Spinal Cord Ependymal Responses to Naturally Occurring Traumatic Spinal Cord Injury in Dogs

Area of Science:

• Neuroscience
• Stem Cell Biology
• Veterinary Medicine

Background:

• The spinal cord ependymal layer (SEL) is a potential source of endogenous neural stem cells for spinal cord injury (SCI) repair.
• Canine models of SCI are valuable, but canine SEL characteristics remain understudied.
• Understanding SEL behavior post-SCI is crucial for developing regenerative therapies.

Purpose of the Study:

• To characterize the histologic and immunohistochemical features of the canine SEL in normal dogs and those with acute SCI.
• To investigate the expression patterns of proliferation (PCNA, Ki-67) and differentiation markers (GFAP, vimentin) in the canine SEL post-SCI.
• To assess changes in cell adhesion and polarity markers (E-cadherin) in the canine SEL following SCI.

Main Methods:

• Histologic examination and immunohistochemical staining of the canine SEL.
• Analysis of normal dogs (n=4) and dogs with acute SCI (n=7) due to intervertebral disk extrusion.
• Staining for PCNA, Ki-67, caspase 3, E-cadherin, GFAP, and vimentin.

Main Results:

• Ki-67 staining was absent in the SEL of both normal and SCI dogs, suggesting limited acute proliferation.
• Increased GFAP-positive cells were observed in the SEL at lesion epicenter and proximal sites after SCI (P < .01).
• E-cadherin staining shifted from apical to membrane-circumferential and cytosolic post-SCI, indicating potential loss of polarity and increased migration.

Conclusions:

• The canine SEL exhibits increased GFAP expression and altered E-cadherin localization after SCI, supporting astrocytic differentiation and potential cell migration.
• These findings suggest the canine SEL may harbor endogenous neural precursors that could be therapeutically modulated for SCI.
• Further investigation into the canine SEL's role in SCI regeneration is warranted for future clinical interventions.