Recent Advances in Nanomedicine for the Diagnosis and Therapy of Liver Fibrosis

Liver-Targeted Delivery Based on Prodrug: Passive and Active Approaches

BACKGROUND

The liver, a central organ in human metabolism, is often the primary target for drugs. However, conditions such as viral hepatitis, cirrhosis, non-alcoholic fatty liver disease (NAFLD), and hepatocellular carcinoma (HCC) present substantial health challenges worldwide. Existing treatments, which suffer from the non-specific distribution of drugs, frequently fail to achieve desired efficacy and safety, risking unnecessary liver harm and systemic side effects.

PURPOSE

The aim of this review is to synthesize the latest progress in the design of liver-targeted prodrugs, with a focus on passive and active targeting strategies, providing new insights into the development of liver-targeted therapeutic approaches.

METHODS

This study conducted an extensive literature search through databases like Google Scholar, PubMed, Web of Science, and China National Knowledge Infrastructure (CNKI), systematically collecting and selecting recent research on liver-targeted prodrugs. The focus was on targeting mechanisms, including the Enhanced Permeability and Retention (EPR) effect, the unique microenvironment of liver cancer, and active targeting through specific transporters and receptors.

RESULTS

Active targeting strategies achieve precise drug delivery by binding specific ligands to liver surface receptors. Passive targeting takes advantage of the EPR effect and tumor characteristics to enrich drugs in liver tumors. The review details successful cases of using small molecule ligands, peptides, antibodies and nanoparticles as drug carriers.

CONCLUSION

Liver-targeted prodrug strategies show great potential in enhancing the efficacy of drug treatment and reducing side effects for liver diseases. Future research should balance the advantages and limitations of both targeting strategies, focusing on optimizing drug design and targeting efficiency, especially for clinical application. In-depth research on liver-specific receptors and the development of innovative targeting molecules are crucial for advancing the field of liver-targeted prodrugs.

Advances in Noninvasive Molecular Imaging Probes for Liver Fibrosis Diagnosis

Liver fibrosis is a wound-healing response to chronic liver injury, which may lead to cirrhosis and cancer. Early-stage fibrosis is reversible, and it is difficult to precisely diagnose with conventional imaging modalities such as magnetic resonance imaging, positron emission tomography, single-photon emission computed tomography, and ultrasound imaging. In contrast, probe-assisted molecular imaging offers a promising noninvasive approach to visualize early fibrosis changes in vivo, thus facilitating early diagnosis and staging liver fibrosis, and even monitoring of the treatment response. Here, the most recent progress in molecular imaging technologies for liver fibrosis is updated. We start by illustrating pathogenesis for liver fibrosis, which includes capillarization of liver sinusoidal endothelial cells, cellular and molecular processes involved in inflammation and fibrogenesis, as well as processes of collagen synthesis, oxidation, and cross-linking. Furthermore, the biological targets used in molecular imaging of liver fibrosis are summarized, which are composed of receptors on hepatic stellate cells, macrophages, and even liver collagen. Notably, the focus is on insights into the advances in imaging modalities developed for liver fibrosis diagnosis and the update in the corresponding contrast agents. In addition, challenges and opportunities for future research and clinical translation of the molecular imaging modalities and the contrast agents are pointed out. We hope that this review would serve as a guide for scientists and students who are interested in liver fibrosis imaging and treatment, and as well expedite the translation of molecular imaging technologies from bench to bedside.

Identification of Early Stage Liver Fibrosis by Modifications in the Interstitial Space Diffusive Microenvironment Using Fluorescent Single-Walled Carbon Nanotubes

During liver fibrosis, recurrent hepatic injuries lead to the accumulation of collagen and other extracellular matrix components in the interstitial space, ultimately disrupting liver functions. Early stages of liver fibrosis may be reversible, but opportunities for diagnosis at these stages are currently limited. Here, we show that the alterations of the interstitial space associated with fibrosis can be probed by tracking individual fluorescent single-walled carbon nanotubes (SWCNTs) diffusing in that space. In a mouse model of early liver fibrosis, we find that nanotubes generally explore elongated areas, whose lengths decrease as the disease progresses, even in regions where histopathological examination does not reveal fibrosis yet. Furthermore, this decrease in nanotube mobility is a purely geometrical effect as the instantaneous nanotube diffusivity stays unmodified. This work establishes the promise of SWCNTs both for diagnosing liver fibrosis at an early stage and for more in-depth studies of the biophysical effects of the disease.

Liver fibrosis: pathological features, clinical treatment and application of therapeutic nanoagents

Liver fibrosis is a reversible damage-repair response, the pathological features of which mainly include damage to hepatocytes, sinusoid capillarization, hepatic stellate cells activation, excessive accumulation of extracellular matrix and inflammatory response. Although some treatments (including drugs and stem cell therapy) for these pathological features have been shown to be effective, more clinical trials are needed to confirm their effectiveness. In recent years, nanomaterials-based therapies have emerged as an innovative and promising alternative to traditional drugs, being explored for the treatment of liver fibrosis diseases. Natural nanomaterials (including extracellular vesicles) and synthetic nanomaterials (including inorganic nanomaterials and organic nanomaterials) are developed to facilitate drug targeting delivery and combination therapy. In this review, the pathological features of liver fibrosis and the current anti-fibrosis drugs in clinical trials are briefly introduced, followed by a detailed introduction of the therapeutic nanoagents for the precise delivery of anti-fibrosis drugs. Finally, the future development trend in this field is discussed.

Selective inhibition of glycolysis in hepatic stellate cells and suppression of liver fibrogenesis with vitamin A-derivative decorated camptothecin micelles

The persistent transformation of quiescent hepatic stellate cells (HSCs) into myofibroblasts (MFs) and the excessive proliferation of MF-HSCs in the liver contribute to the pathogenesis of liver fibrosis, cirrhosis, and liver cancer. Glycolysis inhibition of MF-HSCs can reverse their MF phenotype and suppress their abnormal expansion. Here, we have developed vitamin A-derivative (VA) decorated PEG-PCL polymeric micelles to encapsulate the labile and hydrophobic camptothecin (CPT) and direct its active attack on HSCs, selectively inhibiting of HIF-1α and cellular glycolysis, ultimately repressing hepatic fibrogenesis. The obtained micelles exhibited a good stability, biocompatibility, pH sensitivity, and exceptional HSC-targetability, allowing an efficient accumulation of their carried CPT in acutely and chronically injured livers. On their intracellular release of CPT specifically in MF-HSCs, these CPT micelles nicely inhibited the HIF-1α and a series of glycolytic players in MF-HSCs and prominently suppressed their proliferation and MF phenotypic characteristics. Accordingly, on in vitro administration to the mice challenged by CCl4 or subjected to bile duct ligation, these VA-decorated CPT micelles ameliorated the pathological symptoms of the livers, as evidenced by the significant reduction in serum levels of ALT and AST, infiltration of inflammatory cells, and collagen accumulation, the drastic down-regulation of multiple fibrotic genes, and the good recovery of attenuated hepatocyte CYP2E1 and lipogenesis regulator PPARγ. Overall, the CPT carried by VA-decorated PEG-PCL polymeric micelles can selectively inhibit the glycolysis and expansion of HSCs and thus suppress fibrogenesis, providing an original and effective approach for anti-fibrotic therapy. STATEMENT OF SIGNIFICANCE: Our work introduces an innovative antifibrotic drug system that is developed upon the active targeting of CPT and aims for the fate reversal of HSCs. Through HSC-targeted delivery achieved by PEG-PCL polymeric micelles decorated with vitamin A-derivatives, CPT significantly suppressed the expressions of HIF-1α and glycolytic enzymes in MF-HSCs, as well as their pathologic expansion in mouse livers. It effectively ameliorated chronic liver fibrosis in mice induced by CCl4 injection or BDL and restored the damaged liver structure and function. These compelling findings demonstrate the therapeutic potential of glycolytic HSC-targeting in combating fibrosis and related disorders and thus provide new promise for future clinical management of such prevalent and life-threatening conditions.

Restoration of Sinusoid Fenestrae Followed by Targeted Nanoassembly Delivery of an Anti-Fibrotic Agent Improves Treatment Efficacy in Liver Fibrosis

During the onset of liver fibrosis, capillarized liver sinusoidal endothelial cells (LSECs) limit substance exchange between the blood and the Disse space, further accelerating hepatic stellate cell (HSCs) activation and fibrosis progression. Limited accessibility of therapeutics to the Disse space is often overlooked and remains a major bottleneck for HSCs-targeted therapy in liver fibrosis. Here, an integrated systemic strategy for liver fibrosis treatment is reported, utilizing pretreatment with the soluble guanylate cyclase stimulator, riociguat, followed by insulin growth factor 2 receptor-mediated targeted delivery of the anti-fibrosis agent, JQ1, via peptide-nanoparticles (IGNP-JQ1). The riociguat reversed the liver sinusoid capillarization to maintain a relatively normal LSECs porosity, thus facilitating the transport of IGNP-JQ1 through the liver sinusoid endothelium wall and enhancing the accumulation of IGNP-JQ1 in the Disse space. IGNP-JQ1 is then selectively taken up by activated HSCs, inhibiting their proliferation and decreasing collagen deposition in the liver. The combined strategy results in significant fibrosis resolution in carbon tetrachloride-induced fibrotic mice as well as methionine-choline-deficient-diet-induced nonalcoholic steatohepatitis (NASH) mice. The work highlights the key role of LSECs in therapeutics transport through the liver sinusoid. The strategy of restoring LSECs fenestrae by riociguat represents a promising approach for liver fibrosis treatment.

Liver fibrosis therapy based on biomimetic nanoparticles which deplete activated hepatic stellate cells

Liver fibrosis is one of the most common liver diseases with substantial morbidity and mortality. However, effective therapy for liver fibrosis is still lacking. Considering the key fibrogenic role of activated hepatic stellate cells (aHSCs), here we reported a strategy to deplete aHSCs by inducing apoptosis as well as quiescence. Therefore, we engineered biomimetic all-trans retinoic acid (ATRA) loaded PLGA nanoparticles (NPs). HSC (LX2 cells) membranes, presenting the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), were coated on the surface of the nanoparticles, while the clinically approved agent ATRA with anti-fibrosis ability was encapsulated in the inner core. The biomimetic coating of TRAIL-expressing HSC membranes does not only provide homologous targeting to HSCs, but also effectively triggers apoptosis of aHSCs. ATRA could induce quiescence of activated fibroblasts. While TM-NPs (i.e. membrane coated NPs without ATRA) and ATRA/NPs (i.e. non-coated NPs loaded with ATRA) only showed the ability to induce apoptosis and decrease the α-SMA expression in aHSCs, respectively, TM-ATRA/NPs induced both apoptosis and quiescence in aHSCs, ultimately leading to improved fibrosis amelioration in both carbon tetrachloride-induced and methionine and choline deficient L-amino acid diet induced liver fibrosis mouse models. We conclude that biomimetic TM-ATRA/NPs may provide a novel strategy for effective antifibrosis therapy.

Folate Decoration Supports the Targeting of Camptothecin Micelles against Activated Hepatic Stellate Cells and the Suppression of Fibrogenesis

As the central cellular player in fibrogenesis, activated hepatic stellate cells (aHSCs) are the major target of antifibrotic nanomedicines. Based on our finding that activated HSCs increase the expression of folate receptor alpha (FRα), we tried to apply folic acid (FA) decoration to generate an active drug-targeting at aHSCs and suppress hepato-fibrogenesis. FA-conjugated poly(ethylene glycol)-poly(ε-caprolactone) copolymers (PEG-PCL) were synthesized and self-assembled into the spherical micelles that owned a uniform size distribution averaging at 60 nm, excellent hemo- and cyto-compatibility, and pH-sensitive stability. These FA-modified micelles were preferentially ingested by aHSCs as expected and accumulated more in acutely CCl₄ injured mouse livers compared to nondecorated counterparts. Such an aHSC targetability facilitated the loaded medicinal camptothecin (CPT) to achieve a greater therapeutic efficacy and inhibition of MF phenotypic genes in aHSCs. Encouragingly, though free CPT and nontargeting CPT micelles produced negligible curative outcomes, FA-decorated CPT micelles yielded effectively remedial effects in chronically CCl₄-induced fibrotic mice, as represented by a significant shrinkage of aHSC population, suppression of fibrogenesis, and recovery of liver structure and function, clearly indicating the success of the folate decoration-supported aHSC-targeted strategy for antifibrotic nanomedicines in fibrosis resolution.

Doxorubicin Loaded Gold Nanoparticles Mitigate Liver Fibrosis and Inflammatory Cytokines Gene Expression in Rat

BACKGROUND

Gold nanoparticles have the potential to be used as a carrier in drug delivery system due to their small size, large surface area and short circulation time in blood.

OBJECTIVE

This study aims that doxorubicin conjugation with gold nanoparticles (AuNPs) may reduce its toxicity as well as improve therapeutic efficacy.

METHODS

Five groups of Albino rats were used; 1: healthy control, 2: Injured, 3: injured and treated with Dox, 4: Injured and treated with AuNPs, 5: Injured and treated with AuNPs: Dox. At the end of the experiment, blood and liver tissues were processed for biochemical and histopathological analysis. The expression of collagen, HO-1, IL-6 and TNF-α genes involved in liver fibrosis was observed through real-time PCR.

RESULTS

At the end of the experiment, it was observed that the body weights of DOX treated rats decreased by 0.72%, however, AuNPs and Au: DOX treated rats were 15.3% and 29.13% respectively. The percentage of liver protection determined through alanine aminotransferase and aspartate aminotransferase levels in DOX, AuNPs and AuNPs: DOX treated groups were 39.21%, 79.26%, 98.17% and 47.77%, 84.17%, 97.92% respectively. That represents better recovering liver in Dox-AuNPs treated rats compared to others. Histopathological and gene expression studies further support the findings. The mRNA expression levels of inflammatory and oxidative stress related genes HO-1, IL-6 and TNF-α were upregulated in the injured group but downregulated in the treated group.

CONCLUSION

As depicted through biochemical, histopathological and gene expression studies, Au: DOX conjugate group seems to be protective against liver fibrosis.

Biodistribution Profile of Magnetic Nanoparticles in Cirrhosis-Associated Hepatocarcinogenesis in Rats by AC Biosusceptometry

Since magnetic nanoparticles (MNPs) have been used as multifunctional probes to diagnose and treat liver diseases in recent years, this study aimed to assess how the condition of cirrhosis-associated hepatocarcinogenesis alters the biodistribution of hepatic MNPs. Using a real-time image acquisition approach, the distribution profile of MNPs after intravenous administration was monitored using an AC biosusceptometry (ACB) assay. We assessed the biodistribution profile based on the ACB images obtained through selected regions of interest (ROIs) in the heart and liver position according to the anatomical references previously selected. The signals obtained allowed for the quantification of pharmacokinetic parameters, indicating that the uptake of hepatic MNPs is compromised during liver cirrhosis, since scar tissue reduces blood flow through the liver and slows its processing function. Since liver monocytes/macrophages remained constant during the cirrhotic stage, the increased intrahepatic vascular resistance associated with impaired hepatic sinusoidal circulation was considered the potential reason for the change in the distribution of MNPs.

Magnetic Nanoparticles: Current Advances in Nanomedicine, Drug Delivery and MRI

Magnetic nanoparticles (MNPs) have evolved tremendously during recent years, in part due to the rapid expansion of nanotechnology and to their active magnetic core with a high surface-to-volume ratio, while their surface functionalization opened the door to a plethora of drug, gene and bioactive molecule immobilization. Taming the high reactivity of the magnetic core was achieved by various functionalization techniques, producing MNPs tailored for the diagnosis and treatment of cardiovascular or neurological disease, tumors and cancer. Superparamagnetic iron oxide nanoparticles (SPIONs) are established at the core of drug-delivery systems and could act as efficient agents for MFH (magnetic fluid hyperthermia). Depending on the functionalization molecule and intrinsic morphological features, MNPs now cover a broad scope which the current review aims to overview. Considering the exponential expansion of the field, the current review will be limited to roughly the past three years.

Traditional Chinese medicine: An important source for discovering candidate agents against hepatic fibrosis

Hepatic fibrosis (HF) refers to the pathophysiological process of connective tissue dysplasia in the liver caused by various pathogenic factors. Nowadays, HF is becoming a severe threat to the health of human being. However, the drugs available for treating HF are limited. Currently, increasing natural agents derived from traditional Chinese medicines (TCMs) have been found to be beneficial for HF. A systemic literature search was conducted from PubMed, GeenMedical, Sci-Hub, CNKI, Google Scholar and Baidu Scholar, with the keywords of “traditional Chinese medicine,” “herbal medicine,” “natural agents,” “liver diseases,” and “hepatic fibrosis.” So far, more than 76 natural monomers have been isolated and identified from the TCMs with inhibitory effect on HF, including alkaloids, flavones, quinones, terpenoids, saponins, phenylpropanoids, and polysaccharides, etc. The anti-hepatic fibrosis effects of these compounds include hepatoprotection, inhibition of hepatic stellate cells (HSC) activation, regulation of extracellular matrix (ECM) synthesis & secretion, regulation of autophagy, and antioxidant & anti-inflammation, etc. Natural compounds and extracts from TCMs are promising agents for the prevention and treatment of HF, and this review would be of great significance to development of novel drugs for treating HF.

NIR-II imaging-guided diagnosis and evaluation of the therapeutic effect on acute alcoholic liver injury via a nanoprobe

Acute alcoholic liver injury (AALI) is hard to diagnose on account of no obvious clinical symptoms, and thereby it easily develops into serious liver diseases and threatens people's health. However, traditional methods for detecting AALI are far from satisfactory due to the low sensitivity, invasiveness and non-visualization, and the development of new techniques is in urgent demand. Near-infrared (NIR)-II fluorescence imaging has been widely studied in biochemistry and biomedicine. As the blood flow velocity of the liver is closely related to the progression of AALI, herein, a NIR-II fluorescent nanoprobe, NTPB-NPs, was applied to diagnose AALI by monitoring the fluorescence intensity changes in the liver caused by the variations of the blood flow velocity. More importantly, when medication was applied to alleviate the liver injury of AALI mice, NTPB-NPs could also track the therapeutic effect in situ. In this study, the relationship between hepatic vascular velocity and the progression of AALI was confirmed with NTPB-NPs via NIR-II imaging. To the best of our knowledge, this is the first time that a NIR-II fluorescence imaging technique has been used to diagnose AALI mice and evaluate the therapeutic effect on AALI mice. This study may also provide a potential NIR-II imaging agent for clinical research to improve the management of liver injury related diseases.

Multiplexing Nanodrug Ameliorates Liver Fibrosis via ROS Elimination and Inflammation Suppression

Liver fibrosis is the leading risk factor for hepatocellular carcinoma. Both oxidative stress and inflammation promote the progression of liver fibrosis, but existing therapeutic strategies tend to focus solely on one issue. Additionally, targeting of pathological microstructures is often neglected. Herein, an esterase-responsive carbon quantum dot-dexamethasone (CD-Dex) is developed for liver fibrosis therapy to simultaneously target pathological microstructures, scavenge reactive oxygen species (ROS), and suppress inflammation. Hepatocyte-targeting CD-Dex can efficiently eliminate the intrahepatic ROS, thereby inhibiting the activation of Kupffer cells, preventing further inflammation progression. Moreover, released dexamethasone (Dex) also suppresses inflammatory response by inhibiting the infiltration of inflammatory cells. Antifibrotic experiments demonstrate that CD-Dex significantly alleviates liver injury and collagen deposition, consequently preventing the progression of liver fibrosis. Taken together, these findings suggest that via ROS elimination and inflammation suppression, the newly developed multiplexing nanodrug exhibits great potential in liver fibrosis therapy.

Nanoparticles to Target and Treat Macrophages: The Ockham's Concept?

Nanoparticles are nanomaterials with three external nanoscale dimensions and an average size ranging from 1 to 1000 nm. Nanoparticles have gained notoriety in technological advances due to their tunable physical, chemical, and biological characteristics. However, the administration of functionalized nanoparticles to living beings is still challenging due to the rapid detection and blood and tissue clearance by the mononuclear phagocytic system. The major exponent of this system is the macrophage. Regardless the nanomaterial composition, macrophages can detect and incorporate foreign bodies by phagocytosis. Therefore, the simplest explanation is that any injected nanoparticle will be probably taken up by macrophages. This explains, in part, the natural accumulation of most nanoparticles in the spleen, lymph nodes, and liver (the main organs of the mononuclear phagocytic system). For this reason, recent investigations are devoted to design nanoparticles for specific macrophage targeting in diseased tissues. The aim of this review is to describe current strategies for the design of nanoparticles to target macrophages and to modulate their immunological function involved in different diseases with special emphasis on chronic inflammation, tissue regeneration, and cancer.

Therapeutic and diagnostic targeting of fibrosis in metabolic, proliferative and viral disorders

Fibrosis is a common denominator in many pathologies and crucially affects disease progression, drug delivery efficiency and therapy outcome. We here summarize therapeutic and diagnostic strategies for fibrosis targeting in atherosclerosis and cardiac disease, cancer, diabetes, liver diseases and viral infections. We address various anti-fibrotic targets, ranging from cells and genes to metabolites and proteins, primarily focusing on fibrosis-promoting features that are conserved among the different diseases. We discuss how anti-fibrotic therapies have progressed over the years, and how nanomedicine formulations can potentiate anti-fibrotic treatment efficacy. From a diagnostic point of view, we discuss how medical imaging can be employed to facilitate the diagnosis, staging and treatment monitoring of fibrotic disorders. Altogether, this comprehensive overview serves as a basis for developing individualized and improved treatment strategies for patients suffering from fibrosis-associated pathologies.

Targeting cell-intrinsic metabolism for antifibrotic therapy

In recent years, there have been major advances in our understanding of the mechanisms underlying fibrosis progression and regression, and how coordinated interactions between parenchymal and non-parenchymal cells impact on the fibrogenic process. Recent studies have highlighted that metabolic reprogramming of parenchymal cells, immune cells (immunometabolism) and hepatic stellate cells is required to support the energetic and anabolic demands of phenotypic changes and effector functions. In this review, we summarise how targeting cell-intrinsic metabolic modifications of the main fibrogenic cell actors may impact on fibrosis progression and we discuss the antifibrogenic potential of metabolically targeted interventions.