Biomedical subjects

T Hasan

Publications and source records attributed to T Hasan.

At least 55 records · Page 3Linked to original sources

PubMed1998

Differentiation-specific increase in ALA-induced protoporphyrin IX accumulation in primary mouse keratinocytes.

A treatment regimen that takes advantage of the induction of intracellular porphyrins such as protoporphyrin IX (PPIX) by exposure to exogenous 5-amino-laevulinic acid (ALA) followed by localized exposure to visible light represents a promising new approach to photodynamic therapy (PDT). Acting upon the suggestion that the effectiveness of ALA-dependent PDT may depend upon the state of cellular differentiation, we investigated the effect of terminal differentiation upon ALA-induced synthesis of and the subsequent phototoxicity attributable to PPIX in primary mouse keratinocytes. Induction of keratinocyte differentiation augmented intracellular PPIX accumulation in cells treated with ALA. These elevated PPIX levels resulted in an enhanced lethal photodynamic sensitization of differentiated cells. The differentiation-dependent increase in cellular PPIX levels resulted from several factors including: (a) increased ALA uptake, (b) enhanced PPIX production and (c) decreased PPIX export into the culture media. Simultaneously, steady-state levels of coproporphyrinogen oxidase mRNA increased but aminolaevulinic acid dehydratase mRNA levels remained unchanged. From experiments using 12-o-tetradecanoylphorbol-13-acetate, transforming growth factor beta 1 and calcimycin we demonstrated that the increase in PPIX concentration in terminally differentiating keratinocytes is calcium- and differentiation specific. Stimulation of the haem synthetic capacity is seen in primary keratinocytes, but not in PAM 212 cells that fail to undergo differentiation. Interestingly, increased PPIX formation and elevated coproporphyrinogen oxidase mRNA levels are not limited to differentiating keratinocytes; these were also elevated in the C2C12 myoblast and the PC12 adrenal cell lines upon induction of differentiation. Overall, the therapeutic implications of these results are that the effectiveness of ALA-dependent PDT depends on the differentiation status of the cell and that this may enable selective targeting of several tissue types.

Aminolevulinic Acid↗

PubMed1998

Targeted antimicrobial photochemotherapy.

This study explores a new approach for antimicrobial therapy with light activation of targeted poly-L-lysine (pL)-chlorin e6 (ce6) conjugates. The goal was to test the hypothesis that these conjugates between pL and ce6 would efficiently target photodestruction towards gram-positive (Actinomyces viscosus) and gram-negative (Porphyromonas gingivalis) oral species while sparing an oral epithelial cell line (HCPC-1). Conjugates of ce6 with pL (average molecular weight, 2,000) having a positive, neutral, or negative charge were prepared. Illumination with red light (lambdamax = 671 nm) from a diode array produced a dose-dependent loss of CFU from the bacteria, under conditions that did not affect the viability of the epithelial cells. For P. gingivalis, the cationic conjugate produced 99% killing, while the neutral conjugate killed 91% and the anionic conjugate killed 76% after 1 min of incubation and exposure to red light for 10 min. For A. viscosus, the cationic conjugate produced >99.99% killing while HCPC-1 cells remained intact. The importance of the positive charge was shown by the effectiveness of ce6-monoethylenediamine monoamide (a monocationic derivative of ce6) in killing both bacteria. The clinically employed benzoporphyrin derivative under the same conditions killed epithelial cells while leaving P. gingivalis relatively unharmed. A mixture of ce6 with pL did not show phototoxicity comparable with that of the cationic conjugate. These results were explained by the selective uptake of the conjugates by bacteria (20- to 100-fold) compared to that by mammalian cells, while free ce6 showed much less selectivity for bacteria (5- to 20-fold). The data suggest that the cationic pL-ce6 conjugate may have an application for the photodynamic therapy of periodontal disease.

Animals↗

PubMed1998

Photodynamic synovectomy using benzoporphyrin derivative in an antigen-induced arthritis model for rheumatoid arthritis.

Experimental photodynamic therapy (PDT) has recently been adapted for the treatment of inflammatory and rheumatoid arthritis. The biodistribution of benzoporphyrin derivative monoacid ring A (BPD-MA) and the effect of percutaneous light activation via intra-articular bare cleaved optical fibers was investigated using a rabbit-antigen-induced arthritis model. Qualitative evaluation of intra-articular photosensitizer clearance was performed with laser-induced fluorescence from 0 to 6 h following intravenous injection. The compound was rapidly taken up within the joint and then cleared steadily over the 6 h interval. Biodistribution was determined by fluorescence microscopy and spectrofluoroscopic extraction techniques 3 h following intravenous injection of 2 mg/kg BPD-MA. The biodistribution study demonstrated elevated levels of BPD-MA in synovium (0.35 microgram/g) and muscle (0.35 microgram/g). Fluorescence microscopy demonstrated presence of the compound within pathologic synovium but absence of the photosensitizer within meniscus, ligament, bone and articular cartilage. Tissue effects were evaluated histologically at 2 and 4 weeks posttreatment. BPD-MA-mediated PDT caused synovial necrosis in the region of light activation in 50% of treatment knees at 2 weeks and 43% at 4 weeks. No damage to nonpathologic tissues was observed. These studies indicate that selective destruction of synovium can be achieved by the light-activated photosensitizing agent BPD-MA without damage to articular cartilage or periarticular soft tissues. PDT needs to be further evaluated to optimize treatment parameters to provide for a new minimally invasive synovectomy technique.

Animals↗

PubMed1998

Importance of the treatment field for the application of vascular photodynamic therapy to inhibit intimal hyperplasia.

Intimal hyperplasia (IH) plays a dominant role in the development of restenosis. In previous studies, photodynamic therapy (PDT) prevented IH induced by segmental balloon injury of the rat carotid. The critical elements required to control IH effectively with this technique are not fully understood. This study assessed the importance of the treatment field by studying the repair process of injured vessels, in which the PDT-treatment field did not target the entire injured area. The entire rat common carotid artery was balloon-injured to induce IH, whereas only the cervical segment below the bifurcation was subjected to PDT by external light irradiation after administration of the photosensitizer chloroaluminum sulfonated phthalocyanine. Light irradiation of injured arteries without photosensitizer served as control for PDT, and PDT of uninjured arteries was included as a control group for the balloon injury. Histologic characterization of the repair process was sequentially assessed. Balloon-injured arteries without PDT displayed rapid IH development with a peak at 2 weeks. Photodynamic therapy of balloon-injured arteries resulted in complete local depletion of medial smooth muscle cells (SMC), which was associated with a lack of IH until 2 weeks. However, at 4 and 16 weeks there was significant IH in PDT-treated arteries despite a lack of medial SMC repopulation. A wave of IH progression over the acellular media was observed in these arteries, migrating from the injured non-PDT-treated area. The PDT of uninjured arteries did not result in IH and was also associated with a persistent acellular media. Delayed IH development after PDT of injured vessels can result from IH progression from an injured site not included in the treatment field. This also indicated that the source of cells developing the intimal hyperplasia lesion can originate from an area remote from the lesion. Together with previous results and the determination that PDT itself does not induce IH, it can be reasoned that inclusion of the whole injured artery or a section of an uninjured margin in the treatment field is essential for effective PDT prevention of IH.

Angioplasty, Balloon↗

PubMed1998

Light dosimetry for intraperitoneal photodynamic therapy in a murine xenograft model of human epithelial ovarian carcinoma.

Few studies have been published to date measuring spatially resolved fluence rates in complex tissue geometries. Here the light distributions of three different intraperitoneal light delivery geometries in a murine ovarian cancer model were investigated to assess their influence on the tumorcidal efficacy of photodynamic therapy (PDT). In vivo fluence rate measurements in the peritoneal cavities of mice, with the light intensity being mapped in three transverse planes, were performed using fiber-optic detectors. Three different source fiber designs and placements were tested for their ability to provide uniform irradiation of the peritoneal cavity. The biological response to a PDT protocol comprising three separate treatments administered at 72 h intervals, each consisting of a 0.25 mg kg-1 intraperitoneal injection of benzoporphyrin derivative-mono acid ring A followed 90 min later by delivery of 15 J of 690 nm light, was measured. The tissue response was evaluated by measuring the number of remaining visible lesions and the total residual tumor mass. Fluence rate measurements showed large variations in the fluence rate distribution for similar intended treatments. The most uniform and reproducible illumination was achieved using two 18 mm long cylindrical emitting optical fibers. The biological response was comparable to that produced when a flat-cleaved end optical fiber is used to illuminate the four quadrants of the abdomen sequentially. While a good reproducibility in tumor induction in this animal model exists, no correlation was found between the fluence rate distribution measured in one group of animals and the biological response in a separate group of similarly treated animals. Due to the large intra-animal variability in fluence rate distribution, representative fluence rate mapping in complex tissue geometries is of limited value when applied to an individual PDT treatment. Thus, surveillance of the fluence rate during individual treatments will be required for acceptable PDT dosimetry. To improve the versatility of this particular animal model for PDT research, a large number of extended sources are required to increase uniformity of the illumination in order to reduce unwanted cytotoxic side effects resulting from foci of high fluence rates. In this way, subsequent increase of the total energy delivered to the tumor may be possible.

Animals↗

PubMed1998

Photophysical properties of tin ethyl etiopurpurin I (SnET2) and tin octaethylbenzochlorin (SnOEBC) in solution and bound to albumin.

The photophysical characteristics of two second-generation PDT photosensitizers, tin ethyl etiopurpurin I (SnET2) and tin octaethylbenzochlorin (SnOEBC), have been measured in homogeneous solution and when bound to bovine serum albumin (BSA). The ground state and triplet state absorption spectra have been characterized, as have triplet lifetimes and quantum yields for intersystem crossing, singlet oxygen formation and photobleaching. In total, these parameters provide a complete set of data that can be used to quantitatively compare the photosensitizing efficiencies of these molecules. The photo-bleaching quantum yield of SnET2 is increased dramatically when it is bound to BSA, thus limiting the production of singlet oxygen at incident fluences above 1 J/cm2. In contrast, the quantum yield of photobleaching of SnOEBC is at least an order of magnitude lower than that of SnET2 under these conditions and does not significantly limit the photosensitization process for typical in vivo or in vitro fluences. This difference is expected to play a significant role in determining the relative photo-sensitizing ability of these compounds in vivo.

Animals↗

PubMed1997

Hormonal modulation of the accumulation of 5-aminolevulinic acid-induced protoporphyrin and phototoxicity in prostate cancer cells.

The effect of hormonal modulation on the response of human prostate cancer cell lines to photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PpIX) was studied. Two cell lines, one responsive to androgens (LNCaP) and the other non-responsive (PC-3), were used. Fetal bovine serum was depleted of steroid hormones by stripping with charcoal-dextran, and then resupplied with known concentrations of the androgen 5alpha-dihydrotestosterone (DHT) or the estrogen estradiol. It was found that LNCaP cells alone increased growth rate in response to both added hormones, but only androgen had an effect on PDT treatment. LNCaP cells pretreated with 10(-7) M DHT and then 1 mM ALA accumulated 70% more PpIX, compared to cells pre-treated with 10(-12) M DHT. Exposure of the cells treated with high DHT and ALA to 630 nm light led to an 85% decrease in the number of surviving cells compared to the low DHT treated group. The uptake of 14C-ALA was increased with high DHT treatment of the cells, consistent with the above data. No effect of hormones was seen with PC-3 cells or with either cell line and the exogenous photosensitizer benzoporphyrin derivative.

Aminolevulinic Acid↗

PubMed1997

Biodistribution of charged F(ab')2 photoimmunoconjugates in a xenograft model of ovarian cancer.

The effect of charge modification of photoimmunoconjugates (PICs) on their biodistribution in a xenograft model of ovarian cancer was investigated. Chlorin(e6)c(e6) was attached site specifically to the F(ab')2 fragment of the murine monoclonal antibody OC125, directed against human ovarian cancer cells, via poly-1-lysine linkers carrying cationic or anionic charges. Preservation of immunoreactivity was checked by enzyme-linked immunosorbent assay (ELISA). PICs were radiolabelled with 125I and compared with non-specific rabbit IgG PICs after intraperitoneal (i.p.) injection into nude mice. Samples were taken from normal organs and tumour at 3 h and 24 h. Tumour to normal 125I ratios showed that the cationic OC125F(ab')2 PIC had the highest tumour selectivity. Ratios for c(e6) were uniformly higher than for 125I, indicating that c(e6) became separated from 125I. OC125F(ab')2 gave highest tissue values of 125I, followed by cationic OC125F(ab')2 PIC; other species were much lower. The amounts of c(e6) delivered per gram of tumour were much higher for cationic OC125F(ab')2 PIC than for other species. The results indicate that cationic charge stimulates the endocytosis and lysosomal degradation of the OC125F(ab')2-pl-c(e6) that has bound to the i.p. tumour. Positively charged PICs may have applications in the i.p. photoimmunotherapy of minimal residual ovarian cancer.

Animals↗

PubMed1997

Photodynamic targeting of human retinoblastoma cells using covalent low-density lipoprotein conjugates.

Combination of photosensitizers with carrier molecules has been shown to enhance the efficiency of photodynamic therapy (PDT). Owing to an increased expression of their receptors on some malignant and proliferating cells, low-density lipoproteins (LDLs) are potential endogenous carriers. A photosensitizer, chlorin e6 (Ce6), was covalently bound to LDL via carbodiimide activation. The Ce6-LDL conjugate was evaluated on a fibroblast cell line with defined LDL receptor expression and a retinoblastoma cell line (Y79). Uptake of free Ce6 and Ce6 either covalently bound to or complexed with LDL was measured by spectrofluorimetry. Phototoxicity after irradiation at 660 nm was determined by a mitochondrial activity assay (MTT). Covalent binding to LDL significantly increased the uptake of Ce6 for both cell lines by a factor of 4-5. A Ce6: LDL binding ratio of 50:1 was optimal. A receptor-mediated uptake was demonstrated by saturability and competitive inhibition by free LDL. Binding also occurred at 2 degrees C and was attributed to non-specific associations. Irradiation with 10 J cm-2 of 660 nm light after treatment of cells with Ce6-LDL conjugate reduced the MTT activity by 80%, while free or mixed Ce6 induced a maximum of 10% reduction in the MTT activity following identical treatment conditions. These data suggest that targeting of LDL receptor-bearing cells using covalently bound carriers, such as LDL, might increase the efficiency and selectivity of PDT. Intraocular tumours such as retinoblastomas could be appropriate targets for such an approach owing to the ease of access of light sources and the need for non-invasive approaches in sensitive ocular sites.

Carrier Proteins↗

PubMed1997

Localization of lipoprotein-delivered benzoporphyrin derivative in the rabbit eye.

PURPOSE: Photodynamic therapy (PDT) using the photosensitizer Benzoporphyrin derivative monoacid (BPD-MA or verteporfin) is currently under investigation for the treatment of choroidal neovascularization. We investigated the localization of this photosensitizer using fluorescence microscopy and quantified its presence in ocular tissues after porphyrin extraction using fluorescence spectroscopy. METHODS: Albino rabbits were administered 2mg/kg BPD-MA pre-complexed with low density lipoprotein (LDL) intravenously, or given no treatment. The eyes were enucleated at intervals between 5 minutes and 24 hours after dye injection and were studied with light and fluorescence microscopy, or dissected for porphyrin extraction. RESULTS: At 5 minutes after dye injection, there was bright fluorescence from the choroid and retinal pigment epithelium (RPE) with trace retinal outer segment fluorescence. After 20 minutes, there was increased photoreceptor outer segment and RPE fluorescence but decreased choroidal fluorescence. By 2 hours no fluorescence remained in either the choroid or the photoreceptors and there was diminished fluorescence of the RPE. Trace RPE fluorescence was still visible at 24 hours. Fluorescence localization of liposomal BPD (2mg/kg) at the earliest (5 minutes) time point was indistinguishable from that of the BPD-LDL complex. Using spectrofluorimetry, the highest BPD-MA levels from the eye were measured in the retina/RPE/uvea complex with lower levels measured from the sclera and other tissues. CONCLUSIONS: BPD-MA with LDL rapidly accumulates in the choroid, RPE, and photoreceptors after intravenous injection. Future studies of PDT with BPD-MA for the treatment of fundus disorders may need to address the relationship between dye localization and photodynamically-mediated injury.

Animals↗

PubMed1997

The effect of charge on cellular uptake and phototoxicity of polylysine chlorin(e6) conjugates.

The effect of charge on the cellular uptake, localization and phototoxicity of conjugates between chlorin(e6) (ce6) and poly-L-lysine was studied in vitro. These conjugates (average MW 35-55 kDa) were synthesized to have polycationic, polyanionic or neutral charges. Two human cell lines (A431 epidermoid carcinoma cells and EA.hy926 hybrid endothelial cells) were studied and the cellular uptake of ce6 delivered by the conjugates of varying charge and free ce6 was measured at conjugate ce6 equivalent concentrations up to 0.4 microM. Uptake was time and concentration dependent and temperature dependent in the case of neutral and anionic conjugates. Relative uptake at 6 h for A431 cells was 73:15:4:1 and for EA.hy926 cells was 63:11:3:1 for cationic, anionic, neutral and free ce67 respectively, but EA.hy926 cells took up 1.5-2 times as much ce6 from all the conjugates as A431 cells. Localization as studied by fluorescence microscopy indicated that the cationic conjugate was in aggregates bound to the plasma membrane, while the other forms were internalized in organelles and membranes. Phototoxicity was measured by 3-(4,5-dimethylthiazol-2-yl)-diphenyltetrazolium bromide (MTT) assay after irradiation with 5-20 J cm2 of 666 nm light. In contrast to the uptake, the order of phototoxicity for both cell types per mole of ce6 uptake per cell was neutral >> anionic > cationic > free ce6. Polymeric ce6 conjugates bearing positive, negative and neutral charges may have different tissue-localizing properties and could play a role in photodynamic therapy.

Cell Line↗

PubMed1997

A theoretical study of light fractionation and dose-rate effects in photodynamic therapy.

The efficacy of photodynamic therapy is dependent upon the optical dose rate or upon the fractionation schedule on the light. These effects are thought to be limited by the time required for oxygen diffusion from the capillaries, since this therapy can consume oxygen faster than it can be supplied to tissues distant from the blood vessels. Oxygen diffusion and consumption by metabolic and photochemical mechanisms have been modeled here to compare theoretical predictions with experimental results of varying light fractionations and delivered dose rates. The mathematics of the problem have been described in the literature, and the present study extends these calculations to allow a more direct and quantitative comparison with fractionation experiments, using both analytical and numerical arguments. The optimum fraction time was found to depend only on the intercapillary spacing and not on the intensity of irradiation or the concentration of photosensitizer. The calculations indicate that experimentally observed optimum fractionation times of 30 and 60 s correspond to a distance from capillary to cell of approximately 1 mm. These results suggest that the fractionated light irradiation experiments need careful interpretation, and some possible reasons for longer optimum fractionation times are discussed.

Dose-Response Relationship, Radiation↗

PubMed1997

Occurrence of polymorphous light eruption in lupus erythematosus.

Photosensitivity is a well-known manifestation of lupus erythematosus (LE). Since there are no strict criteria for photosensitivity, varying prevalence figures have been reported. Also, distinction from polymorphous light eruption (PLE) can be difficult. The purpose of this study was to characterize photosensitivity in more detail and to determine the occurrence of PLE in a series of well-documented LE patients. A questionnaire was answered by 337 LE patients seen at dermatology departments in Finland and Sweden, and 63 of the patients were invited for interview. According to the questionnaire, LE lesions were made worse by sunlight in 242 (72%) patients. Symptoms consistent with PLE were reported by 165 (49%) patients. Detailed personal interviews supported the results from the questionnaire, and revealed that PLE had started 2-45 years before the onset of LE in 23 of 37 patients with both diagnoses, and more than 7 years before in 18 of 37 (49%). PLE proved to be common in patients with both systemic and cutaneous LE. The two conditions may often coexist and, in about half of the cases, PLE preceded LE. These two diseases may share pathogenic factors. PLE might predispose to LE in a subgroup of PLE patients.

Adolescent↗

PubMed1997

Photosensitivity in lupus erythematosus, UV photoprovocation results compared with history of photosensitivity and clinical findings.

Photosensitivity, one of the presenting symptoms in lupus erythematosus (LE), is still poorly defined and varying prevalence figures have been reported. The possibility of a coexisting photodermatosis, especially polymorphous light eruption (PLE), has often not been taken into account. We report the results of ultraviolet A (UVA) and B (UVB) photoprovocation tests in 67 clinically photosensitive patients who had confirmed discoid LE (DLE), systemic LE (SLE) or subacute cutaneous LE (SCLE). The results are compared with a detailed history of photosensitivity and with clinical and serological findings. A pathological photoprovocation reaction, graded as weak, moderate or strong, was induced with either UVA or UVB in 69% of patients with LE, in 100% of those with SCLE, in 70% of those with SLE and in 64% of those with DLE, but in none of 14 controls. Only 16% of the pathological reactions were strong and long-lasting, resembling LE lesions, while 48% were moderate or weak and transient, clinically like PLE. Fifty-three per cent of the provocation reactions which were biopsied showed a PLE-like histology or a non-specific inflammatory reaction, and most of them were clinically moderate or weak reactions of short duration. In the remaining, mostly clinically strong or long-lasting reactions, the histology was consistent with LE. A history of sunlight sensitivity did not predict a pathological photoprovocation result but a positive association between the presence of SSA/Ro or SSB/La antibodies and a pathological photoprovocation reaction was found. We have shown that PLE coexists with LE and that both PLE- and LE-like lesions can be induced with UV radiation in LE patients.

Adolescent↗

PubMed1996

Characterization of a xenograft model of human ovarian carcinoma which produces intraperitoneal carcinomatosis and metastases in mice.

A new xenograft model for human epithelial ovarian carcinoma, with extensive intraperitoneal (i.p.) carcinomatosis as the predominant disease manifestation, is described. Cells from the established NIH:OVCAR-5 cell line were injected i.p. into 6- to 8-week-old Swiss nude mice. Comparative analyses between cells cultured in vitro and tumor cells derived ex vivo were performed to assess histologic features, immunohistochemical cell markers, hormonal receptor expression, adhesion to extracellular matrix molecules and chromosomal constitution. Macroscopically, the extent of tumor development appeared to be site-dependent and tumor cell survival was dose-dependent. Advanced disease was characterized by extensive solid tumor burden and ascites with parenchymal invasion, lymphatic metastases and vascular dissemination. Individual tumor nodules exhibited developing neovasculature characterized by the absence of mature basement membrane. Despite some histologic loss of cellular differentiation in advanced disease, antigenic expression was preserved, distinguishing these cells as epithelial in origin. Karyotyping of tumor cells demonstrated multiple numeric and structural chromosomal abnormalities. Serum and ascites CA 125 levels were consistently elevated only in tumor-bearing mice. This new murine model closely resembles the aggressive disease process of human epithelial ovarian carcinoma, in which the efficacy of i.p. and systemic therapeutic modalities can be investigated.

Animals↗

PubMed1996

Effect of charge on the interaction of site-specific photoimmunoconjugates with human ovarian cancer cells.

A marked effect of charge modification on the uptake and phototoxicity of a photoimmunoconjugate (PIC) was demonstrated. A site-specific conjugation strategy was developed to attach the photosensitizer chlorin(e6) (c(e6)) to the F(ab')2 fragment of the murine antiovarian cancer monoclonal antibody OC125. Poly-L-lysine linkers carrying c(e6) with a cationic charge or by polysuccinylation with an anionic charge were used and covalently attached to partially reduced antibody via a heterobifunctional reagent. PICs were purified by column chromatography and were also radiolabeled with 125I. PIC binding and uptake were studied with a human ovarian cancer cell line, NIH-OVCAR-5, and a nonantigen-expressing colon cancer cell line, SW1116, and the data were compared with the binding and uptake of nonspecific rabbit IgG PICs. PICs with both cationic and anionic charges preserved antigen binding as shown by competition studies with native antibody, but the cationic PIC had up to 17 times higher cellular uptake of c(e6), probably due to enhanced internalization. The ratio of c(e6) to 125I retained by the cells varied with the likelihood of internalization and lysosomal degradation. The phototoxicity of the PICs generally varied with their uptake, but a correlation was found between lysosomal hydrolysis as measured by an increased cellular ratio of c(e6):125I and increased relative phototoxicity. These data suggest cationic PICs may have advantages for photoimmunotherapy of disseminated intracavity cancer following local administration.

Antigens, Surface↗

PubMed1996

Intraperitoneal photodynamic therapy of human epithelial ovarian carcinomatosis in a xenograft murine model.

The objective of this investigation was to determine the efficacy of i.p. photodynamic therapy (PDT) against solid, multifocal ovarian carcinoma using a newly described NIH:OVCAR-5 induced murine model. PDT was initiated when diffuse microscopic disease and small multifocal tumor nodules were present, similar to the extent of residual carcinoma that may persist clinically after laparotomy and tumor debulking. The photosensitizer, benzoporphyrin derivative monoacid ring A (BPD-MA), was administered in a dose of 0.25 mg/kg body weight i.p. 90 min prior to light exposure. An argon-pumped dye laser was used to deliver low intensity light (20 J) i.p. through a cylindrically diffusing fiberoptic tip. Treatment regimens consisted of a series of three to five treatments at 3-7 day intervals, with the extent of macroscopic disease or death from disease being the evaluable outcome parameters for tumoricidal and survival studies, respectively. The mean tumor burden at necropsy for treated animals was 0.034 +/- 0.014 g compared to 0.379 +/- 0.065 g in untreated controls (P<0.001). Survival studies were initiated in two groups at day 7 and day 14 following cell inoculation. The first group received either three or five treatments at 5-day intervals, and both had a significant increase in median survival compared to untreated controls (57 and 53 days, respectively, compared to 43 days, P<0.05). The second group was treated every 7 days until death and also had a significant survival advantage over controls (57 days compared to 47 days, P<0.05). These studies suggest that benzoporphyrin derivative mono acid ring A-mediated PDT is a feasible, well-tolerated, experimental treatment approach that elicits a tumoricidal response against diffuse, solid i.p. disease in tumor-bearing mice, with concomitant prolongation of survival and needs careful optimization.

Animals↗

PubMed1996

Benzoporphyrin-lipoprotein-mediated photodestruction of intraocular tumors.

Benzoporphyrin derivative (BPD), a sensitizer currently in clinical trials, was evaluated for the treatment of experimental Greene melanoma implanted in the rabbit iris. To improve tumor targeting, BPD was complexed with low-density lipoprotein (LDL) representing an endogenous carrier system for BPD as previously described. Twelve tumors were irradiated at a sensitizer dose of 2 mg kg-1 body weight using a dye laser at 692 nm. Tumor responses were documented by photography, angiography and light and electron microscopy. All tumors treated with 80 J cm-2 regressed irreversibly. The principal mechanism of tumor necrosis was thrombosis following disruption of endothelial membranes. Ultrastructure data suggested tumor cell damage, although evidence for this being the result of direct PDT-mediated tumor cell death was less clear. These data suggest that BPD-LDL may be used to improve the selectivity of photodynamic tumor therapy possibly by the increased uptake of lipoprotein-delivered sensitizer to neovascular endothelial cells.

Animals↗