Mixing of oppositely charged amphiphilic molecules (catanionic mixing) offers an attractive strategy to produce morphologies different from those formed by individual molecules. We report here on the use of catanionic mixing of anticancer drug amphiphiles to construct multiwalled nanotubes containing a fixed and high drug loading. We found that the molecular mixing ratio, the solvent composition, the overall drug concentrations, as well as the molecular design of the studied amphiphiles are all important experimental parameters contributing to the tubular morphology. We believe these results demonstrate the remarkable potential that anticancer drugs could offer to self-assemble into discrete nanostructures and also provide important insight into the formation mechanism of nanotubes by catanionic mixtures. Our preliminary animal studies reveal that the CPT nanotubes show significantly prolonged retention time in the tumor site after intratumoral injection.

Treatment of Central Nervous System (CNS) disorders still remains a major clinical challenge. The Blood-brain-barrier (BBB), known as the major hindrance, greatly limits therapeutics penetration into the brain. Moreover, even though some therapeutics can cross BBB based on their intrinsic properties or via the use of proper nanoscale delivery vehicles, their therapeutic efficacy is still often limited without the specific uptake of drugs by the cancer or disease-associated cells. As more studies have started to elucidate the pathological roles of major cells in the CNS (for example, microglia, neurons, and astrocytes) for different disorders, nanomedicines that can enable targeting of specific cells in these diseases may provide great potential to boost efficacy. In this review, we aim to briefly cover the pathological roles of endothelial cells, microglia, tumor-associated microglia/macrophage, neurons, astrocytes, and glioma in CNS disorders and to highlight the recent advances in nanomedicines that can target specific disease-associated cells. Furthermore, we summarized some strategies employed in nanomedicine to achieve specific cell targeting or to enhance the drug neuroprotective effects in the CNS. The specific targeting at the cellular level by nanotherapy can be a more precise and effective means not only to enhance the drug availability but also to reduce side effects.

B-cell lymphomas continue to occur with a high incidence. The chimeric antibody known as Rituximab (Rituxan) has become a vital therapy for these patients. Rituximab induces cell death via binding and clustering of the CD20 receptor by Fcγ expressing effector cells. Because of the limited mobility of effector cells, it may be advantageous to cluster CD20 directly using multivalent nanostructures. To explore this strategy, this manuscript introduces a nanoparticle that assembles from a fusion between a single chain antibody and a soluble protein polymer. These hybrid proteins express in Escherichia coli and do not require bioconjugation between the antibody and a substrate. Surprisingly a fusion between an anti-CD20 single chain antibody and a soluble protein polymer assemble worm-like nanostructures, which were characterized using light scattering and cryogenic transmission electron microscopy. These nanoworms competitively bind CD20 on two B-cell lymphoma cell lines, exhibit concentration-dependent induction of apoptosis, and induce apoptosis better than Rituximab alone. Similar activity was observed in vivo using a non-Hodgkin lymphoma xenograft model. In comparison to Rituximab, systemic nanoworms significantly slowed tumor growth. These findings suggest that hybrid nanoworms targeted at CD20 may be useful treatments for B-cell related malignancies. Because of the ubiquity of antibody therapeutics, related nanoworms may have uses against other molecular targets.

Hypothermic circulatory arrest (HCA) provides neuroprotection during cardiac surgery but entails an ischemic period that can lead to excitotoxicity, neuroinflammation, and subsequent neurologic injury. Hydroxyl polyamidoamine (PAMAM) dendrimers target activated microglia and damaged neurons in the injured brain, and deliver therapeutics in small and large animal models. We investigated the effect of dendrimer size on brain uptake and explored the pharmacokinetics in a clinically-relevant canine model of HCA-induced brain injury. Generation 6 (G6, ~6.7 nm) dendrimers showed extended blood circulation times and increased accumulation in the injured brain compared to generation 4 dendrimers (G4, ~4.3 nm), which were undetectable in the brain by 48 hrs after final administration. High levels of G6 dendrimers were found in cerebrospinal fluid (CSF) of injured animals with a CSF/serum ratio of ~20% at peak, a ratio higher than that of many neurologic pharmacotherapies already in clinical use. brain penetration (measured by drug CSF/serum level) of G6 dendrimers correlated with the severity of neuroinflammation observed. G6 dendrimers also showed decreased renal clearance rate, slightly increased liver and spleen uptake compared to G4 dendrimers. These results, in a large animal model, may offer insights into the potential clinical translation of dendrimers.

Background Neuroinflammation mediated by microglia plays a central role in the pathogenesis of perinatal/neonatal brain injury, including cerebral palsy (CP). Therapeutics mitigating neuroinflammation potentially provide an effective strategy to slow the disease progression and rescue normal brain development. Building on our prior results which showed that a generation-4 hydroxyl poly(amidoamine) (PAMAM) dendrimer could deliver drugs specifically to activated glia from systemic circulation, we evaluated the sustained efficacy of a generation-6 (G6) hydroxyl-terminated PAMAM dendrimer that showed a longer blood circulation time and increased brain accumulation. N-acetyl-l-cysteine (NAC), an antioxidant and anti-inflammatory agent that has high plasma protein binding properties and poor brain penetration, was conjugated to G6-PAMAM dendrimer-NAC (G6D-NAC). The efficacy of microglia-targeted G6D-NAC conjugate was evaluated in a clinically relevant rabbit model of CP, with a mild/moderate CP phenotype to provide a longer survival of untreated CP kits, enabling the assessment of sustained efficacy over 15 days of life. Methods G6D-NAC was conjugated and characterized. Cytotoxicity and anti-inflammatory assays were performed in BV-2 microglial cells. The efficacy of G6D-NAC was evaluated in a rabbit model of CP. CP kits were randomly divided into 5 groups on postnatal day 1 (PND1) and received an intravenous injection of a single dose of PBS, or G6D-NAC (2 or 5 mg/kg), or NAC (2 or 5 mg/kg). Neurobehavioral tests, microglia morphology, and neuroinflammation were evaluated at postnatal day 5 (PND5) and day 15 (PND15). Results A single dose of systemic ‘long circulating’ G6D-NAC showed a significant penetration across the impaired blood-brain-barrier (BBB), delivered NAC specifically to activated microglia, and significantly reduced microglia-mediated neuroinflammation in both the cortex and cerebellum white matter areas. Moreover, G6D-NAC treatment significantly improved neonatal rabbit survival rate and rescued motor function to nearly healthy control levels at least up to 15 days after birth (PND15), while CP kits treated with free NAC died before PND9. Conclusions Targeted delivery of therapeutics to activated microglia in neonatal brain injury can ameliorate pro-inflammatory microglial responses to injury, promote survival rate, and improve neurological outcomes that can be sustained for a long period. Appropriate manipulation of activated microglia enabled by G6D-NAC can impact the injury significantly beyond inflammation.