Customization of an Ultrafast Thiol-Norbornene Photo-Cross-Linkable Hyaluronic Acid-Gelatin Bioink for Extrusion-Based 3D Bioprinting.

Light-based three-dimensional (3D) bioprinting has been widely studied in tissue engineering. Despite the fact that free-radical chain polymerization-based bioinks like hyaluronic acid methacrylate (HAMA) and gelatin methacryloyl (GelMA) have been extensively explored in 3D bioprinting, the thiol-ene hydrogel system has attracted increasing attention for its ability in building hydrogel scaffolds in an oxygen-tolerant and cell-friendly way. Herein, we report a superfast curing thiol-ene bioink composed of norbornene-modified hyaluronic acid (NorHA) and thiolated gelatin (GelSH) for 3D bioprinting. A new facile approach was first introduced in the synthesis of NorHA, which circumvented the cumbersome steps involved in previous works. Additionally, after mixing NorHA with macro-cross-linker GelSH, the customized NorHA/GelSH bioinks exhibited fascinating superiorities over the gold standard GelMA bioinks, such as an ultrafast curing rate (1-5 s), much lowered photoinitiator concentration (0.03% w/v), and flexible physical performances. Moreover, the NorHA/GelSH hydrogel greatly avoided excess ROS generation, which is important for the survival of the encapsulated cells. Last, compared with the GelMA scaffold, the 3D-printed NorHA/GelSH scaffold not only exhibited excellent cell viability but also guaranteed cell proliferation, revealing its superior bioactivity. In conclusion, the NorHA/GelSH system is a promising candidate for 3D bioprinting and tissue engineering applications.

Human Adipose-Derived Mesenchymal Stem Cell-Based Microspheres Ameliorate Atherosclerosis Progression In Vitro.

Atherosclerosis (AS) is a chronic inflammatory disease associated with lipid deposition, which could be converted into acute clinical events by thrombosis or plaque rupture. Adipose-derived mesenchymal stem cell (ADSC)-encapsulated repair units could be an effective cure for the treatment of AS patients. In this study, we encapsulate human adipose-derived mesenchymal stem cells (hADSCs) in collagen microspheres to fabricate stem cell repair units. Besides, we show that encapsulation in collagen microspheres and cultured in vitro for 14 days maintain the viability and stemness of hADSCs. Moreover, we generate AS progression model and niche in vitro by combining hyperlipemia serum of AS patients with AS cell models. We further systematically demonstrate that hADSC-based microspheres could ameliorate AS progression by inhibiting oxidative stress injury, cell apoptosis, endothelial dysfunction, inflammation, and lipid accumulation. In addition, we perform transcriptomic analysis and functional studies to demonstrate how hADSCs (three dimensional cultured in microspheres) respond to AS niche compared with healthy microenvironment. These findings reveal a role for ADSC-based microspheres in the treatment of AS and provide new ideas for stem cell therapy in cardiovascular disease. The results may have implications for improving the efficiency of hADSC therapies by illuminating the mechanisms of hADSCs exposed in special pathological niche.

Carboxy-terminal telopeptide levels of type I collagen hydrogels modulated the encapsulated cell fate for regenerative medicine.

The cellular microenvironment has a profound impact on cell proliferation, interaction, and differentiation. In cell encapsulation for disease therapy, type I collagen is an important biomaterial due to its ability to mimic the extracellular matrix. Telopeptides (carboxy-terminal, CTX, and amino-terminal, NTX) protruding from the triple helix structure of type I collagen are cross-link sites, but also mediate the signal transmission in tissue homeostasis. It is worth investigating the features of the hydrogel microenvironment shaped by the tissue-derived type I collagen with various telopeptide levels, which is paramount for encapsulated cell development. Here, we found the fate of encapsulated human adipose-derived stem cells (hADSCs) and human umbilical vein endothelial cells (HUVECs) behaved differently towards decreasing CTX levels in the collagen hydrogels. Even among collagen hydrogels with a small magnitude of CTX variation, similar stiffness and microstructure, the apparent CTX modulation on the proliferation, cell-interaction, and genes expression of encapsulated hADSCs, as well as morphology and tubule structure formation of endothelial cells were observed, suggesting the biological roles of CTX and its modulation on microenvironment for cell development.