Author + information
- Galen Hancock1,
- Debargh Dutta2,
- Pushya Potnis2,
- Nanda Mahashetty2,
- Belay Tesfamariam3 and
- Steven Wood2
The concept of biodegradable polymer-based scaffolds has emerged as an alternative to the permanent metallic device implants to treat a transient vascular healing problem. The development of a suitable polymer has been challenging because it must exhibit vascular biocompatibility while allowing time- and dose-controlled antiproliferative drug release such that complete healing is achieved. The aims of this study were to characterize intimal biocompatibility of biodegradable polymers and drugs using screening assays of apoptosis, oxidative stress, proinflammatory mediators, adhesion molecules, prothrombotic and antithrombotic mediators in endothelial cells.
Endothelial cell line EAHy926 were cultured in chamber slides coated with poly-DL-lactide (PDLA) and paciltaxel for seven days. Flow cytometric analysis was used to measure cytotoxicity, apoptosis (annexin V and 7-amino-actinomycin D staining, 7-AAD), nitrotyrosine expression, thrombomodulin, tissue factor, cell adhesion molecules (PECAM-1, P-selectin and PSGL-1), activated protein C receptor and co-stimulation modulators (CD40L, TNF receptor).
Treatment of endothelial cells with PDLA and paclitaxel induced increase in annexin V expression (4.4%) compared to control (0.3%), but not 7-AAD stained dead cells, indicating enhanced apoptosis. Paciltaxel alone and in combination with PDLA showed upregulation of tissue factor (38.8% vs control 7.3%) and downregulation of thrombomodulin (86.8% vs control 98.5%). Endothelial cells incubated in PDLA and paciltaxel showed a marked increase in nitrotyrosine expression and exhibited an apparent cell death compared to the negative control. Paciltaxel alone or in combination with PDLA showed upregulation of microtubule-associated protein 1A/1B-light chain 3 (31.3% vs. control 5.0%) and p62 protein (56.4% vs. control 7.2%) indicating stimulation of autophagy. PDLA and paciltaxel had minimal effect on the expression of cell adhesion molecules, activated protein C receptor, or co-stimulation modulators.
The results indicate that PDLA and paciltaxel induce nitrative oxidative stress, stimulate autophagy, promote prothrombotic mediators, and cytotoxicity in endothelial cells. The study emphasizes endothelial biocompatibility screening of newly evolving biodegradable polymers as drug carriers and bioresorbable vascular scaffolds.