A novel portable in situ printer for hydrogel multi-structure molding and cell printing.

Skin lesions not only disrupt appearance and barrier functionality but also lead to severe microbial infections and immune-inflammatory responses, seriously affect physical and mental health. In situ printing involves the direct deposition of bio-ink to create or repair damaged tissues or organs within a clinical setting. In this study, we designed and fabricated a novel portable in situ printer. This handheld instrument exhibits excellent printing performance, allowing hydrogels to be patterned and molded on surfaces according to specific requirements. By utilizing a dual-component hydrogels co-printing approach with high and low viscosities, we achieved in situ cell-laden printing using low-viscosity hydrogel. This demonstrates the advantages of the device in maintaining cell viability and achieving hydrogel structuring. This approach opens up the possibilities for the efficient encapsulation of active components such as drugs, proteins, and cells, enabling controlled macro- and micro-structuring of hydrogels. This breakthrough finding highlights the potential of our technical approach in dermatological treatment and wound repair, by dynamically adapting and regulating microenvironments in conjunction with hydrogel scaffolds and cell reparative impetus.

Strategies for vascularized skin models in vitro.

As the largest organ of the human body, the skin has a complex multi-layered structure. The composition of the skin includes cells, extracellular matrix (ECM), vascular networks, and other appendages. Because of the shortage of donor sites, skin substitutes are of great significance in the field of skin tissue repair. Moreover, skin models for disease research, drug screening, and cosmetic testing fall far short of the demand. Skin tissue engineering has made remarkable progress in developing skin models over the years. However, there are still several problems to be resolved. One of the crucial aspects is the lack of vascular systems for nutrient transport and waste disposal. Here, we will focus on the discussion and analysis of advanced manufacturing strategies for prevascularized skin, such as a scaffold-based method, cell coating technology, cell sheet engineering, skin-on-a-chip, and three-dimensional (3D) bioprinting. These key challenges, which restrict the prevascularized skin and provide perspectives on future directions will also be highlighted.

New Method for Preparing Small-Caliber Artificial Blood Vessel with Controllable Microstructure on the Inner Wall Based on Additive Material Composite Molding.

The diameter of most blood vessels in cardiovascular and peripheral vascular system is less than 6 mm. Because the inner diameter of such vessels is small, a built-in stent often leads to thrombosis and other problems. It is an important goal to replace it directly with artificial vessels. This paper creatively proposed a preparation method of a small-diameter artificial vascular graft which can form a controllable microstructure on the inner wall and realize a multi-material composite. On the one hand, the inner wall of blood vessels containing direct writing structure is constructed by electrostatic direct writing and micro-imprinting technology to regulate cell behavior and promote endothelialization; on the other hand, the outer wall of blood vessels was prepared by electrospinning PCL to ensure the stability of mechanical properties of composite grafts. By optimizing the key parameters of the graft, a small-diameter artificial blood vessel with controllable microstructure on the inner wall is finally prepared. The corresponding performance characterization experimental results show that it has advantages in structure, mechanical properties, and promoting endothelialization.

3D bioprinting for fabricating artificial skin tissue.

As an organ in direct contact with the external environment, the skin is the first line of defense against external stimuli, so it is the most vulnerable to damage. In addition, there is an increasing demand for artificial skin in the fields of drug testing, disease research and cosmetic testing. Traditional skin tissue engineering has made encouraging progress after years of development. However, due to the complexity of the skin structures, there is still a big gap between existing artificial skin and natural skin in terms of function. Three-dimensional (3D) bioprinting is an advanced biological manufacturing method. It accurately deposits bioinks into pre-designed three-dimensional shapes to create complex biological tissues. This technology aims to print artificial tissues and organs with biological activities and complete physiological functions, thereby alleviating the problem of tissues and organs in short supply. Here, based on the introduction to skin structure and function, we systematically elaborate and analyze skin manufacturing methods, 3D bioprinting biomaterials and strategies, etc. Finally, the challenges and perspectives in 3D bioprinting skin field are summarized.