Intracellular Cargo Research Articles

No hype in hyperspace

Targeted transport of intracellular vesicular cargos is mediated by myosin, dynein, and kinesin molecular motors operating on actin and microtubule cytoskeletal filaments (1–3). In this issue of Biophysical Journal, a new and powerful method is introduced to dynamically resolve the three-dimensional position and orientation of vesicles to help quantify and categorize these motions (4). The dynamic organization of the cytoskeleton is complex, with actin filaments and microtubules interacting throughout the cytoplasm.

STING-Mediated Lung Inflammation and Beyond.

Mendelian autoinflammatory diseases characterized by constitutive activation of the type I interferon pathway, the so-called type I interferonopathies, constitute a rapidly expanding group of inborn errors of immunity. Among the type I interferonopathies, STING-associated vasculopathy with onset in infancy (SAVI) and COPA syndrome were described in the last 6years, both manifesting a major inflammatory lung component associated with significant morbidity and increased mortality. There is striking clinical and histopathological overlap between SAVI and COPA syndrome, although distinct features are also present. Of note, there is a remarkably high frequency of clinical non-penetrance among individuals harboring pathogenic COPA mutations. SAVI is caused by, principally heterozygous, gain-of-function mutations in STING1 (previously referred to as TMEM173) encoding STING, a key adaptor of the interferon signaling pathway induced by DNA. COPA syndrome results from heterozygous dominant-negative mutations in the coatomer protein subunit alpha, forming part of a complex involved in intracellular cargo protein transport between the Golgi and the endoplasmic reticulum (ER). Of importance, a role for COPA in regulating the trafficking of STING, an ER-resident protein which translocates to the Golgi during the process of its activation, was recently defined, thereby possibly explaining some aspects of the phenotypic overlap between SAVI and COPA syndrome. Here, we review the expanding phenotype of these diseases, highlighting common as well as specific features, and recent advances in our understanding of STING biology that have informed therapeutic decision-making in both conditions. Beyond these rare Mendelian disorders, DNA sensing through STING is likely relevant to the pathology of several diseases associated with lung inflammation, including systemic lupus erythematosus, dermatomyositis, environmental toxin exposure, and viral infection.

Engineered myosins drive filopodial transport.

Engineered, light-inducible artificial myosin motors enable selective and direct manipulation of filopodial extensions and provide refined tools to control intracellular cargo transport in vivo.

Cell-penetrating peptides in the intracellular delivery of viral nanoparticles.

Cell-penetrating peptides (CPPs) are a promising tool for the intracellular delivery of cargo. Due to their ability to cross membranes while also cotransporting various cargoes, they offer great potential for biomedical applications. Several CPPs have been derived from viral proteins with natural roles in the viral replication cycle that require them to breach or fuse to cellular membranes. Additionally, the ability of viruses to cross membranes makes viruses and virus-based particles a convenient model for research on nanoparticle delivery and nanoparticle-mediated gene therapy. In this chapter, we aim to characterize CPPs derived from both structural and nonstructural viral proteins. Their function as enhancers of viral infection and transduction by viral nanoparticles as well as the main features of viral CPPs employed in intracellular cargo delivery are summarized to emphasize their potential use in nanomedicine.

Calixarene-decorated liposomes for intracellular cargo delivery.

Amphiphilic calix[4]arenes, functionalized with guanidinium groups, are used to decorate the outer surface of liposomes and significantly improve the cellular uptake of a cargo compared to plain liposomes. The improved uptake is elicited and mediated by the interaction between the cationic polar heads of the macrocycle units embedded in the liposome bilayer and anionic heparan-sulfate proteoglycans surrounding the exterior of cells.

Extreme first-passage times for random walks on networks.

Many biological, social, and communication systems can be modeled by "searchers" moving through a complex network. For example, intracellular cargo is transported on tubular networks, news and rumors spread through online social networks, and the rapid global spread of infectious diseases occurs through passengers traveling on the airport network. To understand the timescale of search (or "transport" or "spread"), one commonly studies the first-passage time (FPT) of a single searcher (or "transporter" or "spreader") to a target. However, in many scenarios the relevant timescale is not the FPT of a single searcher to a target, but rather the FPT of the fastest searcher to a target out of many searchers. For example, many processes in cell biology are triggered by the first molecule to find a target out of many, and the time it takes an infectious disease to reach a particular city depends on the first infected traveler to arrive out of potentially many infected travelers. Such fastest FPTs are called extreme FPTs. In this paper, we study extreme FPTs for a general class of continuous-time random walks on networks (which includes continuous-time Markov chains). In the limit of many searchers, we find explicit formulas for the probability distribution and all the moments of the kth fastest FPT for any fixed k≥1. These rigorous formulas depend only on network parameters along a certain geodesic path(s) from the starting location to the target since the fastest searchers take a direct route to the target. Hence, the extreme FPTs are independent of the details of the network outside this geodesic(s) and can be drastically faster and less variable than conventional FPTs of single searchers. Furthermore, our results allow one to estimate if a particular system is in a regime characterized by fast extreme FPTs. We also prove similar results for mortal searchers on a network that are conditioned to find the target before a fast inactivation time. We illustrate our results with numerical simulations and uncover potential pitfalls of modeling diffusive or subdiffusive processes involving extreme statistics. In particular, we find that the many searcher limit does not commute with the diffusion limit for random walks, and thus care must be taken when choosing spatially continuous versus spatially discrete diffusion models.

Virus Mimetic Shell-Sheddable Chitosan Micelles for siVEGF Delivery and FRET-Traceable Acid-Triggered Release.

Targeting vascular endothelial growth factor (VEGF) using small interfering RNA (siVEGF) has shown great potential in inhibiting the growth, proliferation, and migration of tumors by reducing the proliferation of blood vessels. On the basis of bionic principles, a novel pH-responsive and virus mimetic shell-sheddable chitosan (CS) micelles (CMs) as siRNA delivery system was introduced in this study. The cyclo(Arg-Gly-Asp-d-Phe-Lys) (cRGD) modified poly(enthylene glycol) (PEG) was conjugated to the HA2 modified chitosan via a hydrazone linkage (cRGD-PEG-Hz-CS-HA2). The cRGD-PEG-Hz-CS-HA2 conjugate could form micelles by interacting with the complex of octanal, Boc-l-lysine, and 9-d-arginine (9R) (octyl-Lys-9R) as a hydrophodic core forming agent, termed as cRGD-PEG-Hz-CS-HA2/octyl-Lys-9R (abbreviated as cRGD/HA2/Hz-CMs).The CMs modified with cRGD can accurately target glioma cells (U87MG cells) with high expression of αvβ3. The payloads of siVEGF were packed into the core of cRGD/HA2/Hz-CMs via electrostatic interaction and hydrophobic interaction. The intracellular cargo release was achieved by the pH-responsive lysis of the hydrazone bond in acidic environment of endosome. Moreover, the exposed HA2, as a pH-sensitive membrane-disruptive peptide, assists the escape of the carriers from endosome into cytosol. In addition, cRGD/HA2/Hz-CMs can effectively deliver siVEGF and silence VEGF gene expression in U87MG cells, leading to the significant tumor growth inhibition. This study demonstrates that cRGD/HA2/Hz-CMs can deliver and release siVEGF in a controlled manner, which was traced by the fluorescence resonance energy transfer (FRET) system in order to achieve RNAi-based anti-angiogenic treatment of cancer in vivo.

Identifying Differing Intracellular Cargo Release Mechanisms by Monitoring In Vitro Drug Delivery from MOFs in Real Time

SummaryMetal-organic frameworks (MOFs) have been proposed as biocompatible candidates for the targeted intracellular delivery of chemotherapeutic payloads, but the site of drug loading and subsequent effect on intracellular release is often overlooked. Here, we analyze doxorubicin delivery to cancer cells by MIL-101(Cr) and UiO-66 in real time. Having experimentally and computationally verified that doxorubicin is pore loaded in MIL-101(Cr) and surface loaded on UiO-66, different time-dependent cytotoxicity profiles are observed by real-time cell analysis and confocal microscopy. The attenuated release of aggregated doxorubicin from the surface of Dox@UiO-66 results in a 12 to 16 h induction of cytotoxicity, while rapid release of pore-dispersed doxorubicin from Dox@MIL-101(Cr) leads to significantly higher intranuclear localization and rapid cell death. In verifying real-time cell analysis as a versatile tool to assess biocompatibility and drug delivery, we show that the localization of drugs in (or on) MOF nanoparticles controls delivery profiles and is key to understanding in vitro modes of action.

Renewal Reward Perspective on Linear Switching Diffusion Systems in Models of Intracellular Transport

In many biological systems, the movement of individual agents is characterized having multiple qualitatively distinct behaviors that arise from a variety of biophysical states. For example, in cells the movement of vesicles, organelles, and other intracellular cargo is affected by their binding to and unbinding from cytoskeletal filaments such as microtubules through molecular motor proteins. A typical goal of theoretical or numerical analysis of models of such systems is to investigate effective transport properties and their dependence on model parameters. While the effective velocity of particles undergoing switching diffusion dynamics is often easily characterized in terms of the long-time fraction of time that particles spend in each state, the calculation of the effective diffusivity is more complicated because it cannot be expressed simply in terms of a statistical average of the particle transport state at one moment of time. However, it is common that these systems are regenerative, in the sense that they can be decomposed into independent cycles marked by returns to a base state. Using decompositions of this kind, we calculate effective transport properties by computing the moments of the dynamics within each cycle and then applying renewal reward theory. This method provides a useful alternative large-time analysis to direct homogenization for linear advection–reaction–diffusion partial differential equation models. Moreover, it applies to a general class of semi-Markov processes and certain stochastic differential equations that arise in models of intracellular transport. Applications of the proposed renewal reward framework are illustrated for several case studies such as mRNA transport in developing oocytes and processive cargo movement by teams of molecular motor proteins.

Microfluidic production and characterization of biofunctionalized giant unilamellar vesicles for targeted intracellular cargo delivery

Lipid-based vesicles have found widespread applications in the life sciences, allowing for fundamental insights into membrane-based processes in cell biology and as carrier systems for drug delivery purposes. So far, mostly small unilamellar vesicles (SUVs) with diameters of ~100 nm have been applied as carrier systems for biomedical applications. Despite this progress, several systematic limitations have arisen due to SUV dimensions, e.g., the size and total amount of applicable cargo is limited. Giant unilamellar vesicles (GUVs) might offer a pragmatic alternative for efficient cargo delivery. However, due to the lack of reliable high-throughput production technologies for GUV-carrier systems, only little is known about their interaction with cells. Here we present a microfluidic-based mechanical droplet-splitting pipeline for the production of carrier-GUVs with diameters of ~2 μm. The technology developed allows for highly efficient cargo loading and unprecedented control over the biological and physicochemical properties of GUV membranes. By generating differently charged (between −31 and + 28 mV), bioligand-conjugated (e.g. with E-cadherin, NrCam and antibodies) and PEG-conjugated GUVs, we performed a detailed investigation of attractive and repulsive GUV-cell interactions. Fine-tuning of these interactions allowed for targeted cellular GUV delivery. Moreover, we evaluated strategies for intracellular GUV cargo release by lysosomal escape mediated by the pH sensitive lipid DOBAQ, enabling cytoplasmic transmission. The presented GUV delivery technology and the systematic characterization of associated GUV-cell interactions could provide a means for more efficient drug administration and will pave the way for hitherto impossible approaches towards a targeted delivery of advanced cargo such as microparticles, viruses or macromolecular DNA-robots.

Role of Autophagy in Lung Inflammation.

Autophagy is a cellular recycling system found in almost all types of eukaryotic organisms. The system is made up of a variety of proteins which function to deliver intracellular cargo to lysosomes for formation of autophagosomes in which the contents are degraded. The maintenance of cellular homeostasis is key in the survival and function of a variety of human cell populations. The interconnection between metabolism and autophagy is extensive, therefore it has a role in a variety of different cell functions. The disruption or dysfunction of autophagy in these cell types have been implicated in the development of a variety of inflammatory diseases including asthma. The role of autophagy in non-immune and immune cells both lead to the pathogenesis of lung inflammation. Autophagy in pulmonary non-immune cells leads to tissue remodeling which can develop into chronic asthma cases with long term effects. The role autophagy in the lymphoid and myeloid lineages in the pathology of asthma differ in their functions. Impaired autophagy in lymphoid populations have been shown, in general, to decrease inflammation in both asthma and inflammatory disease models. Many lymphoid cells rely on autophagy for effector function and maintained inflammation. In stark contrast, autophagy deficient antigen presenting cells have been shown to have an activated inflammasome. This is largely characterized by a TH17 response that is accompanied with a much worse prognosis including granulocyte mediated inflammation and steroid resistance. The cell specificity associated with changes in autophagic flux complicates its targeting for amelioration of asthmatic symptoms. Differing asthmatic phenotypes between TH2 and TH17 mediated disease may require different autophagic modulations. Therefore, treatments call for a more cell specific and personalized approach when looking at chronic asthma cases. Viral-induced lung inflammation, such as that caused by SARS-CoV-2, also may involve autophagic modulation leading to inflammation mediated by lung resident cells. In this review, we will be discussing the role of autophagy in non-immune cells, myeloid cells, and lymphoid cells for their implications into lung inflammation and asthma. Finally, we will discuss autophagy's role viral pathogenesis, immunometabolism, and asthma with insights into autophagic modulators for amelioration of lung inflammation.

The mechanochemistry of the kinesin-2 KIF3AC heterodimer is related to strain-dependent kinetic properties of KIF3A and KIF3C

KIF3AC is a mammalian neuron-specific kinesin-2 implicated in intracellular cargo transport. It is a heterodimer of KIF3A and KIF3C motor polypeptides which have distinct biochemical and motile properties as engineered homodimers. Single-molecule motility assays show that KIF3AC moves processively along microtubules at a rate faster than expected given the motility rates of the KIF3AA and much slower KIF3CC homodimers. To resolve the stepping kinetics of KIF3A and KIF3C motors in homo- and heterodimeric constructs and determine their transport potential under load, we assayed motor activity using interferometric scattering microscopy and optical trapping. The distribution of stepping durations of KIF3AC molecules is described by a rate (k1 = 11 s-1) without apparent kinetic asymmetry. Asymmetry was also not apparent under hindering or assisting mechanical loads in the optical trap. KIF3AC shows increased force sensitivity relative to KIF3AA yet is more capable of stepping against mechanical load than KIF3CC. Interestingly, the behavior of KIF3C mirrors prior studies of kinesins with increased interhead compliance. Microtubule gliding assays containing 1:1 mixtures of KIF3AA and KIF3CC result in speeds similar to KIF3AC, suggesting the homodimers mechanically impact each other's motility to reproduce the behavior of the heterodimer. Our observations are consistent with a mechanism in which the stepping of KIF3C can be activated by KIF3A in a strain-dependent manner, similar to application of an assisting load. These results suggest that the mechanochemical properties of KIF3AC can be explained by the strain-dependent kinetics of KIF3A and KIF3C.

QuoVadoPro, an Autonomous Tool for Measuring Intracellular Dynamics using Temporal Variance.

Trafficking of intracellular cargo is essential to cellular function and can be defective in pathological states including cancer and neurodegeneration. Tools to quantify intracellular traffic are thus necessary for understanding this fundamental cellular process, studying disease mechanisms, and testing the effects of therapeutic pharmaceuticals. In this article we introduce an algorithm called QuoVadoPro that autonomously quantifies the movement of fluorescently tagged intracellular cargo. QuoVadoPro infers the extent of intracellular motility based on the variance of pixel illumination in a series of time-lapse images. The algorithm is an unconventional approach to the automatic measurement of intracellular traffic and is suitable for quantifying movements of intracellular cargo under diverse experimental paradigms. QuoVadoPro is particularly useful to measure intracellular cargo movement in non-neuronal cells, where cargo trafficking occurs as short movements in mixed directions. The algorithm can be applied to images with low temporal or spatial resolutions and to intracellular cargo with varying shapes or sizes, like mitochondria or endoplasmic reticulum: situations in which conventional methods such as kymography and particle tracking cannot be applied. In this article we present a stepwise protocol for using the QuoVadoPro software, illustrate its methodology with common examples, discuss critical parameters for reliable data analysis, and demonstrate its use with a previously published example. © 2020 Wiley Periodicals LLC. Basic Protocol: QuoVadoPro, an autonomous tool for measuring intracellular dynamics using temporal variance.

Kymolyzer, a Semi‐Autonomous Kymography Tool to Analyze Intracellular Motility

The movement of intracellular cargo, such as transcripts, proteins, and organelles, is fundamental to cellular function. Neurons, due to their long axons and dendrites, are particularly dependent on proper intracellular trafficking and vulnerable to defects in the movement of intracellular cargo that are noted in neurodegenerative and neurodevelopmental disorders. Accurate quantification of intracellular transport is therefore needed for studying the mechanisms of cargo trafficking, the influence of mutations, and the effects of potentially therapeutic pharmaceuticals. In this article, we introduce an algorithm called "Kymolyzer." The algorithm can quantify intracellular trafficking along a defined path, such as that formed by the aligned microtubules of axons and dendrites. Kymolyzer works as a semi-autonomous kymography software application. It constructs and analyzes kymographs to measure the movement and distribution of fluorescently tagged objects along a user-defined path. The algorithm can be used under a wide variety of experimental conditions and can extract a diverse array of motility parameters describing intracellular movement, including time spent in motion, percentage of objects in motion, percentage of objects that are stationary, and velocities of motile objects. This article serves as a user manual describing the design of Kymolyzer, providing a stepwise protocol for its use and illustrating its functions with common examples. © 2020 Wiley Periodicals LLC Basic Protocol: Kymolyzer, a semi-autonomous kymography tool to analyze intracellular motility.

Collective intracellular cargo transport by multiple kinesins on multiple microtubules.

The transport of intracellular organelles is accomplished by groups of molecular motors, such as kinesin, myosin, and dynein. Previous studies have demonstrated that the cooperation between kinesins on a track is beneficial for long transport. However, within crowded three-dimensional (3D) cytoskeletal networks, surplus motors could impair transport and lead to traffic jams of cargos. Comprehensive understanding of the effects of the interactions among molecular motors, cargo, and tracks on the 3D cargo transport dynamics is still lack. In this work, a 3D stochastic multiphysics model is introduced to study the synergistic and antagonistic motions of kinesin motors walking on multiple mircotubules (MTs). Based on the model, we show that kinesins attaching to a common cargo can interact mechanically through the transient forces in their cargo linkers. Under different environmental conditions, such as different MT topologies and kinesin concentrations, the transient forces in the kinesins, the stepping frequency and the binding and unbinding probabilities of kinesins are changed substantially. Therefore, the macroscopic transport properties, specifically the stall force of the cargo, the transport direction at track intersections, and the mean-square displacement (MSD) of the cargo along the MT bundles vary over the environmental conditions. In general, conditions that improve the synergistic motion of kinesins increase the stall force of the cargo and the capability of maintaining the transport. In contrast, the antagonistic motion of kinesins temporarily traps the cargo and slows down the transport. Furthermore, this study predicts an optimal number of kinesins for the cargo transport at MT intersections and along MT bundles.

Genome scan detection of selective sweeps among biotypes of the soybean aphid, Aphis glycines, with differing virulence to resistance to A. glycines (Rag) traits in soybean, Glycine max

Multiple biotypes of soybean aphid, Aphis glycines, occur in North America adapted for survival (virulence) on soybean, Glycine max, with one or more different resistance to A. glycines (Rag) traits. The degree of genome-wide variance between biotypes and the basis of virulence remains unknown, but the latter is hypothesized to involve secreted effector proteins. Between 167,249 and 217,750 single nucleotide polymorphisms (SNPs) were predicted from whole genome re-sequencing of A. glycines avirulent biotype 1 (B1) and virulent B2, B3 and B4 colony-derived iso-female lines when compared to the draft B1 genome assembly, Ag_bt1_v6.0. Differences in nucleotide diversity indices (π) estimated within 1000 bp sliding windows demonstrated that 226 of 353 (64.0%) regions most differentiated between B1 and ≥ 2 virulent biotypes, representing < 0.1% of the 308 Mb assembled genome size, are located on 15 unordered scaffolds. Furthermore, these 226 intervals were coincident and show a significant association with 326 of 508 SNPs with significant locus-by-locus FST estimates between biotype populations (r = 0.6271; F1,70 = 45.36, P < 0.001) and genes showing evidence of directions selection (πN/πS > 2.0; r = 0.6233; F1,70 = 50.20, P < 0.001). A putative secreted effector glycoprotein is encoded in proximity to genome intervals of low estimated π (putative selective sweep) within avirulent B1 compared to all three virulent biotypes. Additionally, SNPs are clustered in or in proximity to genes putatively involved in intracellular protein cargo transport and the regulation of secretion. Results of this study indicate that factors on a small number of scaffolds of the A. glycines genome may contribute to variance in virulence towards Rag traits in G. max.

Functions of Lysosomes in Mammalian Female Reproductive System

The lysosome is the most acidic membrane-bound intracellular organelle. Lysosomal acidity is primarily maintained by vacuolar H+-ATPase (V-ATPase) and counter ion channels. There are >60 hydrolytic enzymes in the lysosome for its fundamental digestive role. Lysosomes also play important roles in endocytosis, exocytosis, autophagy, and cell death. Studies that have implicated roles of lysosomes in the female reproductive system are reviewed here. In the ovary, lysosomes are implicated in the preparation of free cholesterol for steroidogenesis and degradation of regulators of steroidogenesis, regulation of follicular atresia, follicle rupture during ovulation, luteal cell survival, and luteal regression. In the oviduct, lysosomes are involved in endocytosis of both serum and oviductal luminal components. In the uterus during the menstrual/estrous cycle, lysosomes are associated with endometrial secretion, apoptosis, and menstruation. In the uterus during early pregnancy, lysosomes are involved in the temporal and directional changes of endocytosis, uterine epithelial acidification upon embryo implantation initiation, and embryo-maternal mutual communications via extracellular vesicles. In the placenta, lysosomes are implicated in nutrient transport and placental separation from the uterus for parturition. In the mammary gland, lysosomes are important for mammary gland development and involution. These findings suggest/demonstrate functions of lysosomes in multiple processes of female reproduction, from ovulation to ovarian steroidogenesis for pregnancy maintenance, and from essential in utero nurturing of developing embryos/fetuses via embryo/fetal-maternal communications, to optional postpartum nurturing of newborns via lactation. Future studies using genetically or modified animal models and pharmacological approaches will provide novel insights into the functions and mechanisms of lysosomes in the mammalian female reproductive system.

Loss of BICD2 in muscle drives motor neuron loss in a developmental form of spinal muscular atrophy

Autosomal dominant missense mutations in BICD2 cause Spinal Muscular Atrophy Lower Extremity Predominant 2 (SMALED2), a developmental disease of motor neurons. BICD2 is a key component of the cytoplasmic dynein/dynactin motor complex, which in axons drives the microtubule-dependent retrograde transport of intracellular cargo towards the cell soma. Patients with pathological mutations in BICD2 develop malformations of cortical and cerebellar development similar to Bicd2 knockout (−/−) mice. In this study we sought to re-examine the motor neuron phenotype of conditional Bicd2−/− mice. Bicd2−/− mice show a significant reduction in the number of large calibre motor neurons of the L4 ventral root compared to wild type mice. Muscle-specific knockout of Bicd2 results in a similar reduction in L4 ventral axons comparable to global Bicd2−/− mice. Rab6, a small GTPase required for the sorting of exocytic vesicles from the Trans Golgi Network to the plasma membrane is a major binding partner of BICD2. We therefore examined the secretory pathway in SMALED2 patient fibroblasts and demonstrated that BICD2 is required for physiological flow of constitutive secretory cargoes from the Trans Golgi Network to the plasma membrane using a VSV-G reporter assay. Together, these data indicate that BICD2 loss from muscles is a major driver of non-cell autonomous pathology in the motor nervous system, which has important implications for future therapeutic approaches in SMALED2.

PX Domain-Containing Kinesin KIF16B and Microtubule-Dependent Intracellular Movements.

As a member of the kinesin-3 family, kinesin family member 16B (KIF16B) has a characteristic PhoX homology (PX) domain that binds to membranes containing phosphatidylinositol-3-phosphate (PI(3)P) and moves along microtubule filaments to the plus end via a process regulated by coiled coils in the stalk region in various cell types. The physiological function of KIF16B supports the transport of intracellular cargo and the formation of endosomal tubules. Ras-related protein (Rab) coordinates many steps of membrane transport and are involved in the regulation of KIF16B-mediated vesicle trafficking. Data obtained from clinical research suggest that KIF16B has a potential effect on the disease processes in intellectual disability, abnormal lipid metabolism, and tumor brain metastasis. In this review, we summarize recent advances in the structural and physiological characteristics of KIF16B as well as diseases associated with KIF16B disorders, and speculating its role as a potential adaptor for intracellular cholesterol trafficking.

Photosensitive nanocarriers for specific delivery of cargo into cells

Nanoencapsulation is a rapidly expanding technology to enclose cargo into inert material at the nanoscale size, which protects cargo from degradation, improves bioavailability and allows for controlled release. Encapsulation of drugs into functional nanocarriers enhances their specificity, targeting ability, efficiency, and effectiveness. Functionality may come from cell targeting biomolecules that direct nanocarriers to a specific cell or tissue. Delivery is usually mediated by diffusion and erosion mechanisms, but in some cases, this is not sufficient to reach the expected therapeutic effects. This work reports on the development of a new photoresponsive polymeric nanocarrier (PNc)-based nanobioconjugate (NBc) for specific photo-delivery of cargo into target cells. We readily synthesized the PNcs by modification of chitosan with ultraviolet (UV)-photosensitive azobenzene molecules, with Nile red and dofetilide as cargo models to prove the encapsulation/release concept. The PNcs were further functionalized with the cardiac targeting transmembrane peptide and efficiently internalized into cardiomyocytes, as a cell line model. Intracellular cargo-release was dramatically accelerated upon a very short UV-light irradiation time. Delivering cargo in a time-space controlled fashion by means of NBcs is a promising strategy to increase the intracellular cargo concentration, to decrease dose and cargo side effects, thereby improving the effectiveness of a therapeutic regime.