Abstract 4933: A 17B-estradiol Conjugated Chitosan-phosphorylcholine Polymer Supports Survival and Amplification of Endothelial Progenitor Cells (EPCs)
Introduction The mobilization of bone marrow derived cells (BMDC) including endothelial progenitors cells (EPCs) accelerates the reendothelialization process. Therefore, methodologies to favour EPC mobilization and amplification at the lesion site are needed. 17B-estradiol (E2) was shown to favour vascular healing through mechanisms involving EPCs. Chitosan (CH), a biodegradable polymer when combined to phosphorylcholine (PC) groups demonstrates an enhanced biocompatibility within a physiological environment and represents an attractive tool for tissue engineering. Hypothesis E2 conjugated CH-PC polymer improves survival, amplification and functionality of bone marrow derived EPC.
Methods: A system of mixed BMDC isolated from C57BL/6 female mice was cultured on fibronectin (control matrix), CH-PC-E2 or CH-PC alone or with soluble E2. BMDC proliferation, survival and organization were evaluated over 14 days. Proportion of mesenchymal cells (CD44+) and hematopoietic cells (CD117+) was determined by flow cytometry analysis. Cell migration through a CH-PC, CH-PC-E2 or fibronectin microfilm was assessed in a transwell system where E2 was used as the chemoattractant.
Results: BMDC adhesion and organization were comparable on the CH-PC, CH-PC-E2 and fibronectin matrixes over tested times. Soluble E2 or conjugated to CH-PC did not affect cell growth in standard proliferation assay. However, in specific population analysis, CH-PC-E2 markedly increased the proportion of hematopoietic cells (7,7±1,2 % vs CH-PC 2,4±0,65% and fibronectin 0,98±0,2%, p<0.05) and EPCs (2,31±0,3% vs CH-PC 0,2±0,05% and fibronectin 0,03±0,01, p<0.05). At the opposite, it decreased mesenchymal fraction (82,4±5,2% vs CH-PC 94,7±1,2% and fibronectin 89,4±3,0%, p<0.05). Moreover, even if all matrixes preserved the heterogeneous morphology of cell populations, only the CH-PC based polymers triggered spontaneous tubules formation suggesting a proangiogenic potential. Finally, the E2-induced migratory activity of BMDC was reduced by half but not abrogated on CH-based matrixes.
Conclusion: E2 conjugated CH-PC promotes EPC amplification and is a promising vehicle for cell delivery at the vascular lesion to increase healing process.