Apamin-Mediated Actively Targeted Drug Delivery for Treatment of Spinal Cord Injury: More Than Just a Concept

Targeting strategies with lipid vectors for nucleic acid supplementation therapy in Fabry disease: a systematic review

Fabry disease (FD) results from a lack of activity of the lysosomal enzyme α-Galactosidase A (α-Gal A), leading to the accumulation of glycosphingolipids in several different cell types. Protein supplementation by pDNA or mRNA delivery presents a promising strategy to tackle the underlying genetic defect in FD. Protein-coding nucleic acids in FD can be either delivered to the most affected sites by the disease, including heart, kidney and brain, or to specialized organs that can act as a production factory of the enzyme, such as the liver. Lipid-based systems are currently at the top of the ranking of non-viral nucleic acid delivery systems, and their versatility allows the linking to the surface of a wide range of molecules to control their biodistribution after intravenous administration. This systematic review follows the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) statement guidelines and provides an overview and discussion of the targeting ligands that have been employed so far to actively vectorize intravenously administered non-viral vectors based on lipid carriers to clinically relevant organs in the treatment of FD, for protein-coding nucleic acid (pDNA and mRNA) supplementation. Among the thirty-two studies included, the majority focus on targeting the liver and brain. The targeting of the heart has been reported to a lesser degree, whereas no articles addressing kidney-targeting have been recorded. Although a great effort has been made to develop organ-specific nucleic acid delivery systems, the design of active-targeted carriers with high quality, good clinical translation, and large-scale manufacturing capacity is still challenging.

Melittin protects against neural cell damage in rats following ischemic stroke

OBJECTIVE

In this study, we explored the neuroprotective effect of melittin (MEL) after brain ischemia using a rat model.

METHODS

The rats underwent middle cerebral artery occlusion (MCAO) for 60 min and were randomly divided into the control group, saline group, and MEL group. Rats in each group were injected intraperitoneally with MEL one day before MCAO until sacrificed. Morris water maze and rotation test were used to assess locomotor function and cognitive ability. The 9.4 Tesla MRI was used to scan and assess the infarct volume of the rat brains. Immunohistochemistry was used to detect the sites of action of MEL on microglia. Western blot and ELISA were used to measure the effect of MEL on the production of pro-inflammatory cytokines. The effect of MEL on neuronal cell apoptosis was observed by flow cytometry.

RESULTS

Compared with the saline group, MEL treatment significantly increased the density of neurons in the cerebral cortical and reduced the cerebral infarct size after MCAO (33.9 ± 8.8% vs. 15.8 ± 3.9%, P < 0.05). Meanwhile, the time for MEL-treated rats to complete the water maze task on the 11th day after MCAO was significantly shorter than that of rats in the saline group (P < 0.05). MEL treatment also prolonged the rotarod retention time on day 14 after MCAO. Immunohistochemistry analysis showed that MEL inhibited the activation of microglia and suppressed the expression of TNF-α, IL-6, and IL-1β in the brain after ischemia. MEL treatment resulted in a significant decrease in TLR4, MyD88, and NF-κB p65 levels in extracts from the ischemic cerebral cortex. Finally, MEL reduced neuronal apoptosis induced by ischemic stroke (P < 0.05).

CONCLUSION

MEL treatment promotes neurological function recovery after cerebral ischemia in rats. These effects are potentially mediated through anti-inflammatory and anti-apoptotic mechanisms.

Brain glucose induces tolerance of Cryptococcus neoformans to amphotericin B during meningitis

Antibiotic tolerance is the ability of a susceptible population to survive high doses of cidal drugs and has been shown to compromise therapeutic outcomes in bacterial infections. In comparison, whether fungicide tolerance can be induced by host-derived factors during fungal diseases remains largely unknown. Here, through a systematic evaluation of metabolite-drug-fungal interactions in the leading fungal meningitis pathogen, Cryptococcus neoformans, we found that brain glucose induces fungal tolerance to amphotericin B (AmB) in mouse brain tissue and patient cerebrospinal fluid via the fungal glucose repression activator Mig1. Mig1-mediated tolerance limits treatment efficacy for cryptococcal meningitis in mice via inhibiting the synthesis of ergosterol, the target of AmB, and promoting the production of inositolphosphorylceramide, which competes with AmB for ergosterol. Furthermore, AmB combined with an inhibitor of fungal-specific inositolphosphorylceramide synthase, aureobasidin A, shows better efficacy against cryptococcal meningitis in mice than do clinically recommended therapies.

Peptide-Based Agents for Cancer Treatment: Current Applications and Future Directions

Peptide-based strategies have received an enormous amount of attention because of their specificity and applicability. Their specificity and tumor-targeting ability are applied to diagnosis and treatment for cancer patients. In this review, we will summarize recent advancements and future perspectives on peptide-based strategies for cancer treatment. The literature search was conducted to identify relevant articles for peptide-based strategies for cancer treatment. It was performed using PubMed for articles in English until June 2023. Information on clinical trials was also obtained from ClinicalTrial.gov. Given that peptide-based strategies have several advantages such as targeted delivery to the diseased area, personalized designs, relatively small sizes, and simple production process, bioactive peptides having anti-cancer activities (anti-cancer peptides or ACPs) have been tested in pre-clinical settings and clinical trials. The capability of peptides for tumor targeting is essentially useful for peptide-drug conjugates (PDCs), diagnosis, and image-guided surgery. Immunomodulation with peptide vaccines has been extensively tested in clinical trials. Despite such advantages, FDA-approved peptide agents for solid cancer are still limited. This review will provide a detailed overview of current approaches, design strategies, routes of administration, and new technological advancements. We will highlight the success and limitations of peptide-based therapies for cancer treatment.

Recent advances in lipid nanovesicles for targeted treatment of spinal cord injury

The effective regeneration and functional restoration of damaged spinal cord tissue have been a long-standing concern in regenerative medicine. Treatment of spinal cord injury (SCI) is challenging due to the obstruction of the blood-spinal cord barrier (BSCB), the lack of targeting of drugs, and the complex pathophysiology of injury sites. Lipid nanovesicles, including cell-derived nanovesicles and synthetic lipid nanovesicles, are highly biocompatible and can penetrate BSCB, and are therefore effective delivery systems for targeted treatment of SCI. We summarize the progress of lipid nanovesicles for the targeted treatment of SCI, discuss their advantages and challenges, and provide a perspective on the application of lipid nanovesicles for SCI treatment. Although most of the lipid nanovesicle-based therapy of SCI is still in preclinical studies, this low immunogenicity, low toxicity, and highly engineerable nanovesicles will hold great promise for future spinal cord injury treatments.

Supramolecular assemblies with spatio-temporal sequential drug delivery capability treat spinal cord injury via neuroprotection and immunoregulation

Spinal cord injury (SCI) can result in irreversible motor and sensory deficits. However, up to data, clinical first-line drugs have ambiguous benefits and debilitating side effects, mainly due to the insufficient accumulation, poor physiological barrier penetration, and lack of spatio-temporal controlled release at lesion tissue. Herein, we proposed a supramolecular assemblies composed of hyperbranched polymer-formed core/shell structure through host-guest interactions. Such HPAA-BM@CD-HPG-C assemblies co-loaded with p38 inhibitor (SB203580) and insulin-like growth factor 1(IGF-1) are able to achieve time- and space-programmed sequential delivery benefiting from their cascaded responsiveness. The core-shell disassembly of HPAA-BM@CD-HPG-C occurs in acidic micro-environment around lesion, achieving preferentially the burst release of IGF-1 to protect survival neurons. Subsequently, the HPAA-BM cores containing SB203580 are endocytosed by the recruited macrophages and degraded by intracellular GSH, accelerating the release of SB203580 to promote the conversion from M1 to M2 macrophage. Hence, the successive synergy of neuroprotection and immunoregulation effects contribute to subsequent nerve repair and locomotor recovery as demonstrated in vitro and in vivo studies. Thus, our fabrication provides a strategy that multiple drugs co-delivery in a spatio-temporal selective manner adapting to the disease progression through self-cascaded disintegration, are expected to realize multidimensional precise treatment of SCI.

Barrier-penetrating liposome targeted delivery of basic fibroblast growth factor for spinal cord injury repair

Nanoparticle technologies offer a non-invasive means to deliver basic fibroblast growth factor (bFGF) for the treatment of spinal cord injury (SCI). However, the inability of bFGF to accumulate at the injury site and inefficient penetration across the blood-spinal cord barrier (BSCB) remain challenges. The present study describes a dual-targeting liposome (bFGF@Lip-Cp&Rp) with injury lesion targeting and BSCB-penetrating capability to deliver bFGF for SCI treatment. The CAQK peptide (Cp) with injury lesion targeting ability and R₂KC peptide (Rp) with BSCB-penetrating capability were grafted onto the liposomes for a flexible and non-invasive drug delivery systems preparation. Results exhibit that the dual-targeted liposomes could significantly cross the BSCB and accumulate at the injury site. During the early stage of SCI, bFGF@Lip-Cp&Rp promotes repair of BSCB and facilitates M2-polarization of macrophages. Regular delivery of bFGF@Lip-Cp&Rp increase HUVECs tube formation and angiogenesis, ameliorate the microenvironment of lesion site, suppress the neuronal apoptosis and axonal atrophy in SCI rats. Importantly, continuous treatment of bFGF@Lip-Cp&Rp supports the restoration of limb motor function in SCI rats. In summary, this research implies that the injury site-targeting and BSCB-penetrating liposomes could be a promising therapeutic approach for the treatment of SCI.

Recent advances in nanomaterials for the treatment of spinal cord injury

Spinal cord injuries (SCIs) are devastating. In SCIs, a powerful traumatic force impacting the spinal cord results in the permanent loss of nerve function below the injury level, leaving the patient paralyzed and wheelchair-bound for the remainder of his/her life. Unfortunately, clinical treatment that depends on surgical decompression appears to be unable to handle damaged nerves, and high-dose methylprednisolone-based therapy is also associated with problems, such as infection, gastrointestinal bleeding, femoral head necrosis, obesity, and hyperglycemia. Nanomaterials have opened new avenues for SCI treatment. Among them, performance-based nanomaterials derived from a variety of materials facilitate improvements in the microenvironment of traumatic injury and, in some cases, promote neuron regeneration. Nanoparticulate drug delivery systems enable the optimization of drug effects and drug bioavailability, thus contributing to the development of novel treatments. The improved efficiency and accuracy of gene delivery will also benefit the exploration of SCI mechanisms and the understanding of key genes and signaling pathways. Herein, we reviewed different types of nanomaterials applied to the treatment of SCI and summarized their functions and advantages to provide new perspectives for future clinical therapies.

Recent advances in drug delivery and targeting to the brain

Our body keeps separating the toxic chemicals in the blood from the brain. A significant number of drugs do not enter the central nervous system (CNS) due to the blood-brain barrier (BBB). Certain diseases, such as tumor growth and stroke, are known to increase the permeability of the BBB. However, the heterogeneity of this permeation makes it difficult and unpredictable to transport drugs to the brain. In recent years, research has been directed toward increasing drug penetration inside the brain, and nanomedicine has emerged as a promising approach. Active targeting requires one or more specific ligands on the surface of nanoparticles (NPs), which brain endothelial cells (ECs) recognize, allowing controlled drug delivery compared to conventional targeting strategies. This review highlights the mechanistic insights about different cell types contributing to the development and maintenance of the BBB and summarizes the recent advancement in brain-specific NPs for different pathological conditions. Furthermore, fundamental properties of brain-targeted NPs will be discussed, and the standard lesion features classified by neurological pathology are summarized.

Protease-Resistant Peptides for Targeting and Intracellular Delivery of Therapeutics

Peptides show high promise in the targeting and intracellular delivery of next-generation bio- and nano-therapeutics. However, the proteolytic susceptibility of peptides is one of the major limitations of their activity in biological environments. Numerous strategies have been devised to chemically enhance the resistance of peptides to proteolysis, ranging from N- and C-termini protection to cyclization, and including backbone modification, incorporation of amino acids with non-canonical side chains and conjugation. Since conjugation of nanocarriers or other cargoes to peptides for targeting and cell penetration may already provide some degree of shielding, the question arises about the relevance of using protease-resistant sequences for these applications. Aiming to answer this question, here we provide a critical review on protease-resistant targeting peptides and cell-penetrating peptides (CPPs). Two main approaches have been used on these classes of peptides: enantio/retro-enantio isomerization and cyclization. On one hand, enantio/retro-enantio isomerization has been shown to provide a clear enhancement in peptide efficiency with respect to parent L-amino acid peptides, especially when applied to peptides for drug delivery to the brain. On the other hand, cyclization also clearly increases peptide transport capacity, although contribution from enhanced protease resistance or affinity is often not dissected. Overall, we conclude that although conjugation often offers some degree of protection to proteolysis in targeting peptides and CPPs, modification of peptide sequences to further enhance protease resistance can greatly increase homing and transport efficiency.

Apamin-Conjugated Alendronate Sodium Nanocomplex for Management of Pancreatic Cancer

Pancreatic cancer has a low survival rate and has limited therapeutic options due to the peculiarity of the tumor tissue. Cancer nanotechnology provides several opportunities to resolve such difficulties as a result of the high surface-to-volume ratio of nanostructures. Peptide-drug nanocomplexes have proved to have immense potential in anticancer activity against pancreatic cancer cells. Thus, in the present study apamin (APA) and alendronate sodium (ALS) were combined to form nanocomplexes (APA-ALS-NC) against pancreatic cancer cells. Optimization of ALS, incubation time, and sonication time in terms of particle size of the nanocomplex was carried out. The optimized formulation was evaluated for anticancer activities in pancreatic cancer cells (PANC-1 cells). A Box-Behnken design using ALS, incubation time, and sonication time as independent factors and particle size as the response was chosen to optimize the APA-ALS-NC formulation. The optimized APA-ALS-NC had a particle size of 161.52 ± 8.4 nm. The evaluation of APA-ALS-NC in PANC-1 cells was carried out using various in vitro tests. The IC₅₀ values were determined by MTT assay and found to be 37.6 ± 1.65, 13.4 ± 0.59, and 1.01 ± 0.04 µg/mL for ALS, APA, and APA-ALS-NC, respectively. The higher cytotoxicity activity of APA-ALS-NC was confirmed from the higher percentage of cells in the necrosis phase (apoptosis study) and the G2-M phase (cell cycle study) compared to that of ALS and APA. While the loss of mitochondrial membrane potential was less for APA-ALS-NC, the levels of IL-1β, TNF-α, caspase-3, ROS, IL-6, and NF-kB showed that APA-ALS-NC can significantly enhance apoptosis and cytotoxicity in PANC-1 cells. Moreover, Bax (10.87 ± 1.36), Bcl-2 (0.27 ± 0.02), and p53 (9.16 ± 1.22) gene expressions confirmed that APA-ALS-NC had a significant apoptotic effect compared to ALS and APA. In summary, the APA-ALS-NC had a more significant cytotoxic effect than ALS and APA. The results of the present study are promising for further evaluation in pre-clinical and clinical trials for arriving at a successful therapeutic strategy against pancreatic cancer.

Nanoparticle-Based Delivery to Treat Spinal Cord Injury-a Mini-review

There is an increasing need to develop improved and non-invasive strategies to treat spinal cord injury (SCI). Nanoparticles (NPs) are an enabling technology to improve drug delivery, modulate inflammatory responses, and restore functional responses following SCI. However, the complex pathophysiology associated with SCI presents several distinct challenges that must be overcome for sufficient NP drug delivery to the spinal cord. The objective of this mini-review is to highlight the physiological challenges and cell types available for modulation and discuss several promising advancements using NPs to improve SCI treatment. We will focus our discussion on recent innovative approaches in NP drug delivery and how the implementation of multifactorial approaches to address the proinflammatory and complex immune dysfunction in SCI offers significant potential to improve outcomes in SCI.

Engineered liposomes targeting the gut-CNS Axis for comprehensive therapy of spinal cord injury

Effective curative therapies for spinal cord injury (SCI), which is often accompanied by intestinal complications, are lacking. Potential therapeutic targets include astrocytes and their enteric nervous system counterpart, enteric glial cells (EGCs). Based on shared biomarkers and similar functions of both cell types, we designed an orally administered targeted delivery system in which the neuropeptide apamin, stabilized by sulfur replacement with selenium, was adopted as a targeting moiety, and the liposome surface was protected with a non-covalent cross-linked chitosan oligosaccharide lactate layer. The system effectively permeated through oral absorption barriers, targeted local EGCs and astrocytes after systemic circulation, allowing for comprehensive SCI therapy. Given the involvement of the gut-organ axis in a growing number of diseases, our research may shed light on new aspects of the oral administration route as a bypass for multiple interventions and targeted therapy.

Development of Relaxin-3 Agonists and Antagonists Based on Grafted Disulfide-Stabilized Scaffolds

Relaxin-3 is a neuropeptide with important roles in metabolism, arousal, learning and memory. Its cognate receptor is the relaxin family peptide-3 (RXFP3) receptor. Relaxin-3 agonist and antagonist analogs have been shown to be able to modulate food intake in rodent models. The relaxin-3 B-chain is sufficient for receptor interactions, however, in the absence of a structural support, linear relaxin-3 B-chain analogs are rapidly degraded and thus unsuitable as drug leads. In this study, two different disulfide-stabilized scaffolds were used for grafting of important relaxin-3 B-chain residues to improve structure and stability. The use of both Veronica hederifolia Trypsin inhibitor (VhTI) and apamin grafting resulted in agonist and antagonist analogs with improved helicity. VhTI grafted peptides showed poor binding and low potency at RXFP3, on the other hand, apamin variants retained significant activity. These variants also showed improved half-life in serum from ~5 min to >6 h, and thus are promising RXFP3 specific pharmacological tools and drug leads for neuropharmacological diseases.

Overcoming the Reticuloendothelial System Barrier to Drug Delivery with a "Don't-Eat-Us" Strategy

Overcoming the reticuloendothelial system (RES) has long been a vital challenge to nanoparticles as drug carriers. Modification of nanoparticles with polyethylene glycol helps them avoid clearance by macrophages but also suppresses their internalization by target cells. To overcome this paradox, we developed an RES-specific blocking system utilizing a "don't-eat-us" strategy. First, a CD47-derived, enzyme-resistant peptide ligand was designed and placed on liposomes (d-self-peptide-labeled liposome, DSL). After mainline administration, DSL was quickly adsorbed onto hepatic phagocyte membranes (including those of Kupffer cells and liver sinusoidal endothelial cells), forming a long-lasting mask that enclosed the cell membranes and thus reducing interactions between phagocytes and subsequently injected nanoparticles. Compared with blank conventional liposomes (CL), DSL blocked the RES at a much lower dose, and the effect was sustained for a much longer time, highly prolonging the elimination half-life of the subsequently injected nanoparticles. This "don't-eat-us" strategy by DSL was further verified on the brain-targeted delivery against a cryptococcal meningitis model, providing dramatically enhanced brain accumulation of the targeted delivery system and superior therapeutic outcome of model drug Amphotericin B compared with CL. Our study demonstrates a strategy that blocks the RES by masking phagocyte surfaces to prolong nanoparticle circulation time without excess modification and illustrates its utility in enhancing nanoparticle delivery.

Surface engineering of nanomaterials with phospholipid-polyethylene glycol-derived functional conjugates for molecular imaging and targeted therapy

In recent years, phospholipid-polyethylene glycol-derived functional conjugates have been widely employed to decorate different nanomaterials, due to their excellent biocompatibility, long blood circulation characteristics, and specific targeting capability. Numerous in vivo studies have demonstrated that nanomedicines peripherally engineered with phospholipid-polyethylene glycol-derived functional conjugates show significantly increased selective and efficient internalization by target cells/tissues. Targeting moieties including small-molecule ligands, peptides, proteins, and antibodies are generally conjugated onto PEGylated phospholipids to decorate liposomes, micelles, hybrid nanoparticles, nanocomplexes, and nanoemulsions for targeted delivery of diagnostic and therapeutic agents to diseased sites. In this review, the synthesis methods of phospholipid-polyethylene glycol-derived functional conjugates, biophysicochemical properties of nanomedicines decorated with these conjugates, factors dominating their targeting efficiency, as well as their applications for in vivo molecular imaging and targeted therapy were summarized and discussed.

1988-2018: Thirty years of drug smuggling at the nano scale. Challenges and opportunities of cell-penetrating peptides in biomedical research

In 1988, two unrelated papers reported the discovery of peptide vectors with innate cell translocation properties, setting the ground for a new area of research that over the years has grown into considerable therapeutic potential. The vectors, named cell-penetrating peptides (CPPs), constitute a now large and diversified family, sharing the extraordinary ability to diffuse unaltered across cell membranes while ferrying diverse associated cargos. Such properties have made CPPs ideal tools for delivery of nucleic acids, proteins and other therapeutic/diagnostic molecules to cells and tissues via covalent conjugation or complexation. This year 2018 marks the 30^th anniversary of a peptide research landmark opening new perspectives in drug delivery. Given its vastness, exhaustive coverage of the main features and accomplishments in the CPP field is virtually impossible. Hence this manuscript, after saluting the above 30^th jubilee, focuses by necessity on the most recent contributions, providing a comprehensive list of recognized CPPs and their latest-reported applications over the last two years. In addition, it thoroughly reviews three areas of peptide vector research of particular interest to us, namely (i) efficient transport of low-bioavailability drugs into the brain; (ii) CPP-delivered disruptors of G protein-coupled receptor (GPCRs) heteromers related to several disorders, and (iii) CPP-mediated delivery of useful but poorly internalized drugs into parasites.

Targeting central nervous system pathologies with nanomedicines

One of the major challenges in drug development is the delivery of therapeutics to the central nervous system (CNS). The blood-brain barrier (BBB), which modulates the passage of molecules from the CNS, presents a formidable obstacle that limits brain uptake of therapeutics and, therefore, impedes the treatment of multiple neurological pathologies. Targeted nanocarriers present an excellent opportunity for drug delivery into the brain leveraging on endogenous receptors to transport therapeutics across the BBB endothelium. Receptor-mediated transport endows multiple benefits over other conventional delivery methods such as the transient permeabilization of the BBB or the direct depositioning of intracranial depots. Herein, different strategies for nanocarrier targeting to the CNS are discussed, highlighting the challenges and recent developments.

Polyethylene glycol in spinal cord injury repair: a critical review

Polyethylene glycol (PEG) is a synthetic biocompatible polymer with many useful properties for developing therapeutics to treat spinal cord injury. Direct application of PEG as a fusogen to the injury site can repair cell membranes, mitigate oxidative stress, and promote axonal regeneration to restore motor function. PEG can be covalently or noncovalently conjugated to proteins, peptides, and nanoparticles to limit their clearance by the reticuloendothelial system, reduce their immunogenicity, and facilitate crossing the blood-brain barrier. Cross-linking PEG produces hydrogels that can act as delivery vehicles for bioactive molecules including growth factors and cells such as bone marrow stromal cells, which can modulate the inflammatory response and support neural tissue regeneration. PEG hydrogels can be cross-linked in vitro or delivered as an injectable formulation that can gel in situ at the site of injury. Chemical and mechanical properties of PEG hydrogels are tunable and must be optimized for creating the most favorable delivery environment. Peptides mimicking extracellular matrix protein such as laminin and n-cadherin can be incorporated into PEG hydrogels to promote neural differentiation and axonal extensions. Different hydrogel cross-linking densities and stiffness will also affect the differentiation process. PEG hydrogels with a gradient of peptide concentrations or Young's modulus have been developed to systematically study these factors. This review will describe these and other recent advancements of PEG in the field of spinal cord injury in greater detail.

Blood-brain barrier shuttle peptides: an emerging paradigm for brain delivery

Brain delivery is one of the major challenges in drug development because of the high number of patients suffering from neural diseases and the low efficiency of the treatments available. Although the blood-brain barrier (BBB) prevents most drugs from reaching their targets, molecular vectors - known as BBB shuttles - offer great promise to safely overcome this formidable obstacle. In recent years, peptide shuttles have received growing attention because of their lower cost, reduced immunogenicity, and higher chemical versatility than traditional Trojan horse antibodies and other proteins.

pPB Peptide-Mediated siRNA-Loaded Stable Nucleic Acid Lipid Nanoparticles on Targeting Therapy of Hepatic Fibrosis

Hepatic fibrosis is a necessary process in the development of liver diseases such as hepatic cirrhosis and its complications, which has become a serious threat to human health. Currently, antifibrotic drug treatment is ineffective, and one reason should be the lack of liver targeting ability. In this report, polypeptide pPB-modified stable nucleic acid lipid nanoparticles (pPB-SNALPs) were prepared to selectively deliver siRNAs against heat shock protein 47 to the liver for targeted therapy of hepatic fibrosis. First, siRNA sequences with high silencing efficiency were screened based on siRNA transfection efficacy. Then, pPB-SNALPs were prepared, which showed a narrow size distribution with a diameter in the range of 110-130 nm and a neutral z-potential of 0 mV. As evidenced by the in vitro and in vivo targeting study, compared with unmodified SNALP, pPB-SNALP showed increased uptake by LX-2 cells and primary hepatic stellate cells (HSC) of mice in vitro and showed increased liver distribution and HSC uptake in vivo. In addition, pPB-SNALP also exhibited an enhanced inhibitory effect on TAA-induced hepatic fibrosis mice with high gp46 mRNA expression in vivo. In summary, our results demonstrated that pPB-SNALP is an effective liver-targeted delivery system. This study could lay a good foundation for the targeted gene therapy of hepatic fibrosis.

Highly Selective Targeting of Hepatic Stellate Cells for Liver Fibrosis Treatment Using a d-Enantiomeric Peptide Ligand of Fn14 Identified by Mirror-Image mRNA Display

Although liver fibrosis is a major public health issue, there is still no effective drug therapy in the clinic. Fibroblast growth factor-inducible 14 (Fn14), a membrane receptor highly specifically expressed in activated hepatic stellate cells (HSCs), is the key driver of liver fibrosis, and thus, it has a great potential as a novel target for the development of effective treatment. Here, we identified a d-enantiomeric peptide ligand of Fn14 through mirror-image mRNA display. This included the chemical synthesis of a d-enantiomer of the target protein (extracellular domain of Fn14), identification of an l-peptide ligand of d-Fn14 using a constructed mRNA peptide library, and identification of a d-enantiomer of the l-peptide, which is a ligand of the natural Fn14 for reasons of symmetry. The obtained d-peptide ligand showed strong binding to Fn14 while maintaining high proteolytic resistance. As a targeting moiety, this d-peptide successfully mediated high selectivity of activated HSCs for liposomal vehicles compared to that of other major cell types in the liver and significantly enhanced the accumulation of liposomes in the liver fibrosis region of a carbon tetrachloride-induced mouse model. Moreover, in combination with curcumin as an encapsulated load, a liposomal formulation conjugated with this d-peptide showed powerful inhibition of the proliferation of activated HSCs and reduced the liver fibrosis to a significant extent in vivo. This Fn14-targeting strategy may represent a promising approach to targeted drug delivery for liver fibrosis treatment. Meanwhile, the mirror-image mRNA display can provide a new arsenal for the development of d-peptide-based therapeutics against a variety of human diseases.

MiniAp-4: A Venom-Inspired Peptidomimetic for Brain Delivery

Drug delivery across the blood–brain barrier (BBB) is a formidable challenge for therapies targeting the central nervous system. Although BBB shuttle peptides enhance transport into the brain non‐invasively, their application is partly limited by lability to proteases. The present study proposes the use of cyclic peptides derived from venoms as an affordable way to circumvent this drawback. Apamin, a neurotoxin from bee venom, was minimized by reducing its complexity, toxicity, and immunogenicity, while preserving brain targeting, active transport, and protease resistance. Among the analogues designed, the monocyclic lactam‐bridged peptidomimetic MiniAp‐4 was the most permeable. This molecule is capable of translocating proteins and nanoparticles in a human‐cell‐based BBB model. Furthermore, MiniAp‐4 can efficiently deliver a cargo across the BBB into the brain parenchyma of mice.

Toxins and derivatives in molecular pharmaceutics: Drug delivery and targeted therapy

Protein and peptide toxins offer an invaluable source for the development of actively targeted drug delivery systems. They avidly bind to a variety of cognate receptors, some of which are expressed or even up-regulated in diseased tissues and biological barriers. Protein and peptide toxins or their derivatives can act as ligands to facilitate tissue- or organ-specific accumulation of therapeutics. Some toxins have evolved from a relatively small number of structural frameworks that are particularly suitable for addressing the crucial issues of potency and stability, making them an instrumental source of leads and templates for targeted therapy. The focus of this review is on protein and peptide toxins for the development of targeted drug delivery systems and molecular therapies. We summarize disease- and biological barrier-related toxin receptors, as well as targeted drug delivery strategies inspired by those receptors. The design of new therapeutics based on protein and peptide toxins is also discussed.

Three valuable peptides from bee and wasp venoms for therapeutic and biotechnological use: melittin, apamin and mastoparan

While knowledge of the composition and mode of action of bee and wasp venoms dates back 50 years, the therapeutic value of these toxins remains relatively unexploded. The properties of these venoms are now being studied with the aim to design and develop new therapeutic drugs. Far from evaluating the extensive number of monographs, journals and books related to bee and wasp venoms and the therapeutic effect of these toxins in numerous diseases, the following review focuses on the three most characterized peptides, namely melittin, apamin, and mastoparan. Here, we update information related to these compounds from the perspective of applied science and discuss their potential therapeutic and biotechnological applications in biomedicine.

Nanocarrier-mediated inhibition of macrophage migration inhibitory factor attenuates secondary injury after spinal cord injury

Spinal cord injury (SCI) can lead to permanent motor and sensory deficits. Following the initial traumatic insult, secondary injury mechanisms characterized by persistent heightened inflammation are initiated and lead to continued and pervasive cell death and tissue damage. Anti-inflammatory drugs such as methylprednisolone (MP) used clinically have ambiguous benefits with debilitating side effects. Typically, these drugs are administered systemically at high doses, resulting in toxicity and paradoxically increased inflammation. Furthermore, these drugs have a small time window postinjury (few hours) during which they need to be infused to be effective. As an alternative to MP, we investigated the effect of a small molecule inhibitor (Chicago sky blue, CSB) of macrophage migration inhibitory factor (MIF) for treating SCI. The pleiotropic cytokine MIF is known to contribute to upregulation of several pro-inflammatory cytokines in various disease and injury states. In vitro, CSB administration alleviated endotoxin-mediated inflammation in primary microglia and macrophages. Nanocarriers such as liposomes can potentially alleviate systemic side effects of high-dose therapy by enabling site-specific drug delivery to the spinal cord. However, the therapeutic window of 100 nm scale nanoparticle localization to the spinal cord after contusion injury is not fully known. Thus, we first investigated the ability of nanocarriers of different sizes to localize to the injured spinal cord up to 2 weeks postinjury. Results from the study showed that nanocarriers as large as 200 nm in diameter could extravasate into the injured spinal cord up to 96 h postinjury. We then formulated nanocarriers (liposomes) encapsulating CSB and administered them intravenously 48 h postinjury, within the previously determined 96 h therapeutic window. In vivo, in this clinically relevant contusion injury model in rats, CSB administration led to preservation of vascular and white matter integrity, improved wound healing, and an increase in levels of arginase and other transcripts indicative of a resolution phase of wound healing. This study demonstrates the potential of MIF inhibition in SCI and the utility of nanocarrier-mediated drug delivery selectively to the injured cord.