Lyophilization of proteins

Mechanism of Insoluble Aggregate Formation in a Reconstituted Solution of Spray-Dried Protein Powder

BACKGROUND

Spray-drying is considered a promising alternative drying method to lyophilization (freeze-drying) for therapeutic proteins. Particle counts in reconstituted solutions of dried solid dosage forms of biologic drug products are closely monitored to ensure product quality. We found that high levels of particles formed after reconstitution of protein powders that had been spray-dried under suboptimal conditions.

METHODS

Visible and subvisible particles were evaluated. Soluble proteins in solution before spray-drying and in the reconstituted solution of spray-dried powder were analyzed for their monomer content levels and melting temperatures. Insoluble particles were collected and analyzed by Fourier transform infrared microscopy (FTIR), and further analyzed with hydrogen-deuterium exchange (HDX).

RESULTS

Particles observed after reconstitution were shown not to be undissolved excipients. FTIR confirmed their identity as proteinaceous in nature. These particles were therefore considered to be insoluble protein aggregates, and HDX was applied to investigate the mechanism underlying aggregate formation. Heavy-chain complementarity-determining region 1 (CDR-1) in the aggregates showed significant protection by HDX, suggesting CDR-1 was critical for aggregate formation. In contrast, various regions became more conformationally dynamic globally, suggesting the aggregates have lost protein structural integrity and partially unfolded after spray-drying.

DISCUSSION

The spray-drying process could have disrupted the higher-order structure of proteins and exposed the hydrophobic residues in CDR-1 of the heavy chain, contributing to the formation of aggregate through hydrophobic interactions upon reconstitution of spray-dried powder. These results can contribute to efforts to design spray-dry resilient protein constructs and improve the robustness of the spray-drying process.

Development of Solid-State Storage for Cell-Free Expression Systems

The fragility of biological systems during storage, transport, and utilization necessitates reliable cold-chain infrastructure and limits the potential of biotechnological applications. In order to unlock the broad applications of existing and emerging biological technologies, we report the development of a novel solid-state storage platform for complex biologics. The resulting solid-state biologics (SSB) platform meets four key requirements: facile rehydration of solid materials, activation of biochemical activity, ability to support complex downstream applications and functionalities, and compatibility for deployment in a variety of reaction formats and environments. As a model system of biochemical complexity, we utilized crudeEscherichia colicell extracts that retain active cellular metabolism and support robust levels of in vitro transcription and translation. We demonstrate broad versatility and utility of SSB through proof-of-concepts for on-demand in vitro biomanufacturing of proteins at a milliliter scale, the activation of downstream CRISPR activity, as well as deployment on paper-based devices. SSBs unlock a breadth of applications in biomanufacturing, discovery, diagnostics, and education in resource-limited environments on Earth and in space.

Microalgae-Sustainable Source for Alternative Proteins and Functional Ingredients Promoting Gut and Liver Health

Dietary proteins derived from animal sources, although containing well-balanced profiles of essential amino acids, have considerable environmental and adverse health effects associated with the intake of some animal protein-based products. Consuming foods based on animal proteins carries a higher risk of developing non-communicable diseases such as cancer, heart disease, non-alcoholic fatty liver disease (NAFLD), and inflammatory bowel disease (IBD). Moreover, dietary protein consumption is increasing due to population growth, posing a supply challenge. There is, therefore, growing interest in discovering novel alternative protein sources. In this context, microalgae have been recognized as strategic crops that can provide a sustainable source of protein. Compared to conventional high-protein crops, using microalgal biomass for protein production presents several advantages in food and feed in terms of productivity, sustainability, and nutritional value. Moreover, microalgae positively impact the environment by not exploiting land or causing water pollution. Many studies have revealed the potential of microalgae as an alternative protein source with the added value of positive effects on human health due to their anti-inflammatory, antioxidant, and anti-cancer properties. The main emphasis of this review is on the potential health-promoting applications of microalgae-based proteins, peptides, and bioactive substances for IBD and NAFLD.

Recombinase polymerase amplification using novel thermostable strand-displacing DNA polymerases from Aeribacillus pallidus and Geobacillus zalihae

Recombinase polymerase amplification (RPA) is an isothermal DNA amplification reaction at around 41 °C using recombinase (Rec), single-stranded DNA-binding protein (SSB), and strand-displacing DNA polymerase (Pol). Component instability and the need to store commercial kits in a deep freezer until use are some limitations of RPA. In a previous study, Bacillus stearothermophilus Pol (Bst-Pol) was used as a thermostable strand-displacing DNA polymerase in RPA. Here, we attempted to optimize the lyophilization conditions for RPA with newly isolated thermostable DNA polymerases for storage at room temperature. We isolated novel two thermostable strand-displacing DNA polymerases, one from a thermophilic bacterium Aeribacillus pallidus (H1) and the other from Geobacillus zalihae (C1), and evaluated their performances in RPA reaction. Urease subunit β (UreB) DNA from Ureaplasma parvum serovar 3 was used as a model target for evaluation. The RPA reaction with H1-Pol or C1-Pol was performed at 41 °C with the in vitro synthesized standard UreB DNA. The minimal initial copy numbers of standard DNA from which the amplified products were observed were 600, 600, and 6000 copies for RPA with H1-Pol, C1-Pol, and Bst-Pol, respectively. Optimization was carried out using RPA components, showing that the lyophilized RPA reagents containing H1-Pol exhibited the same performance as the corresponding liquid RPA reagents. In addition, lyophilized RPA reagents with H1-Pol showed almost the same activity after two weeks of storage at room temperature as the freshly prepared liquid RPA reagents. These results suggest that lyophilized RPA reagents with H1-Pol are preferable to liquid RPA reagents for onsite use.

Spray-Dried and Spray-Freeze-Dried Powder Formulations of an Anti-Interleukin-4Rα Antibody for Pulmonary Delivery

OBJECTIVE

The therapeutic options for severe asthma are limited, and the biological therapies are all parenterally administered. The purpose of this study was to formulate a monoclonal antibody that targets the receptor for IL-4, an interleukin implicated in the pathogenesis of severe asthma, into a dry powder intended for delivery via inhalation.

METHODS

Dehydration was achieved using either spray drying or spray freeze drying, which exposes the thermolabile biomacromolecules to stresses such as shear and adverse temperatures. 2-hydroxypropyl-beta-cyclodextrin was incorporated into the formulation as protein stabiliser and aerosol performance enhancer. The powder formulations were characterised in terms of physical and aerodynamic properties, while the antibody was assessed with regard to its structural stability, antigen-binding ability, and in vitro biological activity after drying.

RESULTS

The spray-freeze-dried formulations exhibited satisfactory aerosol performance, with emitted fraction exceeding 80% and fine particle fraction of around 50%. The aerosolisation of the spray-dried powders was hindered possibly by high residual moisture. Nevertheless, the antigen-binding ability and inhibitory potency were unaffected for the antibody in the selected spray-dried and spray-freeze-dried formulations, and the antibody was physically stable even after one-year storage at ambient conditions.

CONCLUSIONS

The findings of this study establish the feasibility of developing an inhaled dry powder formulation of an anti-IL-4R antibody using spray drying and spray freeze drying techniques with potential for the treatment of severe asthma.

Viability, Stability and Biocontrol Activity in Planta of Specific Ralstonia solanacearum Bacteriophages after Their Conservation Prior to Commercialization and Use

Ralstonia solanacearum is a pathogen that causes bacterial wilt producing severe damage in staple solanaceous crops. Traditional control has low efficacy and/or environmental impact. Recently, the bases of a new biotechnological method by lytic bacteriophages vRsoP-WF2, vRsoP-WM2 and vRsoP-WR2 with specific activity against R. solanacearum were established. However, some aspects remain unknown, such as the survival and maintenance of the lytic activity after submission to a preservation method as the lyophilization. To this end, viability and stability of lyophilized vRsoP-WF2, vRsoP-WM2 and vRsoP-WR2 and their capacity for bacterial wilt biocontrol have been determined against one pathogenic Spanish reference strain of R. solanacearum in susceptible tomato plants in different conditions and making use of various cryoprotectants. The assays carried out have shown satisfactory results with respect to the viability and stability of the bacteriophages after the lyophilization process, maintaining high titers throughout the experimental period, and with respect to the capacity of the bacteriophages for the biological control of bacterial wilt, controlling this disease in more than 50% of the plants. The results offer good prospects for the use of lyophilization as a conservation method for the lytic bacteriophages of R. solanacearum in view of their commercialization as biocontrol agents.

Freeze-Drying of Proteins

Freeze-drying has become one of the most important processes for the preservation of biological products. This chapter provides protocols for freeze-drying of proteins and discusses the importance of formulation, cycle development, and validation. Specific formulations for stabilization of proteins are presented as well as advice on common problems with freeze-drying of proteins.

Microalgae proteins: production, separation, isolation, quantification, and application in food and feed

Many countries have been experienced an increase in protein consumption due to the population growth and adoption of protein-rich dietaries. Unfortunately, conventional-based protein agroindustry is associated with environmental impacts that might aggravate as the humankind increase. Thus, it is important to screen for novel protein sources that are environmentally friendly. Microalgae farming is a promising alternative to couple the anthropic emissions with the production of food and feed. Some microalgae show protein contents two times higher than conventional protein sources. The use of whole microalgae biomass as a protein source in food and feed is simple and well-established. Conversely, the production of microalgae protein supplements and isolates requires the development of feasible and robust processes able to fractionate the microalgae biomass in different value-added products. Since most of the proteins are inside the microalgae cells, several techniques of disruption have been proposed to increase the efficiency to extract them. After the disruption of the microalgae cells, the proteins can be extracted, concentrated, isolated or purified allowing the development of different products. This critical review addresses the current state of the production of microalgae proteins for multifarious applications, and possibilities to concatenate the production of proteins and advanced biofuels.

Lyophilized bone marrow cell extract functionally restores irradiation-injured salivary glands

OBJECTIVE

Bone marrow cell extract (BMCE) was previously reported to restore salivary gland hypofunction caused by irradiation injury. Proteins were shown to be the main active factors in BMCE. However, BMCE therapy requires multiple injections and protein denaturation is a concern during BMCE storage. This study aimed to preserve, by lyophilization (freeze-drying), the bioactive factors in BMCE.

METHODS

We developed a method to freeze-dry BMCE and then to analyze its ingredients and functions in vivo. Freeze-dried (FD) BMCE, freshly prepared BMCE (positive control), or saline (vehicle control) was injected into the tail vein of mice that had received irradiation to damage their salivary glands.

RESULTS

Results demonstrated that the presence of angiogenesis-related factors and cytokines in FD-BMCE remained comparable to those found in fresh BMCE. Both fresh and FD-BMCE restored comparably saliva secretion, increased cell proliferation, upregulated regenerative/repair genes, protected salivary acinar cells, parasympathetic nerves, and blood vessels from irradiation-damaged salivary glands.

CONCLUSION

Lyophilization of BMCE maintained its bioactivity and therapeutic effect on irradiation-injured salivary glands. The advantages of freeze-drying BMCE are its storage and transport at ambient temperature.

Powdered G-Protein-Coupled Receptors

Preparation and storage of functional membrane proteins such as G-protein-coupled receptors (GPCRs) are crucial to the processes of drug delivery and discovery. Here, we describe a method of preparing powdered GPCRs using rhodopsin as the prototype. We purified rhodopsin in CHAPS detergent with low detergent to protein ratio so the bulk of the sample represented protein (ca. 72% w/w). Our new method for generating powders of membrane proteins followed by rehydration paves the way for conducting functional and biophysical experiments. As an illustrative application, powdered rhodopsin was prepared with and without the cofactor 11-cis-retinal to enable partial rehydration of the protein with D₂O in a controlled manner. Quasi-elastic neutron scattering studies using both spatial motion and energy landscape models form the basis for crucial insights into structural fluctuations and thermodynamics of GPCR activation.

Formulation Studies During Preclinical Development of Influenza Hemagglutinin and Virus-Like Particle Vaccine Candidates

A critical element of vaccine formulation studies is the identification of chemical and physical degradation pathways that compromise structural integrity, and which may in turn affect the clinical safety and efficacy, of macromolecular antigens. Formulation development helps optimize and maintain the long-term storage stability and viability of vaccine antigens in pharmaceutically relevant dosage forms. The protocols presented in this manuscript highlight the use of accelerated stability studies for the formulation of influenza vaccine candidates including virus-like particles (VLP) and particle forming hemagglutinin (HA) antigens. Three case studies, each targeting a different facet of preclinical vaccine formulation development, are reviewed: (1) excipient screening experiments to mitigate VLP physical degradation, (2) methods for monitoring a specific chemical perturbation of the recombinant HA antigen and elucidating its effect on in vitro potency, and (3) maintaining HA conformational stability in the presence of freeze-thaw and freeze-drying stresses.

Freeze-drying of proteins

Freeze-drying has become one of the most important processes for the preservation of biological products. This chapter provides protocols for freeze-drying of proteins and discusses the importance of formulation, cycle development, and validation. Specific formulations for stabilization of proteins are presented as well as advice on common problems with freeze-drying of proteins.

Characterization of the physical stability of a lyophilized IgG1 mAb after accelerated shipping-like stress

Upon exposure to shaking stress, an IgG1 mAb formulation in both the liquid and lyophilized state formed subvisible particles. Because freeze-drying was expected to minimize protein physical instability under these conditions, the extent and nature of aggregate formation in the lyophilized preparation were examined using a variety of particle characterization techniques. The effects of formulation variables such as residual moisture content, reconstitution rate, and reconstitution medium were also examined. Upon reconstitution of shake-stressed lyophilized mAb, differences in protein particle size and number were observed by microflow digital imaging, with the reconstitution medium having the largest impact. Shake stress had minor effects on the structure of protein within the particles as shown by SDS-PAGE and FTIR analysis. The lyophilized mAb was shake stressed to different extents and stored for 3 months at different temperatures. Both extent of cake collapse and storage temperature affected the physical stability of the shake-stressed lyophilized mAb upon subsequent storage. These findings demonstrate that physical degradation upon shaking of a lyophilized IgG1 mAb formulation includes not only cake breakage, but also results in an increase in subvisible particles and turbidity upon reconstitution. The shake-induced cake breakage of the lyophilized IgG1 mAb formulation also resulted in decreased physical stability upon storage.

Stabilization of protein by freeze-drying in the presence of trehalose: a case study of tubulin

Microtubules, polymers of the heterodimeric protein αβ-tubulin, are indispensable for many cellular activities such as maintenance of cell shape, division, migration, and ordered vesicle transport. In vitro assays to study microtubule functions and their regulation by associated proteins require the availability of assembly-competent purified tubulin. However, tubulin is a thermolabile protein that rapidly converts into non-polymerizing state. For this reason it is usually stored at -80 °C to preserve its conformation and polymerization properties. In this chapter we describe a method for freeze-drying of assembly-competent tubulin in the presence of nonreducing sugar trehalose and methods enabling evaluation of tubulin functions in rehydrated samples.

Influence of crosslinking on the stiffness and degradation of dermis-derived hydrogels

Natural hydrogels have been investigated for three-dimensional tissue reconstruction and regeneration given their ability to emulate the structural complexity of multi-component extracellular matrices (ECM). Hydrogels rich in ECM can be extracted and assembled from soft tissues, retain a composition specific to the tissue source, and stimulate vascularized tissue formation. However, poor mechanical properties and rapid degradation hinder their performance in regenerative applications. This study investigates the effect of glutaraldehyde (GA) crosslinking on the mechanical properties, biological activity, and degradation of dermis-isolated ECM-rich hydrogels. Compression tests indicated that hydrogel elastic moduli and yield stress values increased significantly with GA exposure time. Lyophilization was shown to decrease yield stress values with respect to non-lyophilized gels. Crosslinked ECM, unlike non-crosslinked gels, was resistant to pepsin degradation in vitro. In a rodent subcutaneous implant model, crosslinking for 0.5 hours or longer drastically slowed degradation relative to controls. Inflammation was low and mature vascularized granulation tissue was observed in all gels, with an increase in vessel density at 1 week in crosslinked gels relative to controls. These results support the potential use of dermis-derived hydrogels as materials for tissue engineering applications and suggest that crosslinking can enhance mechanical properties and prolong hydrogel lifetime while promoting vascularized tissue formation.

Homemade lyophilized cross linking amniotic sustained-release drug membrane with anti-scarring role after filtering surgery in rabbit eyes

AIM

To investigate the antifibrotic effect of the freeze-dried bilayered fibrin-binding amniotic membrane as a drug delivery system on glaucoma surgery in rabbit model. The aim of this study was to prepare a novel local delivery system for the sustained and controllable release of 5-Fu.

METHODS

Twenty-four Japanese white rabbits were randomized into three groups: the experimental group (ocular trabeculectomy in combination with 5-Fu loaded freeze-dried bilayered fibrin-binding amniotic membrane transplantation), the control group (ocular trabeculectomy in combination with 5-Fu) and the blank group (single trabeculectomy). HE staining, massion staining and immunohistochemistry for α-SMA were performed on days 7, 14, 21 and 30 following surgery. The concentration of 5-Fu in rabbit aqueous humor was examined by high performance liquid chromatography (HPLC) 3 days after the surgery.

RESULTS

Statistical differences were noted in intraocular pressure among groups on day 7, 14, 21 and 30 following surgery. Histology further demonstrated that trabeculectomy in combination with freeze-dried bilayered fibrin-binding amniotic membrane yielded well wound healing and no scar formation and was beneficial for long term effect.

CONCLUSION

HPLC showed a good slow-release effect with freeze-dried bilayered fibrin-binding amniotic membrane.

Lyophilization is suitable for storage and shipment of fresh tissue samples without altering RNA and protein levels stored at room temperature

Lyophilization has been widely used for preservation, such as in food industry, pharmacy, biotechnology and tissues engineering, etc. However, there is no report on whether it could affect stability of RNA and protein levels in biological tissue samples. Herein we show that lyophilization can be used for storage of biological tissue samples without loss of bioactivities even stored at room temperature for 7-14 days. To address this issue, C57BL mouse tissues were prepared and dried by lyophilization and a baking method, respectively, followed by examination of morphological structure and total proteins by SDS-PAGE as well as gelatin zymography. Subsequently, the stability of RNAs and proteins, which were lyophilized and stored at room temperature (23°C) for 14 days was further examined by RT-PCR, SDS-PAGE and western blot. Results demonstrated that lyophilization did not alter total protein activities of various tissues, including enzyme activities, immunoreactivities and phosphorylation, and did not affect several RNAs in lyophilized tissues. Taken together, lyophilization may represent a valuable approach for preservation and long-distance shipment of biological samples, particularly for the international exchange of biological samples without altering their bioactivities.