Semaphorin 3A Inhibits Nerve Regeneration During Early Stage after Inferior Alveolar Nerve Transection

Area of Science:

• Neuroscience
• Regenerative Medicine
• Peripheral Nerve Injury

Background:

• Neuroma formation impedes peripheral nerve regeneration.
• The precise role of semaphorin 3A (Sema3A) in early nerve injury and regeneration remains unclear.

Purpose of the Study:

• To investigate the effects of Sema3A on peripheral nerve regeneration during the early stages post-injury.
• To elucidate the chronological expression of Sema3A and its receptor following nerve transection.

Main Methods:

• Immunohistochemistry for Sema3A and PGP9.5 in mouse inferior alveolar nerve (IAN) transection models (postoperative days 1-7).
• Local administration of anti-Sema3A antibody at the injury site.
• DiI labeling to assess trigeminal ganglion neuron survival.

Main Results:

• Sema3A expression was detected in the proximal stump of the injured IAN on postoperative day 1, decreasing over time.
• Blocking Sema3A with an antibody at postoperative day 3 inhibited axon sprouting.
• Anti-Sema3A antibody treatment increased the survival of trigeminal ganglion neurons.

Conclusions:

• Nerve injury triggers Sema3A production in ganglion neurons, transported to the proximal nerve end.
• Sema3A at the proximal nerve stump inhibits distal axonal sprouting, thus impairing early nerve regeneration.
• This study is the first to demonstrate Sema3A's involvement in the early stages of peripheral nerve regeneration.