E-selectin targeting to visualize tumors in vivo

Pharmacokinetic evaluation and antitumor potency of liposomal nanoparticle encapsulated cisplatin targeted to CD24-positive cells in ovarian cancer

CD24, which is upregulated in several human malignancies, is related to Epithelial-mesenchymal-transition (EMT) and has characteristics of cancer stem-like cells, especially in cisplatin-resistant ovarian carcinoma cells. Drug delivery systems represent a promising therapeutic approach for diseases with treatment resistance, and the present study investigated a novel CD24-targeted drug delivery system for advanced ovarian carcinoma. We produced liposomal cisplatin with a red fluorescent substance - cyanine 5.5 (GL-CDDP-Cy5.5). In order to target CD24-positive cells, an anti-CD24 monoclonal antibody was modified to the above drug (CD24-GL-CDDP-Cy5.5). Specific uptake of CD24-GL-CDDP-Cy5.5 was confirmed using a therapeutically resistant ovarian cancer cell line, Caov-3 cells. Antitumor effects of CD24-GL-CDDP-Cy5.5 were then evaluated in Caov-3 ×enograft mice. CD24-GL-CDDP-Cy5.5 showed more specific uptake by flow cytometry than GL-CDDP-Cy5.5. In xenograft mice, GL-CDDP-Cy5.5 and CD24-GL-CDDP-Cy5.5 treatment had significantly higher platinum concentration in disseminated tumor cells than cisplatin (P<0.05). Moreover, CD24-GL-CDDP-Cy5.5 suppressed tumor growth and prolonged survival time compared with other treatments. Median survival times of the control, cisplatin, GL-CDDP-Cy5.5 and CD24-GL-CDDP-Cy5.5 groups were 37, 36, 46 and 54 days after inoculation, respectively. Immunohistochemical analysis showed that CD24-GL-CDDP-Cy5.5 treatment, compared with GL-CDDP-Cy5.5, decreased the number of CD24-positive cells and suppressed the EMT phenomenon significantly (P<0.05). The present study demonstrated that CD24-GL-CDDP-Cy5.5, compared with other treatments, improved therapeutic efficacy. The present results suggested the potential for targeting anticancer therapeutics for CD24-positive cells to prevent disease progression.

A novel mouse model of soft-tissue infection using bioluminescence imaging allows noninvasive, real-time monitoring of bacterial growth

Musculoskeletal infections, including surgical-site and implant-associated infections, often cause progressive inflammation and destroy areas of the soft tissue. Treating infections, especially those caused by multi-antibiotic resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA) remains a challenge. Although there are a few animal models that enable the quantitative evaluation of infection in soft tissues, these models are not always reproducible or sustainable. Here, we successfully established a real-time, in vivo, quantitative mouse model of soft-tissue infection in the superficial gluteus muscle (SGM) using bioluminescence imaging. A bioluminescent strain of MRSA was inoculated into the SGM of BALB/c adult male mice, followed by sequential measurement of bacterial photon intensity and serological and histological analyses of the mice. The mean photon intensity in the mice peaked immediately after inoculation and remained stable until day 28. The serum levels of interleukin-6, interleukin-1 and C-reactive protein at 12 hours after inoculation were significantly higher than those prior to inoculation, and the C-reactive protein remained significantly elevated until day 21. Histological analyses showed marked neutrophil infiltration and abscesses containing necrotic and fibrous tissues in the SGM. With this SGM mouse model, we successfully visualized and quantified stable bacterial growth over an extended period of time with bioluminescence imaging, which allowed us to monitor the process of infection without euthanizing the experimental animals. This model is applicable to in vivo evaluations of the long-term efficacy of novel antibiotics or antibacterial implants.

A novel strategy inducing autophagic cell death in Burkitt's lymphoma cells with anti-CD19-targeted liposomal rapamycin

Relapsed or refractory Burkitt's lymphoma often has a poor prognosis in spite of intensive chemotherapy that induces apoptotic and/or necrotic death of lymphoma cells. Rapamycin (Rap) brings about autophagy, and could be another treatment. Further, anti-CD19-targeted liposomal delivery may enable Rap to kill lymphoma cells specifically. Rap was encapsulated by anionic liposome and conjugated with anti-CD19 antibody (CD19-GL-Rap) or anti-CD2 antibody (CD2-GL-Rap) as a control. A fluorescent probe Cy5.5 was also liposomized in the same way (CD19 or CD2-GL-Cy5.5) to examine the efficacy of anti-CD19-targeted liposomal delivery into CD19-positive Burkitt's lymphoma cell line, SKW6.4. CD19-GL-Cy5.5 was more effectively uptaken into SKW6.4 cells than CD2-GL-Cy5.5 in vitro. When the cells were inoculated subcutaneously into nonobese diabetic/severe combined immunodeficiency mice, intravenously administered CD19-GL-Cy5.5 made the subcutaneous tumor fluorescent, while CD2-GL-Cy5.5 did not. Further, CD19-GL-Rap had a greater cytocidal effect on not only SKW6.4 cells but also Burkitt's lymphoma cells derived from patients than CD2-GL-Rap in vitro. The specific toxicity of CD19-GL-Rap was cancelled by neutralizing anti-CD19 antibody. The survival period of mice treated with intravenous CD19-GL-Rap was significantly longer than that of mice treated with CD2-GL-Rap after intraperitoneal inoculation of SKW6.4 cells. Anti-CD19-targeted liposomal Rap could be a promising lymphoma cell-specific treatment inducing autophagic cell death.