No abstract

Although the disulfide bond crosslinked hyaluronic acid hydrogels have been reported by many research groups, the major researches were focused on effectively forming hydrogels. However, few researchers paid attention to the potential significance of controlling the hydrogel formation and degradation, improving biocompatibility, reducing the toxicity of exogenous and providing convenience to the clinical operations later on. In this research, the novel controllable self-crosslinking smart hydrogels with in-situ gelation property was prepared by a single component, the thiolated hyaluronic acid derivative (HA-SH), and applied as a three-dimensional scaffold to mimic native extracellular matrix (ECM) for the culture of fibroblasts cells (L929) and chondrocytes. A series of HA-SH hydrogels were prepared depending on different degrees of thiol substitution (ranging from 10 to 60%) and molecule weights of HA (0.1, 0.3 and 1.0 MDa). The gelation time, swelling property and smart degradation behavior of HA-SH hydrogel were evaluated. The results showed that the gelation and degradation time of hydrogels could be controlled by adjusting the component of HA-SH polymers. The storage modulus of HA-SH hydrogels obtained by dynamic modulus analysis (DMA) could be up to 44.6 kPa. In addition, HA-SH hydrogels were investigated as a three-dimensional scaffold for the culture of fibroblasts cells (L929) and chondrocytes cells in vitro and as an injectable hydrogel for delivering chondrocytes cells in vivo. These results illustrated that HA-SH hydrogels with controllable gelation process, intelligent degradation behavior, excellent biocompatibility and convenient operational characteristics supplied potential clinical application capacity for tissue engineering and regenerative medicine.

No abstract

Hyperphosphorylation of Tau forming neurofibrillary tangles has been considered as a crucial event in the pathogenesis of Alzheimer's disease (AD). MiR-124-3p belongs to microRNA (miRNA) family and was markedly decreased in AD, however, the functions of miR-124-3p in the pathogenesis of AD remain unknown. We observed that the expression of miR-124-3p was significantly decreased in N2a/APP695swe cells; and transfection of miR-124-3p mimics not only attenuated cell apoptosis and abnormal hyperphosphorylation of Tau protein without any changes of total Tau protein, but also increased expression levels of Caveolin-1, phosphoinositide 3-kinase (PI3K), phospho-Akt (Akt-Ser473)/Akt, phospho-glycogen synthase kinase-3 beta (GSK-3β-Ser9)/GSK-3β in N2a/APP695swe cells. We further found that miR-12-3p directly targeted Caveolin-1; miR-124-3p inhibited abnormal hyperphosphorylation of Tau by regulating Caveolin-1-PI3K/Akt/GSK3β pathway in AD. This study reveals that miR-124-3p may play a neuroprotective role in AD, which may provide new ideas and therapeutic targets for AD.

A collagen type I hydrogel was constructed and used as the scaffold for cartilage tissue engineering. Neonatal rabbit chondrocytes were seeded into the hydrogel, and the constructs were cultured in vitro for 7, 14, and 28 days. The immunomodulatory effect of the hydrogel on seeded chondrocytes was carefully investigated. The expressions of major histocompatibility complex classes I and II of seeded chondrocytes increased with the time, which indicated that the immunogenicity also increased with the time. Meanwhile, the properly designed collagen type I hydrogel could prompt the chondrogenesis of engineered cartilage. The extracellular matrix (ECM) synthesis ability of seeded chondrocytes and the accumulated ECM in the constructs continuously increased with the culture time. Both the isolation and protection, which come from formed ECM and hydrogel scaffold, can effectively control the adverse immunogenicity of seeded chondrocytes and even help to lessen the immunogenicity of the whole engineered cartilage. As the result, the levels of mixed lymphocyte chondrocyte reactions of seed cells and the constructs decreased gradually. The stimulation on allogeneic lymphocytes of the whole constructs was obviously lower than that of the retrieved cells from the constructs. Therefore, properly designed collagen type I hydrogel can give certain immunogenicity-reducing effects on engineered cartilage based on chondrocytes, and it may be a potential immunomodulatory biomaterial in tissue engineering.