Chitosan-modified lipid nanovesicles for efficient systemic delivery of l-asparaginase

Recent trends in targeted delivery of smart nanocarrier-based microbial enzymes for therapeutic applications

Smart carrier-based immobilization has widened the use of enzymes for the treatment of several disorders. Large surface areas, tunable morphology, and surface modification ability aid the targeted and controlled release of therapeutic enzymes from such formulations. Smart nanocarriers, such as polymeric carriers, liposomes, and silica have also increased the stability, half-life, and permeability of these enzymes. In this review, summarize recent advances in the smart immobilization of microbial enzymes and their development as precision nanomedicine for the treatment of cancer, thrombosis, phenylketonuria (PKU), and wound healing. We also discuss the challenges and measures to be adopted for the successful clinical translation of these formulations.

Polyamidoamine Dendrimers Functionalized with ZnO-Chitosan Nanoparticles as an Efficient Surface for L-asparaginase Immobilization

In this study, the third-generation polyamidoamine dendrimer was functionalized with a 5-amino-1H-tetrazole heterocycle to load the synthesis enzyme and its surface groups. Then, chitosan was attached to the dendrimer by a suitable linker, and finally, zinc oxide nanoparticles were inserted into dendrimer cavities to increase loading. FTIR, FESEM, TEM, and DLS analysis showed that this new dendrimer has specific branches, and ZnO nanoparticles were spread between the branches and connected with the branches and chitosan biopolymer. Also proved the presence of stabilized L-asparaginase enzyme and ZnO nanoparticles in the designed system. Furthermore, the extent of L-asparaginase enzyme loading and release was investigated in the laboratory with a dialysis bag. Examining the toxicity of the new third-generation polyamidoamine (PAMAM) dendrimeric nanocarrier based on chitosan-zinc oxide biopolymer (PAMAM-G3@ZnO-Cs nanocarrier) on the Jurkat cell line (human acute lymphoblastic leukemia) at pH 7.4 showed that this nanocarrier effectively encapsulates the drug L-asparaginase and slowly releases it and also preventing the growth of cancer cells. The activity of the loaded enzyme in the nanocarrier and the free enzyme was calculated. During the investigations, it was found that the enzyme attached to the nanocarrier is more stable than the free enzyme at optimal pH and temperature and at high temperatures, acidic and basic pHs. Vmax and Km values were lower for loaded enzymes. The synthesized PAMAM-G3@ZnO-Cs nanocarrier can be a promising candidate in the pharmaceutical industry and medical science for cancer treatment due to its biocompatibility, non-toxicity, stability, and slow release of L-asparaginase.

L-Asparaginase delivery systems targeted to minimize its side-effects

L-asparaginase (L-ASP) is one of the key enzymes used in therapeutic applications, particularly to treat Acute Lymphocytic Leukemia (ALL). L-asparagine is a non-essential amino acid, which means that it can be synthesized by the body and is not required to be obtained through the diet. The synthesis of L-asparagine occurs primarily in the liver, but it also takes place in other tissues throughout the body. In contrast, leukemic cells cannot synthesize L-asparagine due the absence of L-asparagine synthetase and should obtain it from circulating sources for protein synthesis and cell division processes to ensure their vital functions. L-ASP catalyzes the deamination process of L-asparagine amino-acid into aspartic acid and ammonia, depriving leukemic cells of asparagine. This leads to decreased protein synthesis and cell division in tumor cells. However, using L-ASP has side effects, such as hypersensitivity or allergic reaction, antigenicity, short half-life, temporary blood clearance, and toxicity. L-ASP immobilization can minimize the side effects of L-ASP by stopping the immune system from attacking non-human enzymes and improving the enzyme's performance. The first strategy includes modification of enzyme structure, such as covalent binding (conjugation), adsorption to the support material and cross-linking of the enzyme. The chemical modification of residues, often nonspecific, changes the enzyme's hydrophobicity and surface charge, lowering the enzyme's activity. Also, the first strategy exposes the enzyme's surface to the environment. This eliminates its performance and does not allow targeted delivery of the enzyme. The second strategy is based on the entrapment of the enzyme inside the protecting structure or encapsulation. This strategy offers the same benefits as the first. Still, it also enables reducing toxicity, prolonging in vivo half-life, enhancing stability and activity, enables a targeted delivery and controlled release of the enzyme. Compared to the first strategy, encapsulation does not modify the chemical structure of the enzyme since L-ASP is only effective against leukemia in its native tetrameric form. This review aims to present state of the art in L-ASP formulations developed for reducing the side effects of L-ASP, focusing on describing improvements in their safety. The primary focus in the field remains to be improving the overall performance of the L-ASP formulations. Almost all encapsulation systems allow reducing immune response due to screening the enzyme from antibodies and prolonging its half-life. However, the enzyme's activity and stability depend on the encapsulation system type. Therefore, the selection of the right encapsulation system is crucial in therapy due to its effect on the performance parameters of the L-ASP. Biodegradable and biocompatible materials, such as chitosan, alginate and liposomes, mainly attract the researcher's interest in enzyme encapsulation. The research trends are also moving towards developing formulations with targeted delivery and increased selectivity.

Curcumin-Loaded Platelet Membrane Bioinspired Chitosan-Modified Liposome for Effective Cancer Therapy

Cancer is a serious threat to human health, and chemotherapy for cancer is limited by severe side effects. Curcumin (CUR) is a commonly used natural product for antitumor treatment without safety concerns. However, low bioavailability and poor tumor accumulation are great obstacles for its clinical application. Our previous research has demonstrated that platelet membrane-camouflaged nanoparticles can efficiently ameliorate the in vivo kinetic characteristics and enhance the tumor affinity of payloads. Nevertheless, the antitumor efficiency of this formulation still needs to be thoroughly investigated, and its drug release behavior is limited. Herein, CUR-loaded platelet membrane bioinspired chitosan-modified liposome (PCLP-CUR) was constructed to improve CUR release. PCLP-CUR was shown to have long retention time, improved bioavailability, strong tumor targeting capacity and effective cellular uptake. The incorporation of chitosan enabled PCLP-CUR to release cargoes quickly under mild acidic tumor conditions, leading to more complete drug release and favoring subsequent treatment. Both in vitro and in vivo investigations showed that PCLP-CUR could significantly enhance the anticancer efficacy of CUR with minimal side effects through biomimetic membrane and chitosan modification. In summary, this developed delivery system can provide a promising strategy for tumor-targeting therapy and phytochemical delivery.

Advances on Delivery of Cytotoxic Enzymes as Anticancer Agents

Cancer is one of the most serious human diseases, causing millions of deaths worldwide annually, and, therefore, it is one of the most investigated research disciplines. Developing efficient anticancer tools includes studying the effects of different natural enzymes of plant and microbial origin on tumor cells. The development of various smart delivery systems based on enzyme drugs has been conducted for more than two decades. Some of these delivery systems have been developed to the point that they have reached clinical stages, and a few have even found application in selected cancer treatments. Various biological, chemical, and physical approaches have been utilized to enhance their efficiencies by improving their delivery and targeting. In this paper, we review advanced delivery systems for enzyme drugs for use in cancer therapy. Their structure-based functions, mechanisms of action, fused forms with other peptides in terms of targeting and penetration, and other main results from in vivo and clinical studies of these advanced delivery systems are highlighted.

Biomimetic lipidic nanovectors for effective asparaginase supramolecule delivery

Effectiveness of enzyme therapy is limited by enzyme drawbacks such as short half-life, low bioavailability and high immunogenicity. We loaded asparaginase (Aase) into hydroxypropyl- or sulfonbutylether-beta cyclodextrin to form supramolecular amphiphilic molecules by self-assembly followed by entrapment inside the cores of two biomimetic lipidic nanovectors (AS-XLNs). Supramolecular structure was simulated by molecular docking. AS-XLNs maintained superior activity through isolating Aase from external environment due to docking with cyclodextrin and coating with biomimetic membrane. Fluorescent probes and computational simulations were used to reveal possible interactions between serum albumin/trypsin and Aase/nanovector membrane components which were partly responsible for enhanced bioavailability and bioactivity of AS-XLNs compared to Aase. AS-XLNs significantly increased cytotoxicity against pulmonary tumor cells due to synergistic effects of Aase and nanovector membrane components (killing tumor cells through apoptosis induced by asparagine depletion and autophagy inhibition or via targets such as vascular endothelial growth factor A, alpha-amylase, p-selectin or androgen receptor).

L-asparaginase mediated therapy in L-asparagine auxotrophic cancers: A review

Microbial L-asparaginase is the most effective first-line therapeutic used in the treatment protocols of paediatric and adult leukemia. Leukemic cell's auxotrophy for L-asparagine is exploited as a therapeutic strategy to mediate cell death through metabolic blockade of L-asparagine using L-asparaginase. Escherichia coli and Erwinia chrysanthemi serve as the major enzyme deriving sources accepted in clinical practise and the enzyme has bestowed improvements in patient outcomes over the last 40 years. However, an array of side effects generated by the native enzymes due to glutamine co-catalysis and short serum stays augmenting frequent dosages, intended a therapeutic switch towards the development of biobetter alternatives for the enzyme including the formulations resulting in sustained local depletion of L-asparagine. In addition, the treatment with L-asparaginase in few cancer types has proven to elicit drug-induced cytoprotective autophagy mechanisms and therefore warrants concern. Although the off-target glutamine hydrolysis has been viewed in contributing the drug-induced secondary responses in cells deficient with asparagine synthetase machinery, the beneficial role of glutaminase-asparaginase in proliferative regulation of asparagine prototrophic cells has been looked forward. The current review provides an overview on the enzyme's clinical applications in leukemia and possible therapeutic implications in other solid tumours, recent advancements in drug formulations, and discusses the aspects of two-sided roles of glutaminase-asparaginases and drug-induced cytoprotective autophagy mechanisms.

Antiviral Drug Delivery System for Enhanced Bioactivity, Better Metabolism and Pharmacokinetic Characteristics

Antiviral drugs (AvDs) are the primary resource in the global battle against viruses, including the recent fight against corona virus disease 2019 (COVID-19). Most AvDs require multiple medications, and their use frequently leads to drug resistance, since they have poor oral bioavailability and low efficacy due to their low solubility/low permeability. Characterizing the in vivo metabolism and pharmacokinetic characteristics of AvDs may help to solve the problems associated with AvDs and enhance their efficacy. In this review of AvDs, we systematically investigated their structure-based metabolic reactions and related enzymes, their cellular pharmacology, and the effects of metabolism on AvD pharmacodynamics and pharmacokinetics. We further assessed how delivery systems achieve better metabolism and pharmacology of AvDs. This review suggests that suitable nanosystems may help to achieve better pharmacological activity and pharmacokinetic behavior of AvDs by altering drug metabolism through the utilization of advanced nanotechnology and appropriate administration routes. Notably, such AvDs as ribavirin, remdesivir, favipiravir, chloroquine, lopinavir and ritonavir have been confirmed to bind to the severe acute respiratory syndrome-like coronavirus (SARS-CoV-2) receptor and thus may represent anti-COVID-19 treatments. Elucidating the metabolic and pharmacokinetic characteristics of AvDs may help pharmacologists to identify new formulations with high bioavailability and efficacy and help physicians to better treat virus-related diseases, including COVID-19.

Use of Exogenous Enzymes in Human Therapy: Approved Drugs and Potential Applications

The development of safe and efficacious enzyme-based human therapies has increased greatly in the last decades, thanks to remarkable advances in the understanding of the molecular mechanisms responsible for different diseases, and the characterization of the catalytic activity of relevant exogenous enzymes that may play a remedial effect in the treatment of such pathologies. Several enzyme-based biotherapeutics have been approved by FDA (the U.S. Food and Drug Administration) and EMA (the European Medicines Agency) and many are undergoing clinical trials. Apart from enzyme replacement therapy in human genetic diseases, which is not discussed in this review, approved enzymes for human therapy find applications in several fields, from cancer therapy to thrombolysis and the treatment, e.g., of clotting disorders, cystic fibrosis, lactose intolerance and collagen-based disorders. The majority of therapeutic enzymes are of microbial origin, the most convenient source due to fast, simple and cost-effective production and manipulation. The use of microbial recombinant enzymes has broadened prospects for human therapy but some hurdles such as high immunogenicity, protein instability, short half-life and low substrate affinity, still need to be tackled. Alternative sources of enzymes, with reduced side effects and improved activity, as well as genetic modification of the enzymes and novel delivery systems are constantly searched. Chemical modification strategies, targeted- and/or nanocarrier-mediated delivery, directed evolution and site-specific mutagenesis, fusion proteins generated by genetic manipulation are the most explored tools to reduce toxicity and improve bioavailability and cellular targeting. This review provides a description of exogenous enzymes that are presently employed for the therapeutic management of human diseases with their current FDA/EMA-approved status, along with those already experimented at the clinical level and potential promising candidates.

Asparaginase-Phage P22 Nanoreactors: Toward a Biobetter Development for Acute Lymphoblastic Leukemia Treatment

Asparaginase (ASNase) is a biopharmaceutical for Acute Lymphoblastic Leukemia (ALL) treatment. However, it shows undesirable side effects such as short lifetimes, susceptibility to proteases, and immunogenicity. Here, ASNase encapsidation was genetically directed in bacteriophage P22-based virus-like particles (VLPs) (ASNase-P22 nanoreactors) as a strategy to overcome these challenges. ASNase-P22 was composed of 58.4 ± 7.9% of coat protein and 41.6 ± 8.1% of tetrameric ASNase. Km and Kcat values of ASNase-P22 were 15- and 2-fold higher than those obtained for the free enzyme, respectively. Resulting Kcat/Km value was 2.19 × 10⁵ M⁻¹ s⁻¹. ASNase-P22 showed an aggregation of 60% of the volume sample when incubated at 37 °C for 12 days. In comparison, commercial asparaginase was completely aggregated under the same conditions. ASNase-P22 was stable for up to 24 h at 37 °C, independent of the presence of human blood serum (HBS) or whether ASNase-P22 nanoreactors were uncoated or PEGylated. Finally, we found that ASNase-P22 caused cytotoxicity in the leukemic cell line MOLT-4 in a concentration dependent manner. To our knowledge, this is the first work where ASNase is encapsulated inside of VLPs, as a promising alternative to fight ALL.

l-Asparaginase Encapsulation into Asymmetric Permeable Polymersomes

This work reports, for the encapsulation of l-asparaginase, an anticancer enzyme into hybrid PMPC₂₅-PDPA₇₀/PEO₁₆-PBO₂₂ asymmetric polymersomes previously developed by our group, with loading capacities with over 800 molecules per vesicle. Enzyme-loaded polymersomes show permeability and capacity to hydrolyze l-asparagine, which is essential to cancer cells. The nanoreactors proposed in this work can be potentially used in further studies to develop novel therapeutic alternatives based on l-asparaginase.

Biomimetic microbioreactor-supramolecular nanovesicles improve enzyme therapy of hepatic cancer

A novel biomimetic nanovesicle-loaded supramolecular enzyme-based therapeutics has been developed. Here, using a biomimetic lipid-D-α-tocopherol polyethylene glycol succinate (TPGS) hybrid semi-permeable membrane, cyclodextrin supramolecular docking, metal-ion-aided coordination complexing, we combined multiple functional motifs into a single biomimetic microbioreactor-supramolecular nanovesicle (MiSuNv) that allowed effective transport of arginine deiminase (ADI) to hepatic tumor cells to enhance arginine depletion. We compared two intercalated enzyme-carrying supermolecular motifs mainly comprising of 2-hydroxypropyl-β-cyclodextrin and sulfobutyl-ether-β-cyclodextrin, the only two cyclodextrin derivatives approved for injection by the United States Food and Drug Administration. The ADI-specific antitumor effects were enhanced by TPGS (one constituent of MiSuNv, having synergistic antitumor effects), as ADI was separated from adverse external environment by a semi-permeable membrane and sequestered in a favorable internal microenvironment with an optimal pH and metal-ion combination. ADI@MiSuNv contributed to cell cycle arrest, apoptosis and autophagy through the enhanced efficacy of enzyme treatment against Hep3B xenograft tumors in rats.

Biomimetic polysaccharide-cloaked lipidic nanovesicles/microassemblies for improving the enzymatic activity and prolonging the action time for hyperuricemia treatment

The improvement and maintenance of enzymatic activities represent major challenges. However, to address these we developed novel biomimetic polysaccharide hyaluronan (Hn)-cloaked lipidic nanovesicles (BHLN) and microassemblies (BHLNM) as enzyme carriers that function by entrapping enzymes in the core or by tethering them to the inner/outer surfaces via covalent interactions. The effectiveness of these enzyme carriers was demonstrated through an evaluation of the enzymatic activity and anti-hyperuricemia bioactivity of urate oxidase (also called uricase, Uase). We showed that Uase was effectively loaded within the BHLN/BHLNM (UHLN/UHLNM) and maintained good enzymatic bioactivity through a range of effects, including isolation from the external environment due to the vesicle-carrying (shielding effect), avoidance of recognition by the reticuloendothelial system due to Hn-cloaking (long-term effect), production of beneficial conformational changes (allosteric effect) due to a favorable internal microenvironment of construction and vesicle loading, and stabilization due to the reversible conjugation of Uase or vesicle and serum albumin (deposit effect). UHLN/UHLNM had significantly increased bioavailability (∼533% and ∼331% compared to Uase) and demonstrated greatly improved efficacy, whereby the time required for UHLN/UHLNM to lower the plasma uric acid concentration to a normal level was much shorter than that for free Uase. The interactions of the therapeutic enzyme (Uase), biomimetic membrane components (Hn and phospholipid), and serum albumin were investigated with a fluorescent probe and computational simulations to help understand the superior properties of UHLN/UHLNM.

Biomimetic Membrane-Structured Nanovesicles Carrying a Supramolecular Enzyme to Cure Lung Cancer

Platforms for enzyme delivery must simultaneously have plasma stability, high catalytic activity, and low/no immunogenicity of the enzyme. Here, we designed a novel biomimetic membrane-structured nanovesicle (BNV) to efficiently carry supramolecular enzymes to meet the above requirements. We complexed l-asparaginase (Aase) with hydroxypropyl-β-cyclodextrin (HPCD) to form a supramolecular amphiphile (AS) by self-assembly via noncovalent reversible interactions. We then used the first synthesized polyethylene glycol (PEG 2 kDa)-decorated hyaluronan (12 kDa) and HPCD to self-assemble a semipermeable biomimetic membrane-structured nanovesicle (BNV) together with AS loading. As compared to native Aase, AS@BNV exhibited superior catalytic activity preservation, improved catalytic activity, better pharmacokinetics in rats, enhanced cytotoxic effects, increased antitumor efficacy, and decreased side effects. The underlying mechanisms, such as the autophagy inhibition action against tumor cells, protein-protein docking of the interaction between Aase-serum albumin, and decreased hepatic enzymatic activity, were investigated. This approach paves the way for new types of powerful biomimetic-, supramolecular-, and nanocarrier-based enzymatic therapies.

Oral administration of natural polyphenol-loaded natural polysaccharide-cloaked lipidic nanocarriers to improve efficacy against small-cell lung cancer

Oral administration shows good tolerance in patients. Botanic anticancer drugs without serious side effects have attracted increased attention worldwide. However, oral delivery of natural anticancer drugs faces great challenges due to low solubility, gastrointestinal side effects, first-pass effects, and P-glycoprotein efflux. Here, we loaded the natural polyphenol curcumin (Cc) into natural polysaccharide-cloaked lipidic nanocarriers (Cc@CLNs) to improve the efficacy in small-cell lung cancer (SCLC) associated with oral administration. Compared to other nanoformulations, Cc@CLNs have advantages of simple operation, easy scale-up, low cost, and high safety. Cc@CLNs improve bioavailability by inducing synergistic effects (efficient cell membrane penetration, inherent muco-adhesiveness, resistance to pepsin and trypsin degradation, promoted dissolution, enhanced epithelia/M cellular uptake and inhibition of efflux transporters) and countering the tendency of nanocarriers to aggregate and fuse, which limit lipid-based nanosystems. In this study, we first evaluated the oral bioavailability of Cc@CLNs in rats and their efficacy in H446 tumor-bearing mice. The oral bioavailability increased by 8.94-fold, and the tumor growth inhibition rate doubled compared to that achieved with free Cc. We investigated the action of Cc against SCLC stem cells, and Cc@CLNs greatly enhanced this action. The expression of CD133 and ABCG2 in the Cc@CLNs group decreased by 38.05% and 32.57%, respectively, compared to the respective expression levels in the control.

Cytomembrane-mimicking nanocarriers with a scaffold consisting of a CD44-targeted endogenous component for effective asparaginase supramolecule delivery

Highly effective and safe delivery of therapeutic enzymes is pivotal to the success of antitumor therapy. Herein, we report on a targeted enzyme delivery system based on cytomembrane-mimicking nanocarriers (CmN) and a supramolecular technique (SmT). Specifically, each CmN had a scaffold that mainly consisted of a CD44-targeted endogenous component conjugated with polyethylene glycol 2000 (HA-g-PEG) that self-assembled with α-cyclodextrin (ACD). The CmN acted as a microbioreactor with an inner hollow space with the capacity to confine the large molecule asparaginase (Asp) in an Asp/ACD-supramolecular complex conjugated to the inner region. The supramolecular Asp loaded into the CmN (A-S-CmN) exhibited superior stability, kinetic properties, catalytic activity and antitumor effects compared to free Asp due to the dual protection of the supramolecular complex and the nanovesicle, the CD44 targeting-homing ability, the prolonged effects of HA-g-PEG, and the favorable inner microenvironment of the constructed supramolecular CmN. The A-S-CmN also showed a decrease in in vivo toxicity and immunogenicity. CmN combined with SmT therapeutics are easy to implement and extend for use in the delivery of various enzymes and for many types of cancer treatment.

Review of the Application of Nanovesicles and the Human Interstitial Fluid in Gastrointestinal Premalignant Lesion Detection, Diagnosis, Prognosis and Therapy

Premalignant lesions arise from cells that abnormally proliferate and have a tendency to become cancerous. Developing methods to specifically target and remove these premalignant lesions is imperative to the prevention of malignant progression into gastrointestinal (GI) tumors. However, accurate detection and diagnosis of GI precancerous lesions is challenging, as these lesions show little or no structural change. Thus, this prevents early intervention and reduces the success rate of therapy. In this review, we performed a systematic analysis of the technological advancements in the combined application of nanovesicles (NVs) and the human interstitial fluid (HIF) to specifically target GI premalignant lesions. NVs, which include quantum dots (QDs), are small membranous vehicles of a nanometer diameter that are widely used as drug delivery vectors, therapeutic effectors and diagnostic sensors. HIF is the fluid that is present in human interstitial tissues (HITs) in which signaling molecules and agents travel and can be found throughout the body. HIF is exploited by tumor cells for their invasion, migration and spread. Because the HITs span the entire submucosa of the gastrointestinal tract, they have been increasingly targeted in GI tumor therapy. The challenges involved in the combined application of NVs and HIF in the detection, diagnosis, prognosis and therapy of GI premalignant lesions are also discussed.

Development of L-Asparaginase Biobetters: Current Research Status and Review of the Desirable Quality Profiles

L-Asparaginase (ASNase) is a vital component of the first line treatment of acute lymphoblastic leukemia (ALL), an aggressive type of blood cancer expected to afflict over 53,000 people worldwide by 2020. More recently, ASNase has also been shown to have potential for preventing metastasis from solid tumors. The ASNase treatment is, however, characterized by a plethora of potential side effects, ranging from immune reactions to severe toxicity. Consequently, in accordance with Quality-by-Design (QbD) principles, ingenious new products tailored to minimize adverse reactions while increasing patient survival have been devised. In the following pages, the reader is invited for a brief discussion on the most recent developments in this field. Firstly, the review presents an outline of the recent improvements on the manufacturing and formulation processes, which can severely influence important aspects of the product quality profile, such as contamination, aggregation and enzymatic activity. Following, the most recent advances in protein engineering applied to the development of biobetter ASNases (i.e., with reduced glutaminase activity, proteolysis resistant and less immunogenic) using techniques such as site-directed mutagenesis, molecular dynamics, PEGylation, PASylation and bioconjugation are discussed. Afterwards, the attention is shifted toward nanomedicine including technologies such as encapsulation and immobilization, which aim at improving ASNase pharmacokinetics. Besides discussing the results of the most innovative and representative academic research, the review provides an overview of the products already available on the market or in the latest stages of development. With this, the review is intended to provide a solid background for the current product development and underpin the discussions on the target quality profile of future ASNase-based pharmaceuticals.