Abstract 15659: Collagen Biomaterial Enhances Cd34+ Cell Function Through Mir-21b
Introduction: CD34+ cells represent a promising cell for revascularization therapy as they incorporate into newly forming vessels and stimulate endogenous revascularization processes. However, CD34+ cell therapy is limited by low cell numbers and engraftment upon transplantation. In this study, a collagen type I biomaterial (matrix) was used to expand and enhance CD34+ cell function and potential underlying mechanisms were examined.
Methods: CD34+ cells were enriched from human blood mononuclear cells cultured on fibronectin or matrix by magnetic bead separation. Culture supernatants were analyzed for exosome secretion and content.
Results: Compared to fibronectin, matrix derived CD34+ cells had increased proliferation (2.1±0.4 fold), migration (3.2±0.8 fold) and angiogenic potential as determined by incorporation into tube-like structures (3.6±0.6 fold) and capillary network formation (2.3±0.6 fold; p≤0.002). Exosomes are known to regulate the angiogenic effects of CD34+ cells. Here, we observed a 1.4±0.1 fold increase in secreted CD63+CD81+ exosomes from matrix-cultured cells compared to fibronectin. In matrix-derived exosomes, we detected greater levels of two microRNAs, miR-21 (7.4±2.6 fold) and miR-210 (2.7±0.6 fold), compared to fibronectin (p≤0.03). One miR-21 target of interest, Spry1, is a negative regulator of endothelial cell proliferation and angiogenesis. In matrix-cultured cells, Spry1 mRNA and protein levels were reduced by 5.8±1.0 and 2.9±0.1 fold, respectively (p≤0.001). Furthermore, when cells from CVD patients were cultured on matrix, we observed similar results to healthy CD34+ cells: a 3.3±0.9 and 2.5±0.4 fold increase in miR-21 and miR-210, respectively (p≤0.03). Matrix-cultured CVD cells also had improved VEGF-mediated migration (2.9±0.7 fold) and increased capillary network formation in an angiogenesis assay (1.7±0.1 fold).
Conclusion: Our results suggest that matrix culture may be useful for expanding the number and enhancing the function of CD34+ cells in CVD patients, which may be mediated through suppression of Spry1 activity by exosome-derived miR-21. Therefore, our biomaterial offers a novel strategy to enhance the therapeutic potential of CD34+ cells for vascular regeneration.
Author Disclosures: B. McNeill: None. A. Ostojic: None. M. Ruel: Honoraria; Modest; Medtronic (MICS CABG Proctor), Abbott Medical. K.J. Rayner: None. E.J. Suuronen: None.
- © 2016 by American Heart Association, Inc.