5-Aminolevulinic acid-based photodynamic therapy. Clinical research and future challenges

Hemin enhances the 5-aminolevulinic acid-photodynamic therapy effect through the changes of cellular iron homeostasis

BACKGROUND

Photodynamic therapy (PDT) has been utilized as a promising alternative cancer treatment due to its minimum invasiveness over the years. Exogenous 5-aminolevulinic acid (ALA) triggers protoporphyrin IX (PpIX) accumulation, which happens in cancer cells. However, certain types of cancer exhibit reduced effectiveness in the PpIX accumulation mechanism. This study aimed to determine the effect of ALA-PDT combination with hemin on gastric carcinoma TMK-1 cells.

METHODS

This study utilized TMK-1 gastric cancer cell line to evaluate PpIX, ROS, and Fe2+ accumulation following the administration of ALA, hemin, and a combination of ALA and hemin PDT. We also evaluate the mRNA expressions related to iron homeostasis and treatment impacts on cell viability.

RESULTS

The co-addition of ALA and hemin PDT for 4 h of treatment resulted in a significant decrease in cell viability by up to 18 %. While ALA-PDT enhanced PpIX metabolism, the addition of hemin influenced both the production of reactive oxygen species (ROS) and cellular iron homeostasis by inducing Fe2+ accumulation and affecting mRNA levels of IRP, Tfr1, Ferritin, NFS1, and SDHB.

CONCLUSION

These findings suggest that the addition of ALA and hemin enhances phototoxicity in TMK-1 cells. The combination of ALA and hemin with PDT induces cell death, evidenced by increased cytotoxicity properties such as PpIX and ROS, along with significant changes in TMK-1 gastric cancer iron homeostasis. Therefore, the combination of ALA and hemin could be one of the alternatives in photodynamic therapy for cancer in the future.

Application of Photodynamic Therapy with 5-Aminolevulinic Acid to Extracorporeal Photopheresis in the Treatment of Cutaneous T-Cell Lymphoma: A First-in-Human Phase I/II Study

Extracorporeal photopheresis (ECP) is a therapeutic modality used for T-cell-mediated disorders. This approach involves exposing isolated white blood cells to photoactivatable 8-methoxypsoralen (8-MOP) and UVA light, aiming to induce apoptosis in T-cells and thereby modulate immune responses. However, conventional 8-MOP-ECP lacks cell selectivity, killing both healthy and diseased cells, and has shown limited treatment efficacy. An alternative approach under investigation involves the use of 5-aminolevulinic acid (ALA) in conjunction with light, referred to as ALA-based photodynamic therapy. Our previous ex vivo studies suggest that ALA-ECP exhibits greater selectivity and efficiency in killing T-cells derived from patients with T-cell-mediated disorders compared to those treated with 8-MOP-ECP. We have conducted a clinical phase I-(II) study evaluating ALA-ECP safety and tolerability in cutaneous T-cell lymphoma (CTCL). Here, 20 ALA-ECP treatments were administered to one CTCL patient, revealing no significant changes in vital signs. Two adverse events were reported; both evaluated by the Internal Safety Review Committee as non-serious. In addition, five conceivable events with mainly mild symptoms took place. During the study period, a 53% reduction in skin involvement and a 50% reduction in pruritus was observed. In conclusion, the results indicate that ALA-ECP treatment is safe and well tolerated.

Description of mitochondrial oxygen tension and its variability in healthy volunteers

OBJECTIVES

Describing mitochondrial oxygenation (mitoPO2) and its within- and between-subject variability over time after 5-aminolevulinic acid (ALA) plaster application in healthy volunteers.

DESIGN

Prospective cohort study.

SETTING

Measurements were performed in Leiden University Medical Center, the Netherlands.

PARTICIPANTS

Healthy volunteers enrolled from July to September 2020.

INTERVENTIONS

Two ALA plasters were placed parasternal left and right, with a 3-hour time interval, to examine the influence of the calendar time on the value of mitoPO2. We measured mitoPO2 at 4, 5, 7, 10, 28, and 31 hours after ALA plaster 1 application, and at 4, 5, 7, 25, and 28 hours after ALA plaster 2 application.

PRIMARY AND SECONDARY OUTCOME MEASURES

At each time point, five mitoPO2 measurements were performed. Within-subject variability was defined as the standard deviation (SD) of the mean of five measurements per timepoint of a study participant. The between-subject variability was the SD of the mean mitoPO2 value of the study population per timepoint.

RESULTS

In 16 completed inclusions, median mitoPO2 values and within-subject variability were relatively similar over time at all time points for both plasters. An increase in overall between-subject variability was seen after 25 hours ALA plaster time (19.6 mm Hg vs 23.9 mm Hg after respectively 10 and 25 hours ALA plaster time).

CONCLUSIONS

The mitoPO2 values and within-subject variability remained relatively stable over time in healthy volunteers. An increase in between-subject variability was seen after 25 hours ALA plaster time warranting replacement of the ALA plaster one day after its application.

TRIAL REGISTRATION

ClinicalTrials.gov with trial number NCT04626661.

In vitro modeling of recurrent Dermatofibrosarcoma Protuberans: Assessment of 5-aminolevulinic acid photodynamic therapy efficacy

BACKGROUND

Dermatofibrosarcoma Protuberans (DFSP) is a rare, low-grade malignant tumor of the dermis with a high recurrence rate post-surgery. Current treatments, including surgery, radiotherapy, and targeted therapy, have limitations. Photodynamic therapy (PDT) with 5-aminolevulinic acid (5-ALA) is a promising non-invasive approach, but its efficacy in DFSP treatment remains underexplored.

METHODS

This study aimed to evaluate the anti-tumor efficacy of 5-ALA PDT using an in vitro model derived from a recurrent DFSP patient. The cells were treated with varying concentrations of 5-ALA and exposed to red light, followed by assessments of cell viability, proliferation, apoptosis, migration, invasion, angiogenesis, and expression of DFSP-related genes and proteins.

RESULTS

5-ALA PDT significantly reduced DFSP cell viability in a dose-dependent manner and induced apoptosis. It also effectively inhibited cell proliferation, migration, and invasion, as well as suppressed angiogenic activity in conditioned media. Furthermore, 5-ALA PDT downregulated the expression of COL1A1 and PDGFRB, key genes in DFSP pathogenesis.

CONCLUSIONS

The findings provide the first evidence of 5-ALA PDT's in vitro anti-tumor efficacy against DFSP, suggesting its potential as a novel therapeutic approach for DFSP. Further studies are warranted to explore the clinical utility of 5-ALA PDT in preventing DFSP recurrence.

Clinical versus Histological Assessment of Basal Cell Carcinoma Subtype and Thickness of Tumours Selected for Photodynamic Therapy

Photodynamic therapy is an approved treatment for primary, superficial, and small nodular basal cell carcinomas with a thickness of < 2 mm located on low-risk sites. Histologically verified basal cell carcinomas clinically assessed as suited for photodynamic therapy were included. The study aimed to investigate the agreement between clinical and histological assessments of basal cell carcinoma subtypes and thickness of tumours selected for photodynamic therapy with histopathological evaluation as a reference. A total of 343 tumours were included. The agreement between clinical and histological diagnosis of basal cell carcinoma subtype was 72% (p < 0.001). Clinical assessment of subtype had a sensitivity of 93% and specificity of 55% for superficial tumours and a sensitivity of 55% and specificity of 85% for nodular tumours. The mean ± SD thickness values by clinical and histological assessments were 0.95 ± 0.53 and 0.86 ± 0.75. The difference of 0.09 mm was statistically significant (p = 0.017), but not considered to be clinically relevant, although the differences between specific subgroups could be relevant. Among basal cell carcinomas clinically diagnosed as superficial, 91% were histologically consistent with the current photodynamic therapy criteria. The main results suggest that histopathological evaluation should precede photodynamic therapy to ensure selection of suitable basal cell carcinomas. In selected cases, the clinical diagnosis alone may be adequate before proceeding with photodynamic therapy.

Interdisciplinary management of skin cancer

The interdisciplinary treatment of skin cancer in the head and neck area requires close collaboration between different specialist disciplines. The most common non-melanoma skin cancer tumor entities are cutaneous squamous cell carcinoma and basal cell carcinoma as well as their precursor lesions. One of the less common tumors is Merkel cell carcinoma, which also occurs primarily in light-exposed areas and, in contrast to squamous and basal cell carcinoma, is more likely to metastasize. Due to the low tendency of basal cell carcinoma as well as cutaneous squamous cell carcinoma to metastasize, a cure can often be achieved by surgery. If the tumor growth exceeds certain levels it may require collaboration between dermatology and otorhinolaryngology. The primary goal of this interdisciplinary collaboration is to achieve a functional, cosmetically and aesthetically acceptable result in addition to adequate tumor treatment. Depending on the stage of the tumor and the clinical course, a case may be discussed in an interdisciplinary tumor board in order to determine a personalised, appropriate and adequate treatment concept for each patient, including prevention, therapy and follow-up.

New, simplified versus standard photodynamic therapy (PDT) regimen for superficial and nodular basal cell carcinoma (BCC): A single-blind, non-inferiority, randomised controlled multicentre study

BACKGROUND

Topical photodynamic therapy (PDT) is an approved and widely used treatment for low-risk basal cell carcinoma (BCC), comprising two sessions with an interval of 1 week. Simplification of the treatment course can be cost-effective, easier to organize, and cause less discomfort for the patients.

METHODS AND FINDINGS

We performed an investigator-initiated, single-blind, non-inferiority, randomized controlled multicentre study with the objective of investigating whether a simpler and more flexible PDT regimen was not >10% less effective than the standard double PDT in the treatment of primary, superficial, and nodular ≤2 mm-thick BCC and evaluate the cosmetic outcome. With a non-inferiority margin of 0.1 and an expected probability complete response of 0.85, 190 tumours were required in each group. Histologically verified BCCs from seven centres in Norway were randomly assigned (1:1) to either receive a new regimen of single PDT with one possible re-treatment of non-complete responding tumours, or the standard regimen. The primary endpoint was the number of tumours with complete response or treatment failure at 36 months of follow-up, assessed by investigators blinded to the treatment regimen. Intention-to-treat and per-protocol analyses were performed. The cosmetic outcome was recorded. The study was registered with ClinicalTrials.gov, NCT-01482104, and EudraCT, 2011-004797-28. A total of 402 BCCs in 246 patients were included; 209 tumours assigned to the new and 193 to the standard regimen. After 36 months, there were 61 treatment failures with the new and 34 failures with the standard regimen. Complete response rate was 69.5% in the new and 81.1% in the standard treatment group. The difference was 11.6% (upper 97.5% CI 20.3), i.e. > than the non-inferiority margin of 10%. Cosmetic outcomes were excellent or good in 92% and 89% following the new and standard regimens, respectively.

CONCLUSIONS

Single PDT with possible re-treatment of primary, superficial, and nodular ≤ 2-mm-thick BCC was significantly less effective than the approved standard double treatment. The cosmetic outcome was favorable and comparable between the two treatment groups.

Effects of photodynamic therapy in patients with infected skin ulcers: A meta-analysis

The purpose of the meta-analysis was to evaluate and compare the photodynamic therapy's effectiveness in treating infected skin wounds. The results of this meta-analysis were analysed, and the odds ratio (OR) and mean difference (MD) with 95% confidence intervals (CIs) were calculated using dichotomous or contentious random- or fixed-effect models. For the current meta-analysis, 6 examinations spanning from 2013 to 2021 were included, encompassing 154 patients with infected skin wounds were the used studies' starting point. Photodynamic therapy had a significantly lower wound ulcer size (MD, -4.42; 95% CI, -7.56--1.28, p = 0.006), better tissue repair (MD, -8.62; 95% CI, -16.76--0.48, p = 0.04) and lower microbial cell viability (OR, 0.13; 95% CI, 0.04-0.42, p < 0.001) compared with red light exposure in subjects with infected skin wounds. The examined data revealed that photodynamic therapy had a significantly lower wound ulcer size, better tissue repair and lower microbial cell viability compared with red light exposure in subjects with infected skin wounds. However, given that all examinations had a small sample size, consideration should be given to their values.

Evaluation of the effectiveness and safety of photodynamic therapy in the treatment of precancerous diseases of the cervix (neoplasia) associated with the human papillomavirus: A systematic review

This study provides an overview of the effectiveness and safety of PDT for the treatment of HPV-associated precancerous cervical conditions and contains recent findings from relevant research studies. A comprehensive literature search of MEDLINE/PubMed, Cochrane Central Library, and Google Scholar was conducted, including analytic epidemiological studies, and 11 papers were included. The narrative synthesis approach was used to summarize the results of the included studies. Studies were critically appraised using The Joanna Briggs Institute (JBI) tool for assessing the risk of bias. The results of the study demonstrate that CRR for HPV remission ranges from 66.7 % to 92.73 %, whereas for CIN1 it fluctuates from 57.1 % to 83.3 %. The frequency of recurrence of the disease ranged from 3.3 % to 8.9 % during the follow-up period of up to 2 years. Adverse events were observed in 8 (66 %) studies and the most common were cervical stenosis, abdominal pain, vaginal pain, and focal edema. Five types of topical and intravenous applications along with lasers of various wavelengths and intensities were mostly used. However, all studies demonstrated relatively similar results. According to the results, PDT has demonstrated favorable outcomes, but no impressive effect on the treatment of CIN. It should be emphasized, that the effectiveness of PDT for the treatment of HPV-associated CIN may vary depending on some variables, including the kind of PDT agent used, the dosage, duration and frequency of PDT administration, the severity and location of the lesions, and the host immunological response.

In vitro evaluation of the efficacy of photodynamic therapy using 5-ALA on homologous feline mammary tumors in 2D and 3D culture conditions and a mouse subcutaneous model with 3D cultured cells

BACKGROUND

Numerous studies have shown that photodynamic therapy (PDT) has a therapeutic effect on mammary tumor cells, with 5-aminolevulinic acid (5-ALA-HCL) being a commonly used photosensitizer for PDT. Feline mammary tumors (FMTs) are relatively common. However, the cytotoxic and antitumor effects of 5-ALA-PDT on FMTs have not been clarified. To this end, we evaluated the therapeutic effect of 5-ALA-PDT on FMTs through in vitro experiments using an FMT FKR cell line established for this study.

METHODS

We performed 5-ALA-PDT in 2D-cultured FKR-A (adherent cells) and 3D-cultured FKR-S (spheroid cells) cells and performed a series of studies to evaluate the cell viability and determine the protoporphyrin IX (PpIX) content in the cells as well as the expression levels of mRNAs associated with PpIX production and release. An in vivo study was performed to assess the effectiveness of 5-ALA-PDT.

RESULTS

There was a significant difference in the concentration of PpIX in FMT cells under different incubation culture modes (2D versus 3D culture). The concentration of PpIX in FMT cells was correlated with the differences in cell culture (2D and 3D) as well as the expression levels of genes such as PEPT1, PEPT2, FECH, and HO-1.

CONCLUSIONS

In the in vitro study, 5-ALA-PDT had a stronger inhibitory effect on 3D-cultured FKR-S cells, which resemble the internal environment of organisms more closely. We also observed a significant inhibitory effect of 5-ALA-PDT on FMT cells in vivo. To our knowledge, this is the first study on 5-ALA-PDT for FMTs under both 2D and 3D conditions.

Nrf2/HO-1 as a therapeutic target in renal fibrosis

Chronic kidney disease (CKD) is one of the most prevalent chronic diseases and affects between 10 and 14 % of the world's population. The World Health Organization estimates that by 2040, the disease will be fifth in prevalence. End-stage CKD is characterized by renal fibrosis, which can eventually lead to kidney failure and death. Renal fibrosis develops due to multiple injuries and involves oxidative stress and inflammation. In the human body, nuclear factor erythroid 2-related factor 2 (Nrf2) plays an important role in the expression of antioxidant, anti-inflammatory, and cytoprotective genes, which prevents oxidative stress and inflammation damage. Heme oxygenase (HO-1) is an inducible homolog influenced by heme products and after exposure to cellular stress inducers such as oxidants, inflammatory chemokines/cytokines, and tissue damage as an outcome or downstream of Nrf2 activation. HO-1 is known for its antioxidative properties, which play an important role in regulating oxidative stress. In renal diseases-induced tissue fibrosis and xenobiotics-induced renal fibrosis, Nrf2/HO-1 has been targeted with promising results. This review summarizes these studies and highlights the interesting bioactive compounds that may assist in attenuating renal fibrosis mediated by HO-1 activation. In conclusion, Nrf2/HO-1 signal activation could have a renoprotective effect strategy against CKD caused by oxidative stress, inflammation, and consequent renal fibrosis.

Recent advancement of nanomedicine-based targeted delivery for cervical cancer treatment

Cervical cancer is a huge worldwide health burden, impacting women in impoverished nations in particular. Traditional therapeutic approaches, such as surgery, radiation therapy, and chemotherapy, frequently result in systemic toxicity and ineffectiveness. Nanomedicine has emerged as a viable strategy for targeted delivery of therapeutic drugs to cancer cells while decreasing off-target effects and increasing treatment success in recent years. Nanomedicine for cervical cancer introduces several novel aspects that distinguish it from previous treatment options such as tailored delivery system, precision targeting, combination therapies, real-time monitoring and diverse nanocarriers to overcome the limitations of one another. This abstract presents recent advances in nanomedicine-based tailored delivery systems for the treatment of cervical cancer. Liposomes, polymeric nanoparticles, dendrimers, and carbon nanotubes have all been intensively studied for their ability to transport chemotherapeutic medicines, nucleic acids, and imaging agents to cervical cancer cells. Because of the way these nanocarriers are designed, they may cross biological barriers and preferentially aggregate at the tumor site, boosting medicine concentration and lowering negative effects on healthy tissues. Surface modification of nanocarriers with targeting ligands like antibodies, peptides, or aptamers improves specificity for cancer cells by identifying overexpressed receptors or antigens on the tumor surface. Furthermore, nanomedicine-based techniques have made it possible to co-deliver numerous therapeutic drugs, allowing for synergistic effects and overcoming drug resistance. In preclinical and clinical investigations, combination treatments comprising chemotherapeutic medicines, gene therapy, immunotherapy, and photodynamic therapy have showed encouraging results, opening up new avenues for individualized and multimodal treatment regimens. Furthermore, the inclusion of contrast agents and imaging probes into nanocarrier systems has enabled real-time monitoring and imaging of treatment response. This enables the assessment of therapy efficacy, the early diagnosis of recurrence, and the optimization of treatment regimens.

β-Cyclodextrin Nanophotosensitizers for Redox-Sensitive Delivery of Chlorin e6

The aim of this study is to prepare redox-sensitive nanophotosensitizers for the targeted delivery of chlorin e6 (Ce6) against cervical cancer. For this purpose, Ce6 was conjugated with β-cyclodextrin (bCD) via a disulfide bond, creating nanophotosensitizers that were fabricated for the redox-sensitive delivery of Ce6 against cancer cells. bCD was treated with succinic anhydride to synthesize succinylated bCD (bCDsu). After that, cystamine was attached to the carboxylic end of bCDsu (bCDsu-ss), and the amine end group of bCDsu-ss was conjugated with Ce6 (bCDsu-ss-Ce6). The chemical composition of bCDsu-ss-Ce6 was confirmed with 1H and 13C NMR spectra. bCDsu-ss-Ce6 nanophotosensitizers were fabricated by a dialysis procedure. They formed small particles with an average particle size of 152.0 ± 23.2 nm. The Ce6 release rate from the bCDsu-ss-Ce6 nanophotosensitizers was accelerated by the addition of glutathione (GSH), indicating that the bCDsu-ss-Ce6 nanophotosensitizers have a redox-sensitive photosensitizer delivery capacity. The bCDsu-ss-Ce6 nanophotosensitizers have a low intrinsic cytotoxicity against CCD986Sk human skin fibroblast cells as well as Ce6 alone. However, the bCDsu-ss-Ce6 nanophotosensitizers showed an improved Ce6 uptake ratio, higher reactive oxygen species (ROS) production, and phototoxicity compared to those of Ce6 alone. GSH addition resulted in a higher Ce6 uptake ratio, ROS generation, and phototoxicity than Ce6 alone, indicating that the bCDsu-ss-Ce6 nanophotosensitizers have a redox-sensitive biological activity in vitro against HeLa human cervical cancer cells. In a tumor xenograft model using HeLa cells, the bCDsu-ss-Ce6 nanophotosensitizers efficiently accumulated in the tumor rather than in normal organs. In other words, the fluorescence intensity in tumor tissues was significantly higher than that of other organs, while Ce6 alone did not specifically target tumor tissue. These results indicated a higher anticancer activity of bCDsu-ss-Ce6 nanophotosensitizers, as demonstrated by their efficient inhibition of the growth of tumors in an in vivo animal tumor xenograft study.

5-ALA Photodynamic Ablation of Fibroblsatic Sift-Tissues Tumors

BACKGROUND

Fibroblastic soft-tissue tumors share enzymatic anomalies that result in excessive intracellular conversion of 5-aminolevulinic acid (5-ALA) to protoporphyrin IX, a photosensitizer which induces cellular apoptosis upon exposure to visible red light at a wavelength of 635 nm. We hypothesized that red light illumination of the surgical bed remaining after resection of fibroblastic tumors will result in destruction of microscopic tumor residua and may decrease the likelihood of local tumor recurrence.

METHODS

Twenty-four patients with desmoid tumors, solitary fibrous tumors (SFT), and dermatofibrosarcoma protuberans (DFSP) received oral 5-ALA prior to resection of their tumors. Following tumor resection, the exposed surgical bed was illuminated with red light at a wave length of 635 nm at a dose of 150J/cm² for 33 minutes.

RESULTS

Treatment with 5-ALA was associated with minor side effects that included nausea and transient elevation of transaminases. Local tumor recurrence was detected in 1 of the 10 patients with desmoid tumors who had not undergone any previous surgery, none in the 6 patients who had SFT and 1 of the 5 patients who had DFSP.

CONCLUSIONS

5-ALA photodynamic therapy of fibroblastic soft-tissue tumors may result in decreased likelihood of local tumor recurrence. It is associated with minimal side effects and should be considered as adjuvant to tumor resection in these cases.

Reactive Oxygen Species Produced by 5-Aminolevulinic Acid Photodynamic Therapy in the Treatment of Cancer

Cancer is the leading cause of death worldwide and several anticancer therapies take advantage of the ability of reactive oxygen species to kill cancer cells. Added to this is the ancient hypothesis that light alone can be used to kill cancer cells. 5-aminolevulinic acid-photodynamic therapy (5-ALA-PDT) is a therapeutic option for a variety of cutaneous and internal malignancies. PDT uses a photosensitizer that, activated by light in the presence of molecule oxygen, forms ROS, which are responsible for the apoptotic activity of the malignant tissues. 5-ALA is usually used as an endogenous pro-photosensitizer because it is converted to Protoporphyrin IX (PpIX), which enters into the process of heme synthesis and contextually becomes a photosensitizer, radiating a red fluorescent light. In cancer cells, the lack of the ferrochelatase enzyme leads to an accumulation of PpIX and consequently to an increased production of ROS. PDT has the benefit of being administered before or after chemotherapy, radiation, or surgery, without impairing the efficacy of these treatment techniques. Furthermore, sensitivity to PDT is unaffected by the negative effects of chemotherapy or radiation. This review focuses on the studies done so far on 5-ALA-PDT and its efficacy in the treatment of various cancer pathologies.

Real-Time Monitoring of Colorectal Cancer Location and Lymph Node Metastasis and Photodynamic Therapy Using Fucoidan-Based Therapeutic Nanogel and Near-Infrared Fluorescence Diagnostic–Therapy System

We report real-time monitoring of colorectal cancer, lymph node metastasis of colorectal cancer cells, and tumor growth inhibition through photodynamic therapy (PDT) using a near-infrared fluorescence diagnostic–therapy system with a light source for PDT and a fucoidan-based theranostic nanogel (CFN-gel) with good accumulation efficiency in cancer cells. To confirm the effect of the fabricated system and developed CFN-gel, in vitro and in vivo experiments were performed. Chlorin e6 (Ce6) and 5-aminolevulinic acid (5-ALA) were used for comparison. We confirmed that CFN-gel has a high accumulation efficiency in cancer cells and high fluorescence signals in near-infrared light for a long period, and only CFN-gel delayed the growth rate of cancer in terms of its size in PDT. In addition, using the near-infrared fluorescence diagnostic–therapy system and CFN-gel prepared for these experiments, the lymph node metastasis of cancer cells was imaged in real time, and the metastasis was confirmed through H&E staining. The possibility of image-guided surgery and identification of lymph node metastasis in colorectal cancer can be confirmed through CFN-gel and a near-infrared fluorescence diagnostic–therapy system that includes various light sources.

Photocatalytic Carboxylation of C-N Bonds in Cyclic Amines with CO2 by Consecutive Visible-Light-Induced Electron Transfer

Visible-light photocatalytic carboxylation with CO₂ is highly important. However, it still remains challenging for reluctant substrates with low reduction potentials. Herein, we report a novel photocatalytic carboxylation of C-N bonds in cyclic amines with CO₂ via consecutive photo-induced electron transfer (ConPET). It is also the first photocatalytic reductive ring-opening reaction of azetidines, pyrrolidines and piperidines. This strategy is practical to transform a variety of easily available cyclic amines to valuable β-, γ-, δ- and ϵ-amino acids in moderate-to-excellent yields. Moreover, the method also features mild and transition-metal-free conditions, high selectivity, good functional-group tolerance, facile scalability and product derivations. Mechanistic studies indicate that the ConPET might be the key to generating highly reactive photocatalysts, which enable the reductive activation of cyclic amines to generate carbon radicals and carbanions as the key intermediates.

Photodynamic therapy for treating infected skin wounds: A systematic review and meta-analysis from randomized clinical trials

BACKGROUND

Infected skin wounds represent a public health problem that effects 20 million people worldwide. Photodynamic therapy (PDT) is a treatment option with excellent results against several infections.

OBJECTIVE

This study aimed to perform a systematic review and meta-analysis on PDT efficacy for treating infected wounds based on randomized clinical trials (RCTs).

METHODS

PubMed, Scopus, Web of Science, SciELO, and the Cochrane library were searched. The Delphi List criteria and the Revised Cochrane risk-of-bias (Rob 2) were used for evaluating the quality of clinical trials. Meta-analyses were performed with the random-effect model. The odds ratio was the effect measure for binary outcomes, while the standard mean difference was used for continuous outcomes. The trim-and-fill method was used to detect small-study effects. The quality of evidence was verified for each outcome.

RESULTS

Only four out of 573 articles were selected for the qualitative and quantitative analyses. The most frequent cause of infected wounds was impaired venous circulation (75%). All studies used red LED light. PDT reduced healing time and improved the healing process and wound oxygenation. Patients treated with PDT showed 15% to 17% (p = 0.0003/ I²=0%) lower microbial cell viability in the wound and a significantly smaller wound size (0.72 cm²/p = 0.0187/I²=0%) than patients treated with placebo or red-light exposure. There was a high level of evidence for each meta-analysis outcome.

CONCLUSION

PDT can be an excellent alternative treatment for infected skin wounds, though larger trials are needed.

Dual-function microneedle array for efficient photodynamic therapy with transdermal co-delivered light and photosensitizers

Photodynamic therapy (PDT), as a globally accepted method for treating different forms of skin or mucosal disorders, requires efficient co-delivery of photosensitizers and corresponding therapeutic light. The adverse effects of intravenous injection of photosensitizers have been reduced by the development of microneedle arrays for transdermal local photosensitizer delivery. However, the drawbacks of the only available therapeutic light delivery method at the moment, which is directly applying light to the skin surface, are yet to be improved. This study presents a new strategy in which therapeutic light and photosensitizer were transdermally co-delivered into local tissues. A flexible dual-function microneedle array (DfMNA) which contains 400 microneedles was developed. Each microneedle consists of a dissolvable needle tip (140 μm in height) for delivering the photosensitizer and a transparent needle body (660 μm in height) for guiding therapeutic light. Using port-wine stains, which is a frequently occurring skin disorder caused by vascular malformation, as a model disease, the effectiveness of DfMNA mediated PDT has been verified on mice. Compared with the standard operation procedure of clinical PDT, the DfMNA decreases the amount of photosensitizer from 300 μg to 0.5 μg and reduces therapeutic light irradiance from 100 mW cm^-2 to 60 mW cm^-2 while realizing better treatment effects. As a result, the skin damage and the burden on the metabolic system have been alleviated. The DfMNA has a remarkably reduced photosensitizer amount and, for the first time, realized transdermal delivery of therapeutic light for PDT, thus avoiding the disadvantages of existing PDT methodologies.

5-Aminolevulinic Acid-Mediated Photodynamic Therapy Potentiates the Effectiveness of Doxorubicin in Ewing Sarcomas

Ewing sarcomas (ES) are aggressive primary bone tumors that require radical therapy. Promising low toxicity, 5-aminolevulinic acid (5-ALA)-mediated photodynamic therapy (PDT) could enhance the effectiveness of conventional treatment modalities (e.g., doxorubicin (DOX)), improving, thus, the anti-tumorigenic effects. In this study, we investigated the effects of DOX and 5-ALA PDT alone or in combination on three different human ES cell lines. Cell viability, reactive oxygen species (ROS) production, and cellular stiffness were measured 24 h after PDT (blue light-wavelength 436 nm with 5-ALA) with or without DOX. ES cell lines have a different sensitivity to the same doses and exposure of 5-ALA PDT. DOX in combination with 5-ALA PDT was found to be effective in impairing the viability of all ES cells while also increasing cytotoxic activity by high ROS production. The stiffness of the ES cells increased significantly (p < 0.05) post treatment. Overall, our results showed that across multiple ES cell lines, 5-ALA PDT can successfully and safely be combined with DOX to potentiate the therapeutic effect. The 5-ALA PDT has the potential to be a highly effective treatment when used alone or in conjunction with other treatments. More research is needed to assess the effectiveness of 5-ALA PDT in in vivo settings.

5-ALA-guided tumor resection during awake speech mapping in gliomas located in eloquent speech areas: Single-center experience

Background

Achieving maximal functionally safe resection of gliomas located within the eloquent speech areas is challenging, and there is a lack of literature on the combined use of 5-aminolevulinic acid (5-ALA) guidance and awake craniotomy.

Objective

The aim of this study was to describe our experience with the simultaneous use of 5-ALA fluorescence and awake speech mapping in patients with left frontal gliomas located within the vicinity of eloquent speech areas.

Materials and methods

A prospectively collected database of patients was reviewed. 5-ALA was administered at a dose of 20 mg/kg 2 h prior to operation, and an operating microscope in BLUE400 mode was used to visualize fluorescence. All patients underwent surgery using the “asleep–awake–asleep” protocol with monopolar and bipolar electrical stimulation to identify the proximity of eloquent cortex and white matter tracts and to guide safe limits of resection along with fluorescence guidance. Speech function was assessed by a trained neuropsychologist before, during, and after surgery.

Results

In 28 patients operated with cortical mapping and 5-ALA guidance (12 Grade 4, 6 Grade 3, and 10 Grade 2 gliomas), Broca’s area was identified in 23 cases and Wernicke’s area was identified in 5 cases. Fluorescence was present in 14 cases. Six tumors had residual fluorescence due to the positive speech mapping in the tumor bed. Transient aphasia developed in 14 patients, and permanent aphasia developed in 4 patients. In 6 patients operated with cortical and subcortical speech mapping and 5-ALA guidance (4 Grade 4, 1 Grade 3, and 1 Grade 2 gliomas), cortical speech areas were mapped in 5 patients and subcortical tracts were encountered in all cases. In all cases, resection was stopped despite the presence of residual fluorescence due to speech mapping findings. Transient aphasia developed in 6 patients and permanent aphasia developed in 4 patients. In patients with Grade 2–3 gliomas, targeted biopsy of focal fluorescence areas led to upgrading the grade and thus more accurate diagnosis.

Conclusion

5-ALA guidance during awake speech mapping is useful in augmenting the extent of resection for infiltrative high-grade gliomas and identifying foci of anaplasia in non-enhancing gliomas, while maintaining safe limits of functional resection based on speech mapping. Positive 5-ALA fluorescence in diffuse Grade 2 gliomas may be predictive of a more aggressive disease course.

Optical clearing and testing of lung tissue using inhalation aerosols: prospects for monitoring the action of viral infections

Optical clearing of the lung tissue aims to make it more transparent to light by minimizing light scattering, thus allowing reconstruction of the three-dimensional structure of the tissue with a much better resolution. This is of great importance for monitoring of viral infection impact on the alveolar structure of the tissue and oxygen transport. Optical clearing agents (OCAs) can provide not only lesser light scattering of tissue components but also may influence the molecular transport function of the alveolar membrane. Air-filled lungs present significant challenges for optical imaging including optical coherence tomography (OCT), confocal and two-photon microscopy, and Raman spectroscopy, because of the large refractive-index mismatch between alveoli walls and the enclosed air-filled region. During OCT imaging, the light is strongly backscattered at each air–tissue interface, such that image reconstruction is typically limited to a single alveolus. At the same time, the filling of these cavities with an OCA, to which water (physiological solution) can also be attributed since its refractive index is much higher than that of air will lead to much better tissue optical transmittance. This review presents general principles and advances in the field of tissue optical clearing (TOC) technology, OCA delivery mechanisms in lung tissue, studies of the impact of microbial and viral infections on tissue response, and antimicrobial and antiviral photodynamic therapies using methylene blue (MB) and indocyanine green (ICG) dyes as photosensitizers.

FECH Expression Correlates with the Prognosis and Tumor Immune Microenvironment in Clear Cell Renal Cell Carcinoma

Background

Clear cell renal cell carcinoma (ccRCC) is, by far, the most prevalent and fatal kind of kidney cancer. Ferrochelatase (FECH) is an enzyme that performs a significant function in the onset and progression of many distinct kinds of malignant tumors. Nevertheless, its predictive usefulness in renal clear cell carcinoma (RCC) has not yet been fully investigated.

Methods

FECH expression in ccRCC and healthy adjoining tissues was primarily screened utilizing data sourced from The Cancer Genome Atlas (TCGA) and subsequently validated using data from an independent cohort derived from the Gene Expression Omnibus (GEO) and the Human Protein Atlas HPA databases. The relationship among FECH expression, clinicopathological parameters, and overall survival (OS) was assessed utilizing multivariate analysis and Kaplan–Meier survival curves. Additionally, the protein networks with FECH interaction were constructed with the aid of the online Search Tool for the Retrieval of Interacting Genes/Proteins (STRING). Gene ontology (GO) analysis, and gene set enrichment analysis (GSEA) were conducted based on TCGA data, and a single-sample GSEA was utilized to explore the link between FECH expression and the infiltration status of immune cells in the tumor. The Gene Expression Profiling Interactive Analysis (GEPIA) and TIMER databases were utilized to investigate the relationships of FECH expression with the infiltrating immune cells and the matching gene marker sets.

Results

FECH expression was shown to be substantially lowered in ccRCC tumors as opposed to that observed in normal tissues (p < 0.05). Lower levels of FECH expression were shown to have a strong association with higher grades of cancer and more advanced TNM stages. The findings of multivariate and univariate analyses illustrated that the OS in patients with ccRCC with low FECH expression is shorter in contrast with that in the high FECH expression group (p < 0.05). It was discovered that CPOX and frataxin are key proteins that interact with FECH. ccRCC with FECH deficiency was linked to the lack of infiltrating immune cells and their respective marker sets, which included CD4+ T cells.

Conclusion

In ccRCC, decreased FECH expression was linked to disease progression, unfavorable prognosis, and impaired immune cell infiltration.

5 ALA Is a Potent Lactate Dehydrogenase Inhibitor But Not a Substrate: Implications for Cell Glycolysis and New Avenues in 5 ALA-Mediated Anticancer Action

Simple Summary

In the present work, we found that 5-ALA, a natural precursor of heme, can hinder cell glycolysis, which is the main path of energy production for most cancer cells. More specifically, we found that 5-ALA can block an enzyme involved in glycolysis, called lactate dehydrogenase (LDH). We found that 5-ALA has a potency of LDH inhibition comparable to other established LDH inhibitors, such as oxamate or tartronic acid. Nevertheless, 5-ALA has a high accumulation rate in cancers and specifically in the incurable brain cancer glioblastoma multiforme (GBM), which is an important advantage. In fact, because of its high specificity to GBM, 5-ALA is used in the clinic to accurately guide the resection of the tumours, through the light emission of its photoactive product protoporphyrin IX (PpIX). PpIX is the penultimate step in the heme production. Importantly, we show here that continuous administration of 5-ALA killed GBM cells according to their dependence on glycolysis. We additionally found that 20% of externally administered 5-ALA is engaged in the inhibition of LDH, as when LDH was pre-loaded by another inhibitor, tartronic acid, then the cell production of PpIX from 5-ALA was increased by 20%. Since PpIX is an important drug for photodynamic therapy of cancer (excitation by light of PpIX produces oxygen by-products that can kill cancer cells), we additionally discovered that preloading LDH with its inhibitor tartronic acid before performing 5-ALA PDT increases the cancer cell death by 15%.

Abstract

In a course of metabolic experiments, we determined that the addition of δ-aminolevulinic acid (5-ALA) to a panel of glioblastoma multiforme (GBM) cells caused a steep reduction in their glycolytic activity. This reduction was accompanied by a decrease in adenosine triphosphate (ATP) production from glycolysis. These results suggested that 5-ALA is an inhibitor of glycolysis; due to the structural similarity of 5-ALA to the established lactate dehydrogenase (LDH) inhibitors oxamate (OXM) and tartronate (TART), we initially investigated LDH inhibition by 5-ALA in silico. The modelling revealed that 5-ALA could indeed be a competitive inhibitor of LDH but not a substrate. These theoretical findings were corroborated by enzymatic and cell lysate assays in which 5-ALA was found to confer a potent LDH inhibition comparable to that of OXM and TART. We subsequently evaluated the effect of 5-ALA-induced glycolysis inhibition on the viability of GBM cells with diverse metabolic phenotypes. In the Warburg-type cell lines Ln18 and U87, incubation with 5-ALA elicited profound and irreversible cell death (90–98%) at 10 mM after merely 24 h. In T98G, however, which exhibited both high respiratory and glycolytic rates, LD95 was achieved after 72 h of incubation with 20 mM 5-ALA. We additionally examined the production of the 5-ALA photosensitive metadrug protoporphyrin IX (PpIX), with and without prior LDH inhibition by TART. These studies revealed that ~20% of the 5-ALA taken up by the cells was engaged in LDH inhibition. We subsequently performed 5-ALA photodynamic therapy (PDT) on Ln18 GBM cells, again with and without prior LDH inhibition with TART, and found a PDT outcome enhancement of ~15% upon LDH pre-inhibition. We expect our findings to have a profound impact on contemporary oncology, particularly for the treatment of otherwise incurable brain cancers such as GBM, where the specific accumulation of 5-ALA is very high compared to the surrounding normal tissue.

Photodynamic therapy with 5-aminolevulinic acid: A new diagnostic, therapeutic, and surgical aid for neuroblastoma

BACKGROUND

5-Aminolevulinic acid (ALA)-based photodynamic therapy (PDT) is widely used in cancer therapy because of the tumor-specific accumulation of photosensitizing protoporphyrin IX (PpIX). We aimed to assess the susceptibility of human neuroblastoma cell lines to ALA-PDT and determine the mechanism of PDT.

METHODS

We used four human neuroblastoma cell lines (GOTO, NB9, IMR32, and NB1) and a gastric cancer cell line (MKN45) as a positive control. Cells were treated with increasing concentrations of ALA, and the ALA-induced production of PpIX in tumor cells was quantified using fluorescence spectrophotometry. PDT photocytotoxicity was measured by exposing the cells to a 630-nm irradiation for 10 min, and apoptotic cells stained with phosphatidylserine (PS) and propidium iodide (PI) were detected through flow cytometry.

RESULTS

ALA cytotoxicity was not observed in any cell line. The intracellular concentration of PpIX increased in an ALA dose-dependent manner, and intracellular fluorescence of PpIX increased in a time-dependent manner. The viability of NB-1 cells treated with 250 μM 5-ALA rapidly decreased to 5%. Photocytotoxicity was observed in the following order: NB1, IMR32, NB-9, and GOTO. Photocytotoxicity was positively correlated with intracellular PpIX concentrations. PS+/PI- cells increased up to 21% after 12 h, and PS+/PI+ cells accounted for 35% of all cells after 24 h, which suggests that ALA-PDT induced apoptotic cell death.

CONCLUSION

This study shows that neuroblastoma cell lines were susceptible to 5-ALA-PDT, resulting in persistent apoptotic cell death.

LEVELS OF EVIDENCE

N/A for basic study.

Impact of Levetiracetam Treatment on 5-Aminolevulinic Acid Fluorescence Expression in IDH1 Wild-Type Glioblastoma

Simple Summary

The amino acid 5-aminolevulinic acid (5-ALA) is the benchmark regarding intraoperative imaging tools for glioblastoma (GB) surgery, and is known to facilitate the extent of resection, which results in an enhanced 6 month progression-free survival rate. Recent in vitro studies suggest that antiepileptic drugs (AEDs) result in a reduction in the fluorescence quality in gliomas. To date, there is no large clinical series investigating this issue in a homogeneous cohort. Approximately 25% of all GB patients have a symptomatic epilepsy as the initial symptom at presentation. Hence, this potential dilemma is of paramount importance. We found that the preoperative intake of levetiracetam is a significant risk factor for reduced intraoperative fluorescence in IDH1 wild-type GBs. We believe that this issue must be considered in future external validations, and physicians must carefully evaluate the indication of levetiracetam and avoid a prophylactic levetiracetam treatment in terms of the suspected diagnosis of glioblastoma.

Abstract

The amino acid 5-aminolevulinic acid (5-ALA) is the most established neurosurgical fluorescent dye and facilitates the achievement of gross total resection. In vitro studies raised concerns that antiepileptic drugs (AED) reduce the quality of fluorescence. Between 2013 and 2018, 175 IDH1 wild-type glioblastoma (GB) patients underwent 5-ALA guided surgery. Patients’ data were retrospectively reviewed regarding demographics, comorbidities, medications, tumor morphology, neuropathological characteristics, and their association with intraoperative 5-ALA fluorescence. The fluorescence of 5-ALA was graded in a three point scaling system (grade 0 = no; grade 1 = weak; grade 2 = strong). Univariable analysis shows that the intake of dexamethasone or levetiracetam, and larger preoperative tumor area significantly reduce the intraoperative fluorescence activity (fluorescence grade: 0 + 1). Multivariable binary logistic regression analysis demonstrates the preoperative intake of levetiracetam (adjusted odds ratio: 12.05, 95% confidence interval: 3.91–37.16, p = 0.001) as the only independent and significant risk factor for reduced fluorescence quality. Preoperative levetiracetam intake significantly reduced intraoperative fluorescence. The indication for levetiracetam in suspected GB should be carefully reviewed and prophylactic treatment avoided for this tumor entity. Future comparative trials of neurosurgical fluorescent dyes need a special focus on the influence of levetiracetam on fluorescence intensity. Further trials must validate our findings.

Identification of excimer delayed fluorescence by Protoporphyrin IX: A novel access to local chromophore concentration?

Protoporphyrin IX (PpIX) is a molecule produced in the mitochondria following the administration of its approved precursor, aminolevulinic acid (ALA). Strong light absorber at different wavelengths in the visible range, PpIX is extensively used as a photosensitizer (PS) for Photodynamic Therapy (PDT). PpIX is also an ideal molecular probe for the quantification of the tissue oxygen partial pressure (pO₂), as its delayed fluorescence (DF) is quenched by oxygen, creating a direct relationship between the DF lifetime and the pO₂. A limitation of both techniques is the ignorance of the PpIX concentration in tissues when the pO₂ is measured or during PDT. In this study, the prompt (PF) and delayed fluorescence of PpIX dissolved in DiMethylFormamide (DMF) were acquired, in absence of oxygen, at different PpIX concentrations. Measurements of the PpIX emission for different excitation energies and temperatures, as well as spectral considerations led to the conclusion that E-type (thermal) DF was the dominant DF mechanism at low PpIX excited states concentrations (density of absorbed energy Hε[PpIX] < 1 μJ. cm^-3, H:excitation radiant exposure per pulse, ε: molar extinction coefficient at excitation wavelength) while P-type (Triplet Triplet Annihilation) DF took place at higher excited states concentrations (Hε[PpIX] > 10 μJ. cm^-3). The gradual development of a strong, red-shifted structureless DF peak at 670 nm, invisible in the PF and absorption spectra, strongly points towards the first observation of PpIX excimer DF (EDF). It appears that, similarly to other aromatic molecules, PpIX excimers can be formed either by the encounter of two molecules in the first excited triplet state T₁, or by the reaction of an excited singlet S₁ with a triplet T₁. Excimer DF could be beneficially used to determine the local concentration of PpIX, as the initial DF intensity ratio I₀⁶⁷⁰/I₀⁶³⁰ is linearly correlated with the local PpIX concentration, and thus rises up to the challenge of PpIX based pO₂ measurement and PDT. This work could also pave the way for a fine comprehension of the production, diffusion and catabolization of PpIX in biological tissues.

Detection of Canine Urothelial Carcinoma Cells in Urine Using 5-Aminolevulinic Acid

This study aimed to establish a method to detect canine urothelial carcinoma cells in urine using 5-aminolevulinic acid (5-ALA) and to evaluate its diagnostic accuracy. Urine samples were collected from 21 dogs diagnosed with urothelial carcinoma and three urothelial carcinoma cell lines were used. Urine samples obtained from seven healthy dogs were used as controls. Cells in the urine sediment, or urothelial carcinoma cell lines, were cultured with 5-ALA and then observed under a fluorescence microscope. Moreover, we examined the relationship between fluorescence intensity and the presence of metastasis as well as tumor invasion into the bladder wall in cases of urothelial carcinoma. Urine-derived cells from urothelial carcinoma and urothelial carcinoma cell lines showed clearer red fluorescence with the addition of 5-ALA compared to that exhibited by the cells from healthy dogs. The sensitivity and specificity of the diagnosis of urothelial carcinoma were 90% and 86%, respectively. Significant associations were found between fluorescence intensity and tumor metastasis and bladder wall invasion. This study showed that 5-ALA can be used to detect urothelial carcinoma cells in dogs with relatively high diagnostic accuracy. Further, the fluorescence intensity of tumor cells caused by 5-ALA correlated with the clinical condition of urothelial carcinoma cases, which suggested that 5-ALA could be used as a prognostic marker for canine urothelial carcinoma.

Artesunate Inhibits the Growth Behavior of Docetaxel-Resistant Prostate Cancer Cells

Novel therapeutic strategies are urgently needed for advanced metastatic prostate cancer (PCa). Phytochemicals used in Traditional Chinese Medicine seem to exhibit tumor suppressive properties. Therefore, the therapeutic potential of artesunate (ART) on the progressive growth of therapy-sensitive (parental) and docetaxel (DX)-resistant PCa cells was investigated. Parental and DX-resistant PCa cell lines DU145, PC3, and LNCaP were incubated with artesunate (ART) [1-100 µM]. ART-untreated and ‘non-cancerous’ cells served as controls. Cell growth, proliferation, cell cycle progression, cell death and the expression of involved proteins were evaluated. ART, dose- and time-dependently, significantly restricted cell growth and proliferation of parental and DX-resistant PCa cells, but not of ‘normal, non-cancerous’ cells. ART-induced growth and proliferation inhibition was accompanied by G0/G1 phase arrest and down-regulation of cell cycle activating proteins in all DX-resistant PCa cells and parental LNCaP. In the parental and DX-resistant PC3 and LNCaP cell lines, ART also promoted apoptotic cell death. Ferroptosis was exclusively induced by ART in parental and DX-resistant DU145 cells by increasing reactive oxygen species (ROS). The anti-cancer activity displayed by ART took effect in all three PCa cell lines, but through different mechanisms of action. Thus, in advanced PCa, ART may hold promise as a complementary treatment together with conventional therapy.

Photodynamic Effects with 5-Aminolevulinic Acid on Cytokines and Exosomes in Human Peripheral Blood Mononuclear Cells

Photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA), a precursor to the potent photosensitizer, protoporphyrin IX (PpIX), is an established modality for several malignant and premalignant diseases. This treatment is based on the light-activated PpIX in targeted lesions. Although numerous studies have confirmed the necrosis and apoptosis involved in the mechanism of action of this modality, little information is available for the change of exosome levels after treatment. We report from the first study on the effects of ALA-PDT on cytokines and exosomes of human healthy peripheral blood mononuclear cells (PBMCs). The treatment reduced the cytokines and exosomes studied, although there was variation among individual PBMC samples. This reduction is consistent with PDT-mediated survivals of subsets of PBMCs. More specifically, the ALA-PDT treatment apparently decreased all pro-inflammatory cytokines included, suggesting that this treatment may provide a strong anti-inflammatory effect. In addition, the treatment has decreased the levels of different types of exosomes, the HLA-DRDPDQ exosome in particular, which plays an important role in the rejection of organ transplantation as well as autoimmune diseases. These results may suggest future therapeutic strategies of ALA-PDT.

Analysis of Factors Affecting 5-ALA Fluorescence Intensity in Visualizing Glial Tumor Cells-Literature Review

Glial tumors are one of the most common lesions of the central nervous system. Despite the implementation of appropriate treatment, the prognosis is not successful. As shown in the literature, maximal tumor resection is a key element in improving therapeutic outcome. One of the methods to achieve it is the use of fluorescent intraoperative navigation with 5-aminolevulinic acid. Unfortunately, often the level of fluorescence emitted is not satisfactory, resulting in difficulties in the course of surgery. This article summarizes currently available knowledge regarding differences in the level of emitted fluorescence. It may depend on both the histological type and the genetic profile of the tumor, which is reflected in the activity and expression of enzymes involved in the intracellular metabolism of fluorescent dyes, such as PBGD, FECH, UROS, and ALAS. The transport of 5-aminolevulinic acid and its metabolites across the blood–brain barrier and cell membranes mediated by transporters, such as ABCB6 and ABCG2, is also important. Accompanying therapies, such as antiepileptic drugs or steroids, also have an impact on light emission by tumor cells. Accurate determination of the factors influencing the fluorescence of 5-aminolevulinic acid-treated cells may contribute to the improvement of fluorescence navigation in patients with highly malignant gliomas.

Methods to Measure the Inhibition of ABCG2 Transporter and Ferrochelatase Activity to Enhance Aminolevulinic Acid-Protoporphyrin IX Fluorescence-Guided Tumor Detection and Resection

Aminolevulinic acid (ALA) has been clinically used as an intraoperative fluorescence probe for protoporphyrin IX (PpIX) fluorescence-guided tumor resection and a PDT agent for cancer treatment. Although tumor tissues often show increased ALA-PpIX fluorescence compared with normal tissues, which enables the use of ALA for tumor imaging and targeting, weak tumor PpIX fluorescence as well as the heterogeneity in tumor fluorescence severely limits its clinical application. Intracellular PpIX in tumor cells is reduced by two major mechanisms, efflux by ATP-binding cassette (ABC) transporters such as ABCG2 and bioconversion to form heme by ferrochelatase (FECH) in the heme biosynthesis pathway. Targeting these two predominant PpIX-reducing mechanisms for the enhancement of ALA-PpIX have yielded a plethora of promising results and stimulated the clinical exploration of these enhancement strategies. Here we describe our methods of evaluating chemicals for the inhibition of ABCG2 transporter and FECH activity. Our goal is to further encourage research and development of novel ABCG2 and FECH inhibitors and promote a rational use of these inhibitors to optimize ALA-based tumor detection and treatment.

Modular control of multiple pathways of Corynebacterium glutamicum for 5-aminolevulinic acid production

5-aminolevulinic acid (ALA) has broad potential applications in the medical, agricultural and food industries. Several strategies have been implemented successfully to try to improve ALA synthesis. Nonetheless, the low yield has got in the way of large-scale bio-manufacture of 5-ALA. In this study, we explored strain engineering strategies for high-level 5-ALA production in Corynebacterium glutamicum F343 using the C4 pathway. Initially, the glutamate dehydrogenase-encoding gene gdhA was deleted to reduce glutamate yield. Then the C4 pathway was introduced in the gdhA mutant strain F2-A (∆gdhA + hemA), resulting in a 5-ALA yield of up to 3.2 g/L. Furthermore, the accumulations of downstream metabolites such as heme, porphobilinogen, and protoporphyrin IX, were decreased. After evaluating the mechanisms of this synthetic pathway by RNA-Seq, the results showed that genes involved in both the C5 pathway and heme pathways were down-regulated in strain F2-A (∆gdhA + hemA). Interestingly, upstream genes of succinyl-CoA in the tricarboxylic acid (TCA) cycle, such as icd, lpdA, were up-regulated, while its downstream genes, including sucC, sucD, sdhB, sdhA, sdhCD, were down-regulated. These changes amplify the sources of succinyl-CoA and reduce its expenditure, before pulling the carbon flux to produce 5-ALA. Furthermore, the down-regulation of most genes of the heme pathway could reduce the drainage of 5-ALA, which further enhance its accumulation. To alleviate competition between glyoxylate and the TCA cycle, the isocitrate dehydrogenase-encoding gene aceA was also knocked out, resulting in 3.86 g/L of 5-ALA. Finally, the fermentation conditions were optimized, resulting in a maximum 5-ALA yield of 5.6 g/L. Overall, the blocking of the glutamate synthesis pathway could be a powerful strategy to re-allocate the carbon flux to produce 5-ALA. It could also enable the efficient synthesis of other TCA derivatives in C. glutamicum.

In Vitro Low-Fluence Photodynamic Therapy Parameter Screening Using 3D Tumor Spheroids Shows that Fractionated Light Treatments Enhance Phototoxicity

The evaluation of novel photosensitizers (PSs) for photodynamic therapy (PDT) is difficult due to the limitations of two-dimensional cell culture and multiple parameters (dose, light intensity, uptake time), which complicate progression to in vivo experiments and clinical translation. Three-dimensional (3D) cell culture models like multicellular cancer tumor spheroids (MCTS) show great similarities to in vivo avascular tumor conditions, improving the speed and accuracy of screening novel compounds with various treatment combinations. In this study, we utilize C8161 human melanoma spheroids to screen PDT treatment combinations using protoporphyrin IX (PpIX) and drug-loaded carbon dot (CD) conjugates PpIX-CD and PpIX@CD at ultralow fluence values (<10 J/cm²). Conjugates show equivalent light-induced damage to PpIX from 1 μg/mL with significantly less dark cytotoxicity up to 72 h after exposure, shown by LDH release and dsDNA content. Fractionated treatments, carried out by dividing light exposure with 24 h intervals, demonstrate an enhanced PDT effect compared to single exposure at equal concentrations. Light sheet fluorescence microscopy combined with live/dead staining demonstrates that spheroids sustain extensive damage after PDT, with PpIX and PpIX-CD showing improved uptake compared to PpIX@CD. We show that PDT parameter screening can be carried out using a low-cost and convenient combination of assays to improve the efficiency of evaluating novel compounds.

Challenges and opportunities of bioprocessing 5-aminolevulinic acid using genetic and metabolic engineering: a critical review

5-Aminolevulinic acid (5-ALA), a non-proteinogenic five-carbon amino acid, has received intensive attentions in medicine due to its approval by the US Food and Drug Administration (FDA) for cancer diagnosis and treatment as photodynamic therapy. As chemical synthesis of 5-ALA performed low yield, complicated processes, and high cost, biosynthesis of 5-ALA via C4 (also called Shemin pathway) and C5 pathway related to heme biosynthesis in microorganism equipped more advantages. In C4 pathway, 5-ALA is derived from condensation of succinyl-CoA and glycine by 5-aminolevulic acid synthase (ALAS) with pyridoxal phosphate (PLP) as co-factor in one-step biotransformation. The C5 pathway involves three enzymes comprising glutamyl-tRNA synthetase (GltX), glutamyl-tRNA reductase (HemA), and glutamate-1-semialdehyde aminotransferase (HemL) from α-ketoglutarate in TCA cycle to 5-ALA and heme. In this review, we describe the recent results of 5-ALA production from different genes and microorganisms via genetic and metabolic engineering approaches. The regulation of different chassis is fine-tuned by applying synthetic biology and boosts 5-ALA production eventually. The purification process, challenges, and opportunities of 5-ALA for industrial applications are also summarized.

Application of Photodynamic Therapy with 5-Aminolevulinic Acid to Extracorporeal Photopheresis in the Treatment of Patients with Chronic Graft-versus-Host Disease: A First-in-Human Study

Extracorporeal photopheresis (ECP), an immunomodulatory therapy for the treatment of chronic graft-versus-host disease (cGvHD), exposes isolated white blood cells to photoactivatable 8-methoxypsoralen (8-MOP) and UVA light to induce the apoptosis of T-cells and, hence, to modulate immune responses. However, 8-MOP-ECP kills diseased and healthy cells with no selectivity and has limited efficacy in many cases. The use of 5-aminolevulinic acid (ALA) and light (ALA-based photodynamic therapy) may be an alternative, as ex vivo investigations show that ALA-ECP kills T-cells from cGvHD patients more selectively and efficiently than those treated with 8-MOP-ECP. The purpose of this phase I-(II) study was to evaluate the safety and tolerability of ALA-ECP in cGvHD patients. The study included 82 treatments in five patients. One patient was discharged due to the progression of the haematological disease. No significant persistent changes in vital signs or laboratory values were detected. In total, 62 adverse events were reported. Two events were severe, 17 were moderate, and 43 were mild symptoms. None of the adverse events evaluated by the internal safety review committee were considered to be likely related to the study medication. The results indicate that ALA-ECP is safe and is mainly tolerated well by cGvHD patients.

Alectinib treatment improves photodynamic therapy in cancer cell lines of different origin

Background

Photodynamic therapy with a photosensitizer such as protoporphyrin-IX, a light sensitive metabolite of heme synthesis, is a highly selective treatment for various carcinomas. In previous studies, we found a significant down regulation of the relevant enzyme ferrochelatase in gastrointestinal carcinomas leading to an accumulation of protoporphyrin-IX within the tumor cells. Recent studies showed that a novel anti-cancer drug, Alectinib, an orally available, highly selective, potent second-generation inhibitor of anaplastic lymphoma tyrosinkinase binds to ferrochelatase. Therefore, we were interested to see whether Alectinib treatment might lead to an accumulation of protoporphyrin IX.

Methods

Tumor cells of different origin were cultured, treated with LED-light and Alectinib. Results were gained by flow cytometry, immunohistochemistry and western blotting. Apoptosis was determined by flow cytometric analysis of Annexin V-FITC stained cells. In addition, cells were counterstained with propidium iodide to distinguish early apoptotic cells and late apoptotic/necrotic cells.

Results

Here, we report that photodynamic treatment of tumor cell lines of different origin in combination with Alectinib increased protoporphyrin-IX specific fluorescence and concomitantly cell death.

Conclusions

The usage of Alectinib could be another step for enhancing the effectiveness of photodynamic therapy. Further experiments will show whether photodynamic therapy in combination with Alectinib could be a new strategy for the treatment of e.g. peritoneal disseminated carcinomas.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08667-x.

Predictors of therapeutic efficacy of 5-aminolevulinic acid-based photodynamic therapy in human prostate cancer

BACKGROUND

Photodynamic therapy (PDT) is a minimally invasive cancer therapy. However, its therapeutic efficacy for prostate cancer is not yet fully understood. In this study, the predictors of therapeutic efficacy of 5-aminolevulinic acid-based PDT (ALA-PDT) on prostate cancer cells are investigated.

MATERIALS AND METHODS

The human prostate cancer cell lines, PC-3, 22Rv1, DU145, and LNCap were used to investigate the effects of ALA-PDT on protoporphyrin IX (PpIX) intracellular accumulation, which was measured by flow cytometry. The cytotoxicity of ALA-PDT was evaluated by MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay. The levels of porphyrin metabolism-related enzyme and transporter mRNA were comprehensively evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). Protein expression was evaluated by Western blot. A xenograft model was created using PC-3 and 22Rv1, and then, pathological analysis was performed to determine the therapeutic effect of ALA-PDT RESULTS: PC-3 and LNCap cells showed high accumulation of PpIX and high sensitivity to ALA-PDT, while 22Rv1 and DU145 showed low accumulation of PpIX and low sensitivity to ALA-PDT. ALA-PDT-induced cytotoxicity correlated negatively with PpIX accumulation. The in vitro assays identified the ATP-binding cassette transporter subfamily G2 (ABCG2) transporter dimer as a predictor of treatment response. In vivo immunohistochemical staining of ABCG2 transporter showed low expression in PC-3 cells and high expression in 22Rv1 cells, and ALA-PDT-induced tumor tissue degeneration was greater in PC-3 cells than in 22Rv1 cells.

CONCLUSION

The ABCG2 transporter is a useful predictor of the therapeutic effect of ALA-PDT on human prostate cancer cells.

Photodynamic Therapy: Targeting Cancer Biomarkers for the Treatment of Cancers

Simple Summary

Photodynamic therapy (PDT) is a minimally invasive treatment option that can kill cancerous cells by subjecting them to light irradiation at a specific wavelength. The main problem related to most photosensitizers is the lack of tumor selectivity, which leads to undesired uptake in normal tissues resulting in side effects. Passive targeting and active targeting are the two strategies to improve uptake in tumor tissues. This review focused on active targeting and summarizes recent active targeting approaches in which highly potent photosensitizers are rendered tumor-specific by means of an appended targeting moiety that interacts with a protein unique to, or at least significantly more abundant on, tumor cell surfaces compared to normal cells.

Abstract

Photodynamic therapy (PDT) is a well-documented therapy that has emerged as an effective treatment modality of cancers. PDT utilizes harmless light to activate non- or minimally toxic photosensitizers to generate cytotoxic species for malignant cell eradication. Compared with conventional chemotherapy and radiotherapy, PDT is appealing by virtue of the minimal invasiveness, its safety, as well as its selectivity, and the fact that it can induce an immune response. Although local illumination of the cancer lesions renders intrinsic selectivity of PDT, most photosensitizers used in PDT do not display significant tumor tissue selectivity. There is a need for targeted delivery of photosensitizers. The molecular identification of cancer antigens has opened new possibilities for the development of effective targeted therapy for cancer patients. This review provides a brief overview of recent achievements of targeted delivery of photosensitizers to cancer cells by targeting well-established cancer biomarkers. Overall, targeted PDT offers enhanced intracellular accumulation of the photosensitizer, leading to improved PDT efficacy and reduced toxicity to normal tissues.

Downregulating of hemB via synthetic antisense RNAs for improving 5-aminolevulinic acid production in Escherichia coli

Aminolevulinic acid (ALA), a type of natural non-protein amino acid, is a key precursor for the biosynthesis of heme, and it has been broadly applied in medicine, agriculture. Several strategies have been applied to enhance ALA synthesis in bacteria. In the present study, we employed synthetic antisense RNAs (asRNAs) of hemB (encodes ALA dehydratase) to weaken metabolic flux of ALA to porphobilinogen (PBG), and investigated their effect on ALA accumulation. For this purpose, we designed and constructed vectors pET28a-hemA-asRNA and pRSFDuet-hemA-asRNA to simultaneously express 5-ALA synthase (ALAS, encoded by hemA) and PTasRNAs (2 inverted repeat DNA sequences sandwiched with the antisense sequence of hemB), selecting the region ranging from - 57 nt upstream to + 139 nt downstream of the start codon of hemB as a target. The qRT-PCR analysis showed that the mRNA levels of hemB were decreased above 50% of the control levels, suggesting that the anti-hemB asRNA was functioning appropriately. ALA accumulation in the hemB weakened strains were 17.6% higher than that obtained using the control strains while accumulating less PBG. These results indicated that asRNAs can be used as a tool for regulating ALA accumulation in E. coli.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02733-8.

Effect of 5-aminolevulinic acid on gene expression and presence of NKG2D receptor on NK cells

Natural killer (NK) cells are involved in innate and acquired immunity, stimulating and enhancing immune responses via secretion of IFN-γ and TNF-α. NKG2D is among the most important NK's stimulant receptors, the ligands of which are elevated on cancerous and virus-infected cells. We analyzed effect of 5-ALA on gene expression and receptor presentation of NKG2D, which is present on peripheral blood NK cells. Mononuclear cells were isolated from the venous blood samples of healthy individuals. RNA extraction and cDNA synthesis were performed after exposure of samples to 5-ALA, and gene expression was evaluated using Real-Time PCR, and the receptor presence rate on the cell surface was evaluated by flow-cytometry analysis. The results showed the gene expression of NKG2D and the presence of its receptor on NK cells were increased.5-ALA can be used to activate NK cells in their killing activity, preventing the growth and metastasis of cancerous cells.

How Much Protoporphyrin IX Must Be Activated to Obtain Full Efficacy of Methyl Aminolevulinate Photodynamic Therapy? Implication for Treatment Modifications

Photodynamic therapy (PDT) with methyl aminolevulinate (MAL) is a popular treatment for actinic keratoses (AK), and several PDT treatment modalities with similar cure rates are in use. The effect relies on the activation of protoporphyrin IX (PpIX) in premalignant cells. This study aimed to measure PpIX during each treatment modality to determine the minimal PpIX activation and shortest exposure time for optimal cure rate. In four different treatment modalities, we established the PpIX formation up to three hours after MAL application without illumination and measured the speed of PpIX photoactivation during 9 min of red light (37 J/cm²). The level of PpIX three hours after MAL application was set to 100 PpIX units. In comparison, 85 PpIX units were formed during daylight PDT, 57 PpIX units during pulse PDT, and 52 PpIX units without any curettage prior to MAL. The activation of 50 PpIX units should, therefore, be enough to obtain a full effect on AK. Further, red light illumination may be shortened from 9 min to 1–2 min. The results indicate that PDT can be performed successfully with half the illumination time used in daylight PDT today and with one fourth of the illumination time used in classical PDT.

Photosensitivity Reaction From Operating Room Lights After Oral Administration of 5-Aminolevulinic Acid for Fluorescence-Guided Resection of a Malignant Glioma

Orally administered 5-aminolevulinic acid (5-ALA), which was approved in the United States in 2017, is preferentially metabolized by malignant glioma cells into protoporphyrin IX and enhances tumor visualization when using a blue light filter on an operating microscope. Photosensitivity after 5-ALA administration is a known side effect, but a photosensitivity reaction from operating room lights has not yet been documented. We report the case of a 56-year-old man with a history of previous resection of a grade II astrocytoma who presented with imaging concerning for tumor recurrence and possible malignant transformation. Repeat surgical resection utilized 5-ALA. Soon after the surgery, he developed reddening of his skin, particularly over the right side of his head and neck, with blistering and peeling in a distribution that was particularly exposed to operating room lights during surgery. No other areas of his skin experienced the same redness, blistering, or peeling. Topical lotions were applied and the skin changes resolved spontaneously over weeks. Significant photosensitivity after administration of oral 5-ALA is a rare complication, but neurosurgeons who perform fluorescence-guided tumor resection should remain cognizant of its potential association with exposure to intense light, including in the operating room. Phototoxicity typically is self-limited, but awareness is important to minimize its occurrence.

A Novel 89Zr-labeled DDS Device Utilizing Human IgG Variant (scFv): "Lactosome" Nanoparticle-Based Theranostics for PET Imaging and Targeted Therapy

“Theranostics,” a new concept of medical advances featuring a fusion of therapeutic and diagnostic systems, provides promising prospects in personalized medicine, especially cancer. The theranostics system comprises a novel ⁸⁹Zr-labeled drug delivery system (DDS), derived from the novel biodegradable polymeric micelle, “Lactosome” nanoparticles conjugated with specific shortened IgG variant, and aims to successfully deliver therapeutically effective molecules, such as the apoptosis-inducing small interfering RNA (siRNA) intracellularly while offering simultaneous tumor visualization via PET imaging. A 27 kDa-human single chain variable fragment (scFv) of IgG to establish clinically applicable PET imaging and theranostics in cancer medicine was fabricated to target mesothelin (MSLN), a 40 kDa-differentiation-related cell surface glycoprotein antigen, which is frequently and highly expressed by malignant tumors. This system coupled with the cell penetrating peptide (CPP)-modified and photosensitizer (e.g., 5, 10, 15, 20-tetrakis (4-aminophenyl) porphyrin (TPP))-loaded Lactosome particles for photochemical internalized (PCI) driven intracellular siRNA delivery and the combination of 5-aminolevulinic acid (ALA) photodynamic therapy (PDT) offers a promising nano-theranostic-based cancer therapy via its targeted apoptosis-inducing feature. This review focuses on the combined advances in nanotechnology and material sciences utilizing the “⁸⁹Zr-labeled CPP and TPP-loaded Lactosome particles” and future directions based on important milestones and recent developments in this platform.

Recent progress in development and applications of second near-infrared (NIR-II) nanoprobes

Optical probes for near-infrared (NIR) light have clear advantages over UV/VIS-based optical probes, such as their low levels of interfering auto-fluorescence and high tissue penetration. The second NIR (NIR-II) window (1000-1350 nm) offers better light penetration, lower background signal, higher safety limit, and higher maximum permitted exposure than the first NIR (NIR-I) window (650-950 nm). Therefore, NIR-II laser-based photoacoustic (PA) and fluorescence (FL) imaging can offer higher sensitivity and penetration depth than was previously available, and deeper lesions can be treated in vivo by photothermal therapy (PTT) and photodynamic therapy (PDT) with an NIR-II laser than with an NIR-I laser. Advances in creation of novel nanomaterials have increased options for improving light-induced bioimaging and treatment. Nanotechnology can provide advantages such as good disease targeting ability and relatively long circulation times to supplement the advantages of optical technologies. In this review, we present recent progress in development and applications of NIR-II light-based nanoplatforms for FL, PA, image-guided surgery, PDT, and PTT. We also discuss recent advances in smart NIR-II nanoprobes that can respond to stimuli in the tumor microenvironment and inflamed sites. Finally, we consider the challenges involved in using NIR-II nanomedicine for effective diagnosis and treatment.