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This article describes the use of a fluorescent nanoprobe as a functional biomarker for the identification of increased vascular permeability in cancer/arthritis disease models. Synthesis of the fluorescent nanoprobe was achieved by passive loading of a fluorophore inside the nanoparticle using thin film hydration method. The outer layer of the nanoprobe was decorated with poly(ethylene glycol) arms to increase the bioavailability of the fluorophore. Stability studies of the nanoprobe showed that the particles were stable up to 70 days. The uptake and internalization of the fluorescent nanoprobe inside target cells was confirmed by fluorescence microscopy studies. Co-localization of the probe with the target tissue in vivo was unambiguously identified using intravital microscopy. Results from in vivo imaging studies showed that the particles had a long half-life in the circulation and passively targeted tumor or arthritic tissue. The increased and specific uptake of the fluorescent nanoprobe in tumor/arthritic tissue is attributed to an enhanced permeation and retention (EPR) effect. Use of an optical method to validate anti-inflammatory drugs in an arthritis disease model is demonstrated in this study. In general, this methodology could be used for detection of leaky vasculature in different pathological states.

Summary. We analysed 20 patients with BCR-ABL-positive acute lymphoblastic leukaemia (ALL) by quantitative competitive polymerase chain reaction (QC-PCR) to study the kinetics of the leukaemic clone. Consecutive samples of 16 patients (minor-bcr, n 10; major-bcr, n 6) were analysed after conventional chemotherapy and/or bone marrow transplantation (BMT). DNA competitor templates co-amplifying with either p210 or p190 BCR-ABL cDNA were used for quanti®cation of leukaemia-speci®c BCR-ABL mRNA. In all samples, total ABL transcripts were measured as internal control, and the percentage of BCR-ABL/ABL molecules was calculated. Following induction chemotherapy the number of BCR-ABL transcripts was reduced by a maximum of 2±3 logs. In most patients, additional chemotherapy did not lead to further reduction of BCR-ABL mRNA. In two patients, conventional chemotherapy plus autologous BMT in complete haematological remission resulted in a total reduction of the transcript level of more than 3 logs. In two other patients, allogeneic BMT caused a transient reduction of the BCR-ABL transcripts below the detection level of our method (<1 blast cell in 10 5 normal cells) for a period of 7 and 11 months, respectively. The achievement of PCR negativity did not guarantee sustained remission. Both patients relapsed and BCR-ABL transcript levels rose by more than 1 log prior to frank relapse. Our data demonstrate that quanti®cation of BCR-ABL mRNA allows the evaluation of the dynamics of the leukaemic clone and thus is valuable for the evaluation of minimal residual leukaemia following various therapies and the early detection of increasing BCR-ABL transcripts prior to relapse.

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