Experimental Rationale for Using an Eximer Laser for Preparation of Ultrathin Graft for Posterior Lamellar Keratoplasty

Purpose. To rationale experimentally the use of an excimer laser for forming an ultrathin transplant for posterior lamellar keratoplasty. Materials and methods. Atomic force microscopy was used for examination of 10 samples. Control group was 5 corneal flaps obtained by mechanical microkeratome (Moria SLK-2, France). Main group — 5 corneal flaps, obtained by microkeratome and underwent photoablation by “Microscan 500” (Optosystems, Troick, RF) excimer laser at 50 um depth. For quantification of endothelial loss 10 donor corneas (5 pairs) with viable endothelium, preserved in Borzenok—Moroz media, were used. Two groups were formed: main — 5 ultrathin transplants obtained by consistent application of microkeratome and excimer laser, control (from the paired eyes of same donors) — ultrathin transplants prepared by two cuts of microkeratome. Detection of live and dead endothelial cells (EC) was provided by Calcein Violet 450 and Propidium Iodide “vital” fluorescent dyes. Nonparametric Mann—Whitney test was used for statistical analysis. Coefficient of reliability (p < 0.05) was considered to be significant. Results. RMS (roughnessmean square) of the transplant, prepared by excimer laser was — 24.17 ± 12.4 um, and RMS of the transplant prepared by microkeratome — 22.3 ± 18.3 um. Statistical analysis did not reveal significant differences in RMS values in the mentioned groups (p > 0.05). EC death in excimer laser group was 10.35 ± 5.84 %. EC death in microkeratome group — 8.06 ± 1.31 %. No statistically reliable difference of EC death was revealed in the 2 groups (p > 0.05). Conclusions. The investigation has showed identical RMS values in the examined groups, representing high optical qualities of the transplant prepared by excimer laser. EC loss was also comparable in 2 groups. The received results indicate considerable potential of excimer laser transplants for posterior lamellar keratoplasty.

Cancer cells uptake porphyrinsviaheme carrier protein 1

Although exogenous porphyrin accumulation in cancer cells is important for the success of photodynamic therapies, the mechanism is not clear. We hypothesized that a newly reported transporter, heme carrier protein 1 (HCP1), is highly expressed in cancer cells, and transports porphyrins into the cells. We investigated the following three unknowns: whether cancer cells take up hematoporphyrin derivative via HCP1, whether HCP1 is involved in photodynamic therapies, and whether cancer cells highly express HCP1. First, when HCP1-overexpressed cells were treated with hematoporphyrin derivative and then exposed to an eximer laser beam, they emitted a significantly higher intensity of hematoporphyrin derivative fluorescence and became more susceptible to the laser beam than control. Second, when three other types of cancer cells with silenced HCP1 were treated with hematoporphyrin derivative and then exposed to the laser beam, they emitted a significantly lower intensity of hematoporphyrin derivative fluorescence. Third, non-cancer cells slightly expressed HCP1; on the other hand, the three other types of cancer cells clearly expressed HCP1. These results indicated that cancer cells uptake hematoporphyrin derivative via HCP1 and over-expression of HCP1 increases the efficacy of photodynamic therapies by increasing porphyrin accumulation in the cells. This is the first report about a transporter of porphyrin in cancer cells.