Vascular-targeted photodynamic therapy with glucose-conjugated chlorin e6 for dogs with spontaneously occurring tumours.

BACKGROUND: Photodynamic therapy (PDT) using photosensitisers is a minimally invasive treatment for malignant tumours. However, ideal photosensitisers are not yet established. Recently, we developed a new photosensitiser, glucose-conjugated chlorin e6 (G-Ce6). OBJECTIVES: To evaluate the clinical efficacy of vascular-targeted PDT (VTP), a type of PDT utilising a short drug-light interval, using G-Ce6 to treat spontaneously occurring tumours in dogs. METHODS: Five dogs with spontaneously occurring tumours (malignant melanoma: three; haemangiopericytoma: two; and squamous cell carcinoma: one) were subjected to VTP. These dogs were intravenously injected with G-Ce6 at doses of 1-3 mg/kg 5 min before laser irradiation. Tumours were superficially or interstitially irradiated using a 677-nm diode laser. RESULTS: Repeated VTP decreased tumour size, yielding complete remission in three dogs. Complications such as oedema surrounding normal tissues and fistulae were observed, and the oedema was self-limiting. The fistula was cured by debriding the necrotic tissues formed after VTP. CONCLUSIONS: Our findings demonstrate that VTP using G-Ce6 had antitumour effects in dogs with spontaneously occurring tumours.

Indocyanine green conjugated phototheranostic nanoparticle for photodiagnosis and photodynamic therapy.

BACKGROUND: Phototheranostics represents a highly promising paradigm for cancer therapy, although selecting an appropriate optical imager and sensitizer for clinical use remains challenging. METHODS: Liposomally formulated phospholipid-conjugated indocyanine green, denoted as LP-iDOPE, was developed as phototheranostic nanoparticle and its cancer imaging-mediated photodynamic reaction, defined as the immune response induced by photodynamic and photothermal effects, was evaluated with a near-infrared (NIR)-light emitting diode (LED) light irradiator. RESULTS: Using in vivo NIR fluorescence imaging, we demonstrated that LP-iDOPE was selectively delivered to tumor sites with high accumulation and a long half-life. Following low-intensity NIR-LED light irradiation on the tumor region of LP-iDOPE accumulated, effector CD8+ T cells were activated at the secondary lymphoid organs, migrated, and subsequently released cytokines including interferon-γ and tumor necrosis factor-α, resulting in effective tumor regression. CONCLUSIONS: Our anti-cancer strategy based on tumor-specific LP-iDOPE accumulation and low-intensity NIR-LED light irradiation to the tumor regions, i.e., photodynamic reaction, represents a promising approach to noninvasive cancer therapy.

Case Report: Ultrasonography and Magnetic Resonance Imaging of Anterior Segment Dysgenesis in a Calf.

This study includes diagnostic efficacy of the antemortem, combined use of ultrasonography and magnetic resonance imaging (MRI) for the diagnosis of anterior segment dysgenesis. A 7-day-old male Holstein calf presented with progressive unilateral exophthalmos associated with enlargement of the right eyeball soon after birth. Ultrasonography of the enlarged right eyeball showed (1) a 2-cm-thick echogenic parenchymal lesion filling the anterior region of the right eyeball, (2) excess accumulation of the anechoic vitreous humor, and (3) absence of the lens structure. Antemortem examination using T2-weighted and fluid-attenuated inversion recovery MRI revealed a thickened, hyperintense anterior lesion and absence of the lens structure. These imaging findings were suggestive of anterior segment dysgenesis. Antemortem imaging showed no abnormalities other than the abnormal structure and size of the right eyeball; therefore, enucleation of the right eye was performed, which allowed intact healing without suppuration. Ocular ultrasonography enhanced the diagnostic accuracy due to the characteristic ultrasonographic findings of a thickened anterior lesion and absence of the lens structure in the eyeball, suggestive of anterior segment dysgenesis.

Imaging findings and outcomes after traumatic cerebellar injury: a canine case report.

BACKGROUND: Traumatic brain injury (TBI) is a structural injury or physiological disruption of the brain induced by an external force. The cerebellum facilitates movement coordination and provides a sense of equilibrium; damage to this structure can cause a wide variety of symptoms, including ataxia or dystaxia, ocular motor dysfunction, and disequilibrium. TBIs localised to the cerebellum are rare in dogs, and the prognosis following this type of injury remains unclear. CASE PRESENTATION: A 10-year-old female Chihuahua/Dachshund-cross dog weighing 2.8 kg presented after a fall of approximately 1 m the preceding night. The dog exhibited paresis of all limbs and was recumbent with constant extensor rigidity with opisthotonos. The bilateral thoracic limb and right pelvic limb spinal reflexes were exaggerated, while the left pelvic limb spinal reflexes were normal. The menace response was decreased, and vertical nystagmus was observed. Magnetic resonance imaging (MRI) revealed a hyperintense lesion on T2weighted (W) images, fluid-attenuated inversion recovery, and diffusion-weighted imaging (DWI). Mannitol and prednisolone were administered, and the dog recovered. The bilateral pelvic limb postural reactions improved by Day 16. On Day 22, MRI revealed a decrease in the hyperintense area of the T2W images, and this lesion appeared isointense on DWI. CONCLUSIONS: In this case report, a dog with localised injury to the cerebellum that comprised a post-tentorial lesion recovered with a favourable outcome. Moreover, similar to reports in humans, DWI can help diagnose and evaluate TBI in dogs.

Detection of squamous cell carcinoma of presumed pancreatic origin and its metastasis in a spotted seal (Phoca largha) using ultrasonography and computed tomography.

A 21-year-old female spotted seal (Phoca largha), with a swollen abdomen, had a five-month history of anorexia and vomiting. Ultrasonography revealed an extended mass with central necrotic foci in the right cranial abdomen. Computed tomography revealed an abdominal mass with a low-density central lumen and a pulmonary nodular lesion. Cytology of an abdominal specimen collected through fine-needle aspiration indicated a malignant tumor with round, atypical cells with large nuclei. Three days after diagnosis, necropsy revealed a 10-cm large, solid, whitish mass in the pancreatic parenchyma and multiple small nodules in the liver, spleen, mesentery, lungs, and mediastinal lymph nodes. Histopathological analysis showed prolific neoplastic cells with marked atypia and occasional keratinization. Immunohistochemistry revealed that the neoplastic cells were positive for cytokeratin AE1/AE3 antibody. Thus, the seal was diagnosed with squamous cell carcinoma, of presumed pancreatic origin, which had metastasized to multiple organs.

Auranofin: Past to Present, and repurposing.

Auranofin (AF), a gold compound, has been used to treat rheumatoid arthritis (RA) for more than 40 years; however, its mechanism of action remains unknown. We revealed that AF inhibited the induction of proinflammatory proteins and their mRNAs by the inflammatory stimulants, cyclooxygenase-2 and inducible nitric oxide synthase, and their upstream regulator, NF-κB. AF also activated the proteins peroxyredoxin-1, Kelch-like ECH-associated protein 1, and NF-E2-related factor 2, and inhibited thioredoxin reductase, all of which are involved in oxidative or electrophilic stress under physiological conditions. Although the cell membrane was previously considered to be permeable to AF because of its hydrophobicity, the mechanisms responsible for transporting AF into and out of cells as well as its effects on the uptake and excretion of other drugs have not yet been elucidated. Antibodies for cytokines have recently been employed in the treatment of RA, which has had an impact on the use of AF. Trials to repurpose AF as a risk-controlled agent to treat cancers or infectious diseases, including severe acute respiratory syndrome coronavirus 2/coronavirus disease 2019, are ongoing. Novel gold compounds are also under development as anti-cancer and anti-infection agents.

Triple nostrils in a calf.

BACKGROUND: Nasal abnormalities are rare in bovines. In humans, nasal deformities are mainly classified as proboscis lateralis or supernumerary nostrils. This report discusses the etiology of triple nostrils in a calf, based on computed tomography, magnetic resonance imaging, and endoscopy. CASE PRESENTATION: A female Holstein calf presented with triple nostrils. The following abnormalities were observed: (1) formation of a small and flat blind-ended middle nostril between the right and left nostrils; (2) presence of a hair-bearing surface on the muzzle; (3) abnormal curvature of the nasal septum, resulting in a narrower right nasal cavity due to transformation of the nasal bones; and (4) formation of a bone-like structure within the nasal septum. These findings were similar to those of supernumerary nostrils in humans. CONCLUSIONS: To the best of our knowledge, this represents the first description of a calf with triple nostrils. The use of imaging modalities is necessary for investigating the etiology of triple nostrils.

Photohyperthermal therapy using liposomally formulated indocyanine green for feline nasal lymphoma: A case report.

Our previous research has focused on the development of a novel cancer therapy by using photohyperthermal therapy (PHT) with indocyanine green (ICG) as an optical sensitizer. ICG-Lipo is a liposomally formulated ICG derivative in which ICG is tagged with an octadeca-alkyl chain to incorporate into liposome bilayers, and contains antitumor drugs such as carboplatin and paclitaxel within the inner membrane space. The present study reported a case of feline nasal lymphoma that was treated with combination therapy of PHT with ICG-Lipo. An antitumour effect was observed, and the patient entered remission. Complications from the radiation treatment included skin burns and bleeding from the irradiated hard palate. Serious side effects related to the drugs were not observed. This report suggested that PHT using ICG-Lipo enabled efficient and safe treatment of lymphoma, and that treatment with a liposomal drug delivery system was enhanced by PHT.

Ultrasonography of sudden swollen tongue in a calf.

BACKGROUND: In cattle, the lingual diseases are primarily diagnosed postmortem by histopathological examination of the affected tongues obtained after the death or during necropsy. In humans, ultrasonography has been used to provide differential diagnoses, and for preoperative or intraoperative planning of glossectomy in various lingual diseases. This is a bovine clinical case report, in which ultrasonography for sudden swelling of the tongue, which was possibly caused by snake bite, was utilized as a preoperative indication to perform a glossectomy. CASE PRESENTATION: An eight-month-old female Japanese black calf presented with sudden swelling of the tongue with well-defined discoloration in the cranial region. A 10-MHz linear probe on a portable-type ultrasound machine (MyLabOne VET, Esaote Co., Genova, Italy) was applied to the ventral surface of the tongues in the affected case, and also in five healthy calves under sedation to observe normal tongues. Ultrasonography of the swollen tongue in this case revealed that the ventral lingual muscular layers were severely thickened compared with those of normal tongues. However, the muscle layers were regularly aligned with the echogenic muscular fibers. This resembled the lingual muscular architectures of normal tongues. Color-flow Doppler ultrasonography revealed that blood flow was weakened in the small peripheral vessels in the spaces between the lingual muscular structures, and was lacking in the deep lingual artery between the apex and base of the tongue. This finding was very different than that of normal tongues, which exhibited weakened or rich blood flows. Based on ultrasonographic findings, this case was treated with glossectomy. After recovery, the calf grew up normally with a normal appetite and rumination, and did not exhibit mouth pain behavior. Histopathologically, hemorrhagic necrotic changes, together with focal formation of fibrin thrombus in the lingual blood vessels in the affected tongue, were noted. CONCLUSIONS: To the best of our knowledge, the present report is the first description of lingual ultrasonography performed in cattle. In this case, ultrasonography enabled visualization of decreased vascularity, which might be associated with hemorrhage or formation of fibrin thrombus in the suddenly swollen tongue presented.

Photodynamic detection of a feline meningioma using 5-aminolaevulinic acid hydrochloride.

CASE SUMMARY: The present study describes the case of a feline meningioma that was detected using 5-aminolaevulinic acid hydrochloride (5-ALA)-induced protoporphyrin IX (PpIX) fluorescence at surgery. An extra-axial mass in the temporoparietal region was observed by MRI. Following craniectomy and durotomy, photodynamic detection (PDD) was performed for detection of the tumour. Intratumour PpIX was detected using fluorescence spectrum evaluation and high-performance liquid chromatography. PDD revealed bright fluorescence of PpIX induced by 5-ALA, facilitating fluorescence-guided resection of the tumour tissue. Postoperative examination demonstrated an intratumour PpIX protein concentration of 16.8 nmol/g, and based on histopathological findings we diagnosed the mass as meningioma. RELEVANCE AND NOVEL INFORMATION: PDD using 5-ALA has been used to identify the surgical margins during resection of primary human brain tumours. Recently, we have reported post-mortem PDD using 5-ALA for a canine glioblastoma. To our knowledge, this technique has not been previously used for the detection and resection of feline brain tumours. Our findings suggest that PDD using 5-ALA is useful for intraoperative fluorescence-guided resection of malignant meningioma in cats.

Imaging and pathological findings of intramedullary inflammatory pseudotumour in a miniature dachshund: a case report.

BACKGROUND: Inflammatory pseudotumours (IPTs) are distinctive lesions consisting of myofibroblastic spindle cells and a variety of inflammatory cells. The aetiology of IPTs is unknown. Reports of IPTs in veterinary medicine have been scarse. Moreover, only one case of intradural extramedullary IPT has been previously reported. In this report, we introduce the first known case of canine IPT, which occurred in the parenchyma of the spinal cord. CASE PRESENTATION: A 10-year-old female Miniature Dachshund presented with a 2-month-long history of progressively worsening ataxia and tetraparesis. Neurological examination was consistent with a lesion involving the cervical spinal cord. Magnetic resonance imaging revealed an intradural space-occupying lesion in the region of the fourth cervical vertebra. Dorsal laminectomy and resection of the mass were performed. Histopathological examination revealed the proliferation of immature spindle cells (fibroblasts/myofibroblasts and glial cells) and a highly cellular mixture of neutrophils, macrophages and lymphocytic cells. The mass was located in the parenchyma of the spinal cord and was diagnosed as an IPT occurring in the parenchyma of the spinal cord. No causative pathogen was detected. The dog's symptoms improved, during the first month after surgery. However, neurological symptoms, such as laboured breathing and dysuria, subsequently worsened and the dog died 42 days after surgery. CONCLUSIONS: The present study describes a canine case of IPT occurring in the parenchyma of the spinal cord. The diagnosis and determination of the site of the mass was difficult solely based on preoperative imaging in the present case. The outcome of this case was poorer than that observed in cases of canine extramedullary IPT and human intramedullary IPT, in which the patients exhibited recovery. The prognosis after surgical resection cannot be decided from the present case alone. However, patients should be monitored for potential serious complications and recurrence.

Efficacy of 5-Aminolevulinic Acid in Photodynamic Detection and Photodynamic Therapy in Veterinary Medicine.

5-Aminolevulinic acid (5-ALA), a commonly used photosensitizer in photodynamic detection (PDD) and therapy (PDT), is converted in situ to the established photosensitizer protoporphyrin IX (PpIX) via the heme biosynthetic pathway. To extend 5-ALA-PDT application, we evaluated the PpIX fluorescence induced by exogenous 5-ALA in various veterinary tumors and treated canine and feline tumors. 5-ALA-PDD sensitivity and specificity in the whole sample group for dogs and cats combined were 89.5 and 50%, respectively. Notably, some small tumors disappeared upon 5-ALA-PDT. Although single PDT application was not curative, repeated PDT+/-chemotherapy achieved long-term tumor control. We analyzed the relationship between intracellular PpIX concentration and 5-ALA-PDT in vitro cytotoxicity using various primary tumor cells and determined the correlation between intracellular PpIX concentration and 5-ALA transporter and metabolic enzyme mRNA expression levels. 5-ALA-PDT cytotoxicity in vitro correlated with intracellular PpIX concentration in carcinomas. Ferrochelatase mRNA expression levels strongly negatively correlated with PpIX accumulation, representing the first report of a correlation between mRNA expression related to PpIX accumulation and PpIX concentration in canine tumor cells. Our findings suggested that the results of 5-ALA-PDD might be predictive for 5-ALA-PDT therapeutic effects for carcinomas, with 5-ALA-PDT plus chemotherapy potentially increasing the probability of tumor control in veterinary medicine.

Effect of hypoxia on progesterone production by cultured bovine early and mid luteal cells.

A major role of the corpus luteum (CL) is to produce progesterone (P4). The CL has immature vasculature shortly after ovulation, suggesting it exists under hypoxic conditions. To elucidate the mechanism involved in regulation of luteal cell function during CL development, we compared the effect of hypoxia on P4 production by cultured bovine early and mid luteal cells. Luteal cells obtained from early and mid CL were incubated under different O2 concentrations (20% and 3%) with or without hCG (1 U/ml) for 6 h and 24 h. After 6 h of culture in the presence of hCG, P4 production was not affected by hypoxia whereas decrease in its production by mid luteal cells was observed. After 24 h of culture, P4 production was significantly decreased by hypoxia in both stages of luteal cells regardless of the use of hCG. At 6 h of culture, hypoxia increased mRNA expression of hydroxyl-Δ-5-steroid dehydrogenase, 3ß- and steroid Δ-isomerase 1 (HSD3B1) in early luteal cells, and decreased mRNA expression of cytochrome P450 cholesterol side chain cleavage (CYP11A1) enzyme in mid luteal cells. At 24 h of culture, mRNA expressions of steroidogenic acute regulatory protein (STAR), CYP11A1, and HSD3B1 were not affected by hypoxia in both stages of luteal cells. The overall results suggest that early luteal cells maintain P4 production under hypoxic conditions, and hypoxia-induced HSD3B1 may support this P4 production in the bovine early CL.

Hair growth-promoting activities of chitosan and surface-deacetylated chitin nanofibers.

In this study, the effects of chitosan and surface-deacetylated chitin nanofibrils (SDACNFs) on hair growth were evaluated. In human follicle dermal papilla cells in vitro, chitosan and SDACNFs were shown to increase cell growth on day 3 after the initiation of treatment, together with an increase in the production of fibroblast growth factor-7 (FGF-7) by these cells on day 3. Furthermore, in an in vivo study in mice, chitosan and SDACNF application promoted hair growth. The number of anagen follicles significantly increased compared with that in the control group, whereas the number of telogen follicles significantly decreased in the chitosan and SDACNF groups. In the chitosan and SDACNFs groups, moreover, the expression levels of FGF-7 and Sonic hedgehog were significantly upregulated in hair follicles. Overall, our results demonstrated that chitosan and SDACNFs promoted hair growth and therefore may have applications as novel therapeutic agents for the treatment of hair loss in patients.

Effects of TONS504-photodynamic therapy on mouse mammary tumor cells.

In the present study, TONS504 (C51H58N8O5I2; molecular weight, 1,116.9), a novel cationic hydrophilic photosensitizer, was synthesized from protoporphyrin IX dimethyl ester through a five-step process according to a patented method for use in photodynamic therapy (PDT). The subcellular localization of TONS504 and the cytotoxic effects of TONS504-mediated PDT in the mouse mammary tumor EMT6 cell line were investigated. TONS504 was localized primarily in the lysosomes and partially in the mitochondria. The cytotoxic effects of TONS504-mediated PDT in the mouse mammary tumor EMT6 cell line were investigated using a WST8 assay and an Oxidative Stress kit. The cell viability values following treatment with 10 µg/ml TONS504 at light energies of 0, 1, 5 and 10 J/cm2 were 92.5, 101.8, 27.7 and 1.8%, respectively. The percentages of reactive oxygen species (ROS)(+) cells following the same treatment were 8.6, 8.5, 29.2 and 70.1%, respectively, whereas the percentages of apoptotic cells were 7.1, 5.6, 24.8 and 48.7%, respectively. The percentages of ROS(+) and apoptotic cells in the group subjected to TONS504-mediated PDT increased in a manner dependent on the TONS504 concentration and light energy. Further studies are required to evaluate the in vivo pharmacokinetics, tissue distribution and photodynamic effects of TONS504.

Cellular stress induces cancer stem-like cells through expression of DNAJB8 by activation of heat shock factor 1.

In a previous study, we found that DNAJB8, a heat shock protein (HSP) 40 family member is expressed in kidney cancer stem-like cells (CSC)/cancer-initiating cells (CIC) and that it has a role in the maintenance of kidney CSC/CIC. Heat shock factor (HSF) 1 is a key transcription factor for responses to stress including heat shock, and it induces HSP family expression through activation by phosphorylation. In the present study, we therefore examined whether heat shock (HS) induces CSC/CIC. We treated the human kidney cancer cell line ACHN with HS, and found that HS increased side population (SP) cells. Western blot analysis and qRT-PCR showed that HS increased the expression of DNAJB8 and SOX2. Gene knockdown experiments using siRNAs showed that the increase in SOX2 expression and SP cell ratio depends on DNAJB8 and that the increase in DNAJB8 and SOX2 depend on HSF1. Furthermore, treatment with a mammalian target of rapamycin (mTOR) inhibitor, temsirolimus, decreased the expression of DNAJB8 and SOX2 and the ratio of SP cells. Taken together, the results indicate that heat shock induces DNAJB8 by activation of HSF1 and induces cancer stem-like cells.

Bleomycin-Loaded pH-Sensitive Polymer⁻Lipid-Incorporated Liposomes for Cancer Chemotherapy.

Cancer chemotherapeutic systems with high antitumor effects and less adverse effects are eagerly desired. Here, a pH-sensitive delivery system for bleomycin (BLM) was developed using egg yolk phosphatidylcholine liposomes modified with poly(ethylene glycol)-lipid (PEG-PE) for long circulation in the bloodstream and 2-carboxycyclohexane-1-carboxylated polyglycidol-having distearoyl phosphatidylethanolamine (CHexPG-PE) for pH sensitization. The PEG-PE/CHexPG-PE-introduced liposomes showed content release responding to pH decrease and were taken up by tumor cells at a rate 2.5 times higher than that of liposomes without CHexPG-PE. BLM-loaded PEG-PE/CHexPG-PE-introduced liposomes exhibited comparable cytotoxicity with that of the free drug. Intravenous administration of these liposomes suppressed tumor growth more effectively in tumor-bearing mice than did the free drug and liposomes without CHexPG-PE. However, at a high dosage of BLM, these liposomes showed severe toxicity to the spleen, liver, and lungs, indicating the trapping of liposomes by mononuclear phagocyte systems, probably because of recognition of the carboxylates on the liposomes. An increase in PEG molecular weight on the liposome surface significantly decreased toxicity to the liver and spleen, although toxicity to the lungs remained. Further improvements such as the optimization of PEG density and lipid composition and the introduction of targeting ligands to the liposomes are required to increase therapeutic effects and to reduce adverse effects.

Hypoxia increases glucose transporter 1 expression in bovine corpus luteum at the early luteal stage.

A major role of the corpus luteum (CL) is to produce progesterone (P4). The CL has immature vasculature shortly after ovulation, suggesting it exists under hypoxic conditions. Hypoxia-inducible factor-1 (HIF1) induces the expression of glucose transporter 1 (GLUT1). To clarify the physiological roles of GLUT1 in bovine CL, we examined GLUT1 mRNA expression in the CL under hypoxic conditions by quantitative RT-PCR. We also measured the effects of glucose (0-25 mM) and GLUT1 inhibitors (cytochalasin B, STF-31) on P4 production in bovine luteal cells. GLUT1 mRNA expression in bovine CL was higher at the early luteal stage compared to the other later stages. Hypoxia (3% O2) increased GLUT1 mRNA expression in early luteal cells, but not in mid luteal cells. Glucose (0-25 mM) increased P4 production in early luteal cells, but not in mid luteal cells. Both GLUT1 inhibitors decreased P4 production in early and mid luteal cells. Overall, the results suggest that GLUT1 (possibly induced by hypoxic conditions in the early CL) plays a role in the establishment and development of bovine CL, especially in supporting luteal P4 synthesis at the early luteal stage.

Uterine torsion in a full-term pregnant cat.

CASE SUMMARY: A 5-year-old intact female Maine Coon cat presented with a 2 day history of lethargy, anorexia and anaemia. The cat had bred 60 days previously and jumped from a height 3 days earlier, which was followed by a worsening of its condition. Ultrasonography revealed that two fetuses had died and one remained alive. Urgent surgical intervention was deemed necessary, and the cat underwent a blood transfusion and laparotomy. The right uterine horn was dark red in appearance and had rotated 360° in the clockwise direction at its base. Subsequently, an ovariohysterectomy and caesarean section were performed, and the fetus in the left uterine horn initially survived. Although the cat appeared to recover from anaemia and physical injury, the kitten died on postoperative day 1. RELEVANCE AND NOVEL INFORMATION: In cases involving only one twisted uterine horn, the fetuses located in the contralateral horn could potentially survive; however, many such fetuses do not survive, and only a few reports have described fetal survival in a pregnant cat with uterine torsion. In the present case, early surgical intervention and blood transfusion allowed us to save the cat. Our findings demonstrate the life-saving abilities of initial support treatment and early surgical intervention for both the pregnant cat and fetuses in cases of acute abdomen caused by uterine torsion.

Effects of photodynamic therapy with talaporfin sodium on squamous cell carcinoma and sarcoma cells.

BACKGROUND: Photodynamic therapy (PDT) uses a photosensitizer and light to destroy abnormal cells. Talaporfin sodium (NPe6) is a second-generation photosensitizer. METHODS: We evaluated the toxic effects of different combinations of laser and NPe6 doses on squamous cell carcinoma (KLN205) and sarcoma (Meth A) cell lines. The cells were incubated with 0, 5, 10, or 30µg/mL NPe6 for 24h. The cells were then irradiated with 0, 5, 15, or 30mW/cm2 of laser power, and 0, 1, 5, 10, or 20J/cm2 of laser energy. Cell viability was evaluated after 24h. We also evaluated the cytotoxic effects of continuous wave or square-wave modulated laser irradiations (2, 5, or 10Hz, 50% duty) on Meth A cells. RESULTS: The median lethal doses of NPe6 against the KLN205 and Meth A cells after treatment at a fluence rate of 15mW/cm2 and a light dose of 20J/cm2 were 18.6 and 5.0µg/mL, respectively. Meth A cells were more sensitive to PDT than KLN205 cells. There was no significant difference between the effects of continuous wave and square-wave modulated lasers on Meth A cell viability. CONCLUSIONS: NPe6 PDT induced cell death in a dose-dependent manner in KLN205 and Meth A cells. More work is required to evaluate the cytotoxic effects of square-wave modulated laser therapy at low light doses.