inhibit neurite growth

Treatment• 4-aminopyridine * -a potassium channel-

blocking agent• Transplant strategies of myelinating cells

• GM-1* -an acidic glycolipid• Neurotropins (NGF, BDNF, NT-3,GDNF)• Antibodies to neurite growth inhibitors (IN-1)• Matrix proteins, Schwann/OE cell transplants

• Transplant strategies: peripheral nerve grafts to bridge the gap, fetal tissue in bloc* (clinical trial) or disassociated, Schwann cells, olfactory ensheathing (OE) cells, motor neurons, stem cells etc.

• Chondroitinase-ABC to dissolve proteoglycans, local irradiation/mitotic inhibitors to inhibit glial proliferation

TREATMENT STRATEGIES FOR SPINAL CORD INJURY

Problem

9) Need to relearn motor tasks

10) Loss of bladder and bowel function

11) Need improved hand function

12) Chronic pain

Treatment

• Aggressive physical therapy *

• Sacral reconstruction, sacral stimulation of S2, S3, S4 ventral roots*

• Tendon transfer, electrical stimulation of median (flexor m.) and ulnar (adductor m.) nerves*

• Indwelling pumps*, transplantation of cells that secrete analgesic substances*

TREATMENT STRATEGIES FOR SPINAL CORD INJURY

+ - standard clinical treatment * - ongoing clinical trails

ConclusionsConclusions

Claire E. Hulsebosch, Ph.D.Claire E. Hulsebosch, Ph.D.

Program DirectorProgram Director

UTMB Spinal Cord Injury ProgramUTMB Spinal Cord Injury Program

1.1. Ongoing clinical trials in spinal cord injury treatment Ongoing clinical trials in spinal cord injury treatment demonstrate improved function.demonstrate improved function.

2.2. Thirty years ago, patients and families would be told Thirty years ago, patients and families would be told “Nothing can be done, there is no research for “Nothing can be done, there is no research for treatment of spinal cord injury.” This is not true today.treatment of spinal cord injury.” This is not true today.

3.3. More advancements are possible by continued More advancements are possible by continued research efforts.research efforts.