Low Drug Loading Hampers the Clinical Translation of Peptide Drugs-Containing Metered-Dose Inhalers

Protein nanoparticles as potent delivery vehicles for polycytosine RNA-binding protein one

Ma et al recently reported in the World Journal of Diabetes that ferroptosis occurs in osteoblasts under high glucose conditions, reflecting diabetes pathology. This condition could be protected by the upregulation of the gene encoding polycytosine RNA-binding protein 1 (PCBP1). Additionally, Ma et al used a lentivirus infection system to express PCBP1. As the authors' method of administration can be improved in terms of stability and cost, we propose delivering PCBP1 to treat type 2 diabetic osteoporosis by encapsulating it in protein nanoparticles. First, PCBP1 is small and druggable. Second, intravenous injection can help deliver PCBP1 across the mucosa while avoiding acid and enzyme-catalyzed degradation. Furthermore, incorporating PCBP1 into nanoparticles prevents its interaction with water or oxygen and protects PCBP1's structure and activity. Notably, the safety of the protein materials and the industrialization techniques for large-scale production of protein nanoparticles must be comprehensively investigated before clinical application.

Overcoming the Low-Stability Bottleneck in the Clinical Translation of Liposomal Pressurized Metered-Dose Inhalers: A Shell Stabilization Strategy Inspired by Biomineralization

Currently, several types of inhalable liposomes have been developed. Among them, liposomal pressurized metered-dose inhalers (pMDIs) have gained much attention due to their cost-effectiveness, patient compliance, and accurate dosages. However, the clinical application of liposomal pMDIs has been hindered by the low stability, i.e., the tendency of the aggregation of the liposome lipid bilayer in hydrophobic propellant medium and brittleness under high mechanical forces. Biomineralization is an evolutionary mechanism that organisms use to resist harsh external environments in nature, providing mechanical support and protection effects. Inspired by such a concept, this paper proposes a shell stabilization strategy (SSS) to solve the problem of the low stability of liposomal pMDIs. Depending on the shell material used, the SSS can be classified into biomineralization (biomineralized using calcium, silicon, manganese, titanium, gadolinium, etc.) biomineralization-like (composite with protein), and layer-by-layer (LbL) assembly (multiple shells structured with diverse materials). This work evaluated the potential of this strategy by reviewing studies on the formation of shells deposited on liposomes or similar structures. It also covered useful synthesis strategies and active molecules/functional groups for modification. We aimed to put forward new insights to promote the stability of liposomal pMDIs and shed some light on the clinical translation of relevant products.

Special Issue "Delivery Systems of Peptides and Proteins: Challenges, Status Quo and Future Perspectives"

Peptides and proteins have emerged as more important therapeutic molecules compared to small molecular chemicals due to their high specificity and efficacy and low toxicity [...].