miRNA-21-5p is an important contributor to the promotion of injured peripheral nerve regeneration using hypoxia-pretreated bone marrow-derived neural crest cells.

JOURNAL/nrgr/04.03/01300535-202501000-00035/figure1/v/2024-05-14T021156Z/r/image-tiff Our previous study found that rat bone marrow-derived neural crest cells (acting as Schwann cell progenitors) have the potential to promote long-distance nerve repair. Cell-based therapy can enhance peripheral nerve repair and regeneration through paracrine bioactive factors and intercellular communication. Nevertheless, the complex contributions of various types of soluble cytokines and extracellular vesicle cargos to the secretome remain unclear. To investigate the role of the secretome and extracellular vesicles in repairing damaged peripheral nerves, we collected conditioned culture medium from hypoxia-pretreated neural crest cells, and found that it significantly promoted the repair of sensory neurons damaged by oxygen-glucose deprivation. The mRNA expression of trophic factors was highly expressed in hypoxia-pretreated neural crest cells. We performed RNA sequencing and bioinformatics analysis and found that miR-21-5p was enriched in hypoxia-pretreated extracellular vesicles of neural crest cells. Subsequently, to further clarify the role of hypoxia-pretreated neural crest cell extracellular vesicles rich in miR-21-5p in axonal growth and regeneration of sensory neurons, we used a microfluidic axonal dissociation model of sensory neurons in vitro, and found that hypoxia-pretreated neural crest cell extracellular vesicles promoted axonal growth and regeneration of sensory neurons, which was greatly dependent on loaded miR-21-5p. Finally, we constructed a miR-21-5p-loaded neural conduit to repair the sciatic nerve defect in rats and found that the motor and sensory functions of injured rat hind limb, as well as muscle tissue morphology of the hind limbs, were obviously restored. These findings suggest that hypoxia-pretreated neural crest extracellular vesicles are natural nanoparticles rich in miRNA-21-5p. miRNA-21-5p is one of the main contributors to promoting nerve regeneration by the neural crest cell secretome. This helps to explain the mechanism of action of the secretome and extracellular vesicles of neural crest cells in repairing damaged peripheral nerves, and also promotes the application of miR-21-5p in tissue engineering regeneration medicine.

Microfluidic Preparation of Janus Microparticles With Temperature and pH Triggered Degradation Properties.

Based on the phase separation phenomenon in micro-droplets, polymer-lipid Janus particles were prepared on a microfluidic flow focusing chip. Phase separation of droplets was caused by solvent volatilization and Janus morphology was formed under the action of interfacial tension. Because phase change from solid to liquid of the lipid hemisphere could be triggered by physiological temperature, the lipid hemisphere could be used for rapid release of drugs. While the polymer we selected was pH sensitive that the polymer hemisphere could degrade under acidic conditions, making it possible to release drugs in a specific pH environment, such as tumor tissues. Janus particles with different structures were obtained by changing the experimental conditions. To widen the application range of the particles, fatty alcohol and fatty acid-based phase change materials were also employed to prepare the particles, such as 1-tetradecanol, 1-hexadecanol and lauric acid. The melting points of these substances are higher than the physiological temperature, which can be applied in fever triggered drug release or in thermotherapy. The introduction of poly (lactic-co-glycolic acid) enabled the formation of multicompartment particles with three distinct materials. With different degradation properties of each compartment, the particles generated in this work may find applications in programmed and sequential drug release triggered by multiple stimuli.

Functions of corneal endothelial cells do not change after uptake of superparamagnetic iron oxide nanoparticles.

To avoid donor tissue shortages, ex vivo cultured human corneal endothelial cell (HCEC) transplantation is a promising therapeutic resource. Superparamagnetic iron oxide nanoparticle (SPION) cell labeling assists HCEC transplantation by attaching the posterior corneal stroma in ex vivo animal models. However, possible functional changes of the HCECs following SPION labeling remain to be determined. In this study, we used SPIONs to label cultured rabbit CECs (RCECs) in order to observe important cell functions and the levels of cell markers. The synthetic SPIONs exhibited superparamagnetism at room temperature, with saturation magnetization of 55.4 emu/g and negligible remanence or coercivity. The ζ-potential was -24.5 mV and the diameter was 101 ± 55 nm. Immunostaining demonstrated a normal density of zonula occluden-1 (ZO-1), nestin and Ki-67 at cellular junctions or in nuclei from RCECs following SPION labeling at 16 µg/ml. MTT cytotoxicity assay, homotypic adhesion assay, quantitative flow cytometric Ki-67 analysis and RCEC pump function measurement demonstrated no significant differences between the cells with or without SPION labeling (P<0.05, for all assays). Results of this study demonstrated successful labeled cultured RCECs with synthetic SPIONs. Labeled cells possessed several important characteristics required to maintain the transparency and refractive parameters of the cornea, including hexagonal cell morphology, higher cell adhesion ability and proliferative potential, cell pump function and the positive expression of several cell markers.