Purpose
The purpose of the study is to test our hypothesis that if WERI-Rb-1 cells are exposed to topotecan, topotecan loaded Au-tethered DPPC/DPGPTE liposomes treated with near-infrared (NIR) pulsed laser, or AU-011 treated with a light-emitting diode (LED) laser, that the result will be cell death.
Methods
WERI-Rb-1 cells were grown to 3-4x10^5 cells/mL and exposed to different concentrations of topotecan (5-20 µg/50 µL) and topotecan loaded Au-tethered DPPC/DPGPTE liposomes (10-50 µg/50 µL). After treatment with topotecan loaded Au-tethered DPPC/DPGPTE liposomes, the cells were exposed to an 810 nm diode laser (1500 mW, 1000 msec at 50 msec repeat intervals) for 2 minutes. Similarly, WERI-Rb-1 cells were treated with multiple concentrations of AU-011 (Human papillomavirus virus-like particles conjugated with IR700 dye) (0.1-3 nM) and exposed to 16J of light using a LED lamp. Cell viability was determined at multiple time points using a trypan blue viability stain and a hemocytometer.
Results
Topotecan at a concentration of 20 µg/50 µL causes 99.7% cell death (p<0.001) by 4 hours. There was no statistically significant difference in cell viability rates at any time point between the 20 µg/50 µL of topotecan loaded Au-tethered DPPC/DPGPTE liposome groups that received NIR pulsed laser therapy as compared to the same group that did not receive laser therapy. The AU-011 at 0.1 nM, 1 nM, and 3 nM concentrations following exposure to 16J with an LED lamp all resulted in a statistically significant (p < 0.05) increases in cell death (83.3-91.7%, 87.5-100%, and 95.0-100% respectively) compared to the control (1.56-8.75% dead cells) at 1, 4, and 24 hours.
Conclusions
Topotecan at a concentration of 20 µg/50 µL effectively and rapidly kills WERI-Rb-1 cells in vitro. NIR pulsed laser therapy applied for a clinically relevant duration does not cause the necessary rise in temperature of the gold nanoshells to induce the release of a significant amount of topotecan from the liposomes. However, AU-011 in combination with LED therapy presents a promising novel method to effectively induce cell death of retinoblastoma cells locally without being cytotoxic to cells that do not receive LED exposure.
Keywords: 703 retinoblastoma •
607 nanotechnology •
624 oncology