Circulating sclerostin is elevated in short-term and reduced in long-term SCI.

Area of Science:

• Orthopedics
• Endocrinology
• Neuroscience

Background:

• Spinal cord injury (SCI) leads to significant bone loss due to paralysis and lack of mechanical loading.
• Sclerostin, an osteocyte-derived Wnt antagonist, inhibits bone formation and is implicated in bone loss.
• Previous rodent studies show altered sclerostin with mechanical unloading, but human data regarding SCI duration is lacking.

Purpose of the Study:

• To investigate the relationship between circulating sclerostin levels and the duration of spinal cord injury (SCI) in humans.
• To determine if sclerostin serves as a biomarker for bone loss severity in chronic SCI patients.

Main Methods:

• Analysis of serum sclerostin levels in 155 men with SCI (≥1 year post-injury).
• Correlation of sclerostin levels with injury duration (≤5 years vs. >5 years).
• Association of sclerostin with bone mineral density and content in long-term SCI.

Main Results:

• Sclerostin levels were highest in subjects with short-term SCI (≤5 years) and decreased significantly within the first 5 years post-injury.
• No correlation between sclerostin and injury duration was found in subjects with long-term SCI (>5 years).
• In long-term SCI, higher sclerostin levels correlated with greater bone density and mineral content.

Conclusions:

• Sclerostin levels initially rise after SCI due to mechanical unloading but this response is time-limited.
• Circulating sclerostin decreases as bone loss progresses, being lowest in severe osteoporosis.
• Sclerostin may act as a therapeutic target in acute SCI and a biomarker for osteoporosis severity in chronic SCI.