Administered circulating microparticles derived from lung cancer patients markedly improved angiogenesis, blood flow and ischemic recovery in rat critical limb ischemia

Background: We hypothesized that lung cancer patient's circulating microparticles (Lc-MPs) could promote angiogenesis, blood flow in ischemic zone and ischemic recovery in rat critical limb ischemia (CLI). Methods: To investigate the impact of MP therapy on reversing the setting of CLI, adult-male Sprague-Dawley rats (n=50) equally randomized into sham control (SC) (group 1), SC-Lc-MPs (1.0 x 10⁷ particles) (group 2), CLI (group 3), CLI-Hs-MPs (MPs from healthy-subject) (group 4), and CLI-Lc-MPs (group 5) were sacrificed by post-CLI day-14. Results: In vitro study showed that Lc-MPs enhanced VEGFR2 expression, angiogenesis, nitric-oxide production, and endothelial cell proliferation (all p<0.005). By days 7 and 14, Laser Doppler showed significantly higher ischemic/normal blood-flow ratio in groups 1 and 2 compared with group 3, and was significantly higher in group 4 and further elevated in group 5 (p<0.0001). Numbers of small vessels and endothelial markers (CD31⁺ and vWF⁺ cells) and protein expressions (eNOS, CD31) exhibited a pattern identical to Lasre Doppler among the five groups (all p<0.001). Pro-angiogenic factors (VEGF, CXCR4, SDF-1α HGF) at cellular and protein levels showed a significant step-wise increase from groups 1 and 2 to groups 3, 4, and 5 (all p<0.001). Protein expressions of fibrotic (Smad3, TGF-β) and apoptotic (mitochondrial Bax, cleaved caspase 3, and PARP) biomarkers displayed an opposite pattern compared to that of Laser Doppler, whereas the protein expressions of anti-fibrotic (Smad1/5, BMP-2) and anti-apoptotic (Bcl-2) biomarkers showed an identical pattern compared with that of Laser Doppler among groups 1 to 3, and 5 (all p<0.001). Conclusion: Administration of Lc-MPs augmented angiogenesis and restored blood flow in a rat of CLI.