Preclinical characterization of 5-amino-4-oxo-[6-11C]hexanoic acid as an imaging probe to estimate protoporphyrin IX accumulation induced by exogenous aminolevulinic acid

Clinical efficacy of CO2 laser combined with 5-aminolevulinic acid photodynamic therapy in treating periungual and plantar warts

OBJECTIVE

To analyze the clinical application value of CO2 laser combined with 5-aminolevulinic acid photodynamic therapy for periungual and plantar warts.

METHODS

Data from patients with periungual and plantar warts treated at Qingpu branch of Zhongshan Hospital, Fudan University between August 2022 and January 2024 were retrospectively analyzed. After screening based on inclusion and exclusion criteria, 96 patients were included and categorized into two groups according to their treatment regimens: a combination group (n=50, receiving CO2 laser therapy and 5-aminolevulinic acid photodynamic therapy) and a control group (n=46, undergoing CO2 laser treatment alone). The two groups were compared in terms of wart scores before and after treatment, clinical efficacy, recurrence rates during follow-up, and incidence of adverse reactions.

RESULTS

During the 4th, 6th, and 8th weeks of treatment, the wart scores of patients in the combination group were significantly lower than those of the control group (P<0.05), and at these intervals, the overall treatment efficacy in the combination group was significantly higher than that of the control group (P<0.05). At 3-month follow-up, the recurrence rate in the combination group (2.00%) was lower than that in the control group (10.87%) (P<0.05). At the 2nd, 4th, 6th, and 8th weeks of treatment, the Visual Analog Scale scores in the combination group were significantly reduced compared to the control group (P<0.05). No significant difference was found in the incidence of adverse reactions between the two groups during follow-up (P>0.05).

CONCLUSION

The application of CO2 laser therapy combined with 5-aminolevulinic acid photodynamic therapy is effective for patients suffering from periungual and plantar warts, and this combination enhances clinical outcome, mitigates pain, and reduces short-term recurrence.

A hypoxia responsive nanoassembly for tumor specific oxygenation and enhanced sonodynamic therapy

The hypoxic tumor microenvironment (TME) and non-specific distribution of sonosensitizers are two major obstacles that limit practical applications of sonodynamic therapy (SDT) in combating tumors. Here we report a hypoxia-responsive nanovesicle (hMVs) as delivery vehicles of a sonosensitizer to enhance the efficacy of SDT via specific payload release and local oxygenation in the tumor. The nanovesicles are composed of densely packed manganese ferrite nanoparticles (MFNs) embedded in hypoxia-responsive amphiphilic polymer membranes. With δ-aminolevulinic acid (ALA) loaded in the hollow cavities, the hMVs could rapidly dissociate into discrete nanoparticles in the hypoxic TME to release the payload and induce the generation of reactive oxygen species (ROS) under ultrasound (US) radiation. Meanwhile, the released MFNs could catalytically generate O₂ to overcome the hypoxic TME and thus enhance the efficacy of SDT. After treatment, the dissociated MFNs could be readily excreted from the body via renal clearance to reduce long term toxicity. In vitro and in vivo experiments displayed effective tumor inhibition via hMVs-mediated SDT, indicating the great potential of this unique nanoplatform in effective SDT by generating sufficient ROS in deep-seated hypoxic tumors that are not readily accessible by conventional photodynamic therapy.

5-aminolaevulinic acid (5-ALA) accumulates in GIST-T1 cells and photodynamic diagnosis using 5-ALA identifies gastrointestinal stromal tumors (GISTs) in xenograft tumor models

Gastrointestinal stromal tumor (GIST) diagnosis using conventional gastrointestinal endoscopy is difficult because such malignancies cannot be distinguished from other types of submucosal tumors. Photodynamic diagnosis (PDD) is based on the preferential uptake of photosensitizers by tumor tissues and its detection by fluorescence emission upon laser excitation. In this study, we investigated whether PDD using 5-aminolevulinic acid (5-ALA), a standard photosensitizer used worldwide, could be used for GIST diagnosis. 5-ALA is metabolized to endogenous fluorescent protoporphyrin IX (PpIX). We examined the accumulation of PpIX in GIST-T1 cells using flow cytometry and immunofluorescent staining. Furthermore, we established GIST-T1 xenograft mouse models and examined PpIX accumulation in the resultant tumors. PpIX accumulated in GIST-T1 cells and was localized mainly to lysosomes. PpIX accumulation was also observed in murine xenograft tumors. Moreover, tumor and normal tissues could be distinctly identified by relative PpIX fluorescence. Thus, our results demonstrated that PDD with 5-ALA has substantial clinical potential for GIST diagnosis.

The Correlation of Fluorescence of Protoporphyrinogen IX and Status of Isocitrate Dehydrogenase in Gliomas

BACKGROUND

The extent of resection has been reported to be associated with overall survival in gliomas. The use of 5-aminolevulinic acid (5-ALA) has been recognized to increase the extent of tumor resection.

OBJECTIVE

To evaluate what factors affect the intraoperative fluorescence after administration of 5-ALA in gliomas.

METHODS

Correlation of intraoperative fluorescence and several clinical, radiographic, molecular biologic, and histopathologic characters was retrospectively evaluated in 104 patients (53 males and 51 females; mean age 54.2 yr) with gliomas at our institution. To clarify the mechanisms that mutant isocitrate dehydrogenase (IDH) affect the intraoperative fluorescence, in Vitro experiments using genetically engineered glioma cells harboring mutant IDH1 were performed.

RESULTS

Intraoperative fluorescence was observed in 82 patients (78.8%). In addition to age, magnetic resonance imaging enhancement, World Health Organization grades, and MIB-1 index, the status of IDH was revealed to be correlated with intraoperative fluorescence. In Vitro assay revealed that mutant IDH indirectly reduced the amount of exogenous 5-ALA-derived protoporphyrinogen IX in glioma cells by increasing activity of ferrochelatase and heme oxygenase 1.

CONCLUSION

Mutant IDH1/2-induced metabolite changes of exogenous 5-ALA were suggested to contribute to the lesser intraoperative fluorescence in gliomas with mutant IDH1/2 than in those without.

Mechanistic study of PpIX accumulation using the JFCR39 cell panel revealed a role for dynamin 2-mediated exocytosis

5-aminolevulinic acid (5-ALA) has recently been employed for photodynamic diagnosis (ALA-PDD) and photodynamic therapy (ALA-PDT) of various types of cancer because hyperproliferating tumor cells do not utilize oxidative phosphorylation and do not efficiently produce heme; instead, they accumulate protoporphyrin IX (PpIX), which is a precursor of heme that is activated by violet light irradiation that results in the production of red fluorescence and singlet oxygen. The efficiencies of ALA-PDD and ALA-PDT depend on the efficient cellular uptake of 5-ALA and the inefficient excretion of PpIX. We employed the JFCR39 cell panel to determine whether tumor cells originating from different tissues can produce and accumulate PpIX. We also investigated cellular factors/molecules involved in PpIX excretion by tumor cells with the JFCR39 cell panel. Unexpectedly, the expression levels of ABCG2, which has been considered to play a major role in PpIX extracellular transport, did not show a strong correlation with PpIX excretion levels in the JFCR39 cell panel, although an ABCG2 inhibitor significantly increased intracellular PpIX accumulation in several tumor cell lines. In contrast, the expression levels of dynamin 2, which is a cell membrane-associated molecule involved in exocytosis, were correlated with the PpIX excretion levels. Moreover, inhibitors of dynamin significantly suppressed PpIX excretion and increased the intracellular levels of PpIX. This is the first report demonstrating the causal relationship between dynamin 2 expression and PpIX excretion in tumor cells.

Sonodynamic Therapy: Advances and Challenges in Clinical Translation

Sonodynamic therapy (SDT) consists of the synergetic interaction between ultrasound and a chemical agent. In SDT, the cytotoxicity is triggered by ultrasonic stimuli, notably through cavitation. The unique features of SDT are relevant in the clinical context more than ever: the need for efficacy, accuracy, and safety while being noninvasive and preserving the patient's quality of life. However, despite the promising results of this technique, only a few clinical reports describe the use of SDT. The objective of this article is to provide an extensive overview of the clinical and preclinical research conducted in vivo on SDT, to identify the limitations, and to detail the developed strategies to overcome them.

High-Throughput Imaging of PPIX Using Confocal Microscopy

Increases in levels of protoporphyrin IX (PPIX; a heme precursor) may be driven by xenobiotic induction of aminolevulinic acid synthase 1 (ALAS1) expression. ALAS1 is the rate-limiting enzyme of heme biosynthesis and may be upregulated to satisfy the increased need for heme in CYP450 enzymes. Therefore, a high-throughput fluorescence spectroscopy method that detects PPIX would enable the screening of drugs that increase ALAS1 through nuclear hormone receptor-mediated induction of transcription that may cause toxicity or even provide utility in the diagnosis or treatment of cancers that have elevated cellular PPIX levels. This chapter describes a high-throughput plate-based imaging technique for determining cellular protoporphyrin levels by using the GE Healthcare InCell 6000 confocal imaging system to detect the presence and location of PPIX in each cell and may be adapted for use with other imaging systems. Laser excitation and a scientific-grade complementary metal oxide semiconductor (CMOS) camera generate short exposure times, decreasing photobleaching in the target cells that may result in inaccurate measurements of PPIX and increasing screening throughput. Nuclear staining was detected by using a laser with 405-nm excitation and 455-nm emission wavelengths, and the presence of PPIX was measured using 405-nm excitation and 706-nm emission wavelengths. Image analysis involving top-hat segmentation on both nuclear and PPIX staining was performed by using the InCell Analyzer Workstation software. This assay may be adapted to screen for PPIX formation, degradation, and transportation effectors. Indeed, the inclusion of PPIX transport inhibition would be expected to further widen the linear range of fluorescence and improve the method.

Nuclear medicine for photodynamic therapy in cancer: Planning, monitoring and nuclear PDT

Photodynamic therapy (PDT) is a modality with promising results for the treatment of various cancers. PDT is increasingly included in the standard of care for different pathologies. This therapy relies on the effects of light delivered to photosensitized cells. At different stages of delivery, PDT requires imaging to plan, evaluate and monitor treatment. The contribution of molecular imaging in this context is important and continues to increase. In this article, we review the contribution of nuclear medicine imaging in oncology to PDT for planning and therapeutic monitoring purposes. Several solutions have been proposed to plan PDT from nuclear medicine imaging. For instance, photosensitizer biodistribution has been evaluated with a radiolabeled photosensitizer or with conventional radiopharmaceuticals on positron emission tomography. The effects of PDT delivery have also been explored with specific SPECT or PET radiopharmaceuticals to evaluate the effects on cells (apoptosis, necrosis, proliferation, metabolism) or vascular damage. Finally, the synergy between photosensitizers and radiopharmaceuticals has been studied considering the Cerenkov effect to activate photosensitized cells.