Dextran-coated superparamagnetic iron oxide nanoparticles (dextran-SPIO conjugates) offer the attractive possibility of enhancing MRI imaging sensitivity so that small or diffuse lesions can be detected. However, systemically injected SPIO are rapidly removed by macrophages. We engineered embryonic cells (HEK293T) to express major macrophage scavenger receptor (SR) subtypes including SR-AI, MARCO, and endothelial receptor collectin-12. These SRs possess a positively charged collagen-like (CL) domain and they promoted SPIO uptake, while the charge neutral lipoprotein receptor SR-BI did not. In silico modeling indicated a positive net charge on the CL domain, and a net negative charge on the cysteine-rich (CR) domain of MARCO and SR-AI. In vitro experiments revealed that CR domain deletion in SR-AI boosted uptake of SPIO 3-fold, while deletion of MARCO's CR domain abolished this uptake. These data suggest that future studies might productively focus on the validation and further exploration of SR charge fields in SPIO recognition.

angiogenesis ͉ cancer ͉ nanoparticle

Calicheamicin 0II is a member of the enediyne class of antitumor antibiotics that bind to DNA and induce apoptosis. These compounds differ, however, from conventional anticancer drugs as they bind in a sequencespecific manner noncovalently to DNA and cause sequence-selective oxidation of deoxyriboses and bending of the DNA helix. Calicheamicin is clinically employed as immunoconjugate to antibodies directed against, for example, CD33 in the case of gemtuzumab ozogamicin. Here, we show by the use of the unconjugated drug that calicheamicin-induced apoptosis is independent from death-receptor/FADD-mediated signals. Moreover, calicheamicin triggers apoptosis in a p53-independent manner as shown by the use of p53 knockout cells. Cell death proceeds via activation of mitochondrial permeability transition, cytochrome c release and activation of caspase-9 and -3. The overexpression of Bcl-x L or Bcl-2 strongly inhibited calicheamicin-induced apoptosis. Knockout of Bax abrogated cell death after calicheamicin treatment. Thus, the activation of mitochondria and execution of cell death occur through a fully Baxdependent mechanism. Interestingly, caspase inhibition by the pancaspase-inhibitor zVAD-fmk interfered with mitochondrial activation by calicheamicin. This places caspase activation upstream of the mitochondria and indicates that calicheamicin-triggered apoptosis is enhanced through death receptor-independent activation of the caspase cascade, that is, an amplification loop that is required for full activation of the mitochondrial pathway. Oncogene (2003) 22, 9107-9120.

Parkinson’s disease (PD) is associated with the formation of toxic α-synuclein oligomers and their penetration the cell membrane. Familial forms of PD are caused by the point mutations A53T, A30P, E46K, and H50Q. Artificial point mutations E35K and E57K also increase oligomerization and pore formation. We generated structural conformations of α-synuclein and the abovementioned mutants using molecular dynamics. We elucidated four main regions in these conformers contacting the membrane and found that the region including residues 37–45 (Zone2) may have maximum membrane penetration. E57K mutant had the highest rate of interaction with the membrane by Zone2, followed by A53T, E46K, E35K mutants, and wt α-synuclein. The mutant A30P had the smallest percentage of conformers that contact the membrane than all other mutants and wt α-synuclein. These results were confirmed by experiments. We identified the key amino acids that can interact with the membrane (Y38, E62, and N65 (1st hydrophilic layer); E104, E105, and D115 (2nd hydrophilic layer), and V15 and V26 (central hydrophobic layer)) and the residues that are involved in the interprotein contacts (L38, V48, V49, Q62, and T64). Understanding the molecular interactions of α-synuclein mutants is important for the design of compounds blocking the formation of toxic oligomers.

Sparing sensitive healthy tissue from chemotherapy exposure is a critical challenge in the treatment of cancer. The work described here demonstrates the localized in vivo photo-activation of a new chemotherapy prodrug of doxorubicin (DOX). The DOX prodrug (DOX-PCB) was 200 times less toxic to cells, but released pure DOX when exposed to 365 nm light delivered to the tumor tissue using a specialized fiber-optic LED system. This wavelength was chosen because it had good tissue penetration through a 1cm diameter tumor but had very low skin penetration, due to melanin absorption, preventing uncontrolled activation from outside sources. Pharmacokinetic studies showed DOX-PCB had an α circulation half-life of 10 min which is comparable to that of DOX at 20 min. DOX-PCB demonstrated resistance to metabolic cleavage ensuring that exposure to 365nm light was the main mode of in vivo activation. Tissue extractions from tumors exposed to 365 nm light in vivo showed the presence of DOX-PCB as well as activated DOX. The irradiated tumors had 6 times more DOX concentration than nearby control tumors. This in vivo proof of concept demonstrates the first preferential activation of a photocleavable prodrug in deep tumor tissue.

We report here the in vivo combined-modality imaging of multifunctional drug delivery nanoparticles. These dextran core-based stealth liposomal nanoparticles (nanosomes) contained doxorubicin, iron oxide for MRI contrast, and Bodipy for fluorescence. The particles were long-lived in vivo due to surface decoration with polyethylene glycol (PEG) and the incorporation of acetylated lipids which were UV cross-linked for physical stability. We developed a rodent dorsal skinfold window chamber which facilitated both MRI and non-destructive optical imaging of nanoparticle accumulation in the same tumors. Chamber tumors were genetically labeled with DsRed-2 that enabled the MR images, the red fluorescence of the tumor, and the blue fluorescence of the nanoparticles to be co-localized. The nanoparticle design and MR imaging developed with the window chamber were then extended to orthotopic pancreatic tumors expressing DsRed-2. The tumors were MR imaged using iron oxide-dextran liposomes and by fluorescence to demonstrate the deep imaging capability of these nanoparticles.

BackgroundDeposition of α-synuclein and neuroinflammation are key pathological features of Parkinson’s disease (PD). There is no cure for the disease; however, targeting the pathological features might be available to modulate the disease onset and progression. Hypoestoxide (HE) has been demonstrated as a NF-κB modulator, thereby acting as a potential anti-inflammatory and anti-cancer drug.MethodsIn order to assess the effect of HE in a mouse model of PD, mThy1-α-syn transgenic mice received intraperitoneal (IP) injections of either vehicle or HE (5 mg/kg) daily for 4 weeks.ResultsTreatment of HE decreased microgliosis, astrogliosis, and pro-inflammatory cytokine gene expression in α-syn transgenic mice. HE administration also prevented the loss of dopaminergic neurons and ameliorated motor behavioral deficits in the α-syn transgenic mice, and α-synuclein pathology was significantly reduced by treatment of HE. In addition, increased levels of nuclear phosphorylated NF-κB in the frontal cortex of α-syn transgenic mice were significantly reduced by HE administration.ConclusionsThese results support the therapeutic potential of HE for PD and other α-synuclein-related diseases.Electronic supplementary materialThe online version of this article (doi:10.1186/s12974-015-0455-9) contains supplementary material, which is available to authorized users.

Aβ accumulation plays a central role in the pathogenesis of Alzheimer's disease (AD). Recent studies suggest that process of Aβ nucleated polymerization is essential for Aβ fibril formation, pathology spreading and toxicity. Therefore, targeting this process represent an effective therapeutic strategy to slow or block disease progression. To discover compounds that might interfere with the Aβ seeding capacity, toxicity and pathology spreading, we screened a focused library of FDA-approved drugs in vitro using a seeding polymerization assay and identified small molecule inhibitors that specifically interfered with Aβ seeding-mediated fibril growth and toxicity. Mitoxantrone, bithionol and hexachlorophene were found to be the strongest inhibitors of fibril growth and protected primary cortical neuronal cultures against Aβ-induced toxicity. Next, we assessed the effects of these three inhibitors in vivo in the mThy1-APPtg mouse model of AD (8-month-old mice). We found that mitoxantrone and bithionol, but not hexachlorophene, stabilized diffuse amyloid plaques, reduced the levels of Aβ42 oligomers and ameliorated synapse loss, neuronal damage and astrogliosis. Together, our findings suggest that targeting fibril growth and Aβ seeding capacity constitutes a viable and effective strategy for protecting against neurodegeneration and disease progression in AD.