Recent advances in photodynamic diagnosis of gastriccancer using 5-aminolevulinic acid

Photodynamic diagnosis based on 5-aminolevulinic acidinduced protoporphyrin IX has been clinically applied in many fields based upon its evidenced efficacy and adequate safety. In order to establish a personalized medicine approach for treating gastric cancer patients, rapid intraoperative detection of malignant lesions has become important. Feasibility of photodynamic diagnosis using 5-aminolevulinic acid for gastric cancer patients has been investigated, especially for the detection of peritoneal dissemination and lymph node metastasis. This method enables intraoperative realtime fluorescence detection of peritoneal dissemination, exhibiting higher sensitivity than white light observation without histopathological examination. The method also enables detection of metastatic foci within excised lymph nodes, exhibiting a diagnostic accuracy comparable to that of a current molecular diagnostics technique. Although several complicating issues still need to be resolved, such as the effect of tissue autofluorescence and the insufficient depth penetration of excitation light, this simple and rapid method has the potential to become a useful diagnostic tool for gastric cancer, as well as urinary bladder cancer and glioma.

Development of a Photodynamic Diagnosis Method for Oral Squamous Cell Carcinoma Using 5-Aminolevulinic Acid and a Luminescence Plate Reader

Purpose: To establish a simple and accurate photodynamic diagnosis (PDD) method for oral squamous cell carcinoma (OSCC). Methods: OSCC cell lines HSC-2, HSC-3, HSC-4, and Sa3, and normal human oral keratinocytes (HOK) were used. First, we examined the amount of cells needed to detect differences in fluorescence intensities for PDD. OSCC cell lines were adjusted to concentrations of 1 × 104 (104), 1 × 105 (105), and 1 × 106 (106) cells/ml. The experimental groups comprised a group with 5-aminolevulinic acid (5-ALA (+)), and a group without 5-ALA (5-ALA (-)). For each OSCC cell line, 100 μl of each concentration of cells of the 5-ALA groups was seeded onto fluorescence plates, and fluorescence intensity was measured at 60-min intervals for 240 min. Results are expressed as the ratio of fluorescence intensity in 5-ALA (+) to 5-ALA (-). As cells at the concentration of 106 cells/ml provided the clearest results, fluorescence intensities of all cell lines were measured using this concentration at 20-min intervals for 700 min using the same methods. Results: The 5-ALA (+) to (-) ratio increased in a cell concentration-dependent manner at 240 min;the ratio was highest with 106 cells/ml and lowest with 104 cells/ml. With 106 cells/ml in the 5-ALA (+) group, fluorescence intensity increased in a metabolic time-dependent manner;the increase was highest in HSC-2 cells, followed by HSC-4 cells, HSC-3 cells, Sa3 cells, and HOK. Fluorescence intensity was significantly enhanced after 40 min in HSC-2, HSC-3, and HSC-4 cells, after 60 min in Sa3 cells, and after 100 min in HOK compared to the 5-ALA (-) group (P < 0.05). Moreover, fluorescence intensity was significantly increased in OSCC cell lines compared to HOK after 40 min. Conclusion: Early detection of OSCC is possible by screening only microplate reader measurements of fluorescence intensity for PDD.

Photodynamic Therapy of Cancer Cells with Methanesulfonate Salts of 5-Aminolevulinic Acid and Its Derivatives

A series of 5-aminolevulinic acid and its alkylester methanesulfonates was exploited to photodynamic therapy（PDT） of human lymphocytic cells, U-937 in vitro. The PDT efficiency is influenced by the concentration and incubation time. Generally, for ALA and its alkylester methanesulfonates, the cell survival rate decreases and the accumulation ability of PplX increases with the concentration and incubation time. We found that the longer carbon chain methanesulfonates（C5-S, C6-S, C8-S） exhibit better PDT effect than ALA methanesulfonate. This possibly provides a promising route to the clinical application ofPplX-mediated PDT to cancer cell.

OPTIMIZATIONS FOR 5-AMINOLEVULINIC ACID BASED PHOTODYNAMIC THERAPY IN PURGING LEUKEMIA CELL HL60

Objective To optimize experimental parameters for the photosensitization of 5-aminolevulinic acid (ALA) in promyelocytic leukemia cell HL60 and compare them with normal human peripheral blood mononuclear cell (PBMC). Methods ALA incubation time, wavelength applied to irradiate, concentration of ALA incubated, irradiation fluence may modulate the effect of 5-aminolevulinic acid based Photodynamic Therapy (ALA-PDT).The high-pressure mercury lamps of 400W served as light source, the interference filter of 410nm, 432nm, 545nm, 577nm were used to select the specific wavelength. Fluorescence microscope was used to detect the fluorescence intensity and location of protoporphyrin IX (PpIX) endogenously produced by ALA. MTT assay was used to measure the survival of cell. Flow cytometry with ANNEXIN V FITC kit (contains annexin V FITC, binding buffer and PI) was used to detect the mode of cell death. Results ① 1mmol/L ALA incubated 1×105/mL HL60 cell line for 4 hours, the maximum fluorescence of ALA induced PpIX was detected in cytomembrane. ② Irradiated with 410nm for 14.4J/cm2 can result in the minimum survivability of HL60 cell. ③ The main mode of HL60 cell death caused by ALA-PDT is necrosis. Conclusion ALA for 1mmol/L, 4 hours for dark incubation time, 410nm for irradiation wavelength, 14.4J/cm2 for irradiation fluence were the optimal parameters to selectively eliminate promyelocytic leukemia cell HL60 by ALA based PDT. The photosensitization of ALA based PDT caused the necrosis of HL60 cell, so it could be used for inactivation of certain leukemia cells.

Clinical applications of 5-aminolevulinic acid-mediated fluorescence for gastric cancer

5-aminolevulinic acid(ALA) is a naturally occurring amino acid that is a protoporphyrin IX(Pp IX) precursor and a next-generation photosensitive substance. After exogenous administration of ALA, Pp IX specifically accumulates in cancer cells owing to the impaired metabolism of ALA to Pp IX in mitochondria, which results in a red fluorescence following irradiation with blue light and the formation of singlet oxygen. Fluorescence navigation by photodynamic diagnosis(PDD) using ALA provides good visualization and detection of gastric cancer lesions and is a potentially valuable diagnostic tool for gastric cancer for evaluating both the surgical resection margins and extension of the lesion. Furthermore, PDD using ALA might be used to detect peritoneal metastases during preoperative staging laparoscopy, where it could provide useful information for the selection of a therapeutic approach. Another promising application for this modality is in the evaluation of lymph node metastases. Photodynamic therapy(PDT) using ALA to cause selective damage based on the accumulation of a photosensitizer in malignant tissue is expected to be a non-invasive endoscopic treatment for superficial early gastric cancer. ALA has the potential to be used not only as a diagnostic agent but also as a therapeutic drug, resulting in a new strategy for cancer diagnosis and therapy. Here, we review the current use of PDD and PDT in gastric cancer and evaluate its future potential beyond conventional modalities combined with a light energy upconverter, a light-emitting diode and nearinfrared rays as light sources.

5-Aminolevulinic Acid (5-ALA): Analysis of Preclinical and Safety Literature

Problem: 5-ALA has been used for many years at relatively high dose amounts in single doses for photodynamic therapy and immunofluorescence of tumors. An analysis of compiled data relating to safety and any side-effects about the use of 5-ALA at low doses has not yet been published. Purpose: This report analyzes data about the safety of the use of 5-Aminolevulinic Acid (5-ALA) in low doses as a supplement over an extended period of time. Methods: This investigation is a systematic analysis of the current literature ((Medline, and SBI) and snowballing techniques) related to the safety and efficacy of 5-ALA in animals and humans. Clinical trials in progress using 5-ALA were also analyzed. Constant comparative analyses were used to synthesize the findings. Results: The safety of low-dose 5-ALA as a supplement has been demonstrated by animal and human studies. The results suggest that none of the investigations document the presence of symptoms or abnormal laboratory results of clinical significance. The minor laboratory changes documented were judged not clinically significant.

CO_(2)LASER PLUS PHOTODYNAMIC THERAPY VERSUS CO_(2)LASER IN THE TREATMENT OF CONDYLOMA ACUMINATUM:A RANDOMIZED COMPARATIVE STUDY

To compare the efficacy and safety of CO_(2)laser plus 5-aminolevulinic acid(ALA)photodynamic therapy(PDT)with CO_(2)laser for the treatment of multiple condyloma acuminatum(CA),120 patients with multiple CA were allocated into two groups—combined group(CO_(2)laser plus ALA-PDT,n=60)and CO_(2)laser group(CO_(2)laser plus placebo-PDT,n=60).After CO_(2)laser,a 20%ALA or a placebo solution was applied to the CA area 3 h before illumination with red light(635 nm,100mW/cm^(2),80 J/cm^(2)).The treatment was repeated seven days after the first treatment if the lesions were not completely resolved.The complete response rate,recurrence rate and adverse effects in the two groups were analyzed.After two treatments,the complete response rates in the CO_(2)laser group and combined group were 100%(509/509)and 100%(507/507)in the CA(p>0:05),respectively.The recurrence rates in the CO_(2)laser group and combined group were 44.9%(229/509)and 10.6%(54/507)in the CA(p<0:05),respectively.The adverse effects in CO_(2)laser group was more than that in combined group.The combined group is a more effective treatment for multiple CA compared with CO_(2)laser group.T/S.Style the highlighted text as abstract.

Boosting 5-ALA-based photodynamic therapy by a liposomal nanomedicine through intracellular iron ion regulation

5-Aminolevulinic acid(5-ALA)has been approved for clinical photodynamic therapy(PDT)due to its negligible photosensitive toxicity.However,the curative effect of 5-ALA is restricted by intracellular biotransformation inactivation of 5-ALA and potential DNA repair of tumor cells.Inspired by the crucial function of iron ions in 5-ALA transformation and DNA repair,a liposomal nanomedicine(MFLs@5-ALA/DFO)with intracellular iron ion regulation property was developed for boosting the PDT of 5-ALA,which was prepared by co-encapsulating 5-ALA and DFO(deferoxamine,a special iron chelator)into the membrane fusion liposomes(MFLs).MFLs@5-ALA/DFO showed an improved pharmaceutical behavior and rapidly fused with tumor cell membrane for 5-ALA and DFO co-delivery.MFLs@5-ALA/DFO could efficiently reduce iron ion,thus blocking the biotransformation of photosensitive protoporphyrin IX(Pp IX)to heme,realizing significant accumulation of photosensitivity.Meanwhile,the activity of DNA repair enzyme was also inhibited with the reduction of iron ion,resulting in the aggravated DNA damage in tumor cells.Our findings showed MFLs@5-ALA/DFO had potential to be applied for enhanced PDT of 5-ALA.

Photodynamic therapy accelerates skin wound healing through promoting re-epithelialization

Background:Epidermal stem cells(EpSCs)that reside in cutaneous hair follicles and the basal layer of the epidermis are indispensable for wound healing and skin homeostasis.Little is known about the effects of photochemical activation on EpSC differentiation,proliferation and migration during wound healing.The present study aimed to determine the effects of photodynamic therapy(PDT)on wound healing in vivo and in vitro.Methods:We created mouse full-thickness skin resection models and applied 5-aminolevulinic acid(ALA)for PDT to the wound beds.Wound healing was analysed by gross evaluation and haematoxylin–eosin staining in vivo.In cultured EpSCs,protein expression was measured using flow cytometry and immunohistochemistry.Cell migration was examined using a scratch model;apoptosis and differentiation were measured using flow cytometry.Results:PDT accelerated wound closure by enhancing EpSC differentiation,proliferation and migration,thereby promoting re-epithelialization and angiogenesis.PDT inhibited inflammatory infiltration and expression of proinflammatory cytokines,whereas the secretion of growth factors was greater than in other groups.The proportion of transient amplifying cells was significantly greater in vivo and in vitro in the PDT groups.EpSC migration was markedly enhanced after ALAinduced PDT.Conclusions:Topical ALA-induced PDT stimulates wound healing by enhancing re-epithelialization,promoting angiogenesis as well as modulating skin homeostasis.This work provides a preliminary theoretical foundation for the clinical administration of topical ALA-induced PDT in skin wound healing.