Magnetization transfer (MT) MRI measurements were performed in 3 pancreatic ductal adenocarcinoma (PDAC) mouse xenograft models. For each of 28 PDAC xenografts, magnetization transfer ratios (MTR) were calculated and compared to histologic fibrosis levels from reference standard trichrome staining. MTR was found to be significantly higher in tumors grown using BxPC-3 cell line (39.4 ± 5.1, mean ± SD) compared to the MTR for the tumors grown from Panc-1 (32.4 ± 2.8) and Capan-1 (27.3 ± 2.9) cell lines (P < 0.05 for each comparison). Histologic measurements showed a similar trend with BxPC-3 tumors demonstrating significantly higher fibrosis levels (percentage of fibrotic tissue area, 6.48 ± 2.59) when compared to Panc-1 (3.54 ± 2.18) and Capan-1 (2.07 ± 1.60) tumors. MTR measurements were well correlated to quantitative fibrosis levels (r = 0.69, P = 0.01). Results indicated that MTR measurements offer the potential to serve as a valuable in vivo biomarker of desmoplasia in PDAC.

Nanoparticles (NP) have emerged as a novel class of therapeutic agents that overcome many of the limitations of current cancer chemotherapeutics. However, a major challenge to many current NP platforms is unfavorable biodistribution, and limited tumor uptake, upon systemic delivery. Delivery, therefore, remains a critical barrier to widespread clinical adoption of NP therapeutics. To overcome these limitations, we have adapted the techniques of image-guided local drug delivery to develop nano-ablation and nano-embolization. Nano-ablation is a tumor ablative strategy that employs image-guided placement of electrodes into tumor tissue to electroporate tumor cells, resulting in rapid influx of NPs that is not dependent on cellular uptake machinery or stage of the cell cycle. Nano-embolization involves the image-guided delivery of NPs and embolic agents directly into the blood supply of tumors. We describe the design and testing of our innovative local delivery strategies using doxorubicin functionalized superparamagnetic iron oxide nanoparticles (DOX-SPIOs) in cell culture, and the N1S1 hepatoma and VX2 tumor models, imaged by high resolution 7T MRI. We demonstrate that local delivery techniques result in significantly increased intra-tumoral DOX-SPIO uptake, with limited off-target delivery in tumor bearing animal models. The techniques described are versatile enough to be extended to any NP platform, targeting any solid organ malignancy that can be accessed via imaging guidance.

We sought to improve the efficacy of gemcitabine (GEM) for the treatment of advanced pancreatic cancer via local hyperthermia potentiated via a multi-functional nanoplatform permitting both in vivo heating and drug delivery. Herein, we propose a chemohyperthermia approach to synergistically achieve high intra-tumoral drug concentrations while permitting concurrent hyperthermia for more effective tumor cell kill and growth inhibition. Drug delivery and hyperthermia were achieved using a hydroxypropyl cellulose (HPC) grafted porous magnetic drug carrier that is MRI visible to permit in vivo visualization of the biodistribution. These synthesized magnetic drug carriers produced strong T2 weighted image contrast and permitted efficient heating using low magnetic field intensities. The thermo-mechanical response of HPC permitted triggered GEM release confirmed during in vitro drug release studies. During in vitro studies, pancreatic cancer cell growth was significantly inhibited (~82% reduction) with chemohyperthermia compared to chemotherapy or hyperthermia alone. Using PANC-1 xenografts in nude mice, the delivery of injected GEM-loaded magnetic carriers (GEM-magnetic carriers) was visualized with both MRI and fluorescent imaging techniques. Chemohyperthermia with intra-tumoral injections of GEM-magnetic carriers (followed by heating) resulted in significant increases in apoptotic cell death compared to tumors treated with GEM-magnetic carriers injections alone. Chemohyperthermia with GEM-magnetic carriers offers the potential to significantly improve the therapeutic efficacy of gemcitabine for the treatment of pancreatic cancer. In vivo delivery confirmation with non-invasive imaging techniques could permit patient-specific adjustments therapeutic regimens for improve longitudinal outcomes.

No abstract

EGFR family members are essential for proper peripheral nervous system development. A role for EGFR itself in peripheral nervous system development in vivo, however, has not been reported. We investigated whether EGFR is required for cutaneous innervation using Egfr null and skin-targeted Egfr mutant mice. Neuronal markers; including PGP9.5, GAP-43, acetylated tubulin, and neurofilaments; revealed that Egfr null dorsal skin was hyperinnervated with a disorganized pattern of innervation. In addition, receptor subtypes such as lanceolate endings were disorganized and immature. To determine whether the hyperinnervation phenotype resulted from a target-derived effect of loss of EGFR, mice lacking EGFR expression in the cutaneous epithelium were examined. These mice retained other aspects of the cutaneous Egfr null phenotype but exhibited normal innervation. The sensory deficits in Egfr null dorsal skin were not associated with any abnormality in the morphology or density of dorsal root ganglion (DRG) neurons or Schwann cells. However, explant and dissociated cell cultures of DRG revealed more extensive branching in Egfr null cultures. These data demonstrate that EGFR is required for proper cutaneous innervation during development and suggest that it limits axonal outgrowth and branching in a DRG-autonomous manner.