Papers by Author: Deling Kong

Abstract: Electrospinning represents an attractive approach for polymer processing. In the present study, gelatin and poly (propylene carbonate)(PPC) were electrospun successfully and collected on a rotating mandrel to form tubulose scaffolds. Furthermore, to mimic the real structure of animal blood vessels, the polymers were employed in a single tube as distinct layers by the technique of alternate electrospinning. Scanning electronic microscopy (SEM) was used to analyze the morphology and diameter of the fibers, and the porosity of the scaffold. The tubes were seeded with rat bone marrow derived mesenchymal stem cells (BMSCs) and cultured for 2 weeks to evaluate their biocompatibility. The growth and distribution of the cells were observed directly under the fluorescent microscope. The interaction between cells and scaffold was analyzed by SEM and H&E staining. After two weeks culture, the fibers were almost embedded by growing BMSCs. H&E staining and green fluorescent image showed that BMSCs uniformly grew inside the scaffolds. The results showed that electrospun tubes with uniform pores and fibers of smaller diameter were appropriate for BMSCs attachment and proliferation. These primary data indicated that scaffolds fabricated by ectrospinning are structurally biocompatible. The PPC scaffolds may be useful in vascular tissue engineering if they were further modified chemically or with appropriate therapeutic molecules.

Abstract: Recent study shows that endothelial progenitor cells (EPCs) and gene therapy technologies are effective strategies in the inhibition of stenosis and thrombus formation and improving the patency rate of the vascular graft in vivo. In this study, rat EPCs were cultured from bone marrow, and plated in fibronectin-coated plates with EBM-2 medium. Bone marrow mesenchymal stem cells (MSCs) were cultured with alpha minimum essential medium ( -MEM). After two weeks, EPCs were immunohistochemically characterized using antibodies specific for endothelial cells. Retroviral vectors pMSCV-eNOS, pMSCV-tPA, pMSCV-LacZ and pMCSV-GFP were constructed. Retroviral particles were produced using packaging cell line 293T cells. Gene transfer was carried out by exposing cells to virus solution for 6 hours in the presence of 8µg/ml polybrene. For constructing vessels, MSCs and EPCs were seeded on fibronectin coated ePTFE graft in tissue culture condition for 2-4 weeks. The attachment and growth of cells were analyzed with scanning electron microscopy (SEM). Our data showed that the EPCs expressed VEGF, Lectin BS-1, RECA-1, indicating they are endothelial lineage. The concentrated retroviral particles showed many folds higher transduction efficiency to NIH 3T3 cells than the commercial reagent Fugene. SEM data showed dense attachment of MSCs on the graft surface. MSCs/EPCs co-culture gave much better cell coverage on the graft than culture of EPCs alone.