RNA is emerging as a potential therapeutic modality for the treatment of incurable diseases. Despite intense research, the advent to clinical utility remains compromised by numerous biological barriers, hence, there is a need for sophisticated delivery vehicles. In this aspect, lipid nanoparticles (LNPs) are the most advanced platform among nonviral vectors for gene delivery. In this review, we critically review the literature and the reasons for ineffective delivery beyond the liver. We discuss the toxicity issues associated with permanently charged cationic lipids and then turn our attention to next-generation ionizable cationic lipids. These lipids exhibit reduced toxicity and immunogenicity and undergo ionization under the acidic environment of the endosome to release the encapsulated payload to their site of action in the cytosol. Finally, we summarize recent achievements in therapeutic nucleic acid delivery and report on the current status of clinical trials using LNP and the obstacles to clinical translation.

Mantle cell lymphoma (MCL) is an aggressive and incurable mature B cell neoplasm. The current treatments are based on chemotherapeutics and new class of drugs (e.g. Ibrutinib®), which in most cases ends with tumor resistance and relapse. Therefore, further development of novel therapeutic modalities are needed. Exosomes are natural extracellular vesicles, which play an important role in intercellular communication. The specificity of exosome uptake by different target cells remains unknown. In this study, we observed that MCL exosomes are taken up rapidly and preferentially by MCL cells. Only minor fraction of exosomes was internalized into T-cell leukemia and bone marrow stroma cell lines, when these cells were co-cultured with MCL cells. Moreover, MCL patients’ exosomes were taken up by both healthy and patients’ B-lymphocytes with no apparent internalization to T lymphocytes and NK cells. Exosome internalization was not inhibited by specific siRNA against caveolin1 and clathrin but was found to be mediated by cholesterol-dependent pathway. These findings demonstrate natural specificity of exosomes to B-lymphocytes and ultimately might be used for therapeutic intervention in B cells malignancies.

We discuss the state of the art and innovative micro- and nanoscale technologies that are finding niches and opening up new opportunities in medicine, particularly in diagnostic and therapeutic applications. We take the design of point-of-care applications and the capture of circulating tumor cells as illustrative examples of the integration of micro- and nanotechnologies into solutions of diagnostic challenges. We describe several novel nanotechnologies that enable imaging cellular structures and molecular events. In therapeutics, we describe the utilization of micro- and nanotechnologies in applications including drug delivery, tissue engineering, and pharmaceutical development/testing. In addition, we discuss relevant challenges that micro- and nanotechnologies face in achieving cost-effective and widespread clinical implementation as well as forecasted applications of micro- and nanotechnologies in medicine.

Lyophilized unilamellar liposomes (ULV), the dosage form of choice for shelf-life, revert upon reconstitution to the larger multilamellar liposomes (MLV), which is detrimental to the many carrier-mediated therapies that require small particles. High doses of sugars such as trehalose, sucrose and others, included in the original formulations for cryoprotection, were shown to prevent the conversion to MLV. In this study we set out to test whether hyaluronan (HA), the surface-bound ligand in our previously developed targeted bioadhesive liposomes (BAL), can also act as a cryoprotectant. The studies included structural and physicochemical characterization of original and reconstituted hyaluronan-ULV (HA-ULV). For each HA-ULV, similar regular ULV (RL-ULV) served as controls. Four properties were tested: particle size, zeta potential, encapsulation efficiency and half-life of drug release (tau(1/2)), for three drugs-chloramphenicol (CAM), vinblastine (VIN) and mitomycin C (MMC). Encapsulation efficiencies of the original systems were quite alike for similar RL-ULV and HA-ULV ranging from 25% to 70%. All systems acted as sustained-release drug depots, tau(1/2) ranging from 1.3 to 5.3 days. Drug species and lipid composition were the major determinants of encapsulation and release magnitudes. By all tests, as anticipated, lyophilization generated significant changes in the reconstituted RL-ULV: 17-fold increase in diameter; tripling of zeta potential; 25-60% drop in encapsulation efficiencies; 25-30% decrease in tau(1/2). In contrast, the reconstituted HA-ULV retained the same dimensions, zeta potentials, encapsulation efficiencies and tau(1/2) of the original systems. These data clearly show HA to be a cryoprotectant, adding another clinically relevant advantage to HA-BAL. We propose that, like the sugars, HA cryoprotects by providing substitute structure-stabilizing H-bonds.

Resistance to anticancer drugs is considered a major cause of chemotherapy failure. One of the major mediators of resistance is the multidrug extrusion pump protein, P-glycoprotein (P-gp), an ATP-binding cassette (ABC) transporter with broad substrate specificity. In order to bypass this drug resistance mechanism, we have devised phospholipid-based nanoparticle clusters coated with the glycosaminoglycan hyaluronan, the major ligand of CD44, which is upregulated and undergoes different splice variations in many types of cancer cells. These particles, termed glycosaminoglycan particle nanoclusters or gagomers (GAGs), were self-assembled into ∼500 nm diameter clusters, with zeta-potential values of ∼-70 mV. Flow cytometry analysis provided evidence that, unlike free doxorubicin (DOX), a model chemotherapy, DOX entrapped in the GAGs (DOX-GAGs) accumulated in P-gp-overexpressing human ovarian adenocarcinoma cell line and dramatically decreased cell viability, while drug-free GAGs and the commercially available drug DOXIL (PEGylated liposomal DOX) did not produce therapeutic benefit. Furthermore, by using RNA interference strategy, we showed that DOX-GAGs were able to overcome the P-gp-mediated resistant mechanism of these cells. Most importantly, DOX-GAGs showed a superior therapeutic effect over free DOX in a resistant human ovarian adenocarcinoma mouse xenograft model. Taken together, these results demonstrated that GAGs might serve as an efficient platform for delivery of therapeutic payloads by bypassing P-gp-mediated multidrug resistance.