Covalent nano delivery systems for selective imaging and treatment of brain tumors

Noninvasive Brain Tumor Imaging Using Red Emissive Carbonized Polymer Dots across the Blood-Brain Barrier

Surgical resection is recognized as a mainstay in the therapy of malignant brain tumors. In clinical practice, however, surgeons face great challenges in identifying the tumor boundaries due to the infiltrating and heterogeneous nature of neoplastic tissues. Contrast-enhanced magnetic resonance imaging (MRI) is extensively used for defining the brain tumor in clinic. Disappointingly, the commercially available (MR) contrast agents show the transient circulation lifetime and poor blood-brain barrier (BBB) permeability, which seriously hamper their abilities in tumor visualization. In this work, red fluorescent carbonized polymer dots (CPDs) were systematically investigated with respect to their BBB-penetration ability. In summary, CPDs possess long excitation/emission wavelengths, low toxicity, high photostability, and excellent biocompatibility. CPDs exhibit high internalization in glioma cells in time- and dose-dependent procedures, and internalized CPDs locate mainly in endolysosomal structures. In vitro and in vivo studies confirmed the BBB permeability of CPDs, contributing to the early stage diagnosis of brain disorders and the noninvasive visualization of the brain tumor without compromised BBB. Furthermore, owing to the high tumor to normal tissue ratio of CPDs under ex vivo conditions, our nanoprobe holds the promise to guide brain-tumor resection by real-time fluorescence imaging during surgery.

The cluster [Re6Se8I6]3- penetrates biological membranes: drug-like properties for CNS tumor treatment and diagnosis

Tumorigenic cell lines are more susceptible to [Re₆Se₈I₆]^3- cluster-induced death than normal cells, becoming a novel candidate for cancer treatment. Still, the feasibility of using this type of molecules in human patients remains unclear and further pharmacokinetics analysis is needed. Using coupled plasma optical emission spectroscopy, we determined the Re-cluster tissue content in injected mice, as a biodistribution measurement. Our results show that the Re-cluster successfully reaches different tissues, accumulating mainly in heart and liver. In order to dissect the mechanism underlying cluster biodistribution, we used three different experimental approaches. First, we evaluate the degree of lipophilicity by determining the octanol/water partition coefficient. The cluster mostly remained in the octanol fraction, with a coefficient of 1.86 ± 0.02, which indicates it could potentially cross cell membranes. Then, we measured the biological membrane penetration through a parallel artificial membrane permeability assays (PAMPA) assay. The Re-cluster crosses the artificial membrane, with a coefficient of 122 nm/s that is considered highly permeable. To evaluate a potential application of the Re-cluster in central nervous system (CNS) tumors, we analyzed the cluster's brain penetration by exposing cultured blood-brain-barrier (BBB) cells to increasing concentrations of the cluster. The Re-cluster effectively penetrates the BBB, reaching nearly 30% of the brain side after 24 h. Thus, our results indicate that the Re-cluster penetrates biological membranes reaching different target organs-most probably due to its lipophilic properties-becoming a promising anti-cancer drug with high potential for CNS cancer's diagnosis and treatment.

Drug Delivery in Cancer Therapy, Quo Vadis?

The treatment of malignancies has undergone dramatic changes in the past few decades. Advances in drug delivery techniques and nanotechnology have allowed for new formulations of old drugs, so as to improve the pharmacokinetics, to enhance accumulation in solid tumors, and to reduce the significant toxic effects of these important therapeutic agents. Here, we review the published clinical data in cancer therapy of several major drug delivery systems, including targeted radionuclide therapy, antibody-drug conjugates, liposomes, polymer-drug conjugates, polymer implants, micelles, and nanoparticles. The clinical outcomes of these delivery systems from various phases of clinical trials are summarized. The success and limitations of the drug delivery strategies are discussed based on the clinical observations. In addition, the challenges in applying drug delivery for efficacious cancer therapy, including physical barriers, tumor heterogeneity, drug resistance, and metastasis, are discussed along with future perspectives of drug delivery in cancer therapy. In doing so, we intend to underscore that efficient delivery of cancer therapeutics to solid malignancies remains a major challenge in cancer therapy, and requires a multidisciplinary approach that integrates knowledge from the diverse fields of chemistry, biology, engineering, and medicine. The overall objective of this review is to improve our understanding of the clinical fate of commonly investigated drug delivery strategies, and to identify the limitations that must be addressed in future drug delivery strategies, toward the pursuit of curative therapies for cancer.

Recent advances in cell-mediated nanomaterial delivery systems for photothermal therapy

Cell-mediated “Trojan Horse” delivery vehicles overcome the drug delivery barriers to transport nano-agents enhancing the efficiency of photothermal therapy.