CELL COLONIZATION POTENTIAL OF THERMOPLASTIC SILICONE-BASED POLYURETHANE (TSPU) POLYMER FOR NOVEL HEART VALVE PROSTHESIS

To investigate the colonization potential of Ovine Endothelial Progenitor Cells (OEPCs) on thermoplastic silicone-based polyurethane (TSPU) polymer under static condition. Functionalised TSPU (F-TSPU) was prepared by first subjecting the TSPU nonwovens to plasma treatment, followed by sterilization with 70% ethanol for seven minutes and then coupling with VEGF under sterile conditions. TSPU without any additional treatment or modification, identified as NF-TSPU, were used as control. OEPCs were seeded at the density of 5x104 cell/cm2 onto square 4 cm2 sized polymers under static conditions. Samples were taken at three time points: 1, 3 and 7 days. Samples were examined through live/dead staining and scanning electron microscopy (SEM) to check the progression of cellular colonization on the polymer. MTS assay was used to quantify the metabolic activity of the cells on the polymer. Cells seeded on the polymer surface were clearly visible on the SEM images. On day 3, the cells could be observed as patches on surface but did not cover all the surface. By day 7, the cells had almost filled the polymer surface. In case of F-TSPU, at Day 7, the underlying fiber pattern of the polymer could be observed on the cell sheet covering the polymer. Whereas this feature was not seen for NF-TSPU, indicating that the cells attached firmly to F-TSPU compared to NF-TSPU. Bright green fluorescence was observed on samples that underwent live/dead staining, indicating presence of live cells. Only a few red spots, representing dead cells, were seen. The metabolic activity on NF-TSPU was quantified to be higher than in the F-TSPU, though the difference was not statistically significant. Static cell seeding experiments showed that OEPCs were able to attach and grow on the surface of both types of TSPU. These are promising results suggesting that TSPU holds potential for engineering of a new generation of heart valve prostheses, which will be assessed in pre-clinical animal models in the near future.