Purging of murine erythroblastic leukemia by ZnPcS2P2-based-photodynamic therapy

Secure transplantation by tissue purging using photodynamic therapy to eradicate malignant cells

The field of photodynamic therapy (PDT) for treating various malignant neoplasms has been given researchers' attention due to its ability to be a selective and minimally invasive cancer therapy strategy. The possibility of tumor cell infection and hence high recurrence rates in cancer patients tends to restrict autologous transplantation. So, the photodynamic tissue purging process, which consists of selective photoinactivation of the malignant cells in the graft, is defined as a compromising strategy to purify contaminated tissues before transplantation. In this strategy, the direct malignant cells' death results from the reactive oxygen species (ROS) generation through the activation of a photosensitizer (PS) by light exposure in the presence of oxygen. Since new PS generations can effectively penetrate the tissue, PDT could be an ideal ex vivo tissue purging protocol that eradicates cancer cells derived from various malignancies. The challenge is that the applied pharmacologic ex vivo tissue purging should efficiently induce tumor cells with minor influence on normal tissue cells. This review aims to provide an overview of the current status of the most effective PDT strategies and PS development concerning their potential application in ex vivo purging before hematopoietic stem cell or ovarian tissue transplantation.

Demethylation of cancer/testis antigens and CpG ODN stimulation enhance dendritic cell and cytotoxic T lymphocyte function in a mouse mammary model

Background. Cancer/testis antigens (CTAs) are ideal targets for cancer immunotherapy in virtue of their restricted expression profile in normal tissues. However, CTA-targeted immunotherapy has been rather disappointing clinical setting for CTAs are downregulated by cytosine-phosphate-guanosine (CpG) methylation in their promoter regions, so that tumor cells have low immunogenicity. Methods. We reinduced mouse CTA P1A through demethylation process and generated P1A-specific cytotoxic lymphocytes (CTLs) by immunizing BALB/c (H-2^d) mice with dendritic cells pulsed with a P1A-specific peptide and CpG oligodeoxynucleotide (ODN) immune adjuvant. Results. We found that demethylation and CpG ODN immune adjuvant stimulation facilitated DC maturation and enhanced the allogenic capacity of P1A-specific CTLs against target cells both in vitro and in vivo. Conclusions. Our results suggested that CTA induction and immune adjuvant stimulation is a feasible strategy in cancer immunotherapy.

Use of a novel sonosensitizer in sonodynamic therapy of U251 glioma cells in vitro

The aim of the present study was to investigate the effect of ZnPcS(2)P(2)-meditated sonodynamic therapy (SDT) on U251 human glioma cells and to identify its underlying biological mechanism. The growth inhibition rate was determined by MTT assay. The apoptotic rate was examined by flow cytometry. Fine structures were observed with transmission electron microscopy (TEM). Generation of reactive oxygen species (ROS) was detected spectrophotometrically. Caspase-3, -8 and -9 expression was detected by Western blot analysis. The growth inhibition rate of U251 human glioma cells indicated that ZnPcS(2)P(2)-meditated SDT had a better growth inhibition rate of tumor cells at a concentration of 5.0 μg/ml ZnPcS(2)P(2), at a 4-h incubation time with ZnPcS(2)P(2), and at 6 h re-incubation following SDT. At 6 h after SDT, the growth inhibition rate of cells was significantly higher compared to other groups, apoptosis could be detected in SDT by flow cytometry. TEM examination revealed morphological features of apoptosis or necrosis. Furthermore, caspase-3, -8 and -9 expression following SDT was found to be increased by Western blot analysis. Finally, generation of ROS in cells was also elevated. In conclusion, ZnPcS(2)P(2)-SDT is capable of inducing U251 cell apoptosis or necrosis and has satisfying antitumor effects. The mechanism of ZnPcS(2)P(2)-meditated SDT involves ROS generation in U251 cells, which initiates subsequent apoptosis through the mitochondrial and death receptor pathways.

Targeted indocyanine-green-loaded calcium phosphosilicate nanoparticles for in vivo photodynamic therapy of leukemia

Leukemia is one of the most common and aggressive adult cancers, as well as the most prevalent childhood cancer. Leukemia is a cancer of the hematological system and can be divided into a diversity of unique malignancies based on the onset of the disease as well as the specific cell lineages involved. Cancer stem cells, including recently identified leukemia stem cells (LSCs), are hypothesized to be responsible for cancer development, relapse, and resistance to treatment, and new therapeutics targeting these cellular populations are urgently needed. Nontoxic and nonaggregating calcium phosphosilicate nanoparticles (CPSNPs) encapsulating the near-infrared fluoroprobe indocyanine green (ICG) were recently developed for diagnostic imaging and drug delivery as well as for photodynamic therapy (PDT) of solid tumors. Prior studies revealed that specific targeting of CPSNPs allowed for enhanced accumulation within breast cancer tumors, via CD71 targeting, or pancreatic cancer tumors, via gastrin receptor targeting. In the present study, ICG-loaded CPSNPs were evaluated as photosensitizers for PDT of leukemia. Using a novel bioconjugation approach to specifically target CD117 or CD96, surface features enhanced on leukemia stem cells, in vitro ICG-CPSNP PDT of a murine leukemia cell line and human leukemia samples were dramatically improved. Furthermore, the in vivo efficacy of PDT was dramatically enhanced in a murine leukemia model by utilizing CD117-targeted ICG-CPSNPs, resulting in 29% disease-free survival. Altogether, this study demonstrates that leukemia-targeted ICG-loaded CPSNPs offer the promise to effectively treat relapsing and multidrug-resistant leukemia and to improve the life of leukemia patients.

Purging efficacy of ZnPcH₁-based photodynamic therapy on chronic myeloid leukemia bone marrow

INTRODUCTION

Ex vivo purging is an emerging technique for successful transplantation of autologous hematopoietic stem cells in the treatment of leukemia. Among them, photodynamic therapy (PDT) might be a promising modality. The objective of this study was to evaluate the purging efficacy of ex vivo PDT on chronic myeloid leukemia (CML).

METHODS

A new amphiphilic mono-α-substituted zinc (II) phthalocyanine (ZnPcH₁) was used as a PDT photosensitizer. Nest reverse transcription polymerase chain reaction (RT-PCR) and real-time quantitative PCR of BCR/ABL1 fusion gene remained positive were performed to determine the purging effects of ZnPcH₁-PDT on the mixture of CML cell line K562 cells and normal bone marrow mononuclear cells (MNC) and on the CML cells from the bone marrow of patients with CML who had achieved complete hematology remission but whose BCR/ABL1 fusion genes remained positive.

RESULTS

CML cells exhibited higher susceptibility to ZnPcH₁-PDT than normal granulocyte/macrophage progenitors. PDT could eliminate K562 cells from K562-normal MNC mixture and the residual BCR/ABL1 positive CML cells from the bone marrow of patients with CML.

CONCLUSION

Our data suggest that ZnPcH₁-PDT may be a useful modality for purging CML cells for autologous grafts.

Hexaminolevulinate-mediated photodynamic purging of leukemia cells from BM

Photodynamic therapy (PDT) with porphyrin precursors has been established for tumor treatment. This study aimed at examining applicability of hexaminolevulinate (HAL) for photodynamic purging of leukemic cells from BM grafts and evaluating the clinical relevance of in vitro models. The PDT dose resulting in no colony formation by leukemic cells in vitro, in pure form or in a mixture with BM cells, was insufficient for complete killing of the leukemic cells ex vivo and for the treatment of the leukemia-bearing animals in vivo. The efficacy of HAL-PDT in cell lines in vitro should be verified in clinically relevant in vivo models.

Intravenous repeated-dose toxicity study of ZnPcS2P2-based-photodynamic therapy in beagle dogs

The purpose of current study was to investigate the potential repeated dosed toxicity of ZnPcP(2)S(2)-based photodynamic therapy (ZnPc-PDT) in Beagle dogs. Twenty-four Beagle dogs were randomly allocated to four groups, in which they were administered ZnPcS(2)P(2) preparation intravenously at dosages of 0, 0.5, 1.5, and 4.5mg/kg body weight and then were irradiated with 670nm laser for 6min at subsequent 48 and 72h, once every four days for successively 10 times. There were no abnormal changes in clinical observations. After the administration most animals showed dysphoria and several had light edema on their faces. The results showed no mortality and no abnormity in ophthalmoscopy, electrocardiography, hematology, blood biochemistry and urinalysis, except that some statistical changes in specific indexes such as APTT in 1.5 and 4.5mg/kg groups, and these changes disappeared at the end of recovery. Histopathological examination showed hepatic spotty and lytic necrosis in Beagle dogs of 4.5mg/kg group, and at the end of recovery the damages alleviated. Additionally, some Kelly and Khaki granules presented in liver, spleen, lungs, kidneys, ovaries, lymph nodes, marrows and injection points. These drug pigmentations will provide valuable information about distribution of ZnPcP(2)S(2). Based on the results; the NOAEL was considered to be 1.5mg/kg and ZnPc-PDT appears to be a safety and promising approach in clinic.

Intravenous repeated-dose toxicity study of ZnPcS2P2-based-photodynamic therapy in Wistar rats

The purpose of the current study was to investigate the potential repeated-dose toxicity of ZnPcP2S2-based photodynamic therapy (ZnPc-PDT) in Wistar rats. The animals were administered ZnPcS2P2 intravenously ten times successively every 4 d and irradiated with a 670 nm laser light for 6 min at subsequent 48 h and 72 h. At the end of the treatment period, 10 rats/sex/group were sacrificed, while 5 rats/sex/group were sacrificed after a two-week recovery period. During the test period, clinical signs, mortality, body weights, food and water consumption, ophthalmoscopy, hematology, serum biochemistry, urinalysis, organ weights, gross findings and histopathology were examined. The association between the increased liver weight and hepatic spotty and lytic necrosis seen in high dose females corroborates the conclusion that high dose ZnPc-PDT could induce hepatic injury in Wistar rats and they are probably related to the abnormality of certain biochemical parameters of females in the high dose group. Furthermore, microscopic examination for the ZnPc-PDT groups shows the presence of some Kelly and khaki granules in Kupffer cells and endothelia of the livers, epithelia of the renal tubules, marginal sinus and medulla of the spleens, alveolar walls of the lungs, reticular cells and macrophages of the mesenteric lymph nodes, testicular Leydig cells, epididymal epithelial cells, endometrial stromal cells, and interstitial cells and corpora lutea of the ovaries from all or most of the animals. There were no adverse effects on mortality, clinical signs, food and water consumption, ophthalmoscopy, uranalysis, hematology, serum biochemistry, body weights and necropsy findings in control, low and mid dose groups. Based on these results, it was concluded that the intravenous repeated-dose of ZnPcP2S2-PDT induced the abnormalities of liver weights, hepatic biochemistry and histopathology, and pigmentation in the several important organs in Wistar rats at 4 mg kg(-1) d(-1). The target organ was determined to be liver (and spleen perhaps), but this was not so obvious in males. The no-observed-adverse-effect level (NOAEL) was considered to be 1.0 mg kg(-1) for both sexes.