Advances in stem cell therapy for spinal cord injury

Introduction & Abstract:

• Spinal cord injury (SCI) is a severe condition with significant personal and societal implications. Currently, there’s no effective treatment for the neurological deficits caused by major SCI.
• Stem cell transplantation emerges as a promising therapeutic strategy. The report aims to discuss the epidemiology, pathophysiology, and experimental and clinical stem cell strategies for SCI.

Epidemiology:

• Globally, the annual incidence of SCI is between 15-40 cases per million people.
• In Canada, approximately 85,000 people live with SCI, with over 4,000 new cases annually. In the U.S., over 1 million people have SCI, with more than 12,000 new cases each year.
• Traumatic SCIs primarily result from motor vehicle accidents, sports injuries, falls, and workplace trauma. Males, especially young adults, are more prone to SCI than females.

Clinical Trial Design & Management:

• The American Spinal Injury Association (ASIA) grading scale is widely used to assess the severity of SCI and response to treatment. The ASIA Impairment Scale (AIS) ranges from A (complete SCI) to E (normal sensory and motor function).
• Acute treatments often involve surgical interventions, such as decompression and spinal stabilization. Methylprednisolone, a steroid, showed some neuroprotective effects but is controversial due to limited efficacy and potential side effects.

Pathophysiology:

• The most common type of traumatic SCI is acute compression of the spinal cord. The primary trauma leads to necrosis, edema, hemorrhage, and vasospasm. This initiates a series of secondary pathophysiological mechanisms, including ischemia, apoptosis, and inflammation, which further damage the spinal cord.
• Eventually, a fluid-filled cavity forms in the center of the cord, surrounded by a rim containing some preserved axons. The glial scar, formed by hypertrophic astrocytes and other cells, acts as a barrier to regeneration.

General Features of Cell Therapy:

• Cell therapy is a promising strategy for SCI. It can potentially mitigate secondary events through neuroprotection and restore lost tissue through regeneration.
• Various stem cell-based strategies for experimental and clinical SCI include the use of embryonic stem (ES) cells, mesenchymal stem cells (MSCs), neural stem/progenitor cells (NSPCs), and induced pluripotent stem cells (iPSCs).

Definition and Rationale for Stem Cells:

• Stem cells can continuously proliferate and generate daughter cells committed to differentiation. Progenitor cells have limited proliferative and differentiation potential.
• Several mechanisms for recovery have been proposed, including replacement of damaged cells, remyelination of spared axons, restoration of neuronal circuitry, and creation of a favorable environment for axonal regeneration.