Spinal cord regeneration in rats made immunologically unresponsive to CNS antigens

Journal of Neurology, Neurosurgery, and Psychiatry, 1979 · DOI: · Published: January 1, 1979

Simple Explanation

This study investigates whether suppressing the immune response in rats can enhance the regeneration of nerve fibers after spinal cord injury. The researchers induced immunological unresponsiveness to central nervous system (CNS) antigens in rats to see if it would promote spinal cord regeneration. The study also examined the combined effect of induced immunological unresponsiveness and treatment with cyclophosphamide, an immunosuppressant drug, on spinal cord regeneration. The researchers used electrophysiological testing and radioisotope studies to evaluate nerve fiber regeneration after spinal cord transection.

Study Duration

70 days

Participants

Female isogeneic rats

Evidence Level

Not specified

Key Findings

1
Rats made immunologically unresponsive to CNS tissue alone did not show increased corticospinal regeneration as measured by axonal transport.
2
Rats made immunologically unresponsive to CNS tissue, and treated with cyclophosphamide, showed corticospinal axonal regeneration by tritiated proline transport.
3
Electrophysiological evidence suggested regeneration of long ascending sensory pathways in tolerant animals and those tolerant animals treated with cyclophosphamide.

Research Summary

The study examined the effect of induced immunological unresponsiveness to CNS antigens, alone and in conjunction with cyclophosphamide, on spinal cord regeneration in rats after complete spinal cord transection. The results indicated that inducing immunological unresponsiveness alone did not significantly increase corticospinal regeneration, but electrophysiological evidence suggested regeneration of long ascending sensory pathways. The combination of induced immunological unresponsiveness and cyclophosphamide treatment resulted in corticospinal axonal regeneration as measured by tritiated proline transport and electrophysiological techniques, as well as electrophysiological evidence of ascending sensory tract regeneration.

Practical Implications

Immunological Response Interference

The study adds to the indirect evidence that an immunological response to CNS tissue in some way interferes with central axonal regeneration.

Combination Therapy Potential

Combining immunosuppression with other regeneration-promoting strategies may hold promise for enhancing spinal cord repair.

Further Research

Further studies are needed to identify specific measures of immune reactivity that are altered by treatments promoting axonal regeneration in the CNS.

Study Limitations

1
A successful protocol for inducing and maintaining immunological unresponsiveness to CNS antigens has yet to be developed.
2
The electrophysiological method detects only those axons which regenerate and form a synapse on a lower motor neurone.
3
HRP implanted in the lumbar cord did not label cortical neurones in the sensorimotor cortex.

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