The Role of Endothelial Progenital Cells and Fibrin on Vascularization and Stability in Orbital Implant

ABSTRACT

PURPOSE: The effects of endothelial progenitor cells (EPCs) and fibrin on fibrovascular growth into porous polyethylene orbital implants (Medpor(R) sheet) were investigated using stem cells. METHODS: EPCs were separated from human adipose fat tissue for culture. Fluorescence-activated cell sorting (FACS) was used to identify the phenotype and to analyze the purity of EPCs cultivated from human adipose tissue. Processed Medpor(R) sheets were inserted in each quadrant of the subcutaneous fat layer under the dorsal surface of 20 anesthetized athymic nude mice, using sterile methods. Medpor(R) sheets processed with endothelial progenitor cells and fibrin were inserted into the two top quadrants, a Medpor(R) sheet processed with fibrin was inserted in the lower right quadrant, and an unprocessed Medpor(R) sheet was inserted in the lower left quadrant of each mouse. The mice were sacrificed on the seventh day. The adhesiveness and blood vessel formation were quantified by weight and the number of blood cells within the Medpor(R) sheets. Hematoxylin and eosin (H&E) and toluidine blue stains were used to analyze fibrovascular and cell growth within the Medpor(R) sheets. RESULTS: The sheets processed with EPCs and fibrin were heavier and contained more white and red blood cells (p<0.001) than the other sheets. The sheets processed with fibrin alone were heavier (p<0.01) and contained more blood cells (p<0.001) than the unprocessed sheets. The degree of vessel formation and tissue adhesiveness was greatest in the group of Medpor(R) sheets processed with EPCs and fibrin. The sheets processed with fibrin only had greater tissue adhesiveness and fibrovascular proliferation than the unprocessed Medpor(R) sheets. CONCLUSIONS: Endothelial progenitor cells and fibrin applied to Medpor(R) sheets improve fibrovascular proliferation and tissue adhesiveness. When both are applied together, a synergistic effect is seen.