3D bioprinting platform development for high-throughput cancer organoid models construction and drug evaluation.

The evaluation of anti-tumor drugs is critical for their development and clinical guidance. Tumor organoid models are gaining increased attention due to their ability to better mimic real tumor tissues, as well as lower time and economic costs, which makes up for the shortcomings of cell lines and xenograft models. However, current tumor organoid cultures based on the Matrigel have limitations in matching with high-throughput engineering methods due to slow gelation and low mechanical strength. Here, we present a novel composite bioink for culturing colorectal cancer organoids that provides an environment close to real tissue growth conditions and exhibits excellent photocrosslinking properties for rapid gel formation. Most importantly, the tumor organoids viability in the composite bioink after printing was as high as 97%, which also kept multicellular polar structures consistent with traditional culture methods in the Matrigel. Using 3D bioprinting with this composite bioink loaded with organoids, we demonstrated the feasibility of this drug evaluation model by validating it with clinically used colorectal cancer treatment drugs. Our results suggested that the composite bioink could effectively cultivate tumor organoids using 3D bioprinting, which had the potential to replace less reliable manual operations in promoting the application of tumor organoids in drug development and clinical guidance.

Injectable Hydrogel Delivery System with High Drug Loading for Prolonging Local Anesthesia.

Peripheral nerve block is performed for precise pain control and lesser side effects after surgery by reducing opioid consumption. Injectable hydrogel delivery systems with high biosafety and moisture content have good clinical application prospects for local anesthetic delivery. However, how to achieve high drug loading and long-term controlled release of water-soluble narcotic drugs remains a big challenge. In this study, heterogeneous microspheres and an injectable gel-matrix composite drug delivery system are designed in two steps. First, heterogeneous hydrogel microspheres loaded with ropivacaine (HMS-ROP) are prepared using a microfluidic chip and in situ alkalization. An injectable self-healing hydrogel matrix (Gel) is then prepared from modified carboxymethylcellulose (CMC-ADH) and oxidized hyaluronic acid (OHA). A local anesthetic delivery system, Gel/HMS-ROP/dexmedetomidine (DEX), with long-term retention and drug release in vivo is prepared by combining HMS-ROP and Gel/DEX. The drug loading of HMS-ROP reached 41.1%, with a drug release time of over 160 h in vitro, and sensory and motor blockade times in vivo of 48 and 36 h, respectively. In summary, the sequential release and synergistic analgesic effects of the two anesthetics are realized using core-shell microspheres, DEX, and an injectable gel, providing a promising strategy for long-acting postoperative pain management.

Single-Atom Ni Supported on TiO2 for Catalyzing Hydrogen Storage in MgH2.

As an efficient and clean energy carrier, hydrogen is expected to play a key role in future energy systems. However, hydrogen-storage technology must be safe with a high hydrogen-storage density, which is difficult to achieve. MgH2 is a promising solid-state hydrogen-storage material owing to its large hydrogen-storage capacity (7.6 wt %) and excellent reversibility, but its large-scale utilization is restricted by slow hydrogen-desorption kinetics. Although catalysts can improve the hydrogen-storage kinetics of MgH2, they reduce the hydrogen-storage capacity. Single-atom catalysts maximize the atom utilization ratio and the number of interfacial sites to boost the catalytic activity, while easy aggregation at high temperatures limits further application. Herein, we designed a single-atom Ni-loaded TiO2 catalyst with superior thermal stability and catalytic activity. The optimized 15wt%-Ni0.034@TiO2 catalyst reduced the onset dehydrogenation temperature of MgH2 to 200 °C. At 300 °C, the H2 released and absorbed 4.6 wt % within 5 min and 6.53 wt % within 10 s, respectively. The apparent activation energies of MgH2 dehydrogenation and hydrogenation were reduced to 64.35 and 35.17 kJ/mol of H2, respectively. Even after 100 cycles of hydrogenation and dehydrogenation, there was still a capacity retention rate of 97.26%. The superior catalytic effect is attributed to the highly synergistic catalytic activity of single-atom Ni, numerous oxygen vacancies, and multivalent Tix+ in the TiO2 support, in which the single-atom Ni plays the dominant role, accelerating electron transfer between Mg2+ and H- and weakening the Mg-H bonds. This work paves the way for superior hydrogen-storage materials for practical unitization and also extends the application of single-atom catalysis in high-temperature solid-state reactions.

3D printed heterogeneous hybrid hydrogel scaffolds for sequential tumor photothermal-chemotherapy and wound healing.

Surgical resection remains the mainstay of melanoma treatment. However, due to the difficulties in controlling tumor recurrence and wound healing simultaneously, high postoperative recurrence rates and wound reconstruction remain the most significant challenges. As a result, a heterogeneous hybrid hydrogel scaffold was designed in this work to achieve sequential photothermal therapy and chemotherapy for melanoma recurrence inhibition and wound healing. A 3D printing platform was used to create a SA-GG@PDA hybrid hydrogel scaffold, which was prepared from a hybrid bioink consisting of sodium alginate (SA), gellan gum (GG), and polydopamine nanoparticles (PDA NPs). The printability, biocompatibility, and mechanical qualities of the hybrid bioink were all satisfactory. PDA NPs were generated in situ in the hybrid bioink, providing superior photothermal effects to the scaffold. After coating with a thermosensitive gelatin hydrogel loaded with the chemotherapeutic drug doxorubicin (DOX), the heterogeneous hydrogel scaffold could accelerate drug release under photothermal triggering and achieve photothermal-chemotherapy to suppress tumor cell proliferation and recurrence after surgical resection. Subsequently, the printed porous hybrid hydrogel scaffold enhanced HUVEC proliferation and migration, as well as tissue ingrowth, promoting wound healing following surgery. In the same mouse model, the sequential treatment with the heterogeneous SA-GG@PDA + DOX hydrogel scaffold was tested. The fabrication of the heterogeneous SA-GG@PDA + DOX hydrogel scaffold with multifunctional capabilities seemed to be a potential technique for preventing tumor recurrence and promoting wound healing following surgery.

Elevated miR-195-5p expression in deep vein thrombosis and mechanism of action in the regulation of vascular endothelial cell physiology.

Deep vein thrombosis (DVT) is one of the most common cardiovascular diseases. The apoptosis of vascular endothelial cells is the most important cause of venous thrombosis. MicroRNAs (miRNAs) play important roles in the regulation of cell apoptosis. miRNA (miR)-195 is upregulated in the blood of patients with DVT, and it was predicted that Bcl-2 is a potential target of miR-195-5p. Therefore, it was hypothesized that miR-195-5p may play an important role in the development of DVT by targeting Bcl-2. The present study aimed to investigate the expression of miR-195-5p in DVT patients, and to explore whether miR-195-5p is involved in the development of DVT by regulating the apoptosis of vascular endothelial cells. The level of miR-195-5p was detected using reverse transcription-quantitative PCR. Dual luciferase reporter assays were used to determine the relationship between Bcl-2 and miR-195-5p. Cell viability was detected using MTT assays, and cell apoptosis was analyzed by flow cytometry. Protein levels of Bcl-2 and Bax were measured by western blotting. The results indicated that miR-195-5p was significantly upregulated in the blood of DVT patients. It was also revealed that Bcl-2 was a direct target of miR-195-5p, and that Bcl-2 was downregulated in the blood of patients with DVT. miR-195-5p downregulation promoted cell viability and inhibited the apoptosis of human umbilical vein endothelial cells (HUVECs). miR-195-5p upregulation inhibited cell viability and increased the apoptosis of HUVECs. All of the observed effects of miR-195-5p upregulation on HUVECs were reversed by raised Bcl-2 expression. In conclusion, miR-195-5p was significantly upregulated in patients with DVT, and it may be involved in the development of DVT by regulating the apoptosis of vascular endothelial cells. Therefore, miR-195-5p may be a potential target for predicting and treating DVT.

Enhanced ROS production leads to excessive fat accumulation through DAF-16 in Caenorhabditis elegans.

Growing evidence shows that enhanced reactive oxygen species (ROS) production is an important contributor to obesity and its co-morbidities, but the functional link between ROS and obesity remains elusive. In this study we used the model animal Caenorhabditis elegans to explore the role of ROS in obesity. Initially, when ROS production was enhanced by treatment with low concentration of paraquat or juglone, both abnormal high fat accumulation and fatty acid composition were observed in wild type worms. We found that the abnormal fat accumulation was associated with increased expression of fat-5, which encodes an isoform of stearoyl-CoA synthetase, and which is regulated by daf-16 encoding the forkhead transcription factor and being activated by downregulation daf-2. When mutant daf-16 worms were used, the abnormal fat accumulation induced by ROS was suppressed. Collectively, we demonstrate that enhanced ROS production can lead to excessive fat accumulation and the change of fatty acid composition. This abnormal phenomenon at least in part depends on the daf-16 pathway by which fat-5 was regulated. The results point towards a role of ROS in obesity in the context of important conserved signaling pathway, thereby guide further studies and future therapeutic interventions.