Experimental grounds for using chlorin e6 in the photodynamic therapy of malignant tumors.

The toxicity, pharmacokinetics and antitumour effect of chlorin e6 after light irradiation were studied. The LD50 value of chlorin e6 in C3H mice is 189 +/- 9 mg kg-1 and in Wistar white rats is 113 +/- 18 mg kg-1 14 days after intraperitoneal injection. The concentration of chlorin e6 in blood, liver, kidney, spleen and tumors (sarcoma M-1 and sarcoma 45) of the rats was determined by a fluorescence method, 3, 6, 12, 18, 24, 48 and 72 h after administration at a dose of 10 mg kg-1. For this purpose, chlorin e6 was extracted from tissues by the detergent Triton X-100. The depth of necrosis in sarcoma 45, the regression rate of sarcoma M-1 and the animal cure rate were evaluated after chlorin e6 administration at doses of 1-10 mg kg-1 and subsequent irradiation with krypton laser light. Depending on the dose and the time interval between chlorin e6 injection and irradiation, the depth of necrosis in sarcoma 45 varied from 5.0 to 15.0 mm. The cure rate of the animals with sarcoma M-1 varied from 10% to 60%. The antitumor effect was directly proportional to the chlorin e6 dose and light energy exposure and inversely proportional to the time interval between photosensitizer injection and irradiation.

Sensitivity of different rat tumour strains to photodynamic treatment with chlorin e6.

Transplantable rat tumours (sarcoma M-1, sarcoma 45, alveolar liver cancer PC-1 and Pliss' lymphosarcoma) were used to study chlorin e6 accumulation in tumours and its photodynamic effect. Tumours were irradiated by krypton ion laser light (647 and 676 nm; 90 J cm-2) 15 min and 24 h after chlorin e6 injection at doses of 5 and 10 mg kg-1. The relationship between some morphological peculiarities of these tumour strains, photosensitizer accumulation in tumours and their response to the photodynamic treatment is discussed.

Photodynamic therapy with chlorin e6. A morphologic study of tumor damage efficiency in experiment.

Morphological changes in rat sarcoma M-1 after photodynamic treatment with chlorin e6 were studied. The frequency of necrosis appearance and the depth of its spreading in tumor tissue were evaluated after intraperitoneal injection of chlorin e6 in doses of 1-10 mg kg-1 and subsequent irradiation by a krypton laser with light energy density 22.5-135 J cm-2, using the method of vital staining with Evans blue. It was found that the antitumoral effect of photodynamic treatment was strengthened by increasing the dose of the agent and light and reduced by increasing the time interval between chlorin e6 injection and light irradiation. The treatment being given in the parameters mentioned produced a depth of tumor necrosis which varied from 4.0 mm to 16.6 mm. The mechanisms of tumor tissue damage after photodynamic treatment in vivo are discussed.

[Hematopoietic stem cell count in mice with stimulated and suppressed erythropoiesis. II. Hypertransfusion of syngeneic erythrocytes and chronic hypoxia]. / Soderzhanie stvolovykh krovetvornykh kletok u myshei v usloviiakh stimulirovannogo i podavlennogo éritropoéza. II. Gipertransfuziia singennykh éritrotsitov i khronicheskaia gipoksiia.

Polypotential hemopoietic stem cell numbers were monitored by means of the splenic colony-forming unit (CFU-S) method in bone marrow and spleen of CBA mice in condition of suppressed erythropoiesis (after syngeneic red blood cell hypertransfusion and chronic hypoxia). Erythropoietic activity determined by radioactive isotope 59Fe uptake in erythroid cells of spleen, bone marrow and erythrocytes of peripheral blood sharply decreased after these treatments. CFU-S contents in bone marrow and spleen increased during a week after syngeneic red blood cell hypertransfusion and after chronic hypoxia. It is assumed that the increase in hemopoietic stem cell contents in hemopoietic organs of mice under inhibited erythropoiesis may be interpreted due to the appearance of vacant differentiation potencies of stem cells, which in the normal state is realized in production of erythroid cells.

[Hematopoietic stem cell count in mice with stimulated and suppressed erythropoiesis. I. Blood loss and acute hypoxia]. / Soderzhanie stvolovykh krovetvornykh kletok u myshei v usloviiakh stimulirovannogo i podavlennogo éritropoeza. I. Krovopoteria i ostraia gipoksiia.

Polypotential hemopoietic stem cell numbers were determined by means of the splenic colony-forming unit (CFU-S) method in bone marrow and spleen of CBA mice in different periods after bleeding and acute hypoxia. After these treatments, radioactive isotope (59Fe) uptake by erythroid cells, considered as an index of erythropoietic activity, enhanced in the spleen, but in the bone marrow it either diminished (after acute hypoxia), or remained unchanged (after bleeding). Bleeding caused a considerable increase in the splenic CFU-S numbers, but the bone marrow CFU-S contents were unchanged. It was found that splenic CFU-S number decreased on the 1st and 4th days after acute hypoxia, but increased on the 7th day; bone marrow CFU-s numbers increased on the 7th day. Possible mechanisms involved in the hemopoietic stem cell perturbation in the hemopoietic organs after the erythropoiesis stimulating treatment are discussed.

Splenic plaque-forming cells (PFC) and stem cells (CFU-s) during acute phenylhydrazine-induced enhanced erythropoiesis.

The erythroid status and levels of splenic plaque-forming cells (PFC) to sheep red blood cells (SRBC) were monitored in mice subsequent to acute phenylhydrazine (PHZ)-induced hemolytic anemia. From ferrokinetic measurements, we noted a shift in erythropoiesis from bone marrow to spleen. The levels of splenic PFC were significantly depressed following PHZ-induced erythroid differentiation. Although this immune depression may reflect competition at the stem cell levels, whereby pluripotent stem cells (CFU-s) are preferentially differentiated into the erythroid line at the expense of lymphopoietic pathways, other possibilities cannot be excluded. In this regard, we have shown that loading of the mononuclear phagocyte system (MPS) by PHZ-damaged erythrocytes effected profound depressions in splenic PFC numbers. Lastly, in addition to the well-documented increases in CFU-s migration from marrow to spleen during enhanced erythropoiesis, we noted increased migration of B lymphocytes (as assessed by PFC) in marrow-shielded lethally-irradiated mice given PHZ. We also provide data which show that PHZ-damaged RBC evoke increased migration of CFU-s in normal mice, indicating a possible involvement of the MPS in stem cell migration.

[Different effect of testosterone on polypotential stem hematopoietic stem cells and immunocompetent B-lymphocytes]. / Razlichnoe vliianie testosterona na polipotentnye stvolovye krovetvornye kletki i immunokompetentnye B-limfotsity.

A research was made to study the dynamics of the proliferative, colony-forming and migration capacity of stem hemopoietic cells in (CBA X C57Bl) F1 hybrid mice under the influence of testosterone propionate, 10 mg/100 g, as well as the migration of immunocompetent B lymphocytes from the bone marrow to the spleen and the accumlation of their progeny, antibody-producing cells, in the spleen. The immunodepressive effect of testosterone was manifested by a decrease in the migration of B cells and the number of antibody-producing cells in the spleen. On the contrary, testosterone had a stimulating effect on the functional activity of stem hemopoietic cells, increasing their proliferation and migration. Under conditions of the suppressed erythropoietic differentiation of multipotent stem hemopoietic cells the injection of testosterone resulted in an increase in the number of antibody-producing cells in the spleen. This suggests that the stimulation of erythropoiesis and immunosuppression, induced by testosterone, are interconnected and determined by the direct action of the hormone on the cellular cycle of the stem cells, as well as by their prevailing differentiation towards the erythroid series, resulting in the decrease of their differentiation into B cells.

[Antibody-forming capacity of mouse spleen cells after hypoxic hypoxia and the administration of erythropoietin]. / Antiteloobrazuiushchaia sposobnost' kletok selezenki myshei posle gipoksicheskoi gipoksii i vvedeniia éritropoétina.

In CBA mice the absolute and relative (per 10(6) spleen cells) number of antibody-forming cells (AFC) in the spleen was cut by half on the 1st, 4th, and 7th days after acute hypoxia (12 hours, 6700 m), and on the 1st and 4th days after cessation of chronic hypoxia (16 days, 16 hours, 6700 m). The number of AFC in the spleen returned to the normal level on the 7th day after cessation of chronic hypoxia. Single or double erythropoietin injections caused approximately a 1.15--2-fold decrease in spleen AFC number in posthypoxic mice in comparison with control animals.

[Antibody formation and B-cell migration from bone marrow to spleen in mice under conditions of stimulation and suppression of erythropoiesis]. / Antitelogenez i migratsiia B-kletok iz kostnogo mozga v selezenku u myshei v usloviiakh stimuliatsii i podavleniia éritropoéza

The effect of erythropoietic stimulation and suppression on the production of antibody-forming cells (AFC) in the spleen and on the B-cell migration from the bone marrow to the spleen was investigated in the CBA mice. Erythropoiesis stimulation proved to sharply increase the AFC count in the spleen and the B-cell migration from the bone marrow to the spleen 1 and 4 days after the bleeding. Erythropoiesis suppression resulted in a slight increase of the AFC count in the spleen 4 and 7 days after the transfusion of syngeneic red blood cells. However, the erythropoietic suppression inhibited the B-cell migration from the bone marrow to the spleen. Possible mechanisms of the effect of the erythropoietic stimulation and suppression on the antibody production are discussed.