Polymeric matrix hydrophobicity governs saponin packing-density on nanoparticle surface and the subsequent biological interactions

PEG vs. zwitterions: How these surface decorations determine cellular uptake of lipid-based nanocarriers

AIM

To evaluate the impact of polyethylene glycol (PEG) and zwitterionic surface decoration of lipid-based nanocarriers (NC) on cellular uptake.

METHODS

Anionic, neutral and cationic zwitterionic lipid-based NCs based on lecithin were compared with conventional PEGylated lipid-based NCs regarding stability in biorelevant fluids, interaction with endosome mimicking membranes, cytocompatibility, cellular uptake and permeation across intestinal mucosa.

RESULTS

PEGylated and zwitterionic lipid-based NCs exhibited a droplet size between 100 and 125 nm with a narrow size distribution. For the PEGylated and zwitterionic lipid-based NCs only minor alterations in size and PDI in fasted state intestinal fluid and mucus containing buffer were observed, demonstrating similar bioinert properties. Erythrocytes interaction studies revealed enhanced endosomal escape properties for zwitterionic lipid-based NCs compared to PEGylated lipid-based NCs. For the zwitterionic lipid-based NCs negligible cytotoxicity on Caco-2 and HEK cells, even in the highest tested concentration of 1 % (v/v) was recorded. The PEGylated lipid-based NCs showed a cell survival of ≥75 % for concentrations ≤0.05 % on Caco-2 and HEK cells, which was considered as non-toxic. For the zwitterionic lipid-based NCs up to 60-fold higher cellular uptake on Caco-2 cells was determined compared to PEGylated lipid-based NCs. For the cationic zwitterionic lipid-based NCs the highest cellular uptake with 58.5 % and 40.0 % in Caco-2 and HEK cells, respectively, was determined. The results were confirmed visually by life cell imaging. Ex-vivo permeation experiments using rat intestinal mucosa demonstrated up to 8.6-fold enhanced permeation of the lipophilic marker coumarin-6 in zwitterionic lipid-based NCs compared to the control. Up to 6.9-fold enhanced permeation of coumarin-6 in neutral zwitterionic lipid-based NCs compared to the PEGylated counterpart was recorded.

CONCLUSION

The replacement of PEG surfactants with zwitterionic surfactants is a promising approach to overcome the drawbacks of conventional PEGylated lipid-based NCs regarding intracellular drug delivery.

Bioengineering Extracellular Vesicles for the Treatment of Cardiovascular Diseases

Cardiovascular diseases (CVD) remain one of the leading causes of mortality worldwide. Despite recent advances in diagnosis and interventions, there is still a crucial need for new multifaceted therapeutics that can address the complicated pathophysiological mechanisms driving CVD. Extracellular vesicles (EVs) are nanovesicles that are secreted by all types of cells to transport molecular cargo and regulate intracellular communication. EVs represent a growing field of nanotheranostics that can be leveraged as diagnostic biomarkers for the early detection of CVD and as targeted drug delivery vesicles to promote cardiovascular repair and recovery. Though a promising tool for CVD therapy, the clinical application of EVs is limited by the inherent challenges in EV isolation, standardization, and delivery. Hence, this review will present the therapeutic potential of EVs and introduce bioengineering strategies that augment their natural functions in CVD.

Nanoparticle Fraught Liposomes: A Platform for Increased Antibiotic Selectivity in Multidrug Resistant Bacteria

Increasing antibiotic concentrations within bacterial cells while reducing them in mammalian ones would ultimately result in an enhancement of antibacterial actions, overcoming multidrug resistance, all while minimizing toxicity. Nanoparticles (NPs) have been used in numerous occasions to overcome antibiotic resistance, poor drug solubility, and stability. However, the concomitant increase in antibiotic concentration in mammalian cells and the resultant toxicity are usually overlooked. Without compromising bacterial cell fusion, large liposomes (Lip) have been reported to show reduced uptake in mammalian cells. Therefore, in this work, small NP fraught liposomes (NP-Lip) were formulated with the aim of increasing NP uptake and antibiotic delivery in bacterial cells but not in mammalian ones. Small polylactic-co-glycolic acid NPs were therefore loaded with erythromycin (Er), an antibiotic with low membrane permeability that is susceptible to drug efflux, and 3c, a 5-cyanothiazolyl urea derivative with low solubility and stability. In vitro experiments demonstrated that the incorporation of small NPs into large Lip resulted in a reduction in NP uptake by HEK293 cells while increasing it in Gram-negative bacteria (Escherichia coli DH5α, E. coli K12, and Pseudomonas aeruginosa), consequently resulting in an enhancement of antibiotic selectivity by fourfold toward E. coli (both strains) and eightfold toward P. aeruginosa. Ocular administration of NP-Lip in a P. aeruginosa keratitis mouse model demonstrated the ability of Er/3c-loaded NP-Lip to result in a complete recovery. More importantly, in comparison to NPs, the ocular administration of NP-Lip showed a reduction in TNF-alpha and IL-6 levels, implying reduced interaction with mammalian cells in vivo. This work therefore clearly demonstrated how tailoring the nano-bio interaction could result in selective drug delivery and a reduction in toxicity.

The Effect of Bone Morphogenetic Protein 2 (BMP-2)/Estrogen Composite Nanoparticles on the Differentiation Function of Osteoporotic Bone Marrow Mesenchymal Stem Cells (BMSCs)

The menopausal hormone abnormal changes such as estrogen deficiency and increased FSH secretion in female patients in old age may cause osteoporosis which is plagued by patients. The pathogenesis of osteoporosis is not yet fully understood. BMP in the transforming growth factor-β superfamily is a key member in the process of bone growth and development, among which BMP-2 exerts critical roles. Impaired osteogenic differentiation of bone marrow mesenchymal stem cells (BMSC) contributes to the progress of osteoporosis. BMSC plays an indispensable role in treating osteoporosis and can develop into different directions through induction. As the regenerative medicine nanotechnology has become a new medical method, it is believed that BMSC can be used to treat osteoporosis and other related diseases. Our study analyzed the effects of BMP-2/estrogen composite nanoparticles on the proliferation and differentiation of osteoporotic BMSC cells to provide a reliable reference for the future treatment. Our results showed that BMP-2/estrogen composite nanoparticles promoted BMSC cell proliferation, increased ALP activity, decreased apoptosis rate, increased the expression of Col-1, Runx2 and Osterix, upregulated the osteogenic marker BMP-2. As confirmed by Alizarin Red staining, it could differentiate into osteoblasts and the content of Trap was decreased. In conclusion, our study confirms that BMP-2/estrogen composite nanoparticles can promote BMSC cell proliferation, osteogenic differentiation, and inhibit osteoclast differentiation, thereby providing new treatments and theoretical reference basis for treating osteoporosis.