Circulating angiogenic biomolecules at rest and in response to upper-limb exercise in individuals with spinal cord injury

Abstract

Objective

Individuals with spinal cord injury (SCI) show structural and functional vascular maladaptations and muscle loss in their lower limbs. Angiogenic biomolecules play important roles in physiological and pathological angiogenesis, and are implicated in the maintenance of muscle mass. This study examined the responses of angiogenic molecules during upper-limb aerobic exercise in patients with SCI and in able-bodied (AB) individuals.

Methods

Eight SCI patients with thoracic lesions (T₆–T₁₂, ASIA A) and eight AB individuals performed an arm-cranking exercise for 30 minutes at 60% of their VO_2max. Plasma concentrations of vascular endothelial growth factor (VEGF-A₁₆₅), VEGF receptor 1 (sVEGFr-1), VEGF receptor 2 (sVEGFr-2), metalloproteinase 2 (MMP-2), and endostatin were measured at rest, after exercise, and at 1.5 and 3.0 hours during recovery.

Results

The two-way analysis of variance showed non-significant main effects of “group” and significant main effects of “time/exercise” for all angiogenic biomolecules examined (P < 0.01–0.001). The arm-cranking exercise significantly increased plasma concentrations of VEGF, sVEGFr-1, sVEGFr-2, MMP-2, and endostatin in both groups (P < 0.001–0.01). The magnitude of the increase was similar in both patients with SCI and AB individuals, as shown by the non-significant group × time interaction for all angiogenic parameters.

Conclusions

Upper-limb exercise (arm-cranking for 30 minutes at 60% of VO_2max) is a sufficient stimulus to trigger a coordinated circulating angiogenic response in patients with SCI. The response of angiogenic molecules to upper-limb aerobic exercise in SCI appears relatively similar to that observed in AB individuals.

Keywords:

• Angiogenesis
• Arm exercise
• Exercise
• Endostatin
• Metalloproteinase
• Spinal cord injury
• Vascular endothelial growth factor

Acknowledgments

The authors thank all the participants for their cooperation and their voluntary participation in this study. This study was partially supported by the Research Committee of the Aristotle University of Thessaloniki, scholarships and sponsorships of research programs 2011 (Excellence Awards 2011; code number 50141).