A month-long effect from a single injection of microencapsulated human growth hormone

Hyaluronic Acid in Nanopharmaceuticals: An Overview

Hyaluronic acid (HA) is a naturally occurring, long, unbranched polysaccharide that plays a critical role in maintaining skin structure and hydration. Its unique properties make it a valuable component in the field of nanopharmaceuticals. The combination of HA into nanopharmaceuticals enhances its ability to interact with various therapeutic agents, improving the delivery and efficacy of drugs. HA-based nanoparticles, including solid lipid nanoparticles, and polymeric nanogels, offer controlled release, enhanced stability, and targeted delivery of therapeutic agents. These innovations significantly improve therapeutic outcomes and reduce side effects, making HA an essential tool in modern medicine. In general, HA-modified liposomes enhance drug encapsulation and targeting, while HA-modified solid lipid nanoparticles (SLNs) provide a solid lipid core for drug encapsulation, offering controlled release and stability. This article provides an overview of the potential applications and recent advancements of HA in nanopharmaceuticals, emphasizing its significant impact on the evolving field of targeted drug delivery and advanced therapeutic strategies. By delving into the unique properties of HA and its compatibility with various therapeutic agents, this review underscores the promising potential of HA in revolutionizing nanopharmaceuticals.

Supramolecular interaction in the action of drug delivery systems

Complex diseases and diverse clinical needs necessitate drug delivery systems (DDSs), yet the current performance of DDSs is far from ideal. Supramolecular interactions play a pivotal role in various aspects of drug delivery, encompassing biocompatibility, drug loading, stability, crossing biological barriers, targeting, and controlled release. Nevertheless, despite having some understanding of the role of supramolecular interactions in drug delivery, their incorporation is frequently overlooked in the design and development of DDSs. This perspective provides a brief analysis of the involved supramolecular interactions in the action of drug delivery, with a primary emphasis on the DDSs employed in the clinic, mainly liposomes and polymers, and recognized phenomena in research, such as the protein corona. The supramolecular interactions implicated in various aspects of drug delivery systems, including biocompatibility, drug loading, stability, spatiotemporal distribution, and controlled release, were individually analyzed and discussed. This perspective aims to trigger a comprehensive and systematic consideration of supramolecular interactions in the further development of DDSs. Supramolecular interactions embody the true essence of the interplay between the majority of DDSs and biological systems.

A Superlong-Acting Growth Hormone-Polypeptide Fusion for Growth Hormone Deficiency Treatment

Recombinant human growth hormone (rhGH) is clinically used to treat growth hormone deficiency (GHD). However, daily administration of rhGH is required due to its poor stability and short blood circulation, which causes pains and burdens as well as inconvenience to patients. In this study, a method for genetically fusing rhGH to a thermosensitive polymer of elastin-like polypeptide (ELP) is reported, using which the rhGH-ELP thermosensitive fusion protein can be purified by the thermosensitivity of ELP instead of chromatography. The ELP fusion not only drastically improves the stability of rhGH, but also enables the in situ formation of a sustained-release depot of rhGH-ELP upon subcutaneous (SC) injection, which exhibits gentle release with a platform-to-trough fluctuation in blood and a very long circulatory half-life of 594.6 h. In contrast, rhGH exhibits a peak-to-trough fluctuation in blood with a very short circulatory half-life of 0.7 h. As a result, a single subcutaneous injection of rhGH-ELP can consecutively promote the linear growth of rats and the development of major tissues and organs over 3 weeks without obvious side effects, whereas rhGH is required to be injected daily to achieve similar therapeutic results.

Chrysanthemum sporopollenin: A novel vaccine delivery system for nasal mucosal immunity

Objective

Mucosal immunization was an effective defender against pathogens. Nasal vaccines could activate both systemic and mucosal immunity to trigger protective immune responses. However, due to the weak immunogenicity of nasal vaccines and the lack of appropriate antigen carriers, very few nasal vaccines have been clinically approved for human use, which was a major barrier to the development of nasal vaccines. Plant-derived adjuvants are promising candidates for vaccine delivery systems due to their relatively safe immunogenic properties. In particular, the distinctive structure of pollen was beneficial to the stability and retention of antigen in the nasal mucosa.

Methods

Herein, a novel wild-type chrysanthemum sporopollenin vaccine delivery system loaded with a w/o/w emulsion containing squalane and protein antigen was fabricated. The unique internal cavities and the rigid external walls within the sporopollenin skeleton construction could preserve and stabilize the inner proteins. The external morphological characteristics were suitable for nasal mucosal administration with high adhesion and retention.

Results

Secretory IgA antibodies in the nasal mucosa can be induced by the w/o/w emulsion with the chrysanthemum sporopollenin vaccine delivery system. Moreover, the nasal adjuvants produce a stronger humoral response (IgA and IgG) compared to squalene emulsion adjuvant. Mucosal adjuvant benefited primarily from prolongation of antigens in the nasal cavity, improvement of antigen penetration in the submucosa and promotion of CD8+ T cells in spleen.

Disccusion

Based on effective delivering both the adjuvant and the antigen, the increase of protein antigen stability and the realization of mucosal retention, the chrysanthemum sporopollenin vaccine delivery system has the potential to be a promising adjuvant platform. This work provide a novel idea for the fabrication of protein-mucosal delivery vaccine.

Pathogen-derived peptides in drug targeting and its therapeutic approach

Peptides, short stretches of amino acids or small proteins that occupy a strategic position between proteins and amino acids, are readily accessible by chemical and biological methods. With ideal properties for forming high-affinity and specific interactions with host target proteins, they have established an important niche in the drug development spectrum complementing small molecule and biological therapeutics. Among the most successful biomedicines in use today, peptide-based drugs show great promise. This, coupled with recent advances in synthetic and nanochemical biology, has led to the creation of tailor-made peptide therapeutics for improved biocompatibility. This review presents an overview of the latest research on pathogen-derived, host-cell-interacting peptides. It also highlights strategies for using peptide-based therapeutics that address cellular transport challenges through the introduction of nanoparticles that serve as platforms to facilitate the delivery of peptide biologics and therapeutics for treating various inflammatory diseases. Finally, this paper describes future perspectives, specific pathogen-based peptides that can enhance specificity, efficiency, and capacity in functional peptide-based therapeutics, which are in the spotlight as new treatment alternatives for various diseases, and also presents verified sequences and targets that can increase chemical and pharmacological value.

Shape-specific microfabricated particles for biomedical applications: a review

The storied history of controlled the release systems has evolved over time; from degradable drug-loaded sutures to monolithic zero-ordered release devices and nano-sized drug delivery formulations. Scientists have tuned the physico-chemical properties of these drug carriers to optimize their performance in biomedical/pharmaceutical applications. In particular, particle drug delivery systems at the micron size regime have been used since the 1980s. Recent advances in micro and nanofabrication techniques have enabled precise control of particle size and geometry-here we review the utility of microplates and discoidal polymeric particles for a range of pharmaceutical applications. Microplates are defined as micrometer scale polymeric local depot devices in cuboid form, while discoidal polymeric nanoconstructs are disk-shaped polymeric particles having a cross-sectional diameter in the micrometer range and a thickness in the hundreds of nanometer range. These versatile particles can be used to treat several pathologies such as cancer, inflammatory diseases and vascular diseases, by leveraging their size, shape, physical properties (e.g., stiffness), and component materials, to tune their functionality. This review highlights design and fabrication strategies for these particles, discusses their applications, and elaborates on emerging trends for their use in formulations.

Sustained transdermal delivery of human growth hormone from niosomal gel: in vitro and in vivo studies

Human growth hormone (hGH) is widely used to treat several diseases for decades. However, the current treatment regime requires frequent injections via subcutaneous route due to short in vivo half-life, which leads to pain and poor patient compliance. In this study, a novel transdermal (non-invasive) hGH loaded niosomes gel was prepared to reduce the frequency of subcutaneous injections and to improve the patient compliance. Niosomes were prepared by film hydration technique at three levels of cholesterol. The particle size and entrapment efficiency increases with an increase in the level of cholesterol. Transmission electron microscopy images confirmed the spherical shape of niosomes without aggregation. Texture profiles analysis indicates that the niosomal gel has the required mechanical properties for transdermal application. The ex vivo permeation profile showed sustain hGH release for 4 days from the niosomal gel compared to 24 h from the control gel without niosomes. A rabbit skin irritation study showed no sign of irritation after application of niosomal gel. The pharmacokinetic parameters in the rat model showed 7.22-fold higher bioavailability with niosomal gel compared to control gel. In conclusion, the study demonstrated the potential of niosomal gel as an effective long-term sustained release strategy for hGH delivery to replace traditional subcutaneous injections.

Long-acting recombinant human growth hormone in the treatment of pediatric growth hormone deficiency, how far have we got?

The widespread availability of recombinant human growth hormone (GH) since 1985 has made it possible to extend growth hormone therapy indications for children with different etiologies of short stature. It is now accepted that GH is effective in increasing height velocity in children with GH deficiency (GHD) and well tolerated in both the short and long terms. Nevertheless, one major factor in the inter-individual variability of the growth response to GH in GHD children is adherence to daily injections. In an attempt to improve patient adherence, there has been a strong effort from industry to create a long-acting form of growth hormone to ease the burden of its use. It is theorized that by decreasing injection frequency, Long-Acting GH (LAGH) would improve adherence and therefore outcomes. These agents can be divided broadly into depot formulations, PEGylated formulations, prodrug formulations, noncovalent albumin-binding GH and GH fusion proteins. In 2021, two LAGH formulations are on the market in China and South Korea, and several promising agents are under clinical investigation at various stages of development throughout the world. A number of safety issues related to LAGH have been identified and need to be further investigated. © 2022 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.

Insight into the Microcosm of the Human Growth Hormone and Its Interactions with Polymers and Copolymers: A Molecular Dynamics Perspective

Therapeutic proteins nowadays have increasingly been applied for their considerable potential in treating a wide variety of diseases. The effectiveness and potency of native therapeutic proteins are limited by various factors (e.g., stability, blood circulation time, specificity). Over the past years, a great deal of effort has been devoted to developing safe and efficient protein delivery systems. Entrapment of protein into polymeric and copolymeric matrices is common among the different types of protein-based drug formulation. However, despite the massive efforts toward developing therapeutic protein delivery in experimental studies and industrial applications, there is relatively little data on the influence of polymers and copolymers on therapeutic proteins at the atomic and molecular levels. Herein, molecular dynamics (MD) simulations are used to study the effects of biocompatible synthetic polymers including methoxy poly(ethylene glycol) (MPEG), poly(lactic acid) (PLA), and poly(lactic acid) copolymers (poly(lactic-co-glycolic acid)) PLGA and MPEG-PLA(PELA)) on the structure and dynamics of the human growth hormone (hGH), and the results are compared with previous experimental findings. Our results indicate that the hGH conformation remains stable both in pure water and in the presence of polymers, and these results are in good agreement with previous experimental data. It is shown that the MPEG chains are self-assembled and folded into a semicrystalline structure; therefore, only a small portion of the protein interacts with the polymer. The other three polymers, however, interact well with the protein and partially cover its surface. Our findings suggest that the use of these polymers for protein encapsulation has the advantage of reducing protein aggregation and thus increasing drug serum half-life. Eventually, we anticipate that the research results will expand the current knowledge about encapsulation mechanisms and the molecular interactions between hGH and the polymers.

Engineering microenvironment of biodegradable polyester systems for drug stability and release control

Polymeric systems made of poly(lactic acid) or poly(lactic-co-glycolic acid) are widely used for long-term delivery of small and large molecules. The advantages of poly(lactic acid)/poly(lactic-co-glycolic acid) systems include biodegradability, safety and a long history of use in US FDA-approved products. However, as drugs delivered by the polymeric systems and their applications become more diverse, the significance of microenvironment change of degrading systems on long-term drug stability and release kinetics has gained renewed attention. In this review, we discuss various issues experienced with acidifying microenvironment of biodegradable polymer systems and approaches to overcome the detrimental effects of polymer degradation on drug stability and release control.

Usefulness and Potential Pitfalls of Long-Acting Growth Hormone Analogs

Daily recombinant human GH (rhGH) is currently approved for use in children and adults with GH deficiency (GHD) in many countries with relatively few side-effects. Nevertheless, daily injections can be painful and distressing for some patients, often resulting in non-adherence and reduction of treatment outcomes. This has prompted the development of numerous long-acting GH (LAGH) analogs that allow for decreased injection frequency, ranging from weekly, bi-weekly to monthly. These LAGH analogs are attractive as they may theoretically offer increased patient acceptance, tolerability, and therapeutic flexibility. Conversely, there may also be pitfalls to these LAGH analogs, including an unphysiological GH profile and differing molecular structures that pose potential clinical issues in terms of dose initiation, therapeutic monitoring, incidence and duration of side-effects, and long-term safety. Furthermore, fluctuations of peak and trough serum GH and IGF-I levels and variations in therapeutic efficacy may depend on the technology used to prolong GH action. Previous studies of some LAGH analogs have demonstrated non-inferiority compared to daily rhGH in terms of increased growth velocity and improved body composition in children and adults with GHD, respectively, with no significant unanticipated adverse events. Currently, two LAGH analogs are marketed in Asia, one recently approved in the United States, another previously approved but not marketed in Europe, and several others proceeding through various stages of clinical development. Nevertheless, several practical questions still remain, including possible differences in dose initiation between naïve and switch-over patients, methodology of dose adjustment/s, timing of measuring serum IGF-I levels, safety, durability of efficacy and cost-effectiveness. Long-term surveillance of safety and efficacy of LAGH analogs are needed to answer these important questions.

An Update on Pharmaceutical Strategies for Oral Delivery of Therapeutic Peptides and Proteins in Adults and Pediatrics

While each route of therapeutic drug delivery has its own advantages and limitations, oral delivery is often favored because it offers convenient painless administration, sustained delivery, prolonged shelf life, and often lower manufacturing cost. Its limitations include mucus and epithelial cell barriers in the gastrointestinal (GI) tract that can block access of larger molecules including Therapeutic protein or peptide-based drugs (TPPs), resulting in reduced bioavailability. This review describes these barriers and discusses different strategies used to modify TPPs to enhance their oral bioavailability and/or to increase their absorption. Some seek to stabilize the TTPs to prevent their degradation by proteolytic enzymes in the GI tract by administering them together with protease inhibitors, while others modify TPPs with mucoadhesive polymers like polyethylene glycol (PEG) to allow them to interact with the mucus layer, thereby delaying their clearance. The further barrier provided by the epithelial cell membrane can be overcome by the addition of a cell-penetrating peptide (CPP) and the use of a carrier molecule such as a liposome, microsphere, or nanosphere to transport the TPP-CPP chimera. Enteric coatings have also been used to help TPPs reach the small intestine. Key efficacious TPP formulations that have been approved for clinical use will be discussed.

Long-Acting Growth Hormone Preparations - Current Status and Future Considerations

CONTEXT

Long-acting GH (LAGH) preparations are currently being developed in an attempt to improve adherence. The profile of GH action following administration of LAGH raises practical questions about clinical monitoring and long-term safety and efficacy of these new therapeutic agents.

METHODS

Recent literature and meeting proceedings regarding LAGH preparations are reviewed.

RESULTS

Multiple LAGH preparations are currently at various stages of development, allowing for decreased GH injection frequency from daily to weekly, biweekly, or monthly. Following administration of LAGH, the serum peak and trough GH and IGF-I levels vary depending upon the mechanism used to prolong GH action. Randomized, controlled clinical trials of some LAGH preparations have reported non-inferiority compared with daily recombinant human GH (rhGH) for improved growth velocity and body composition in children and adults with GH deficiency (GHD), respectively. No significant LAGH-related adverse events have been reported during short-term therapy.

CONCLUSION

Multiple LAGH preparations are proceeding through clinical development with some showing promising evidence of short-term clinical efficacy and safety in children and adults with GHD. The relationship of transient elevations of GH and IGF-I following administration of LAGH to efficacy and safety remain to be elucidated. For LAGH to replace daily rhGH in the treatment of individuals with GHD, a number of practical questions need to be addressed including methods of dose adjustment, timing of monitoring of IGF-I, safety, efficacy, and cost-effectiveness. Long-term surveillance of efficacy and safety of LAGH preparations will be needed to answer these clinically relevant questions.

Lipid and PLGA Microparticles for Sustained Delivery of Protein and Peptide Drugs

Solid lipid particles have a great potential in sustained drug delivery, the lipid excipients are solid at room temperature with a slow degradation rate. Poly (D, L-lactic-coglycolic acid) (PLGA) has been successfully clinically applied for the sustained delivery of peptide drugs. A recent study showed the advantage of hybrid PLGA-lipid microparticles (MPs) over PLGA MPs for the sustained delivery of peptide drug in vivo. In this paper, we briefly present PLGA MPs, solid lipid MPs and PLGA lipid hybrid MP prepared by the double emulsion method and the spray drying method and discuss the effects of excipients on encapsulation efficiency of protein and peptide drugs in the MPs. The pros and cons of PLGA MPs, solid lipid MPs and PLGA lipid hybrid MP as carriers for sustained delivery of protein and peptide drugs are also discussed.

Optimal Design of Needle Array for Effective Drug Delivery

Recently, the multi-needle drug injection has been adopted to overcome the shortcomes of conventional single-needle injection, enhancing the efficiency of drug delivery. However, the effect of needle array on the efficacy of drug delivery has not been fully elucidated. In this study, the interactions of drug analogous solution injected from a pair of needles were analyzed to examine the design criteria of effective multi-needle devices for drug delivery. Temporal and spatial variations of relative contents of the solution in the tissues were compared according to the distance between two adjacent needles (DN). As the DN increases from 5 to 20 D, where D is the needle diameter, the solution from each needle encounters 3.5 times faster, and 4.22 times more solution was accumulated. At the same time, the effective spreading area was continuously increased from 54.2 to 177.8 mm² and RCS gradient decreases from 0.087 to 0.037, due to the overlapping effect of the spreading solution from neighboring needles. Finally, based on the experimental results, an optimal design criterion of needle array for effective drug delivery was proposed. The present results would be helpful in the design of multi-needle injection devices and eventually offer advantage to patients with effective drug delivery.

Harnessing Nanoparticles for Immunomodulation and Vaccines

The first successful use of nanoparticles (NPs) for vaccination was reported almost 40 years ago with a virus-like particle-based vaccine against Hepatitis B. Since then, the term NP has been expanded to accommodate a large number of novel nano-sized particles engineered from a range of materials. The great interest in NPs is likely not only a result of the two successful vaccines against hepatitis B and Human Papilloma Virus (HPV) that use this technology, but also due to the versatility of those small-sized particles, as indicated by the wide range of applications reported so far, ranging from medicinal and cosmetics to purely technical applications. In this review, we will focus on the use of NPs, especially virus-like particles (VLPs), in the field of vaccines and will discuss their employment as vaccines, antigen display platforms, adjuvants and drug delivery systems.

Dual-nozzle spray deposition process for improving the stability of proteins in polymer microneedles

Simultaneous deposition of protein and polymer solutions via the dual-nozzle spray deposition process forms mechanically stable microneedles and shows improved protein's structural stability during microneedle fabrication.

Development and Characterization of Sodium Hyaluronate Microparticle-Based Sustained Release Formulation of Recombinant Human Growth Hormone Prepared by Spray-Drying

The purpose of this study was to develop and characterize a sodium hyaluronate microparticle-based sustained release formulation of recombinant human growth hormone (SR-rhGH) prepared by spray-drying. Compared to freeze-drying, spray-dried SR-rhGH showed not only prolonged release profiles but also better particle property and injectability. The results of size-exclusion high-performance liquid chromatography showed that no aggregate was detected, and dimer was just about 2% and also did not increase with increase of inlet temperature up to 150 °C. Meanwhile, the results of reversed-phase high-performance liquid chromatography revealed that related proteins increased slightly from 4.6% at 100 °C to 6.3% at 150 °C. Thermal mapping test proved that product temperature did not become high to cause protein degradation during spray-drying because thermal energy was used for the evaporation of surface moisture of droplets. The structural characterization by peptide mapping, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and circular dichroism revealed that the primary, secondary, and tertiary structures of rhGH in SR-rhGH were highly comparable to those of reference somatropin materials. The biological characterization by rat weight gain and cell proliferation assays provided that bioactivity of SR-rhGH was equivalent to that of native hGH. These data establish that spray-dried SR-rhGH is highly stable by preserving intact rhGH and hyaluronate microparticle-based formulation by spray-drying can be an alternative delivery system for proteins.

Poly(amino carbonate urethane)-based biodegradable, temperature and pH-sensitive injectable hydrogels for sustained human growth hormone delivery

In this study, a new pH-/temperature-sensitive, biocompatible, biodegradable, and injectable hydrogel based on poly(ethylene glycol)-poly(amino carbonate urethane) (PEG-PACU) copolymers has been developed for the sustained delivery of human growth hormone (hGH). In aqueous solutions, PEG-PACU-based copolymers existed as sols at low pH and temperature (pH 6.0, 23 °C), whereas they formed gels in the physiological condition (pH 7.4, 37 °C). The physicochemical characteristics, including gelation rate, mechanical strength and viscosity, of the PEG-PACU hydrogels could be finely tuned by varying the polymer weight, pH and temperature of the copolymer. An in vivo injectable study in the back of Sprague-Dawley (SD) rats indicated that the copolymer could form an in situ gel, which exhibited a homogenous porous structure. In addition, an in vivo biodegradation study of the PEG-PACU hydrogels showed controlled degradation of the gel matrix without inflammation at the injection site and the surrounding tissue. The hGH-loaded PEG-PACU copolymer solution readily formed a hydrogel in SD rats, which subsequently inhibited the initial hGH burst and led to the sustained release of hGH. Overall, the PEG-PACU-based copolymers prepared in this study are expected to be useful biomaterials for the sustained delivery of hGH.

DNA hydrogel microspheres and their potential applications for protein delivery and live cell monitoring

Microfluidic devices have been extensively developed as methods for microscale materials fabrication. It has also been adopted for polymeric microsphere fabrication and in situ drug encapsulation. Here, we employed multi-inlet microfluidic channels for DNA hydrogel microsphere formation and in situ protein encapsulation. The release of encapsulated proteins from DNA hydrogels showed different profiles accordingly with the size of microspheres.

Protein powders for encapsulation: a comparison of spray-freeze drying and spray drying of darbepoetin alfa

PURPOSE

To evaluate spray-freeze drying and spray drying processes for fabricating micron-sized particles of darbepoetin alfa (NESP, Aranesp) with uniform size distribution and retention of protein integrity, requirements for encapsulation.

METHODS

Darbepoetin alfa was spray-freeze dried using ultrasonic atomization at 120 kHz and 25 kHz and spray dried at bench-top and pilot scales. Reconstituted powders were evaluated by size exclusion chromatography and UV/VIS spectroscopy. Powder physical properties were also characterized.

RESULTS

Spray-freeze drying resulted in aggregation of darbepoetin alfa. Aggregates (primarily insoluble) formed on drying and/or reconstitution. Particle size distributions were broad (span > or = 3.6) at both nozzle frequencies. Annealing before drying reduced aggregate levels slightly but increased particle size over 5-fold. Spray drying at inlet temperatures up to 135 degrees C (and outlet temperatures up to 95 degrees C) showed little impact on integrity. Integrity at bench-top and pilot scales was identical, with 0.2% dimer and no high molecular weight or insoluble aggregates detected. Particle size was small (< or = 2.3 microm) with uniform distribution (span < or = 1.4) at both process scales.

CONCLUSIONS

Under the conditions tested spray drying, conducted at bench-top and pilot scales with commercially available equipment, was superior to spray-freeze drying for the fabrication of darbepoetin alfa particles for encapsulation.

Characterization of recombinant human growth hormone variants from sodium hyaluronate-based sustained release formulation of rhGH under heat stress

This study provides the findings of investigations of potential product-related variants on recombinant human growth hormone (rhGH) in a once-weekly sustained release formulation (SR-rhGH) of sodium hyaluronate microparticles and on the rhGH bulk solution used as the active ingredient for SR-rhGH under extreme stress conditions of 24 h at 60 °C. The extent of rhGH degradation was much higher in solution (33%) than in SR-rhGH (10%). The degradation products, especiallyMet14 sulfoxide and deamidated rhGH variants, were separated and quantified by a modified reversed-phase high-performance liquid chromatography (RP-HPLC) method at reduced flow rate. The primary degradation product of rhGH was found to be deamidated rhGH, although an unknown peak was also detected. In contrast, the primary degradation product of SR-rhGH was Met14 sulfoxide rhGH, with no unknown peaks. Using a cell proliferation assay, the biological activities of the isolated products of SR-rhGH degradation were found to be equivalent to those of native hGH, as determined by comparison with a National Institute for Biological Standards and Control standard. In conclusion, SR-rhGH is structurally and functionally stable and maintains the intactness of rhGH.

Controlled release of an anthrax toxin-neutralizing antibody from hydrolytically degradable polyethylene glycol hydrogels

In this study, hydrophilic and hydrolytically degradable poly (ethylene glycol) (PEG) hydrogels were formed via Michael-type addition and employed for sustained delivery of a monoclonal antibody against the protective antigen of anthrax. Taking advantage of the PEG-induced precipitation of the antibody, burst release from the matrix was avoided. These hydrogels were able to release active antibodies in a controlled manner from 14 days to as long as 56 days in vitro by varying the polymer architectures and molecular weights of the precursors. Analysis of the secondary and tertiary structure and the in vitro activity of the released antibody showed that the encapsulation and release did not affect the protein conformation or functionality. The results suggest the promise for developing PEG-based carriers for sustained release of therapeutic antibodies against toxins in various applications.

Single-injection vaccines: Progress, challenges, and opportunities

Currently, vaccination is the most efficient and cost-effective medical treatment for infectious diseases; however, each year 10 million infants remain underimmunized due to current vaccination schedules that require multiple doses to be administered across months or years. These dosing regimens are especially challenging in the developing world where limited healthcare access poses a major logistical barrier to immunization. Over the past four decades, researchers have attempted to overcome this issue by developing single-administration vaccines based on controlled-release antigen delivery systems. These systems can be administered once, but release antigen over an extended period of time to elicit both primary and secondary immune responses resulting in antigen-specific immunological memory. Unfortunately, unlike controlled release systems for drugs, single-administration vaccines have yet to be commercialized due to poor antigen stability and difficulty in obtaining unconventional release kinetics. This review discusses the current state of single-administration vaccination, challenges delaying the development of these vaccines, and potential strategies for overcoming these challenges.

Nanostructure controlled sustained delivery of human growth hormone using injectable, biodegradable, pH/temperature responsive nanobiohybrid hydrogel

The clinical efficacy of a therapeutic protein, the human growth hormone (hGH), is limited by its short plasma half-life and premature degradation. To overcome this limitation, we proposed a new protein delivery system by the self-assembly and intercalation of a negatively charged hGH onto a positively charged 2D-layered double hydroxide nanoparticle (LDH). The LDH-hGH ionic complex, with an average particle size of approximately 100 nm, retards hGH diffusion. Nanobiohybrid hydrogels (PAEU/LDH-hGH) were prepared by dispersing the LDH-hGH complex into a cationic pH- and temperature-sensitive injectable PAEU copolymer hydrogel to enhance sustained hGH release by dual ionic interactions. Biodegradable copolymer hydrogels comprising poly(β-amino ester urethane) and triblock poly(ε-caprolactone-lactide)-poly(ethylene glycol)-poly-(ε-caprolactone-lactide) (PCLA-PEG-PCLA) were synthesized and characterized. hGH was self-assembled and intercalated onto layered LDH nanoparticles through an anion exchange technique. X-ray diffraction and zeta potential results showed that the LDH-hGH complex was prepared successfully and that the PAEU/LDH-hGH nanobiohybrid hydrogel had a disordered intercalated nanostructure. The biocompatibility of the nanobiohybrid hydrogel was confirmed by an in vitro cytotoxicity test. The in vivo degradation of pure PAEU and its nanobiohybrid hydrogels was investigated and it showed a controlled degradation of the PAEU/LDH nanobiohybrids compared with the pristine PAEU copolymer hydrogel. The LDH-hGH loaded injectable hydrogels suppressed the initial burst release of hGH and extended the release period for 13 days in vitro and 5 days in vivo. The developed nanohybrid hydrogel has the potential for application as a protein carrier to improve patient compliance.

A biomimetic approach to active self-microencapsulation of proteins in PLGA

A biomimetic approach to organic solvent-free microencapsulation of proteins based on the self-healing capacity of poly (DL)-lactic-co-glycolic acid (PLGA) microspheres containing glycosaminoglycan-like biopolymers (BPs), was examined. To screen BPs, aqueous solutions of BP [high molecular weight dextran sulfate (HDS), low molecular weight dextran sulfate (LDS), chondroitin sulfate (CS), heparin (HP), hyaluronic acid (HA), chitosan (CH)] and model protein lysozyme (LYZ) were combined in different molar and mass ratios, at 37 °C and pH7. The BP-PLGA microspheres (20-63 μm) were prepared by a double water-oil-water emulsion method with a range of BP content, and trehalose and MgCO3 to control microclimate pH and to create percolating pores for protein. Biomimetic active self-encapsulation (ASE) of proteins [LYZ, vascular endothelial growth factor165 (VEGF) and fibroblast growth factor (FgF-20)] was accomplished by incubating blank BP-PLGA microspheres in low concentration protein solutions at ~24 °C, for 48 h. Pore closure was induced at 42.5 °C under mild agitation for 42h. Formulation parameters of BP-PLGA microspheres and loading conditions were studied to optimize protein loading and subsequent release. LDS and HP were found to bind >95% LYZ at BP:LYZ>0.125 w/w, whereas HDS and CS bound >80% LYZ at BP:LYZ of 0.25-1 and <0.33, respectively. HA-PLGA microspheres were found to be not ideal for obtaining high protein loading (>2% w/w of LYZ). Sulfated BP-PLGA microspheres were capable of loading LYZ (~2-7% w/w), VEGF (~4% w/w), and FgF-20 (~2% w/w) with high efficiency. Protein loading was found to be dependent on the loading solution concentration, with higher protein loading obtained at higher loading solution concentration within the range investigated. Loading also increased with content of sulfated BP in microspheres. Release kinetics of proteins was evaluated in-vitro with complete release media replacement. Rate and extent of release were found to depend upon volume of release (with non-sink conditions observed <5 ml release volume for ~18 mg loaded BP-PLGA microspheres), ionic strength of release media and loading solution concentration. HDS-PLGA formulations were identified as having ideal loading and release characteristics. These optimal microspheres released ~73-80% of the encapsulated LYZ over 60 days, with >90% of protein being enzymatically active. Nearly 72% of immunoreactive VEGF was similarly released over 42 days, without significant losses in heparin binding affinity in the release medium.

A solvent-free thermosponge nanoparticle platform for efficient delivery of labile proteins

Protein therapeutics have gained attention recently for treatment of a myriad of human diseases due to their high potency and unique mechanisms of action. We present the development of a novel polymeric thermosponge nanoparticle for efficient delivery of labile proteins using a solvent-free polymer thermo-expansion mechanism with clinical potential, capable of effectively delivering a range of therapeutic proteins in a sustained manner with no loss of bioactivity, with improved biological half-lives and efficacy in vivo.

Protein Encapsulation via Polypeptide Complex Coacervation

Proteins have gained increasing success as therapeutic agents; however, challenges exist in effective and efficient delivery. In this work, we present a simple and versatile method for encapsulating proteins via complex coacervation with oppositely charged polypeptides, poly(l-lysine) (PLys) and poly(d/l-glutamic acid) (PGlu). A model protein system, bovine serum albumin (BSA), was incorporated efficiently into coacervate droplets via electrostatic interaction up to a maximum loading of one BSA per PLys/PGlu pair and could be released under conditions of decreasing pH. Additionally, encapsulation within complex coacervates did not alter the secondary structure of the protein. Lastly the complex coacervate system was shown to be biocompatible and interact well with cells in vitro. A simple, modular system for encapsulation such as the one presented here may be useful in a range of drug delivery applications.

Injectable controlled release depots for large molecules

Biodegradable, injectable depot formulations for long-term controlled drug release have improved therapy for a number of drug molecules and led to over a dozen highly successful pharmaceutical products. Until now, success has been limited to several small molecules and peptides, although remarkable improvements have been accomplished in some of these cases. For example, twice-a-year depot injections with leuprolide are available compared to the once-a-day injection of the solution dosage form. Injectable depots are typically prepared by encapsulation of the drug in poly(lactic-co-glycolic acid) (PLGA), a polymer that is used in children every day as a resorbable suture material, and therefore, highly biocompatible. PLGAs remain today as one of the few "real world" biodegradable synthetic biomaterials used in US FDA-approved parenteral long-acting-release (LAR) products. Despite their success, there remain critical barriers to the more widespread use of PLGA LARproducts, particularly for delivery of more peptides and other large molecular drugs, namely proteins. In this review, we describe key concepts in the development of injectable PLGA controlled-release depots for peptides and proteins, and then use this information to identify key issues impeding greater widespread use of PLGA depots for this class of drugs. Finally, we examine important approaches, particularly those developed in our research laboratory, toward overcoming these barriers to advance commercial LAR development.

Long-term delivery of protein therapeutics

INTRODUCTION

Proteins are effective biotherapeutics with applications in diverse ailments. Despite being specific and potent, their full clinical potential has not yet been realized. This can be attributed to short half-lives, complex structures, poor in vivo stability, low permeability, frequent parenteral administrations and poor adherence to treatment in chronic diseases. A sustained release system, providing controlled release of proteins, may overcome many of these limitations.

AREAS COVERED

This review focuses on recent development in approaches, especially polymer-based formulations, which can provide therapeutic levels of proteins over extended periods. Advances in particulate, gel-based formulations and novel approaches for extended protein delivery are discussed. Emphasis is placed on dosage form, method of preparation, mechanism of release and stability of biotherapeutics.

EXPERT OPINION

Substantial advancements have been made in the field of extended protein delivery via various polymer-based formulations over last decade despite the unique delivery-related challenges posed by protein biologics. A number of injectable sustained-release formulations have reached market. However, therapeutic application of proteins is still hampered by delivery-related issues. A large number of protein molecules are under clinical trials, and hence, there is an urgent need to develop new methods to deliver these highly potent biologics.

Developments in human growth hormone preparations: sustained-release, prolonged half-life, novel injection devices, and alternative delivery routes

Since the availability of recombinant human growth hormone (rhGH) enabled the application of human growth hormone both in clinical and research use in the 1980s, millions of patients were prescribed a daily injection of rhGH, but noncompliance rates were high. To address the problem of noncompliance, numerous studies have been carried out, involving: sustained-release preparations, prolonged half-life derivatives, new injectors that cause less pain, and other noninvasive delivery methods such as intranasal, pulmonary and transdermal deliveries. Some accomplishments have been made and launched already, such as the Nutropin Depot^® microsphere and injectors (Zomajet^®, Serojet^®, and NordiFlex^®). Here, we provide a review of the different technologies and illustrate the key points of these studies to achieve an improved rhGH product.

Development of Recombinant Human Growth Hormone (rhGH) sustained-release microspheres by a low temperature aqueous phase/aqueous phase emulsion method

A novel method has been developed to protect Recombinant Human Growth Hormone (rhGH) in poly (lactic-co-glycolic acid) (PLGA) microspheres using an aqueous phase/aqueous phase emulsion and S/O/W multi-emulsion method. This method develops a novel rhGH sustained-release system, which is based on the combination of rhGH-loaded dextran microparticles and PLGA microspheres. The process to fabricate rhGH-loaded dextran microparticles involves an aqueous phase/aqueous phase emulsion system formed at the reduced temperature. RhGH was first dissolved in water together with dextran and polyethylene glycol, followed by stirring at the speed of 2000 rpm for 20-30s at 0°C, and then a freezing process could enable the dextran phase to separate from the continuous PEG phase and rhGH could preferentially be loaded with dextran. The sample after freezing and phase separation was then lyophilized to powder and washed with dichloromethane to remove the PEG. Once loaded in the dextran microparticles (1-4 μm in diameter), rhGH gained resistance to interface tensions and was encapsulated into PLGA microspheres without aggregation thereafter. RhGH released from PLGA microspheres was in a sustained manner with minimal burst and maximally reduced incomplete release in vitro. Single subcutaneous injection of rhGH-loaded PLGA microspheres to rats resulted in a stable plasma concentration for 30 days avoiding the drug concentration fluctuations after multiple injections of protein solutions. In a hypophysectomized rat model, the IGF-1 and bodyweight results showed that there were higher than the levels obtained for the sustained release formulation by W/O/W for 40 days. These results suggest that the microsphere delivery system had the potential to be an injectable depot for sustained-release of the biocompatible protein of rhGH.

An overview of clinical and commercial impact of drug delivery systems

Drug delivery systems are widely researched and developed to improve the delivery of pharmaceutical compounds and molecules. The last few decades have seen a marked growth of the field fueled by increased number of researchers, research funding, venture capital and the number of start-ups. Collectively, the growth has led to novel systems that make use of micro/nano-particles, transdermal patches, inhalers, drug reservoir implants and antibody-drug conjugates. While the increased research activity is clearly an indication of proliferation of the field, clinical and commercial translation of early-stage research ideas is critically important for future growth and interest in the field. Here, we will highlight some of the examples of novel drug delivery systems that have undergone such translation. Specifically, we will discuss the developments, advantages, limitations and lessons learned from: (i) microparticle-based depot formulations, (ii) nanoparticle-based cancer drugs, (iii) transdermal systems, (iv) oral drug delivery systems, (v) pulmonary drug delivery, (vi) implants and (vii) antibody-drug conjugates. These systems have impacted treatment of many prevalent diseases including diabetes, cancer and cardiovascular diseases, among others. At the same time, these systems are integral and enabling components of products that collectively generate annual revenues exceeding US $100 billion. These examples provide strong evidence of the clinical and commercial impact of drug delivery systems.

Effect of polymer porosity on aqueous self-healing encapsulation of proteins in PLGA microspheres

Self-healing (SH) poly(lactic-co-glycolic acid) (PLGA) microspheres are a unique class of functional biomaterials capable of microencapsulating process-sensitive proteins by simple mixing and heating the drug-free polymer in aqueous protein solution. Drug-free SH microspheres of PLGA 50/50 with percolating pore networks of varying porosity (ϵ = 0.49-73) encapsulate increasing lysozyme (≈1 to 10% w/w) with increasing ϵ, with typically ≈20 to 25% pores estimated accessible to entry by the enzyme from the external solution. Release kinetics of lysozyme under physiological conditions is continuous over more than two weeks and most strongly influenced by ϵ and protein loading before reaching a lag phase until 28 d at the study completion. Recovered enzyme after release is typically predominantly monomeric and active. Formulations containing acid-neutralizing MgCO3 at ≥ 4.3% exhibit >97% monomeric and active protein after the release with full mass balance recovery. Hence, control of SH polymer ϵ is a key parameter to development of this new class of biomaterials.

Polymeric nanoparticle system to target activated microglia/macrophages in spinal cord injury

The possibility to control the fate of the cells responsible for secondary mechanisms following spinal cord injury (SCI) is one of the most relevant challenges to reduce the post traumatic degeneration of the spinal cord. In particular, microglia/macrophages associated inflammation appears to be a self-propelling mechanism which leads to progressive neurodegeneration and development of persisting pain state. In this study we analyzed the interactions between poly(methyl methacrylate) nanoparticles (PMMA-NPs) and microglia/macrophages in vitro and in vivo, characterizing the features that influence their internalization and ability to deliver drugs. The uptake mechanisms of PMMA-NPs were in-depth investigated, together with their possible toxic effects on microglia/macrophages. In addition, the possibility to deliver a mimetic drug within microglia/macrophages was characterized in vitro and in vivo. Drug-loaded polymeric NPs resulted to be a promising tool for the selective administration of pharmacological compounds in activated microglia/macrophages and thus potentially able to counteract relevant secondary inflammatory events in SCI.

IL-1Ra and its delivery strategies: inserting the association in perspective

Interleukin-1 receptor antagonist (IL-1Ra) is a naturally occurring anti-inflammatory antagonist of interleukin-1 family of pro-inflammatory cytokines. The broad spectrum anti-inflammatory effects of IL-1Ra have been investigated against various auto-immune diseases such as diabetes mellitus, rheumatoid arthritis. Despite of its outstanding broad spectrum anti-inflammatory effects, IL-1Ra has short biological half-life (4-6 h) and to cope with this problem, up till now, many delivery strategies have been applied either to extend the half-life and/or prolong the steady-state sustained release of IL-1Ra from its target site. Here in our present paper, we have provided an overview of all approaches attempted to prolong the duration of therapeutic effects of IL-1Ra either by fusing IL-1Ra using fusion protein technology to extend the half-life and/or development of new dosage forms using various biodegradable polymers to prolong its steady-state sustained release at the site of administration. These approaches have been characterized by their intended impact on either in vitro release characteristics and/or pharmacokinetic and pharmacodynamic parameters of IL-1Ra. We have also compared these delivery strategies with each other on the basis of bioactivity of IL-1Ra after fusion with fusion protein partner and/or encapsulation with biodegradable polymer.

Controlled release of human growth hormone fused with a human hybrid Fc fragment through a nanoporous polymer membrane

Nanotechnology has been applied to the development of more effective and compatible drug delivery systems for therapeutic proteins. Human growth hormone (hGH) was fused with a hybrid Fc fragment containing partial Fc domains of human IgD and IgG4 to produce a long-acting fusion protein. The fusion protein, hGH-hyFc, resulted in the increase of the hydrodynamic diameter (ca. 11 nm) compared with the diameter (ca. 5 nm) of the recombinant hGH. A diblock copolymer membrane with nanopores (average diameter of 14.3 nm) exhibited a constant release rate of hGH-hyFc. The hGH-hyFc protein released in a controlled manner for one month was found to trigger the phosphorylation of Janus kinase 2 (JAK2) in human B lymphocyte and to exhibit an almost identical circular dichroism spectrum to that of the original hGH-hyFc, suggesting that the released fusion protein should maintain the functional and structural integrity of hGH. Thus, the nanoporous release device could be a potential delivery system for the long-term controlled release of therapeutic proteins fused with the hybrid Fc fragment.

Development of dextran nanoparticles for stabilizing delicate proteins

One of the most challenging problems in the development of protein pharmaceuticals is to deal with stabilities of proteins due to its complicated structures. This study aims to develop a novel approach to stabilize and encapsulate proteins into dextran nanoparticles without contacting the interface between the aqueous phase and the organic phase. The bovine serum albumin, granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor (G-CSF), β-galactosidase, and myoglobin were selected as model proteins. The proteins were added into an aqueous solution containing the dextran and polyethylene glycol, and then encapsulated into dextran nanoparticles by aqueous-aqueous freezing-induced phase separation. The encapsulation efficiency and recovery of dextran nanoparticles were determined. The dextran nanoparticles loaded with proteins were characterized by scanning electron microscopy and particle size analysis. The protein aggregation was determined by size-exclusion chromatography-high-performance chromatography, and the bioactivity of proteins recovered during formulation steps was determined. The bioactivity of GM-CSF, G-CSF, and β-galactosidase were examined by the proliferation of TF-1 cell, NSF-60 cell, and ortho-nitrophenyl-β-galactoside assay, respectively. The results of bioactivity recovered show that this novel dextran nanoparticle can preserve the protein's bioactivity during the preparation process. LysoSensor™ Yellow/Blue dextran, a pH-sensitive indicator with fluorescence excited at two channels, was encapsulated into dextran nanoparticles to investigate the ability of dextran nanoparticles to resist the acidic microenvironment (pH < 2.5). The result shows that the dextran nanoparticles attenuate the acidic microenvironment in the poly (lactic-co-glycolic acid) microsphere by means of the dilution effect. These novel dextran nanoparticles provided an appealing approach to stabilize the delicate proteins for administration.