In vitro and in vivo photosensitizing capabilities of 5-ALA versus Photofrin (R) in vascular endothelial cells

Background and Objective: The objective of the present study was to evaluat e the feasibility of photodynamic therapy (PDT) for complicated hemangiomas . The photosensitizing activities of 5-aminolevulinic acid (5-ALA) and Phot ofrin(R) were evaluated in vitro with human dermal microvascular endothelia l cells (MEC) and in vivo with the chicken cox comb. Study Design/Materials and Methods: The in vitro absorption and photosensit izing activities of 5-ALA and Photofrin(R) were examined in a MEC culture s ystem. The percentages of MEC killed by different drug concentrations at a wavelength of 630 nm were measured by either live/dead or lactate dehydroge nase-released assays. Similarly, the in vivo biological activities of B-ALA and Photofrin(R) exposed to different total light dosages at 630 nm were s tudied by determining the amount of necrosis produced in chicken combs. Results: MEC incubated with B-ALA at a concentration of 35 mu g/ml and expo sed to laser light at 630 nm at a power density of 100 mW/cm(2) showed a 50 % cell kill. MEC incubated with Photofrin(R) at a concentration of 3.5 mu g /ml and exposed to laser light at 630 nm at a power density of 100 mW/cm(2) showed a 50% cell kill. Chicken combs that received 200 mg/kg of 5-ALA exp osed to laser light at 630 nm at a power density of 100 mW/cm(2) had an inj ury depth of 362.5 +/- 27.6 mu m at histologic examination. Combs exposed t o a power density of 100 or 120 mW/cm(2) showed injury depths of 732.5 +/- 29.1 and 792.5 +/- 36.0 mu m, respectively. Chicken combs that received 2.5 mg/kg of Photofrin(R) exposed to laser light at 630 nm at a power density of 80 mW/cm(2) had an injury depth of 535.6 +/- 22.3 mu m at histologic exa mination. Combs exposed to a power density of 100 or 120 mW/cm(2) showed in jury depths of 795.8 +/- 32.5 and 805.2 +/- 49.1 pm, respectively. Conclusion: Both 5-ALA and Photofrin(R) have the capability to destroy MEC in vitro and vasculature in vivo. However, Photo-frin(R) achieved a higher degree of cell kill and tissue destruction at lower drug concentrations and at lower power densities. (C) 1999 Wiley-Liss, Inc.