Biomedical subjects

J G Levy

Publications and source records attributed to J G Levy.

At least 55 records · Page 3Linked to original sources

PubMed1994

Photodynamic therapy; a comparison with other immunomodulatory treatments of adjuvant-enhanced arthritis in MRL-lpr mice.

Although numerous experimental immunomodulatory regimens have been reported to be effective in the treatment of rheumatoid arthritis, they also produce undesirable side effects. An alternative specific modality of localized treatment is photodynamic therapy (PDT). In this study we treated 13-week-old MRL-lpr mice whose spontaneous arthritis was enhanced by intradermal injection of Freund's complete adjuvant (FCA). One group received transcutaneous photodynamic therapy at days 0, 10, and 20, following the FCA injection. The other groups were injected with 1 mg/kg per day indomethacin, 40 mg/kg per day cyclosporin A (CsA), or treated with 3 Gy sublethal whole body irradiation (WBI). The development of swelling was monitored for 1 month, at which time proteinuria, lymphadenopathy and the histopathology of the joints and kidneys were assessed. The results demonstrated that PDT and the conventional treatments significantly ameliorated swelling of the hindlimbs from 70% in the untreated FCA-injected animals to below the 19% level characteristic of the unmanipulated control. Histological examination showed a reduction in pannus formation, and cartilage and bone destruction, the characteristics of adjuvant-enhanced arthritis. PDT did not affect the survival rate, lymphoproliferation, or proteinuria of the treated animals. However, indomethacin increased proteinuria, and was less effective in preventing cartilage and bone destruction. Furthermore, lower doses of CsA and WBI exacerbated arthritis activity. These results indicate that photodynamic therapy can inhibit the development of adjuvant-enhanced arthritis in MRL-lpr mice with similar effectiveness to the conventional treatments, but without their negative side effects.

Animals↗

PubMed1994

Activation of benzoporphyrin derivative in the circulation of mice without skin photosensitivity.

In vitro experiments with benzoporphyrin derivative monoacid ring A (BPD) confirmed earlier studies that it was taken up rapidly (within 30 min) to maximum concentrations by all cells tested. It was also confirmed that rapidly dividing tumor cell lines and mitogen-activated murine T lymphocytes took up significantly more (5-10-fold) BPD than did normal splenic lymphocytes. Further experiments were undertaken to determine whether BPD could be activated by whole-body irradiation with red light in the blood of animals, shortly after intravenous (i.v.) administration, in the absence of skin photosensitivity. It was found that shaved and depilated mice injected i.v. 60 min earlier with BPD at between 0.5 and 1.0 mg/kg could tolerate 160 J/cm2 of broad-band red light (560-900 nm) delivered, at a relatively low rate, over a 90 min time interval without developing skin photosensitivity or general phototoxicity. During the treatment time, plasma levels of BPD were between 0.7 and 1.0 micrograms/mL. The light treatment resulted in between 70 and 80% photoinactivation of circulating BPD. When L1210 tumor cells were preincubated with BPD and injected i.v. into mice immediately before total-body light treatment (160 J/cm2 of 590-900 nm light delivered over 90 min), significant reductions in circulating clonogenic tumor cells were observed in blood samples taken immediately following treatment. This indicated that sufficient light was being delivered to BPD in the blood flowing in the peripheral vasculature to effect cytotoxicity to cells containing the photosensitizer without causing either vascular or skin photosensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Wavelength-dependent effects of benzoporphyrin derivative monoacid ring A in vivo and in vitro.

Benzoporphyrin derivative monoacid ring A (BPD-MA) is a chlorin-like photosensitizer currently in clinical trials for cancer and psoriasis. It has maximal absorption peaks at both 630 and 690 nm and can be activated at both these wavelengths. In vitro phototoxicity tests using the P815 murine mastocytoma cell lines conducted over wavelengths of light between 678 and 700 nm emitted by an argon-ion pumped dye laser showed that equivalent cell kill could be achieved between 682 and 690 nm. Tests on in vivo phototoxicity of normal skin of DBA/2 mice injected with 2 mg/kg of BPD-MA and exposed to light at 125 J/cm2, between 620 and 700 nm, demonstrated peaks of normal skin damage occurring at 630-640 nm and 680-690 nm. In tests carried out with light between 620 and 700 nm, at 10 nm increments, it was seen that light delivered at 680-690 nm caused slightly more damage to normal skin than light delivered at 630-640 nm. When lower doses of light between 675 and 705 nm were tested using smaller increments, it was determined that equivalent skin damage occurred over a range of 680-695 nm. Antitumor efficacy in tumor-bearing DBA/2 mice was tested between 683 and 695 nm. It was found that equivalent antitumor efficacy, determined by assessing tumor-free status at 20 days posttreatment, occurred at wavelengths between 685 and 693 nm.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Effect of porphyrins on the hematopoietic recovery of mice treated with gamma-radiation.

Porphyrins are a group of organic compounds involved in a wide spectrum of fundamental biological processes. Non-metallic, naturally occurring and synthetic porphyrin derivatives may produce cytotoxic effects in malignant or normal tissues exposed to visible light. Supra-clinical doses of the photosensitizing porphyrin, Photofrin are hematostimulatory when administered to normal and immunosuppressed inbred mice. To determine if a non-photosensitizing metalloporphyrin has similar hematostimulatory activity, we have synthesized iron (III) hematoporphyrin chloride (FeHp) and administered it to sub-lethally irradiated mice. FeHp (10 mg/kg) given 1 and 4 days or 1, 4 and 7 days following sub-lethal (7 Gy) whole body irradiation significantly increased spleen colony forming units of progenitor cells of the granulocyte-macrophage lineage (CFU-GM) 14 days post-irradiation, relative to irradiated controls. In addition, total splenocyte numbers were significantly increased 17 days post-irradiation in mice that had received FeHp 1 and 4 days post-irradiation. When FeHp was given 24 hours prior to irradiation and again 48 hours or 48 and 96 hours post-irradiation, significant increases in splenic CFU-GM and spleen cell numbers, relative to control mice, were observed 15 days post-irradiation. A non-metallic photosensitizing monomeric fraction of Photofrin, deuteroporphyrin IX, 2,4 (4,2) hydroxyethyl vinyl (HVD) was compared to Photofrin for its ability to influence the hematopoietic recovery of irradiated mice. Only Photofrin but not HVD given in 3 doses (10 mg/kg) 1, 4 and 7 days following irradiation (4.8 Gy) significantly enhanced the recovery of spleen cellularity and splenic CFU-GM. In addition, Photofrin significantly increased bone marrow CFU-GM 7 and 10 days following the sub-lethal dose of gamma-radiation. The mechanism by which certain porphyrins augment hematopoiesis in the mouse is unknown. However, the identification of FeHp as a non-photosensitizing monomeric porphyrin with hematostimulatory activity in vivo, indicates that further study of metalloporphyrins is warranted and may reveal their clinical potential within the context of therapeutically-induced immunosuppression.

Animals↗

PubMed1994

Photosensitizers in photodynamic therapy.

Photodynamic therapy (PDT) is based on the use of light-sensitive molecules called photosensitizers. Photoactivation causes the formation of singlet oxygen, which produces peroxidative reactions that can cause cell damage and death. Porfimer sodium (Photofrin, manufactured by Lederle Parenterals, Carolina, Puerto Rico, under license from Quadra Logic Technologies, Inc, Vancouver, BC, Canada) is the photosensitizer that has been studied most extensively. Patients generally have to be hospitalized for 2 days prior to light treatment after administration of porfimer sodium; it takes approximately 48 hours after injection to reach optimal concentration in tumor tissue. The tumoricidal capacity of PDT with porfimer sodium is determined in part by the maximum depth of penetration of light having a wavelength of 630 nm. Porfimer sodium causes cutaneous photosensitivity that may last for up to 6 weeks. Benzoporphyrin derivative (BPD verteporfin; BPD-Quadra Logic Technologies, Inc, Vancouver, BC, Canada), another photosensitizer, accumulates more rapidly in tumor tissue, permitting optimal PDT 30 to 150 minutes following intravenous administration. It is rapidly cleared from the body, and skin photosensitivity does not extend beyond a few days. The primary mechanism of action of PDT is related to the selective accumulation of photosensitizers in cancer tissue. Photodynamic therapy also shows promise in the treatment of a number of nonneoplastic conditions, including psoriasis, macular degeneration of the retina, atherosclerotic plaque and restenosis, bone marrow purging for treatment of leukemias with autologous bone marrow transplantation, inactivation of viruses in blood or blood products, and several autoimmune conditions, including rheumatoid arthritis. Physiologic characteristics shared by this disparate group of diseases, and the mechanisms by which they may mediate photoactivation, are discussed.

Antiviral Agents↗

PubMed1994

Reversal of CAMAL-mediated alterations of normal and leukemic in vitro myelopoiesis using inhibitors of proteolytic activity.

CAMAL (common antigen of myelogenous acute leukemia) is an antigenic preparation isolated in this laboratory from the bone marrow or peripheral blood leucocytes of persons with myeloid leukemias. Material from CAMAL preparations, which migrates in the range of 30 to 35 kDa by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE, P30-35 CAMAL), was shown to exert an inhibitory effect on in vitro colony formation by progenitor cells from normal healthy donors. The same preparations of P30-35 CAMAL, in contrast, exerted a stimulatory effect on in vitro colony formation by progenitor cells from patients with chronic myelogenous leukemia (CML). We now report that both the inhibitory effect on normal colony formation and the stimulatory effect on CML colony formation mediated by P30-35 CAMAL were blocked using phenyl methyl sulfonyl fluoride (PMSF), an inhibitor of the activity of serine proteases. Similarly, both the P30-35 CAMAL-mediated inhibitory effect on normal colony formation and the P30-35 CAMAL-mediated stimulatory effect on CML colony formation were blocked using the peptide ala-pro-phe-CMK, also an inhibitor of serine protease activity. These results suggest the involvement of proteolytic activity, either directly or indirectly, in the alterations of in vitro myelopoiesis exerted by P30-35 CAMAL.

Amino Acid Chloromethyl Ketones↗

PubMed1993

Relationship between collagen-induced and adjuvant arthritis in the Lewis rat.

Adjuvant arthritis (AA) and type II collagen (CII)-induced arthritis (CIA) in the rat serve as models of chronic human arthritis. Adoptive transfer of AA was observed in 21 of 25 Lewis rats given concanavalin A (Con A)-treated spleen cells prepared from animals immunized with Mycobacterium butyricum in mineral oil (complete Freund's adjuvant, CFA). No arthritic changes were noted in rats given spleen cells obtained from donors that had received incomplete Freund's adjuvant (IFA, 0/22), type I collagen in IFA (CI-IFA, 0/6) or CII-IFA (0/28). Administration of spleen cells from IFA, CI-IFA or CII-IFA-injected animals did not modify the development of CIA when these rats were subsequently challenged with CII-IFA. However, partial protection against induction of AA was provided by the transfer of spleen cells prepared from rats immunized with CII-IFA (6/11) but not by those obtained from rats injected with IFA (1/15) or CI-IFA (0/3). Rats that did not develop clinically evident arthritis following the administration of spleen cells prepared from CFA-injected rats were also resistant to AA induction by CFA. Pre-treatment of rats with a synthetic peptide, corresponding to amino acids 180-188 of the Mycobacterium 65 kD heat shock protein (65 kD HSP), significantly delayed the onset of AA, but not that of CIA. Disease-specific resistance to AA, provided by spleen cells prepared from rats injected with CII-IFA and by pre-treatment with the 65 kD HSP 180-188 peptide, may result from the induction of protective tolerance to arthritogenic epitopes present in the Mycobacterium and CII preparations.

Amino Acid Sequence↗

PubMed1993

Photosensitizers as virucidal agents.

The photosensitizer, benzoporphyrin derivative monoacid ring A (BPD-MA) has been studied regarding its ability to destroy enveloped viruses in blood and blood products when activated by light. Its maximum wavelength of absorption (690 nm) has proven useful in terms of activation of the photosensitizer in materials containing red blood cells. Experiments conducted on whole blood of patients infected with the human immunodeficiency virus (HIV) demonstrated that BPD-MA and light could effectively eliminate the virus when treated materials were placed in culture and tested for viral p24, but did not appear to damage blood cells or blood components. Since HIV is largely intracellular in infected individuals, these results were investigated further. We have shown, using flow cytometry, that in HIV-infected blood, BPD-MA and light appear to selectively destroy white cells that bear the interleukin 2 receptor and the DR antigen. These markers are prevalent on activated lymphocytes, and since HIV replicates only in CD4+ T cells which are activated, this finding provides an explanation for the selective killing of HIV.

Acquired Immunodeficiency Syndrome↗

PubMed1993

Modified polyvinyl alcohol-benzoporphyrin derivative conjugates as phototoxic agents.

Photosensitizing and biodistribution characteristics of a photosensitizer (benzoporphyrin derivative, monoacid ring A; BPD) conjugated to a macromolecule (modified polyvinyl alcohol; M-PVA, molecular weight = 10,000) were tested in vitro and in vivo. Modified PVA was loaded with BPD at molar ratios 1:12, 1:25, 1:50, 1:75 and 1:100. Most of the work was carried out with a conjugate having a 1:25 molar ratio. In vitro photosensitization was tested using A549 (human lung carcinoma), A432 (human epidermoid carcinoma) and P815 (mastocytoma of DBA/2 mice) cell lines. Photosensitization of M1 (rhabdomyosarcoma of DBA/2 mice) tumors was tested in an in vivo/in vitro assay, in which tumor-bearing mice were injected intravenously with free or conjugated 3H-BPD and 3 h later light activation of tumor cells was carried out in vitro. Biodistribution studies were carried out using M1 tumor-bearing DBA/2 mice and 3H-BPD either free or conjugated to M-PVA. The results of these studies showed that the conjugation of BPD to M-PVA resulted in the formation of a macromolecular photosensitizer that retained full photosensitizing activity of the photosensitizer molecules and at the same time gained new characteristics, advantageous for photodynamic treatment, especially in vivo. In vitro M-PVA-BPD conjugates were at least as efficient in photosensitization of tumor cells as an equivalent number of free BPD molecules, both in the presence and in the absence of serum. Although the biodistribution was in general comparable to free BPD, the conjugate (1:25) reached slightly higher levels in the blood, kidney, lung and spleen, and lower levels in the liver, brain, skin and muscle in comparison with free BPD.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

In vitro and in vivo uptake of benzoporphyrin derivative into human and miniswine atherosclerotic plaque.

Benzoporphyrin derivative (BPD) has been demonstrated to be a new potent photosensitizer for photodynamic therapy (PDT). Although most of the work on BPD has been focused on its potential applications for cancer treatment, BPD may have potential clinical uses in the treatment of atherosclerosis. The purpose of this study was to determine in vitro and in vivo uptake of BPD into atherosclerotic plaque. Samples of atherosclerotic human femoral and popliteal arteries were incubated with BPD-monoacid, ring A (BPD-MA) for 1 h in the following concentrations: 1, 5, 10, 20, 30 and 40 micrograms/mL. Fluorescence from all samples was determined by chemical extraction with a spectrofluorometer. The tissue concentration for human arteries was 0.37 +/- 0.03, 2.78 +/- 1.5, 3.6 +/- 1.91, 7.15 +/- 2.36, 8.06 +/- 3.09 and 14.6 +/- 4.81 micrograms/g, respectively. In addition, three miniswine were rendered atherosclerotic and given BPD 2.0 mg/kg intravenously. The concentration of BPD-MA in miniswine aorta was 93-190 ng/g and the plaque/normal ratio was 1.7-3.5. For miniswine iliac arteries, the [BPD-MA] was 60-178 ng/g and the plaque/normal ratio was 1.1-3.3. Normal miniswine carotid artery contained 54 ng/g. This study showed that BPD-MA was taken up in atherosclerotic vessels both in vitro and in vivo and may have potential for PDT of atherosclerosis.

Animals↗

PubMed1993

Liposomal delivery of a photosensitizer, benzoporphyrin derivative monoacid ring A (BPD), to tumor tissue in a mouse tumor model.

Biodistribution studies were carried out on 14C-labeled benzoporphyrin derivative monoacid ring A (BPD), which had been formulated as a unilamellar liposome or taken from a stock solution in dimethyl sulfoxide diluted into phosphate-buffered saline immediately before intravenous injection into DBA/2 mice. By and large the general distribution of BPD to various organs and tissues was comparable for both formulations. It was noted, however, that liposomal material appeared to enter tissues more rapidly and to be cleared more rapidly, as demonstrated by shorter half-lives for a number of tissues including skin, lung and fat, and generally lower levels in most tissues 24 h following administration. Accumulation in tumor tissue was slightly higher with liposomal BPD, and clearance rates for this tissue were equivalent (half-lives 16.1 h for liposomal BPD and 16.9 h for aqueous BPD). When the two preparations were tested in a bioassay in tumor-bearing mice, photodynamic therapy (PDT) with liposomal BPD proved to be superior to the aqueous preparation when PDT was administered 3 h following intravenous administration of BPD. Plasma distribution studies in vitro demonstrated that 91.1 +/- 0.3% of the liposomal BPD distributed to the lipoprotein fraction within the first hour of mixing, whereas only 49.1 +/- 2.6% of nonliposomal BPD was associated with lipoprotein under the same conditions. Furthermore, while lipoprotein-associated liposomal BPD distributed evenly between all three types of lipoprotein (high, low and very low density), a majority of nonliposomal BPD associated with the high-density lipoprotein fraction.

Animals↗

PubMed1993

Stress protein expression in murine tumor cells following photodynamic therapy with benzoporphyrin derivative.

Photodynamic therapy (PDT) has been proven as a method of tumor eradication and is currently being used clinically to treat a wide variety of malignancies. Although it is understood that the interaction of light and sensitizer results in the production of potentially damaging oxygen species, the mechanism by which tumors are destroyed has yet to be defined fully. Using a new porphyrin sensitizer, benzoporphyrin derivative (BPD), we examined protein expression in murine tumor cells following treatment as an indication of molecular changes to target tissue concurrent with PDT-mediated damage. In order to assess the relevance of the results obtained using an in vitro PDT model, metabolic labeling of proteins synthesized subsequent to PDT was performed both in tumor cells grown and treated in tissue culture dishes and in cells explanted from PDT-treated solid tumors. We observed that the oxidative stress associated with PDT-resulted in the induction of a number of proteins corresponding to a set of heat-shock or stress proteins, and that the pattern of expression was similar when tumor cells were treated in vitro and in vivo. These results support the use of in vitro models in the dissection of the molecular effects of PDT and provide the foundation for future experiments that will examine the role of the immune system in tumor eradication by PDT.

Animals↗

PubMed1993

Stimulation of leukemic myelopoiesis by P30-35 CAMAL, an inhibitor of normal myelopoiesis.

CAMAL (common antigen in myelogenous acute leukemia) is an antigenic preparation isolated in this laboratory from the bone marrow or peripheral blood cells of persons with myeloid leukemias and shown in an immunoperoxidase slide test to be diagnostic of these leukemias. CAMAL has been shown to be inhibitory to myelopoiesis by normal progenitor cells in vitro. This activity is associated with material which was further purified from CAMAL preparations, and which migrates at 30-35 kDa by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). We now report that material from CAMAL preparations highly enriched for this 30-35 kDa material is stimulatory to in vitro colony formation by progenitor cells from patients with chronic myelogenous leukemia (CML). This stimulatory effect on CML colony formation was observed to be consistent. Colony formation was stimulated in a biphasic fashion; enhancement was seen at low (1 to 10 ng/ml) and high (100 to 200 ng/ml) concentrations of P30-35 CAMAL, but enhancement was reduced or absent at an intermediate concentration of P30-35 CAMAL (10 to 70 ng/ml), and was not observed at P30-35 CAMAL levels above 200 ng/ml, or below 1 ng/ml. The colony types in cultures of CML clinical specimens targetted for enhancement by P30-35 CAMAL were identified. At low concentrations of P30-35 CAMAL primitive colonies were increased, whereas at high concentrations of P30-35 CAMAL, an increase in all colony types was observed. In addition, an increase in the size of some colonies within P30-35 CAMAL-treated cultures was frequently observed. Colony formation by two cell lines derived from the leucocytes of a patient with CML was enhanced by treatment with P30-35 CAMAL in a manner similar to the stimulation observed using primary cells from CML clinical specimens.

Antigens, Differentiation, Myelomonocytic↗

PubMed1993

Biodistribution of a benzoporphyrin derivative-monoclonal antibody conjugate in A549-tumor-bearing nude mice.

Biodistribution of the photosensitizer benzoporphyrin derivative monoacid ring A (BPD) was compared in DBA/2 mice bearing the syngeneic M-1 tumor and nude mice bearing the A549 human squamous cell carcinoma. These studies, using internally labeled 14C-BPD showed that in general, biodistribution between the two strains was equivalent with the exception of two tissues; lymph nodes (BPD levels were higher in nude mice) and tumor (BPD levels were lower in nude mice). Further studies were carried out in A549-tumor-bearing nude mice in which the biodistribution of BPD conjugated to a monoclonal antibody (5E8) with specificity for an antigen on A549 cells was compared to a conjugate prepared with an irrelevant monoclonal antibody (T48). These studies showed that both conjugates had biodistribution characteristics which distinguished them from free BPD in that they remained in the circulation and most tissues for significantly longer times than did free BPD. Also, with the exception of the 5E8-BPD conjugate and A549 tumor tissue, levels in all tissues were highest at the 3-h time point following injection of conjugates. In the case of A549 tumor and the 5E8-BPD conjugate the highest concentration of 14C-labeled material was observed at the 14-h time point following injection. The results reported herein show that the conjugates tested behaved differently from free BPD, indicating that the materials did not become dissociated in vivo and that the specific conjugate (5E8-BPD) demonstrated specificity for the A549 tumor in terms of the kinetics of its accumulation in tumor tissue.

Animals↗

PubMed1993

Inhibition of murine hematopoiesis by CAMAL, an inhibitor of human hematopoiesis.

CAMAL (common antigen of myelogenous acute leukemia) is an antigenic preparation isolated in this laboratory from the bone marrow or peripheral blood leucocytes of persons with myeloid leukemias and shown using an immunoperoxidase slide test to be diagnostic of these leukemias. Material further purified from CAMAL preparations, which migrates in the range of 30-35 kilodaltons (kDa) by sodium dodecyl sulphate/polyacrylamide gel electrophoresis (SDS-PAGE), which is referred to as P30-35 CAMAL, and was previously shown to be inhibitory to colony formation by progenitor cells from normal healthy human donors in vitro. This inhibitory activity was directed toward neutrophilic granulocyte colonies (CFU-G) in particular. We now report that P30-35 CAMAL is inhibitory to colony formation by murine progenitor cells in vitro. Colonies from P30-35 CAMAL-treated cultures of murine bone marrow cells were reduced in number and in size, an effect similar to that seen in cultures of human cells. As in assays using human cells, murine CFU-G appeared to be preferentially targeted by the inhibitory activity of P30-35 CAMAL. In addition, day 10 spleen colony formation was inhibited by P30-35 CAMAL in an ex vivo assay. Hence, the effects of P30-35 CAMAL on murine progenitor cells appear to parallel the effects observed using human cells. These observations support the possibility that CAMAL might be a regulatory protein in hematopoiesis which is conserved between species.

Amino Acid Sequence↗

PubMed1993

Efficacy of benzoporphyrin derivative, a photosensitizer, in selective destruction of leukemia cells using a murine tumor model.

The ability of a photosensitizer, benzoporphyrin derivative monoacid ring A (BPD), and light to selectively kill leukemic cells in comparison to normal hemopoietic progenitors was investigated using a murine model, the L1210 tumor of DBA/2 mice. In vitro experiments indicated that treatment of cells with BPD and light effected a 5 to 6 log reduction of clonogenic L1210 cells under conditions which caused less than a 1 log reduction of committed myeloid progenitors, determined by colony-forming cells. This apparent therapeutic window was tested in vivo using lethally irradiated DBA/2 mice hematopoietically reconstituted with 10(6) syngeneic donor splenocytes or 5 x 10(5) bone marrow cells mixed with L1210 cells and treated with BPD and light. Reconstitution with 10(6) splenocytes resulted in successful engraftment of approximately 50% of recipients, indicating that these conditions provided limiting numbers of essential stem cells. The minimum tumor-eliciting dose was determined to be between 10(1) and 10(2) L1210 cells. Experiments in which 10(6) splenocytes were mixed with 10(6) L1210 cells and treated with BPD and light demonstrated that at 100 ng/mL of BPD and a specified light dose (5.4 joules [J]/cm2), 50% of recipients underwent successful engraftment and did not develop leukemic ascites. Animals that died under this regimen died from failure to engraft rather than from tumor burden. These results establish that this approach can effectively lower tumor burden by 4 logs with virtually no loss of essential hemopoietic progenitors. Similar results were obtained when animals received bone marrow rather than splenocytes.

Animals↗

PubMed1992

Photosensitizing efficiency of two regioisomers of the benzoporphyrin derivative monoacid ring A (BPD-MA).

Benzoporphyrin derivative, monoacid ring A (BPD-MA), currently in clinical trials as a photosensitizer for photodynamic therapy for cancer, consists of two regioisomers (A1 and A2) present in equal proportions. The contribution of the regioisomers to the overall photosensitizing potency of BPD-MA was tested in vitro and in vivo. The in vitro photosensitizing potencies of BPD-MA-A1 and -A2 were tested in a standard cytotoxicity assay using M1 (rhabdomyosarcoma of DBA/2 mice) tumor cells and were found to be equivalent. The in vivo photosensitizing efficacies of the regioisomers were tested in the M1 tumor model in DBA/2 mice and were also found to be equivalent. Biodistribution of the regioisomers in mouse plasma, tumor and liver was studied in M1 tumor-bearing DBA/2 mice at 15 min and 3 hr post intravenous injection of [14C]BPD-MA-A1/A2 at 4 mg/kg body weight. Plasma and extracts from tumor and liver were analysed by HPLC and tested for radioactivity. The two regioisomers were eliminated from plasma and liver at different rates, which resulted in A1:A2 ratios of 1:0.28 in plasma and 1:0.75 in liver at 3 hr post injection. The differential elimination was not observed to any significant degree in the tumor, where even at 3 hr post injection the A1:A2 ratio was 1:1.15. Therefore, we concluded that in tumor tissue, at 3 hr post injection, the time at which laser photodynamic therapy is carried out, both regioisomers were present in about equal proportions. Further, both regioisomers were fully active as determined by an in vitro cytotoxicity assay following extraction.

Animals↗

PubMed1992

Viral inactivation in blood and red cell concentrates with benzoporphyrin derivative.

Using both the vesicular stomatitis virus (VSV) and feline leukemia virus (FeLV) as models we have shown that the photosensitizer benzoporphyrin derivative ring A (BPD), when activated with red light (600-700 nm), is effective in eliminating both free virus and virally infected cells from spiked blood products and whole blood drawn from viremic cats experimentally infected with FeLV, under conditions which appear to share red blood cells. The effect of photodynamic therapy on infected lymphocytes, as visualized by scanning electron microscopy, initially appeared as a limited area of tiny holes in the membrane. These holes were subsequently seen to increase in size until the membrane appeared completely decomposed. The red cell membranes however, seem to be undamaged by such photodynamic treatment.

Animals↗