Local 5-aminolevulinic acid application for laser light-induced fluorescence diagnosis of early staged colon cancer in rats

Multiphoton morpho-functional imaging of healthy colon mucosa, adenomatous polyp and adenocarcinoma

Two-photon spectral resolved imaging was used to image fresh human biopsies of colon tissue and to characterize healthy colon mucosa, adenomatous polyp and adenocarcinoma by means of a morpho-functional analysis. Morphological examination, performed using endogenous tissue fluorescence, discriminated adenomatous and adenocarcinoma tissues from normal mucosa in terms of cellular asymmetry and nucleus-to-cytoplasm ratio. Good agreement was found between multiphoton images and histological examination performed on the same samples. Further characterization, performed by means of spectral-resolved analysis of NADH and FAD fluorescence, demonstrated an altered metabolic activity in both adenomatous and adenocarcinoma tissues compared to healthy mucosa. This morpho-functional approach may represent a powerful method to be used in combination with endoscopy for in vivo optical diagnosis of colon cancer and may be extended to other tissues.

Laparoscopic fluorescence diagnosis of peritoneal metastases from human hepatoblastoma in nude rats

AIM

Fluorescence diagnosis is gaining clinical importance for the detection of malignancies in various medical disciplines. The technique relies on the specific metabolic capacity of a lesion to produce a fluorescent compound. It is still unknown whether pediatric solid tumors like hepatoblastoma (HB) are susceptible to this technique as well.

METHODS

Human HB (3 x 10(6)) cells were laparoscopically injected (4 mm scope, 18-G needle) underneath the peritoneum of 7 nude rats (mean weight, 198 g). Tumor growth was allowed for 7 weeks. Photosensitization was induced by peritoneal lavage with aminolevulinic acid (3%). After 3 hours, the animals were investigated with white light laparoscopy (WL) and laparoscopic fluorescence diagnosis (LFD), applying the Storz PDD system. Every suspicious lesion was analyzed by spectrometry and harvested for histology.

RESULTS

Every tumor seen in WL also demonstrated strong fluorescence during LFD (100%). One micrometastasis, almost invisible in WL, was obviously illuminating in LFD. Spectrometry demonstrated the specific peak of the aminolevulinic acid metabolite protoporphyrin IX at 635 nm and a 6.34-fold increase of the fluorescence intensity. Histology revealed HB in all specimens.

CONCLUSION

Human HB can be detected with LFD in a rat model. This finding opens a wide spectrum of experimental and clinical investigations to evaluate the impact of fluorescence diagnosis for pediatric oncology.

On the Role of Iron and one of its Chelating Agents in the Production of Protoporphyrin IX Generated by 5-Aminolevulinic Acid and its Hexyl Ester Derivative Tested on an Epidermal Equivalent of Human Skin

Photodynamic therapy (PDT) with 5-aminolevulinic acid (ALA) or its derivatives as precursors of protoporphyrin IX (PPIX) is routinely used in dermatology for the treatment of various pathologies. However, this methodology suffers to some extent from a limited efficacy. Therefore, the main goal of this study was to investigate the modulation and pharmacokinetics of PPIX buildup after a 5 h incubation with ALA (1.5 mM) and one of its derivatives, the hexyl ester of ALA (h-ALA) (1.5 mM), on the human epidermal equivalent Epidex. PPIX production was modulated with (L+) ascorbic acid iron (II) salt (LAI) or the iron (II)-specific chelating agent deferoxamine (DFO). PPIX fluorescence from the Epidex layers was measured up to 150 h after the precursor administration using a microspectrofluorometer (lambda(ex): 400 +/- 20 nm; lambda(det): 635 nm). The maximum PPIX fluorescence intensity induced by h-ALA was about 1.7 x larger than that induced by ALA. The addition of DFO resulted in a more than 50% increase in PPIX fluorescence for both precursors. The decay half life measured for PPIX fluorescence is 30 and 42.5 h, respectively, for ALA and h-ALA. These half lives are doubled when the samples contain DFO. In the samples with the highest fluorescence intensity, a modified fluorescence spectrum was observed after 10 h, with the emergence of a peak at 590 nm, which is attributed to zinc protoporphyrin IX (Zn PPIX).

Videoscopic fluorescence diagnosis of peritoneal and thoracic metastases from human hepatoblastoma in nude rats

BACKGROUND

Various medical disciplines are employing photodynamic diagnosis (PDD) when searching for malignancies. It is still unknown whether pediatric solid tumors such as hepatoblastoma are susceptible to this technique as well.

METHODS

Human hepatoblastoma cells were injected into the abdomen or right thoracic cavity of nude rats. Tumor growth was allowed for 7 weeks. Then, photosensitization was induced by peritoneal lavage with 5-aminolevulinic acid (ALA). Applying the Storz PDD system and one 4-mm scope, all animals were investigated by videoscopic white light diagnosis (WD) and PDD. Suspicious lesions were marked and analyzed by spectrometry and histology.

RESULTS

Positive fluorescence was documented for every tumor seen by WD in the abdomen or right thoracic cavity. Spectrometry of lesions showed a 6.34-fold increased fluorescence intensity. Histology revealed hepatoblastoma in all specimens.

CONCLUSIONS

Human hepatoblastoma can be detected by PDD in a rat model. Considering the clinical success of this method in other specialties, our findings indicate that further investigations to evaluate the benefit of PDD for children with hepatoblastoma should be performed.

Thoracoscopic fluorescence diagnosis (TFD) of pleural malignancies: experimental studies

BACKGROUND

Fluorescence diagnosis (FD) using the photosensitiser 5-aminolaevulinic acid (ALA) was experimentally combined with conventional video assisted thoracic surgery (VATS) to improve tumour staging in advanced lung cancer with pleural tumour spread.

METHODS

A disseminated pleural carcinosis affecting the entire pleural cavity was induced by inoculation of human adenocarcinoma cells in nude rats. After 5-7 weeks of tumour growth the animals were randomised into six groups with different photosensitisation parameters. Pleural lavage was performed either with 1.5% or 3.0% ALA solution. Photosensitisation times varied were 2, 4, or 6 hours. Conventional white light VATS was first performed to evaluate tumour growth in the pleural cavity. Fluorescence illumination of the light source, the D-light, was then used to examine the site for additional tumours which were previously invisible. The tumour fluorescence intensity was measured spectrometrically and compared with normal tissue.

RESULTS

Compared with conventional white light VATS alone, thoracoscopic fluorescence diagnosis (TFD) detected up to 30% additional pleural malignant lesions. The highest diagnostic sensitivity was reached 6 hours after 3.0% ALA pleural lavage. Photosensitiser accumulation in the tumour, measured indirectly by spectrometry, was up to 11 times higher than in normal tissue.

CONCLUSIONS

TFD increases sensitivity of VATS for tumour staging. It may prevent unnecessary thoracotomies in cancer patients and facilitate surgical planning.