Abels C, Heil P, Dellian M, Kuhnle G E, Baumgartner R, Goetz A E
Institute for Surgical Research, Klinikum Grosshadern, Ludwig-Maximilians-University, Munich, Germany.
Br J Cancer. 1994 Nov;70(5):826-33. doi: 10.1038/bjc.1994.406.
For successful photodynamic diagnosis (PDD) and effective photodynamic therapy (PDT) with the clinically used 'photosensitiser' 5-aminolaevulinic acid (ALA), knowledge of the maximal fluorescence intensity and of the maximal tumour-host tissue fluorescence ratio following systemic or local application is required. Therefore, time course and type of porphyrin accumulation were investigated in neoplastic and surrounding host tissue by measuring the kinetics and spectra of ALA-induced fluorescence in vivo. Experiments were performed in the amelanotic melanoma A-Mel-3 grown in the dorsal skinfold chamber preparation of Syrian golden hamsters. The kinetics of fluorescent porphyrins was quantified up to 24 h after i.v. injection of 100 mg kg-1, 500 mg kg-1 or 1,000 mg kg-1 body weight ALA by intravital fluorescence microscopy and digital image analysis (n = 18). In separate experiments fluorescence spectra were obtained for each dose by a simultaneous optical multichannel analysing device (n = 3). A three-compartment model was developed to simulate fluorescence kinetics in tumours. Maximal fluorescence intensity (per cent of reference standard; mean +/- s.e.) in the tumour arose 150 min post injection (p.i.) (1,000 mg kg-1, 109 +/- 34%; 500 mg kg-1, 148 +/- 36%) and 120 min p.i. (100 mg kg-1, 16 +/- 8%). The fluorescence in the surrounding host tissue was far less and reached its maximum at 240 min (100 mg kg-1, 6 +/- 3%) and 360 min p.i. (500 mg kg-1, 50 +/- 8%) and (1,000 mg kg-1, 6 +/- 19%). Maximal tumour-host tissue ratio (90:1) was encountered at 90 min after injection of 500 mg kg-1. The spectra of tissue fluorescence showed maxima at 637 nm and 704 nm respectively. After 300 min (host tissue) and 360 min (tumour tissue) additional emission bands at 618 nm and 678 nm were detected. These bands indicate the presence of protoporphyrin IX (PPIX) and of another porphyrin species in the tumour not identified yet. Tumour selectivity of ALA-induced PPIX accumulation occurs only during a distinct interval depending on the administered dose. Based on the presented data the optimal time for PDD and PDT in this model following intravenous administration of 500 mg kg-1 ALA would be around 90 min and 150 min respectively. The transient selectivity is probably caused by an earlier and higher uptake of ALA in the neoplastic tissue most likely as a result of increased vascular permeability of tumours as supported by the mathematical model.
为了使用临床应用的“光敏剂”5-氨基乙酰丙酸（ALA）成功进行光动力诊断（PDD）并实施有效的光动力治疗（PDT），需要了解全身或局部应用后最大荧光强度以及最大肿瘤-宿主组织荧光比率。因此，通过测量体内ALA诱导荧光的动力学和光谱，研究了肿瘤组织和周围宿主组织中卟啉积累的时间进程和类型。实验在叙利亚金仓鼠背部皮褶腔制备物中生长的无黑色素黑色素瘤A-Mel-3上进行。通过活体荧光显微镜和数字图像分析，对静脉注射体重100mg/kg-1、500mg/kg-1或1000mg/kg-1的ALA后长达24小时的荧光卟啉动力学进行了定量分析（n = 18）。在单独的实验中，通过同步光学多通道分析装置获得每个剂量的荧光光谱（n = 3）。开发了一个三室模型来模拟肿瘤中的荧光动力学。肿瘤中的最大荧光强度（相对于参考标准的百分比；平均值±标准误）在注射后150分钟出现（1000mg/kg-1，109±34%；500mg/kg-1，148±36%），注射后120分钟出现（100mg/kg-1，16±8%）。周围宿主组织中的荧光要少得多，在240分钟（100mg/kg-1，6±3%）和注射后360分钟（500mg/kg-1，50±8%）以及（1000mg/kg-1，6±19%）达到最大值。注射500mg/kg-1后90分钟时，肿瘤-宿主组织最大比率为90:1。组织荧光光谱分别在637nm和704nm处出现最大值。在300分钟（宿主组织）和360分钟（肿瘤组织）后，在618nm和678nm处检测到额外的发射带。这些波段表明肿瘤中存在原卟啉IX（PPIX）和另一种尚未鉴定的卟啉物质。ALA诱导的PPIX积累的肿瘤选择性仅在取决于给药剂量的特定时间间隔内发生。根据所提供的数据，在静脉注射500mg/kg-1 ALA后，该模型中PDD和PDT的最佳时间分别约为90分钟和150分钟。这种短暂的选择性可能是由于肿瘤组织中ALA的摄取更早且更高，这很可能是由于肿瘤血管通透性增加所致，数学模型也支持这一点。
