Analytical methods for investigating in vivo fate of nanoliposomes:A review

Nanoliposomes are considered to be the most successful nanoparticle drug delivery system, but their fate in vivo has not been fully understood due to lack of reliable bioanalytical methods, which seriously limits the development of liposomal drugs. Hence, an overview of currently used bioanalytical methods is imperative to lay the groundwork for the need of developing a bioanalytical method for liposome measurements in vivo. Currently, major analytical methods for nanoliposomes measurement in vivo include fluorescence labeling, radiolabeling, magnetic resonance imaging（MRI）, mass spectrometry and computed tomography. In this review, these bioanalytical methods are summarized, and the advantages and disadvantages of each are discussed. We provide insights into the applicability and limitations of these analytical methods in the application of nanoliposomes measurement in vivo, and highlight the recent development of instrumental analysis techniques. The review is devoted to providing a comprehensive overview of the investigation of nanoliposomes design and associated fate in vivo, promoting the development of bioanalytical techniques for nanoliposomes measurement, and understanding the pharmacokinetic behavior, effectiveness and potential toxicity of nanoliposomes in vivo.

Impact of molecular weight on the mechanism of cellular uptake of polyethylene glycols(PEGs) with particular reference to P-glycoprotein

Polyethylene glycols(PEGs)in general use are polydisperse molecules with molecular weight(MW)distributed around an average value applied in their designation e.g.,PEG 4000.Previous research has shown that PEGs can act as P-glycoprotein(P-gp)inhibitors with the potential to affect the absorption and efflux of concomitantly administered drugs.However,questions related to the mechanism of cellular uptake of PEGs and the exact role played by P-gp has not been addressed.In this study,we examined the mechanism of uptake of PEGs by MDCK-mock cells,in particular,the effect of MW and interaction with P-gp by MDCK-hMDRl and A549 cells.The results show that:(a)the uptake of PEGs by MDCK-hMDR1 cells is enhanced by P-gp inhibitors;(b)PEGs stimulate P-gp ATPase activity but to a much lesser extent than verapamil;and(c)uptake of PEGs of low MW(<2000 Da)occurs by passive diffusion whereas uptake of PEGs of hish MW(>5000 Da)occurs by a combination of passive diffusion and caveolae-mediated endocytosis.These findings suggest that PEGs can engage in P-gp-based drug interactions which we believe should be taken into account when using PEGs as excipients and in PEGylated drugs and drug delivery systems.

Cell-derived nanovesicles from mesenchymal stem cells as extracellular vesicle-mimetics in wound healing

Wound healing is a dynamic process that involves a series of molecular and cellular events aimed at replacing devitalized and missing cellular components and/or tissue layers.Recently,extracellular vesicles(EVs),naturally cell-secreted lipid membrane-bound vesicles laden with biological cargos including proteins,lipids,and nucleic acids,have drawn wide attention due to their ability to promote wound healing and tissue regeneration.However,current exploitation of EVs as therapeutic agents is limited by their low isolation yields and tedious isolation processes.To circumvent these challenges,bioinspired cell-derived nanovesicles(CDNs)that mimic EVs were obtained by shearing mesenchymal stem cells(MSCs)through membranes with different pore sizes.Physical characterisations and highthroughput proteomics confirmed that MSC-CDNs mimicked MSC-EVs.Moreover,these MSC-CDNs were efficiently uptaken by human dermal fibroblasts and demonstrated a dose-dependent activation of MAPK signalling pathway,resulting in enhancement of cell proliferation,cell migration,secretion of growth factors and extracellular matrix proteins,which all promoted tissue regeneration.Of note,MSC-CDNs enhanced angiogenesis in human dermal microvascular endothelial cells in a 3D PEGfibrin scaffold and animal model,accelerating wound healing in vitro and in vivo.These findings suggest that MSC-CDNs could replace both whole cells and EVs in promoting wound healing and tissue regeneration.