Musashi-1 is the candidate of the regulator of hair cell progenitors during inner ear regeneration

Emerging Roles of RNA-Binding Proteins in Inner Ear Hair Cell Development and Regeneration

RNA-binding proteins (RBPs) regulate gene expression at the post-transcriptional level. They play major roles in the tissue- and stage-specific expression of protein isoforms as well as in the maintenance of protein homeostasis. The inner ear is a bi-functional organ, with the cochlea and the vestibular system required for hearing and for maintaining balance, respectively. It is relatively well documented that transcription factors and signaling pathways are critically involved in the formation of inner ear structures and in the development of hair cells. Accumulating evidence highlights emerging functions of RBPs in the post-transcriptional regulation of inner ear development and hair cell function. Importantly, mutations of splicing factors of the RBP family and defective alternative splicing, which result in inappropriate expression of protein isoforms, lead to deafness in both animal models and humans. Because RBPs are critical regulators of cell proliferation and differentiation, they present the potential to promote hair cell regeneration following noise- or ototoxin-induced damage through mitotic and non-mitotic mechanisms. Therefore, deciphering RBP-regulated events during inner ear development and hair cell regeneration can help define therapeutic strategies for treatment of hearing loss. In this review, we outline our evolving understanding of the implications of RBPs in hair cell formation and hearing disease with the aim of promoting future research in this field.

Growth and Differentiation of Circulating Stem Cells After Extensive Ex Vivo Expansion

Background:

Stem cell therapy is gaining momentum as an effective treatment strategy for degenerative diseases. Adult stem cells isolated from various sources (i.e., cord blood, bone marrow, adipose tissue) are being considered as a realistic option due to their well-documented therapeutic potentials. Our previous studies standardized a method to isolate circulating multipotent cells (CMCs) that are able to sustain long term in vitro culture and differentiate towards mesodermal lineages.

Methods:

In this work, long-term cultures of CMCs were stimulated to study in vitro neuronal and myogenic differentiation. After induction, cells were analysed at different time points. Morphological studies were performed by scanning electron microscopy and specific neuronal and myogenic marker expression were evaluated using RT-PCR, flow cytometry and western blot. For myogenic plasticity study, CMCs were transplanted into in vivo model of chemically-induced muscle damage.

Results:

After neurogenic induction, CMCs showed characteristic dendrite-like morphology and expressed specific neuronal markers both at mRNA and protein level. The calcium flux activity of CMCs under stimulation with potassium chloride and the secretion of noradrenalin confirmed their ability to acquire a functional phenotype. In parallel, the myogenic potential of CMCs was confirmed by their ability to form syncytium-like structures in vitro and express myogenic markers both at early and late phases of differentiation. Interestingly, in a rat model of bupivacaine-induced muscle damage, CMCs integrated within the host tissue taking part in tissue repair.

Conclusion:

Overall, collected data demonstrated long-term cultured CMCs retain proliferative and differentiative potentials suggesting to be a good candidate for cell therapy.

siRNA-loaded selenium nanoparticle modified with hyaluronic acid for enhanced hepatocellular carcinoma therapy

Background

Small interfering RNA (siRNA) as a new therapeutic modality holds promise for cancer treatment. However, the traditional viral carriers are prone to immunogenicity and risk of insertional mutagenesis.

Methods

In order to provide a tumor-targeted delivery carrier of siRNA in cancer therapy, the hyaluronic acid (HA)-selenium (Se)-polyethylenimine (PEI) nanoparticle (NP) was fabricated by decorating SeNP with HA as a tumor-targeting moiety and by linking the polycationic polymers polyethylenimine PEI onto the surface of SeNP. The siRNA was loaded to the surface of SeNP HA-Se-PEI via the electrostatic interaction between siRNA and PEI to prepare the functionalized SeNP HA-Se-PEI@siRNA.

Results

The HA-Se-PEI@siRNA was internalized into the HepG2 cell mainly in a clathrin-mediated endocytosis manner. Owing to the active tumor-targeted effect mediated by HA, HA-Se-PEI@siRNA achieved the obvious higher transfection efficiency, greater gene silencing ability, and stronger cytotoxicity in the HepG2 cell compared with the passive tumor-targeted NP Se-PEI@siRNA. The knockdown of hairy and enhancer of split 5 by HA-Se-PEI@siRNA induced the HepG2 cell cycle arrest at the G0/G1 phase and apoptosis. Furthermore, the treatment with HA-Se-PEI@siRNA resulted in greater antitumor efficacy compared with the Se-PEI@siRNA in vitro and in vivo. In addition, the HA-Se-PEI@siRNA was almost no toxic to the key organs of mice.

Conclusion

These findings provided an alternative therapeutic route for targeted cancer treatments.

Developmental signature, synaptic connectivity and neurotransmission are conserved between vertebrate hair cells and tunicate coronal cells

In tunicates, the coronal organ represents a sentinel checking particle entrance into the pharynx. The organ differentiates from an anterior embryonic area considered a proto-placode. For their embryonic origin, morphological features and function, coronal sensory cells have been hypothesized to be homologues to vertebrate hair cells. However, vertebrate hair cells derive from a posterior placode. This contradicts one of the principle historical criteria for homology, similarity of position, which could be taken as evidence against coronal cells/hair cells homology. In the tunicates Ciona intestinalis and C. robusta, we found that the coronal organ expresses genes (Atoh, Notch, Delta-like, Hairy-b, and Musashi) characterizing vertebrate neural and hair cell development. Moreover, coronal cells exhibit a complex synaptic connectivity pattern, and express neurotransmitters (Glu, ACh, GABA, 5-HT, and catecholamines), or enzymes for their synthetic machinery, involved in hair cell activity. Lastly, coronal cells express the Trpa gene, which encodes an ion channel expressed in hair cells. These data lead us to hypothesize a model in which competence to make secondary mechanoreceptors was initially broadly distributed through placode territories, but has become confined to different placodes during the evolution of the vertebrate and tunicate lineages.

Folate-targeted selenium nanoparticles deliver therapeutic siRNA to improve hepatocellular carcinoma therapy

To obtain a tumor targeting siRNA delivery vehicle for hepatocellular carcinoma treatments, functionalized selenium nanoparticles, Se–PEI–FA, were first prepared by decorating selenium nanoparticles with polycationic polymers, polyethylenimine (PEI), linked with folic acid (FA). FA functions as the tumor-targeted molecule to enhance tumor targeting activity, and PEI conjugates FA and siRNA. Se–PEI–FA@siRNA entered HepG2 cells principally via clathrin-mediated endocytosis. Due to the active tumor targeting effectiveness of FA, Se–PEI–FA@siRNA has significantly higher cellular uptake and gene silencing efficiency, and more apparent cytotoxicity, in HepG2 cells compared with Se–PEI@siRNA. The silencing of HES5 by Se–PEI–FA@siRNA could induce HepG2 cells arrest at G0/G1 phase possibly via inhibiting protein expression of CDK2, cyclinE, and cyclinD1, and up-regulating the protein expression of p21. More importantly, Se–PEI–FA@siRNA exhibits more significant antitumor efficacy compared with Se–PEI@siRNA in vivo. Additionally, Se–PEI–FA@siRNA exhibits low toxicity to the important organs of tumor-bearing mice. This research provides an effective strategy for the design of tumor-targeted nanodrugs against hepatocellular carcinoma.

We provide an effective strategy for the design of tumor-targeted nanodrugs against hepatocellular carcinoma by functionalising Se nanoparticles with polyethylenimine linked with folic acid and siRNA.