Roberto Palomba

Despite a few clinical successes, the efficacy of cancer nanomedicines remains limited by rapid clearance by the mononuclear phagocytic system and poor permeation across the abnormal tumor vasculature. We previously showed that methyl palmitate nanoparticles (MPN) can safely and reversibly inhibit the phagocytic activity of immune cells for several hours, thereby improving tumor accumulation and the efficacy of systemically administered nanomedicines. Here, we demonstrate that, on a shorter time scale, MPN can induce vasodilation, introducing an additional mechanism to enhance the accumulation of therapeutic agents within malignant tissue. Upon internalization by macrophages and endothelial cells, MPN could potentially trigger the release of endogenous nitric oxide (NO), a key mediator of vasodilation, in a concentration-, and time-dependent manner. Following MPN administration, raster-scanning optoacoustic mesoscopy (RSOM) revealed vasodilation across multiple tissues, with a strong effect observed in tumors. To assess enhanced tumor accumulation, we injected 70 kDa fluorescent dextran and demonstrated via histology a markedly increased fluorescence signal exclusively in MPN-treated tumors compared to controls 24 h later. In addition, positron emission tomography (PET) imaging of 89Zr-labeled Feraheme nanoparticles showed significantly greater tumor accumulation after a 15 min MPN pretreatment. Finally, general serum biochemistry panels and histological analyses of major organs in healthy mice revealed that MPN did not induce observable short-term toxicity under the tested conditions (single or repeated MPN dosing). Overall, this study demonstrates that MPN-induced vasodilation occurring within minutes enhances intratumoral deposition of macromolecules and small nanoparticles. Together with their longer-term effects on phagocytosis inhibition, these findings indicate that MPN can improve therapeutic delivery through complementary, time-dependent mechanisms that increase tumor perfusion and vascular permeability.

Despite a few clinical successes, the efficacy of cancer nanomedicines remains limited by rapid clearance by the mononuclear phagocytic system and poor permeation across the abnormal tumor vasculature. We previously showed that methyl palmitate nanoparticles (MPN) can safely and reversibly inhibit the phagocytic activity of immune cells for several hours, thereby improving tumor accumulation and the efficacy of systemically administered nanomedicines. Here, we demonstrate that, on a shorter time scale, MPN can induce vasodilation, introducing an additional mechanism to enhance the accumulation of therapeutic agents within the malignant tissue. Upon internalization by macrophages and endothelial cells, MPN trigger the release of endogenous nitric oxide (NO), a key mediator of vasodilation, in a concentration-, and time-dependent manner. Following MPN administration, raster-scanning optoacoustic mesoscopy (RSOM) revealed vasodilation across multiple tissues, with the strongest effect observed in tumors. To assess enhanced tumor accumulation, we injected 70 kDa fluorescent dextran and demonstrated via histology a markedly increased fluorescence signal exclusively in MPN-treated tumors compared to controls 24 hours later. In addition, positron emission tomography (PET) imaging of ⁸⁹ Zr-labeled clinical iron oxide nanoparticles (Feraheme) showed significantly greater tumor accumulation after a 15-minute MPN pretreatment. Finally, general serum biochemistry panels and histological analyses of major organs in healthy mice revealed no toxicity following either single or repeated MPN dosing. Overall, this study demonstrates that MPN-induced vasodilation occurring within minutes enhances intra-tumoral deposition of macromolecules and small nanoparticles. Together with their longer-term effects on phagocytosis inhibition, these findings indicate that MPN can improve therapeutic delivery through complementary, time-dependent mechanisms that increase tumor perfusion and vascular permeability.

Osteoarthritis (OA) is the most common joint disorder, characterized by a vicious cycle of synovial inflammation and cartilage degradation. Intra-articular injection of hyaluronic acid (HA)-based products, one of the currently available treatments, provides only temporary symptomatic relief without addressing the underlying inflammation. Here, we engineered several configurations of 20 × 5 μm square-shaped HA-based hydrogel microparticles (μHA) by photopolymerizing HA-methacrylate chains within a sacrificial template. The μHA mechano-pharmacological properties were tuned by adjusting the HA concentration, molecular weight, and degree of methacrylation, resulting in microparticles with a Young's modulus ranging from a few tens (30 kPa) to a few hundred (200 kPa) kilopascals; a structure stable for over a month under oxidative stress conditions; and reduced friction in simulated synovial fluids. Under H₂O₂-induced oxidative conditions, μHA decreased the production of proinflammatory cytokines (IL-6, IL-1β, and TNF-α) in human chondrocytes to basal levels. In a three-dimensional OA cartilage model, μHA reduced glycosaminoglycan release and matrix metalloproteinase-13 activity, demonstrating chondroprotective effects. In a rigorous murine model of early-stage post-traumatic OA, a single intra-articular injection of μHA lowered proinflammatory gene expression in the synovium to basal levels. In summary, μHA offers a drug-free approach to managing OA by enhancing lubrication and reducing inflammation, providing a sustained therapeutic activity over several weeks.

Lipid nanoparticles (LNP) have been extensively studied for their ability to encapsulate and protect RNA molecules from degradation. More recently, a few studies have begun to explore their applications as carriers for brain drug delivery via various administration routes. Nose-to-brain delivery represents a promising alternative to both invasive local injections and systemic administration, offering the possibility to bypass the blood-brain barrier and directly access the brain, achieve rapid absorption, reduce systemic exposure, and allow for ease of administration. In order to evaluate the viability of this alternative route, it is essential to acquire a better understanding of the intraneuronal mass transport of LNP, particularly in terms of how effectively and efficiently they deliver their payloads from the periphery to neuronal cell bodies. However, most previous studies have focused primarily on the delivery vector itself rather than on the fate of the transported cargo. In this study, we investigate the retrograde trafficking of nucleic acid-loaded LNP in primary cortical neurons, focusing on the transport of both the particle and the payload. Three distinct LNP were formulated to characterize different aspects of their interaction with the cells, with the major LNP player of this study containing a red-fluorescent Rhodamine B-tagged lipid and a green fluorescently FAM-tagged RNA. Flow cytometry was used to document LNP uptake by primary cortical neurons over time. Additionally, confocal microscopy was then used to investigate the colocalization of LNP and RNA after a conventional 2D culture treatment. As a final step, a compartmentalized chip that separates the somal and the axonal regions of cortical neurons was used to study the intraneuronal dynamics of LNP and their cargo. In this second setup, LNP were selectively administered at the axonal compartment, and the fluorescent signals from the vector (red) and the payload (green) were imaged through time-lapse microscopy. The progressive accumulation of RNA found at cellular bodies also in the absence of the red signal suggested an efficient retrograde transport of the LNP payload toward the soma. Comprehensively, this work demonstrates that primary cortical neurons are capable of efficiently uptaking LNP and of intracellularly transporting both LNP and their RNA cargo. Interestingly, a different colocalization trend (LNP-RNA) emerged depending on the followed setup. Localized axonal transfection appeared to favor dissociation of RNA from the LNP and subsequent accumulation at the soma. Overall, our work provides a fundamental in vitro proof of concept of the RNA delivery to the cellular bodies of primary cortical neurons via the retrograde transport of LNP vectors administered at the axonal termini. This finding, together with the image-analysis-based quantification of the RNA accumulation described in our work, paves the way for future studies aimed at designing lipid-based nanoparticles for RNA therapeutic delivery to the brain via peripheral administration.

Recombinant tissue-type plasminogen activator (tPA) is the only approved thrombolytic drug for acute ischemic stroke, a condition associated with severe disabilities and high mortality. However, when the blood-brain barrier (BBB) is damaged, tPA can exacerbate cerebral injury and increase the risk of hemorrhagic transformation, limiting its use to a small subset of patients. To address this challenge and minimize extravascular accumulation, we combined tPA with micrometer-sized particles (DPN). We then tested their safety and neuroprotective effects. After a 1 h transient occlusion of the middle cerebral artery, free tPA, tPA-DPN, or saline was administered to assess mice survival, neurological behavior, and infarcted area extent. Free-tPA exacerbated brain damage, resulting in a modest 10% survival rate at 24 h post intervention. Conversely, tPA-DPN displayed a far better prognosis, with a 75% survival rate comparable to that of saline. No statistical differences were documented between tPA-DPN and saline for the Activity Score and the Neurological Severity Score. tPA-DPN did not increase lesion volume or BBB permeability, unlike free-tPA, which led to an over 2-fold enlarged lesion volume and 50% higher BBB permeability. The safety profile of tPA-DPN is attributed to the robust conjugation of tPA onto DPN and the lack of DPN extravasation, resulting in negligible cerebrovascular damage of free tPA and glial and neuron impairment. The vascular confinement of tPA linked to microscopic particles reduces drug side effects and represents a valuable strategy for safe and effective tPA delivery, even in the postacute stroke phase.

Osteoarthritis (OA) is a debilitating joint disease characterized by cartilage degradation, leading to pain and functional impairment. A key contributor to OA progression is the decline in cartilage lubrication. In physiological conditions, synovial fluid (SF) macromolecules like hyaluronic acid (HA), phospholipids, and lubricin play a crucial role in the boundary lubrication of articular cartilage. In early OA, cartilage damage triggers inflammation, altering SF composition and compromising the lubrication layer. This increases friction between mating interfaces, worsening cartilage degradation and local inflammation. Therefore, early-stage restoration of lubrication (by injecting in the joint different classes of compounds and formulations) could alleviate, and potentially reverse, OA progression. In the light of this, a broad variety of lubricants have been investigated for their ability to reduce friction in OA joints and promote cartilage repair in clinical and preclinical studies. This review examines recent advancements in lubricant-based therapy for OA, focusing on natural, bioinspired, and alternative products. Starting from the currently applied therapy, mainly based on natural lubricants as HA, we will present their modified versions, either in hydrogel form or with specific biomimetic moieties with the aim of reducing their clearance from the joint and of enhancing their lubricating properties. Finally, the most advanced and recent formulation, represented by alternative strategies, will be proposed. Particular emphasis will be placed on those ones involving new types of hydrogels, microparticles, nanoparticles, and liposomes, which are currently under investigation in preclinical studies. The potential application of particles and liposomes could foster the transition from natural lubricants to Drug Delivery Systems (DDSs) with lubricant features; transition which could provide more complete OA treatments, by simultaneously providing lubrication replacement and sustained release of different payloads and active agents directly at the joint level. Within each category, we will examine relevant preclinical studies, highlighting challenges and future prospects.

Editorial: Novel approaches aiming to overcome current nanomedicine limitations

Surface tension provides microbubbles (MB) with a perfect spherical shape. Here, we demonstrate that MB can be engineered to be nonspherical, endowing them with unique features for biomedical applications. Anisotropic MB were generated via one-dimensionally stretching spherical poly(butyl cyanoacrylate) MB above their glass transition temperature. Compared to their spherical counterparts, nonspherical polymeric MB displayed superior performance in multiple ways, including i) increased margination behavior in blood vessel–like flow chambers, ii) reduced macrophage uptake in vitro, iii) prolonged circulation time in vivo, and iv) enhanced blood–brain barrier (BBB) permeation in vivo upon combination with transcranial focused ultrasound (FUS). Our studies identify shape as a design parameter in the MB landscape, and they provide a rational and robust framework for further exploring the application of anisotropic MB for ultrasound-enhanced drug delivery and imaging applications.