3D Bioprinting of Bone Marrow Mesenchymal Stem Cell-Laden Silk Fibroin Double Network Scaffolds for Cartilage Tissue Repair.

3D bioprinting is one of the latest trends in regenerative medicine due to its capacity for constructing highly organized tissues with living cells. In this work, silk fibroin (SF) together with hydroxypropyl methyl cellulose (HPMC) was used to print bone marrow mesenchymal stem cell (BMSC)-laden double network (DN) hydrogel for cartilage tissue repair. The ß-sheet structure formed among SF molecules was set as the rigid and brittle first network, while the cross-linking of HPMC-MA was set as the soft and ductile second network. Compared to the single network hydrogel, the fracture strength, breaking elongation, and compressive reproducibility increased significantly. Thereafter, the evaluation of cell proliferation and biochemical assay of this BMSC-laden 3D bioprinted hydrogel proved that it could ensure sufficient nutrient supply and great biochemical supportability in tissue engineering. This SF-based bioink with remarkable mechanical properties holds great promise as candidate for cartilage tissue regeneration.

Discovery of pyrazolone spirocyclohexadienone derivatives with potent antitumor activity.

Starting from easy accessible pyrazoletetrahydropyran acetals, a series of new pyrazolone spirocyclohexadienone derivatives were synthesized and assayed for antitumor activity. Compound 10s was identified to possess good antitumor activity. It could induce MDA-MB-231 cancer cell apoptosis in a concentration dependent manner and arrest the cell cycle progression mainly at the G1 phase.

MicroRNA­153­3p suppresses retinoblastoma cell growth and invasion via targeting the IGF1R/Raf/MEK and IGF1R/PI3K/AKT signaling pathways.

Mounting evidence has demonstrated that microRNAs (miRNAs or miRs) play significant roles in various types of human tumors, including retinoblastoma (RB). However, the biological role and regulatory mechanisms of miRNAs in RB remain to be fully elucidated. The present study was designed to identify the regulatory effects of miRNAs in RB and the underlying mechanisms. Differentially expressed miRNAs in RB tissue were screened out based on the Gene Expression Omnibus (GEO) dataset, GSE7072, which revealed that miR­153 in particular, displayed the highest fold change in expression. It was identified that miR­153 was significantly downregulated in RB tissues, and its downregulation was closely associated with a larger tumor base and differentiation. Functional analysis revealed that the overexpression of miR­153 inhibited RB cell proliferation, migration and invasion, and promoted the apoptosis of WERI­RB­1 and Y79 cells. In addition, insulin­like growth factor 1 receptor (IGF1R) was identified as a target of miR­153 in RB cells. More importantly, it was demonstrated that miR­153 upregulation inhibited the expression of its target gene, IGF1R, which inhibited the activation of the Raf/MEK and PI3K/AKT signaling pathways. Collectively, the present study demonstrates for the first time, to the best of our knowledge, that miR­153 functions as a tumor suppressor in RB by targeting the IGF1R/Raf/MEK and IGF1R/PI3K/AKT signaling pathways. Collectively, the findings presented herein demonstrate that miR­153 targets IGF1R and blocks the activation of the Raf/MEK and PI3K/AKT signaling pathway, thus preventing the progression of RB. Thus, this miRNA may serve as a novel prognostic biomarker and therapeutic target for RB.

Construction of a Silk Fibroin/Polyethylene Glycol Double Network Hydrogel with Co-Culture of HUVECs and UCMSCs for a Functional Vascular Network.

The success of complex tissue and internal organ reconstruction relies principally on the fabrication of a 3D vascular network, which guarantees the delivery of oxygen and nutrients in addition to the disposal of waste. In this study, a rapidly forming cell-encapsulated double network (DN) hydrogel is constructed by an ultrasonically activated silk fibroin network and bioorthogonal-mediated polyethylene glycol network. This DN hydrogel can be solidified within 10 s, and its mechanical property gradually increases to ∼20 kPa after 30 min. This work also demonstrates that coencapsulation of human umbilical vein endothelial cells (HUVECs) and umbilical cord-derived mesenchymal stem cells (UCMSCs) into the DN hydrogel can facilitate the formation of more mature vessels and complete the capillary network in comparison with the hydrogels encapsulated with a single cell type both in vitro and in vivo. Taking together, the DN hydrogel, combined with coencapsulation of HUVECs and UCMSCs, represents a strategy for the construction of a functional vascular network.

An injectable BMSC-laden enzyme-catalyzed crosslinking collagen-hyaluronic acid hydrogel for cartilage repair and regeneration.

Articular cartilage has limited self-healing ability due to its lack of abundant nutrients and progenitor cells. In this study, an injectable hydrogel system consisting of collagen type I-tyramine (Col-TA) and hyaluronic acid-tyramine (HA-TA) was fabricated as the bone marrow mesenchymal stem cell (BMSC)-laden hydrogel system for cartilage regeneration. Next, the physiochemical properties of this hydrogel system were well characterized and optimized, including gelation time, stiffness, water absorption and degradability. Further, the proliferation and differentiation of BMSCs within the Col-HA hydrogel were evaluated, and the ability of in vivo cartilage repair was also examined in the presence of the transforming growth factor-ß1 (TGF-ß1). These results illustrate that this hydrogel can offer a great microenvironment for BMSC growth and cartilage differentiation both in vitro and in vivo, and the Col-HA hydrogel can serve as an ideal hydrogel for cartilage tissue regeneration.

Fabrication of an injectable BMSC-laden double network hydrogel based on silk fibroin/PEG for cartilage repair.

An injectable BMSC-encapsulated double network (DN) hydrogel was fabricated via silk fibroin (SF) and poly(ethylene glycol) (PEG), which could efficiently support the survival and proliferation of BMSCs in vitro as well as cartilage repair in vivo, and provides a new strategy for cartilage tissue engineering.

Bone Marrow Mesenchymal Stem Cells Encapsulated in a Hydrogel System via Bioorthogonal Chemistry for Liver Regeneration.

Liver tissue engineering is going to be an effective treatment for end-stage liver disease. In this work, we distributed bone marrow mesenchymal stem cells (BMSCs) into a fast-forming hydrogel system to develop a liver-mimicking construct for liver regeneration. The advantage of this hydrogel system was that this BMSC-encapsulating hydrogel could be formed via a bioorthogonal reaction between 2-cyanobenzothiazole and cysteine within several seconds. Thereafter, we explored the morphology, biocompatibility, and expressions of hepatic differentiation markers of this hydrogel system. These results illustrated that this system could provide a suitable niche for BMSC proliferation and differentiation, which could aid in future biomedical research of liver regeneration.

Photo-crosslinkable, bone marrow-derived mesenchymal stem cells-encapsulating hydrogel based on collagen for osteogenic differentiation.

Many patients suffer from bone injury and self-regeneration is not effective. Developing new strategies for effective bone injury repair is highly desired. Herein, collagen, an important component of the extracellular matrix, was modified with glycidyl methacrylate. The water solubility and photochemical cross-linking ability of the resulting collagen derivative was then improved. Thereafter, BMSC-laden hydrogel was fabricated using collagen modified with glycidyl methacrylate and hyaluronic acid modified with methacrylic anhydride under UV light in the presence of I 2959. The physicochemical properties were characterized suggesting that the hydrogel had great potential for enhancing cell adhesion and proliferation. Furthermore, without adding the bone morphogenetic protein-2, the collagen also promoted osteogenic differentiation of BMSCs within the hydrogel. Altogether, this hydrogel system provides a general strategy to fabricate cell-encapsulating hydrogel based on collagen and could be used as 3D scaffold for bone injury repair.

Injectable hydrogels from enzyme-catalyzed crosslinking as BMSCs-laden scaffold for bone repair and regeneration.

Bone-marrow-derived mesenchymal stem cells possess great potential for tissue engineering and regenerative medicine. In the work, an injectable BMSCs-laden hydrogel system was formed by enzyme-catalyzed crosslinking of hyaluronic acid-tyramine and chondroitin sulfate-tyramine in the presence of hydrogen peroxide and horseradish peroxidase, which was used as a 3D scaffold to explore the behavior of the mesenchymal stem cells. Afterward, the gelation rate, mechanical properties, as well as the degradation process of the scaffold were well characterized and optimized. Furthermore, bone morphogenetic protein-2 was encapsulated in the scaffold, which was used to improve the osteogenic properties. The results illustrated that such a BMSCs-laden hydrogel not only offered a proper microenvironment for the adhesion, proliferation and differentiation of mesenchymal stem cells in vitro, but also promoted bone regeneration in vivo. Therefore, this injectable BMSCs-laden hydrogel may serve as an efficient 3D scaffold for bone repair and regeneration.

Bone Marrow-Derived Mesenchymal Stem Cells Encapsulated in Functionalized Gellan Gum/Collagen Hydrogel for Effective Vascularization.

Gellan gum hydrogel holds great potential in tissue engineering, but the high phase transition temperature greatly inhibits the applications in biomedical field. In this study, gellan gum was modified with methacrylic anhydride, and then the phase transition temperature was reduced. The functionalized gellan gum together with type I collagen was gelled by ion/photo dual-cross-linking for fabricating bone marrow-derived mesenchymal stem cells (BMSCs)-encapsulating hydrogel for vascularization. After the ratio between gellan gum and collagen was optimized, the hydrogel with proper pore size and mechanical properties was prepared. The WST assay demonstrated that the hydrogel could offer excellent microenvironment for cell survival and proliferation. Finally, real-time quantitative polymerase chain reaction suggests that the hydrogel could promote BMSCs to differentiate into endothelial cells. Together, this work provides a general strategy for fabricating BMSCs-encapsulating hydrogel in one step, which has the potential for 3D-printing live cell scaffold for study of vasculogenic differentiation.

Fast-forming BMSC-encapsulating hydrogels through bioorthogonal reaction for osteogenic differentiation.

An injectable in situ fast-forming hydrogel was easily fabricated through the inverse electron demand Diels-Alder click reaction between trans-cyclooctene and tetrazine. This hydrogel system simultaneously encapsulated bone morphogenetic protein-2 and BMSCs which showed potential applications in 3D bio-printing and tissue engineering.