5-Aminolevulinic acid-induced fluorescence diagnosis of pleural malignant tumor

A Microfluidic System for Detecting Tumor Cells Based on Biomarker Hexaminolevulinate (HAL): Applications in Pleural Effusion

Malignant pleural effusion is a common clinical problem, which often occurs in cases of malignant tumors, especially in lung cancer. In this paper, a pleural effusion detection system based on a microfluidic chip, combined with specific tumor biomarker, hexaminolevulinate (HAL), used to concentrate and identify tumor cells in pleural effusion was reported. The lung adenocarcinoma cell line A549 and mesothelial cell line Met-5A were cultured as the tumor cells and non-tumor cells, respectively. The optimum enrichment effect was achieved in the microfluidic chip when the flow rates of cell suspension and phosphate-buffered saline achieved 2 mL/h and 4 mL/h, respectively. At the optimal flow rate, the proportion of A549 increased from 28.04% to 70.01% due to the concentration effect of the chip, indicating that tumor cells could be enriched by a factor of 2.5 times. In addition, HAL staining results revealed that HAL can be used to identify tumor cells and non-tumor cells in chip and clinical samples. Additionally, the tumor cells obtained from the patients diagnosed with lung cancer were confirmed to be captured in the microfluidic chip, proving the validity of the microfluidic detection system. This study preliminarily demonstrates the microfluidic system is a promising method with which to assist clinical detection in pleural effusion.

Photodynamic Diagnosis for Pleural Disseminated Lesions of Lung Cancer Using a Combination of 5-Aminolevulinic Acid and Autofluorescence Observation System

PURPOSE

We developed a diagnostic method for pleural disseminated lesions of lung cancer using a combination of 5-aminolevulinic acid (5ALA) and autofluorescence observation system. We utilized a phenomenon in which externally ingested 5ALA is metabolized to protoporphyrin IX, a precursor of heme, which remains inside malignant cells and emits red fluorescence of approximately 630 nm. The diagnosis was made employing an observation system based on autofluorescence emitted from normal tissues that we have investigated.

METHODS

Between January 2017 and April 2019, we examined 82 lung cancer patients with suspected pleural invasion. We orally administered 5ALA (20 mg/m2) to the patients 4 hours before surgery, and malignant pleural lesions were thoracoscopically visualized using the autofluorescence observation system.

RESULTS

(1) Pleural disseminated lesions were observed in six patients. Of these lesions, two were not detected by usual white light inspection, and the use of this method enabled the diagnosis of disseminated lesions. (2) Regarding the diagnosis of lung cancer pleural invasion to estimate the risk of pleural dissemination, if limited to adenocarcinoma, the sensitivity was 93.9%; specificity, 74.3%; positive predictive value, 60.8%; and negative predictive value, 96.2%.

CONCLUSION

This method may facilitate the detection of minute disseminated lesions that are difficult to detect by usual inspection. In addition, the degree of pleural invasion may be diagnosed to evaluate the need for limited resection such as segmentectomy.

Photodynamic diagnosis of visceral pleural invasion of lung cancer with a combination of 5-aminolevulinic acid and autofluorescence observation systems

BACKGROUND

Visceral pleural invasion (PL) is a prognostic factor in lung cancer. In the lung, lymph flows along the pleura, in addition to the flow toward the pulmonary hilum just as the pulmonary arteries and veins run toward it. Even with the same tumor diameter, a PL1 or higher level of pleural invasion is indicative of a more advanced disease stage. Final diagnosis based on the PL level is made by pathological examination of excised specimens. However, if an intraoperative diagnosis can be established, proper selection of the surgical procedure can be made, and unnecessary surgeries for disseminated lesions can be avoided. We investigated optical diagnostic techniques for identifying the presence or absence of visceral pleural invasion in lung cancer by capitalizing on the phenomenon of 5-amino-levulinic acid (5-ALA) being metabolized to a photosensitizing substance or protoporphyrin IX within malignant tumors, generating red luminescence in response to excitation light.

METHOD

This study included 38 patients with primary lung cancer who underwent surgery. They received 5-ALA (20mg/kg) orally 4h before surgery and then we assessed the presence or absence of pleural invasion using an autofluorescence observation system. At visceral pleural invasion sites, we were able to confirm tumor sites visualized in red with a clear border in contrast to the green autofluorescence generated in normal tissues.

RESULT

Red luminescence could be confirmed in 100% of PL1-PL3 patients (14/14) and 41.6% of PL0 patients (10/24) with primary lung cancer. PL0 patients in whom visualization was possible were preoperatively diagnosed as having PL1 and many of them showed vascular channel invasion. The sensitivity, specificity, positive predictive value, and negative predictive value of this diagnostic technique were 100%, 58.0%, 63.1%, and 100%, respectively. Red fluorescence emission was observed significantly more often in pleural invasion cases.

CONCLUSION

Accurate intraoperative diagnosis for visceral pleural invasion in lung cancer may contribute to determining the indications for limited operations such as segmental resection. In addition, accurate local diagnosis has the possibility of being applicable to photodynamic therapy.

Recent advances in production of 5-aminolevulinic acid using biological strategies

5-Aminolevulinic acid (5-ALA) is the precursor for the biosynthesis of tetrapyrrole compounds and has broad applications in the medical and agricultural fields. Because of the disadvantages of chemical synthesis methods, microbial production of 5-ALA has drawn intensive attention and has been regarded as an alternative in the last years, especially with the rapid development of metabolic engineering and synthetic biology. In this mini-review, recent advances on the application and microbial production of 5-ALA using novel biological approaches (such as whole-cell enzymatic-transformation, metabolic pathway engineering and cell-free process) are described and discussed in detail. In addition, the challenges and prospects of synthetic biology are discussed.

A pilot study of autofluorescence in the diagnosis of pleural disease

BACKGROUND

Conventional medical thoracoscopy (MT), routinely performed in patients with pleural disease, does not always lead to a conclusive diagnosis. The endoscopic appearance of pleural diseases under white light could be misleading. Autofluorescence has been shown to be an interesting and effective diagnostic tool. The objective of this study was to evaluate the diagnostic value of autofluorescence imaging during MT.

METHODS

Patients with undiagnosed pleural effusion admitted to our clinical center between August 2013 and February 2014 were enrolled. MT was performed first with white light and then by autofluorescence. Endoscopic results of different diseases were recorded, and biopsy specimens were obtained for pathologic analysis. We calculated the diagnostic sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the two methods by comparing them with the pathologic results.

RESULTS

Thirty-seven eligible patients were studied, including 21 with malignancy, nine with tuberculous pleurisy, three with infective pleurisy, and four with no diagnosed condition. Autofluorescence revealed additional malignant lesions, which were missed under white light in five patients. The diagnostic sensitivity and NPV of autofluorescence were 100% (95% CI, 98.5%-100%) and 100% (95% CI, 93.9%-100%), respectively. Autofluorescence was superior to white light, with a sensitivity of 92.8% (95% CI, 89.3%-95.3%) and NPV of 76.8% (95% CI, 67.0%-84.4%). For the specificity and PPV, no significant difference was found.

CONCLUSIONS

The advantage of autofluorescence is its high sensitivity and NPV. It is useful to detect microlesions and delineate the pathologic margins. Autofluorescence can benefit patients with its better visualization.

Fluorescence in neurosurgery: Its diagnostic and therapeutic use. Review of the literature

Fluorescent agents, e.g. 5-aminolevulinic acid (5-ALA), fluorescein and indocyanine green (ICG) are in common use in neurosurgery for tumor resection and neurovascular surgery. Protoporphyrine IX (PPIX) as major metabolite of 5-ALA is a strong fluorescent substance accumulated within malignant glioma tissue and a very sensitive and specific tool for visualizing high grade glioma tissue during surgery. Furthermore, 5-ALA or rather PPIX also offers an intratumoral therapeutic option stimulated by laser light in specific wavelength. Fluorescein was demonstrated to show similar fluorescent reactions in neurosurgery, but is controversial in its use, especially in high grade tumor surgery. Intraoperative angiography during resection of arterio-venous malformations, extracranial-intracranial-bypass or aneurysm surgery is supported by ICG fluorescence. Generally ICG will provide beneficial information for both, exposure of the pathology and illustration of healthy structures. This manuscript shows an overview of the literature focussing fluorescence in neurosurgery.

Photodynamic diagnosis of pleural malignant lesions with a combination of 5-aminolevulinic acid and intrinsic fluorescence observation systems

BACKGROUND

We have developed a new diagnostic method using the photosensitizer 5-aminolevulinic acid (5ALA) for diagnosing intrathoracic malignant lesions. When ingested exogenously, 5ALA is metabolized to a heme precursor, protoporphyrin IX, which stays in malignant cells and emits red to pink luminescence of about 630 nm.

METHODS

We enrolled 40 patients who underwent respiratory surgery and consented to participate in this study. Twenty-eight patients had primary lung cancer, 8 metastatic lung tumors, 2 malignant pleural tumors, and 2 benign tumors. Localization of malignant lesions was attempted by observing such lesions with an autofluorescence imaging system and by comparing the color tone of the autofluorescence between malignant lesions and normal tissues after oral administration of 5ALA. Malignant lesions on the pleural surface emitted pink autofluorescence in contrast to the green autofluorescence of the surrounding normal tissues.

RESULTS

When 28 patients with primary lung cancer were examined according to the degree of pleural infiltration (pl), red fluorescence was confirmed in 10 of 10 patients (100%) with p11-p13 and 5 of 18 patients (27.7%) with p10. The latter 5 patients had been diagnosed with PL1 preoperatively or intraoperatively.

CONCLUSION

This system achieved accurate localization of malignant lesions, suggesting that it may also be applicable to photodynamic therapy.

Photodynamic diagnoses of malignant pleural diseases using the autofluorescence imaging system

BACKGROUND

We conducted a study on photodynamic diagnosis (PDD) using autofluorescence in video-assisted thoracic surgery for minute intrathoracic small dissemination or early malignant pleural mesothelioma.

METHODS

Autofluorescence is the spontaneous emission of light that occurs when mitochondria, lysosomes, and other intracellular organelles absorb light. In normal tissues, green autofluorescence of approximately 520 nm is observed in response to 400-450 nm blue excitation rays. However, in cancer lesions, green autofluorescence is reduced due to thickening of the mucosal epithelium, a decrease in autofluorescent substances, etc., and the color spectrum thus shifts to red-violet. This phenomenon is the basis of PDD.

RESULTS

The color spectrum shift was observed in all tumors located on the pleural surface but not in cases with pleural fibrous disease. Among patients with primary lung cancer, those with pleural infiltration (pl) scores of 1 or greater showed color spectrum shifts due to reduced autofluorescence.

CONCLUSION

Localization of pleural lesions by autofluorescence imaging was found to be useful. In primary lung cancer cases, differentiation between pl0 and pl1 lesions appears to be useful for determining therapeutic strategies including surgical procedures.

Diagnostic laparoscopy with 5-aminolevulinic-acid-mediated photodynamic diagnosis enhances the detection of peritoneal micrometastases in advanced gastric cancer

OBJECTS

Recently, we reported that diagnostic laparoscopy with photodynamic diagnosis using oral 5-aminolevulinic acid (ALA-PDD) is a promising tool for diagnosing early peritoneal metastases in gastric cancer. The present study evaluated the usefulness of adding ALA-PDD to conventional diagnostic laparoscopy and assessed the association of the ALA-PDD results with peritoneal fluid cytology and molecular diagnostic testing.

METHODS

Diagnostic laparoscopy using sequential white light (WL) and ALA-PDD observations was performed in 52 advanced gastric cancer patients, and the sensitivity of ALA-PDD for detecting peritoneal disease was compared to WL. Peritoneal fluid samples from the same patients were also subjected to cytological examination and molecular diagnosis using a transcription-reverse transcription concerted reaction (TRC).

RESULTS

Twenty-four of the 52 patients (46%) had no macroscopic evidence of peritoneal metastases on WL examination; however, ALA-PDD detected dissemination in 5 of these 24 patients (21%) (pd-P). Cytological examination was negative in 4 of the 5 pd-P patients, and molecular testing using TRC was negative in 3 of the 5 pd-P patients.

CONCLUSIONS

This study demonstrated that diagnostic laparoscopy with ALA-PDD improved the sensitivity for the detection of peritoneal metastases. ALA-PDD may be a useful technique for the preoperative staging of advanced gastric cancer and can complement examinations of peritoneal lavage fluids.

Aminolevulinic acid (ALA): photodynamic detection and potential therapeutic applications

Aminolevulinic acid (ALA) is a heme precursor that may have potential applications for photodynamic detection and photodynamic therapy-based treatment of solid tumors in a variety of malignancies. ALA may have a role in other applications in surgical oncology based on its ability to discriminate neoplastic tissue from adjacent normal tissue. In this review, we provide a comprehensive summary of the published studies of ALA in noncutaneous solid malignancies.