title: Indocyanine green: intracellular uptake and phototherapeutic effects in vitro.
abstract: Indocyanine green (ICG; absorption peak in human plasma 805 nm) was investigated for ICG-mediated phototherapy in vitro. The cellular uptake of ICG (1 microM-50 microM) into HaCaT keratinocytes after an incubation period of 24 h increased up to an intracellular ICG concentration of 12.1 +/- 1.3 nmol per 10(6) cells. To examine dose dependent phototoxic effects in vitro, keratinocytes were incubated with 0 microM-50 microM ICG for 24 h and irradiated by a diode laser (805 nm) with different energy densities (0, 12, 24, 48 J cm-2). All applied ICG concentrations except for 5 microM yielded a cell killing effect in combination with irradiation depending significantly on ICG concentration and light dose. Cell viability for dark control and cells incubated with 50 microM ICG and irradiated with 48 J cm-2 was 0.82 +/- 0.15 and 0.07 +/- 0.02, respectively. Sodium azide (100 mM), a quencher of reactive oxygen species, inhibited significantly the cell killing using 50 microM ICG and 24 J cm-2. Taken together, photoactivation of ICG by irradiation with a diode laser was shown to induce effectively cell killing of HaCaT keratinocytes. Moreover, this effect was inhibited by sodium azide, thus irradiation of ICG might induce a photodynamic reaction.
authors.affiliation: Department of Dermatology, University of Regensburg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Fickweiler
authors.forename: R M
authors.initials: RM
authors.lastname: Szeimies
authors.forename: W
authors.initials: W
authors.lastname: Bäumler
authors.forename: P
authors.initials: P
authors.lastname: Steinbach
authors.forename: S
authors.initials: S
authors.lastname: Karrer
authors.forename: A E
authors.initials: AE
authors.lastname: Goetz
authors.forename: C
authors.initials: C
authors.lastname: Abels
authors.forename: F
authors.initials: F
authors.lastname: Hofstädter
authors.forename: M
authors.initials: M
authors.lastname: Landthaler
mesh_terms: D000970:Antineoplastic Agents / Q000378:metabolism* / Q000494:pharmacology; D001386:Azides / Q000494:pharmacology; D002460:Cell Line; D006801:Humans; D007208:Indocyanine Green / Q000378:metabolism* / Q000494:pharmacology; D015603:Keratinocytes / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D009153:Mutagens / Q000494:pharmacology; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000378:metabolism* / Q000494:pharmacology; D019810:Sodium Azide
chemical_list: D000970:Antineoplastic Agents; D001386:Azides; D009153:Mutagens; D017319:Photosensitizing Agents; D019810:Sodium Azide; D007208:Indocyanine Green