Localized magnetic hyperthermia as a treatment modality for cancer has generated renewed interest, particularly if it can be targeted to the tumor site. We examined whether tumor-tropic neural progenitor cells (NPCs) could be utilized as cell delivery vehicles for achieving preferential accumulation of core/shell iron/iron oxide magnetic nanoparticles (MNPs) within a mouse model of melanoma. We developed aminosiloxane-porphyrin functionalized MNPs, evaluated cell viability and loading efficiency, and transplanted neural progenitor cells loaded with this cargo into mice with melanoma. NPCs were efficiently loaded with core/shell Fe/Fe 3 O 4 MNPs with minimal cytotoxicity; the MNPs accumulated as aggregates in the cytosol. The NPCs loaded with MNPs could travel to subcutaneous melanomas, and after A/C (alternating current) magnetic field (AMF) exposure, the targeted delivery of MNPs by the cells resulted in a measurable regression of the tumors. The tumor attenuation was significant (p<0.05) a short time (24 hours) after the last of three AMF exposures. Keywords nanotechnology; cell-based; targeted delivery; magnetic nanoparticles; magnetic hyperthermia; melanoma; neural progenitor cellsThe incidence and mortality rate of malignant melanoma continues to increase at an alarming rate worldwide.1 Disseminated melanoma is not curable using current clinical * Corresponding author: Deryl Troyer, Department of Anatomy and Physiology, 228 Coles Hall, Kansas State University, Manhattan, KS 66506, USA troyer@vet.ksu.edu,. ** Both of these authors contributed equally to this work. Supporting Information Available:Supplemental Figures S1 and S2 show a TEM image of MNPs and a photo of a hemacytometer grid with trypan blue-stained, MNP-loaded NPCs, respectively. The figures and accompanying legends are available This material is available free of charge via the Internet at http://pubs.acs.org. NIH Public AccessAuthor Manuscript ACS Nano. Author manuscript; available in PMC 2011 December 28. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript tools; traditional chemotherapy is ineffective due to inherent drug-resistant characteristics of the disease.2 , 3The pioneering studies of Gordon et al. demonstrated induced intracellular hyperthermia using dextran magnetite nanoparticles in a high frequency magnetic field (such as 500 kHz); the advantages of magnetic nanoparticles (MNPs), such as negligible or low toxicity, biocompatibility, injectability into the blood stream, and potential accumulation in the target tumor, make them prime candidates for hyperthermia applications.4 However, the specific absorption rates (SARs) of those early systems were low. It will be of great importance to achieve a high monodispersity of the magnetic nanoparticles, because only then can the A/ C-excitation be optimized to achieve very high specific absorption rates. Magnetic hyperthermia has recently garnered new interest as a cancer therapy because technological advances allow heat delivery to be more precisely contro...

Ehrlichia chaffeensis, a tick-transmitted rickettsial, is the causative agent of human monocytic ehrlichiosis. To examine protein expression patterns, we analyzed total, membrane, and immunogenic proteomes of E. chaffeensis originating from macrophage and tick cell cultures. Total proteins resolved by onedimensional gel electrophoresis and subjected to liquid chromatography-electrospray ionization ion trap mass spectrometry allowed identification of 134 and 116 proteins from macrophage-and tick cell-derived E. chaffeensis, respectively. Because a majority of immunogenic proteins remained in the membrane fraction, individually picked total and immunogenic membrane proteins were also surveyed by liquid chromatography-tandem mass spectrometry and matrix-assisted laser desorption ionization-time of flight methods. The analysis aided the identification of 48 additional proteins. In all, 278 genes of the E. chaffeensis genome were verified as functional genes. They included genes for DNA and protein metabolism, energy metabolism and transport, membrane proteins, hypothetical proteins, and many novel proteins of unknown function. The data reported in this study suggest that the membrane of E. chaffeensis is very complex, having many expressed proteins. This study represents the first and the most comprehensive analysis of E. chaffeensis-expressed proteins. This also is the first study confirming the expression of nearly one-fourth of all predicted genes of the E. chaffeensis genome, validating that they are functionally active genes, and demonstrating that classic shotgun proteomic approaches are feasible for tick-transmitted intraphagosomal bacteria. The identity of novel expressed proteins reported in this study, including the large selection of membrane and immunogenic proteins, will be valuable in elucidating pathogenic mechanisms and developing effective prevention and control methods.

Targeted gene delivery, transfection efficiency and toxicity concerns remain a challenge for effective gene therapy. In this study, we dimerized the HIV-1 TAT peptide and formulated a nanoparticle vector (dTAT NP) to leverage the efficiency of this cell penetrating strategy for tumor-targeted gene delivery in the setting of intratracheal administration. Expression efficiency for dTAT NP-encapsulated luciferase or angiotensin II type 2 receptor (AT2R) plasmid DNA (pDNA) was evaluated in Lewis Lung carcinoma (LLC) cells cultured in vitro or in vivo in orthotopic tumor grafts in syngeneic mice. In cell culture, dTAT NP was an effective pDNA transfection vector with negligible cytotoxicity. Transfection efficiency was further increased by addition of calcium and glucose to dTAT/pDNA NP. In orthotopic tumor grafts, immunohistochemical analysis confirmed that dTAT NP successfully delivered pDNA to the tumor, where it was expressed primarily in tumor cells along with the bronchial epithelium. Notably, gene expression in tumor tissues persisted at least 14 days after intratracheal administration. Moreover, bolus administration of dTAT NP-encapsulated AT2R or TRAIL pDNA markedly attenuated tumor growth. Taken together, our findings offer a preclinical proof of concept for a novel gene delivery system that offers an effective intratracheal strategy for administering lung cancer gene therapy.

SummaryThe targeted delivery of therapeutics to the tumor site is highly desirable in cancer treatment, because it is capable of minimizing collateral damage. Herein, we report the synthesis of a nanoplatform, which is composed of a 15 ± 1 nm diameter core/shell Fe/Fe3O4 magnetic nanoparticles (MNPs) and the topoisomerase I blocker SN38 bound to the surface of the MNPs via a carboxylesterase cleavable linker. This nanoplatform demonstrated high heating ability (SAR = 522 ± 40 W/g) in an AC-magnetic field. For the purpose of targeted delivery, this nanoplatform was loaded into tumor-homing double-stable RAW264.7 cells (mouse monocyte/macrophage-like cells (Mo/Ma)), which have been engineered to express intracellular carboxylesterase (InCE) upon addition of doxycycline by a Tet-On Advanced system. The nanoplatform was taken up efficiently by these tumor-homing cells. They showed low toxicity even at high nanoplatform concentration. SN38 was released successfully by switching on the Tet-On Advanced system. We have demonstrated that this nanoplatform can be potentially used for thermochemotherapy. We will be able to achieve the following goals: (1) Specifically deliver the SN38 prodrug and magnetic nanoparticles to the cancer site as the payload of tumor-homing double-stable RAW264.7 cells; (2) Release of chemotherapeutic SN38 at the cancer site by means of the self-containing Tet-On Advanced system; (3) Provide localized magnetic hyperthermia to enhance the cancer treatment, both by killing cancer cells through magnetic heating and by activating the immune system.

Enzyme activated prodrugs have been investigated and sought after as highly specific, low side effect treatments, especially for cancer therapy. Unfortunately, excellent targets for enzyme activated therapy are rare. Here we demonstrate a system based on cell delivery that can carry both a prodrug and an activating enzyme to the cancer site. Raw264.7 cells (mouse monocyte/macrophage like cells, Mo/Ma) were engineered to express intracellular rabbit carboxylesterase (InCE), which is a potent activator of the prodrug irinotecan to SN38. InCE expression was regulated by the TetOn® system, which silences the gene unless a tetracycline, such as doxycycline, is present. Concurrently, an irinotecan-like prodrug, conjugated to dextran, was synthesized that could be loaded into the cytoplasm of Mo/Ma. To test the system, a murine pancreatic cancer model was generated by intraperitoneal (i.p.) injection of Pan02 cells. Engineered Mo/Ma were loaded with the prodrug and were injected i.p. Two days later, doxycycline was given i.p. to activate InCE, which activated the prodrug. A survival study demonstrated that this system significantly increased survival in a murine pancreatic cancer model. Thus, for the first time, a prodrug/activating enzyme system self-contained within tumor-homing cells has been demonstrated that can prolong the life of i.p. pancreatic tumor bearing mice.