Isolation and characterization of an established endothelial cell line from transgenic mouse hemangiomas.

A murine endothelial cell line was isolated from hemangiomas induced by expression of the polyoma early region gene in transgenic mice. After two cell sortings using acetylated low-density lipoprotein with a fluorescent label (Dil-Ac-LDL), a pure population of endothelial cells has been carried for more than 60 passages from the animal. The cells retain endothelial cell properties such as a characteristic cobblestone appearance at confluency, contact-inhibited growth, and active uptake of Ac-LDL. Expression analysis shows that the cells express both the polyoma transgene and the von Willebrand factor, an endothelial cell marker. Subcutaneous injection of the cultured endothelial cells into nontransgenic histocompatible mice or nude mice led to hemangioma formation, and endothelial cells were re-isolated by cell sorting from these secondary hemangiomas. This cell line represents a renewable source of murine endothelial cells derived from transgenic mice that can be studied both in vitro and by reintroduction into a host.

Interstitial laser photochemotherapy of rhodamine-123-sensitized rat glioma.

The effect of interstitial laser photochemotherapy with the mitochondrial-specific intravital dye rhodamine-123 (Rh-123) was studied using a malignant rat glioma model system (RT2). Tumors were transplanted subcutaneously into the flank of athymic mice and into the cerebrum of adult rats. The Rh-123 photosensitization was produced by direct intratumoral injection of Rh-123 into the mouse RT2 flank tumors and by intravenous Rh-123 administration to adult rats with implanted RT2 intracerebral tumors. Intratumoral irradiation with 150 mW of argon laser light for an exposure time of 15 minutes was performed using a conical sapphire-tipped quartz optical fiber. Control groups of animals received either no treatment, Rh-123 injections, or administration of 150 mW of argon laser light for 15 minutes. Both flank and intracerebral tumors showed progressive diminution in size after treatment with Rh-123 photochemotherapy. There was no evidence of tumor recurrence in 60% of Rh-123 photochemotherapy-treated tumors. Recurrences in tumors treated with Rh-123 photochemotherapy usually appeared at the periphery of the original tumor at 10 days after treatment. Histologically, photochemotherapy-treated intracerebral tumors showed progressive shrinkage with increasing tumor necrosis over time. The finding of residual or recurrent tumor at the periphery of the original tumor mass suggests that the lack of penetration of the blue-green (argon) light was responsible for preventing complete tumor ablation. Our results suggest that Rh-123 photochemotherapy can destroy malignant gliomas in vivo; however, the poor penetrability of the photoactivating blue-green light may limit the effectiveness of this treatment for large or extensively invasive tumors.