Abstract
Purpose: :
Most patients with uveal melanoma in the United States are treated with brachytherapy, which has remained unchanged for 40 years. Local delivery of therapeutic agents may prevent the complications associated with brachytherapy such as extraocular muscle trauma, collateral radiation toxicity, and the necessity of two separate surgeries. This study is to evaluate the possibility of injecting the microspheres into the suprachoroidal space (SCS) of a tumor bearing eye with microdevices.
Methods: :
A rabbit model of uveal melanoma was created by injecting cultured human uveal melanoma cells into the SCS of immunosuppressed rabbits. Rabbits were immunosuppressed by daily injection of 10-15 mg/kg Cyclosporine A, and 1.5 x 106 of 92.1 human uveal melanoma cells in a volume of 100 µl suspension were injected into the SCS of the rabbits with a hollow microneedle. At post-injection week 4, a microcatheter (iTrackTM 370P microcatheter; iScience InterventionalTM, Menlo Park, CA) was introduced and advanced into the SCS adjacent to the tumor, and 10 µm fluorescent particles (FluoSpheres®; Invitrogen, Carlsbad, CA) were injected in 2 rabbits. Resin beads (30 µm; Sirtex Medical, Sydney, Australia) were prepared and injected into SCS in one rabbit in a similar manner. Additionally, resin beads were injected into the SCS of rabbit control eyes using a 1 mm microneedle. After one week, the eyes were enucleated and submitted for histopathological examination.
Results: :
A tumor was developed in the choroid of the rabbits. Fundus examination showed yellow-tinted area around the tumor in the posterior pole, suggesting the location of the fluorescent microspheres. Histopathological examination showed polystyrene microspheres or resin beads located in the SCS of the rabbit eyes. There was no inflammation associated with the microspheres. Microbeads were present in the SCS of the eyes injected using microneedles.
Conclusions: :
Our study shows that microspheres can be successfully injected into the suprachoroidal space using a microcatheter or microneedle. This technique will enable us to deliver therapeutic agents directly adjacent to and into intraocular melanoma.
Keywords: melanoma • drug toxicity/drug effects • oncology