We suggest a novel method that uses
artificial blood cells (
hemoglobin vesicles, Hb-Vs) as
photosensitizers in
dye laser treatment (at 595-nm wavelength) for
port-wine stains (i.e., capillary malformations presenting as red birthmarks) based on the results of animal experiments. As compared with human red blood cells, Hb-Vs have the same absorbance of 595 nm wavelength light and produce the same level of heat following
dye laser irradiation. Small sized Hb-Vs (250 nm) distribute in the plasma phase in blood and tend to flow in the marginal zone of microvessels.
Intravenous injections of Hb-Vs caused the dilatation of microvessels, and
dye laser treatment with Hb-Vs destroyed the vessel wall effectively. Following the
intravenous injection of Hb-Vs, the microvessels contained more Hb that absorbed
laser photons and produced heat. This extra Hb tended to flow near the endothelial cells, which were the target of the
laser treatment. These attributes of Hb-Vs will potentially contribute to enhancing the efficacy of
dye laser treatment for
port-wine stains.
Hemoglobin is a type of
porphyrin. Thus, our proposed treatment may have aspects of
photodynamic therapy using
porphyrin that leads to a cytotoxicity effect by
active oxygen.