Dual crosslinking silk fibroin/pectin-based bioink development and the application on neural stem/progenitor cells spheroid laden 3D bioprinting.

The human nervous system is an incredibly intricate physiological network, and neural cells lack the ability to repair and regenerate after a brain injury. 3-dimensional (3D) bioprinting technology offers a promising strategy for constructing biomimetic organ constructs and in vitro brain/disease models. The bioink serves as a pivotal component that emulates the microenvironment of biomimetic construct and exerts a profound influence on cellular behaviors. In this study, a series of mechanically adjustable and dual crosslinking bioinks were developed using photocrosslinkable methacrylated silk fibroin (SilMA) in combination with the ionic crosslinking material, pectin, or pectin methacryloyl (PecMA) with silk fibroin (SF) supplementation. SilMA/pectin exhibited superior properties, with SilMA providing biocompatibility and adjustable mechanical properties, while the addition of pectin enhanced printability. The porous structure supported neural cell growth, and 15 % SilMA/0.5 % pectin bioinks displayed excellent printability and shape fidelity. Neural stem/progenitor cells (NSPCs)-loaded bioinks were used to construct a 3D brain model, demonstrating sustained vitality and high neuronal differentiation without the need for growth factors. The SilMA/pectin bioinks demonstrated adjustable mechanical properties, favorable biocompatibility, and an environment highly conducive to neural induction, offering an alternative approach for neural tissue engineering applications or in vitro brain models.

An injectable, dual crosslinkable hybrid pectin methacrylate (PECMA)/gelatin methacryloyl (GelMA) hydrogel for skin hemostasis applications.

Biomaterials for effective hemorrhage control are urgently needed in clinics as uncontrolled bleeding is associated with high mortality. Herein, we developed an injectable and in situ photo-crosslinkable hybrid hemostatic hydrogel by combining pectin methacrylate (PECMA) and gelatin methacryloyl (GelMA). This modular material system combines ionic- and photo-crosslinking chemistries to design interpenetrating networks (IPN) exhibiting tunable rheology, highly porous structure, and controllable swelling and mechanical properties. By simply changing the calcium (0-15 mM) and polymer (1.5-7%) content used for the sequential crosslinking of hydrogels via calcium gelation and UV-photopolymerization, it was possible to precisely modulate the injectability, degradation, and swelling ratio. Moreover, it is demonstrated that PECMA/GelMA hydrogels present good cytocompatibility and uniquely synergize the hemostatic properties of calcium ions on PECMA, the amine residues on GelMA, and the highly porous network toward rapid blood absorption and fast coagulation effect. An in vitro porcine skin bleeding model confirmed that the hydrogel could be directly injected into the wound and rapidly photo-crosslinked, circumventing the bleeding and decreasing the coagulation time by 39%. Importantly, the crosslinked hydrogel could be easily removed to prevent secondary wound injury. Overall, this injectable hybrid PECMA/GelMA hydrogel stands as a promising hemostatic material.

Prolonged fecal shedding of CTX-M-15-producing Escherichia coli and recurrent sepsis in a patient after cord blood stem-cell transplantation.

An extended-spectrum beta-lactamase (CTX-M-15 type)-producing Escherichia coli persisted in the intestinal tract for >5 months in a pediatric patient after cord blood stem-cell transplantation and caused 2 episodes of sepsis. The bla(CTX-M-15) is carried by a large plasmid of approximately 130 kb in size. The prolonged shedding of the highly resistant E. coli posed a great challenge to infection control and public health.