Three-dimensional (3D) printing technology has emerged as a revolutionary manufacturing strategy that could realize rapid prototyping and customization. It has revolutionized the manufacturing process in the fields of electronics, energy, bioengineering and sensing. Based on digital model files, powdered metal, plastic and other materials were used to construct the required objects by printing layer by layer. In addition, 3D printing possesses remarkable advantages in realizing controllable compositions and complex structures, which could further produce 3D objects with anisotropic functions. In recent years, 3D bioprinting technology has been applied to manufacture functional tissue engineering scaffolds with its ability to assemble complicated construction under precise control, which has attracted great attention. Bioprinting creates 3D scaffolds by depositing and assembling biological and/or non-biological materials with an established tissue. Compared with traditional technology, it can create a structure tailored to the patient according to the medical images. This conception of 3D bioprinting draws on 3D printing technology, which could be utilized to produce personalized implants, thereby opening up a new way for bio-manufacturing methods. As a promising tool, 3D bioprinting can create complex and delicate biomimetic 3D structures, simulating extracellular matrix and preparing high precision multifunctional scaffolds with uniform cell distribution for tissue repair and regeneration. It can also be flexibly combined with other technologies such as electrospinning and thermally induced phase separation, suitable for tissue repair and regeneration. This article reviews the relevant research and progress of 3D bioprinting in tissue repair and regeneration in recent years. Firstly, we will introduce the physical, chemical and biological characteristics of biological scaffolds prepared by 3D bioprinting from several aspects. Secondly, the significant effects of 3D bioprinting on nerves, skin, blood vessels, bones and cartilage injury and regeneration are further expounded. Finally, some views on the clinical challenges and future opportunities of 3D bioprinting are put forward.

The process of bone healing is complex and involves the participation of osteogenic stem cells, extracellular matrix, and angiogenesis. The advancement of bone regeneration materials provides a promising opportunity to tackle bone defects. This study introduces a composite hydrogel that can be injected and cured using UV light. Hydrogels comprise bioactive glass (BG) and PCL@GelMA coaxial nanofibers. The addition of BG and PCL@GelMA coaxial nanofibers improves the hydrogel’s mechanical capabilities (353.22 ± 36.13 kPa) and stability while decreasing its swelling (258.78 ± 17.56%) and hydration (72.07 ± 1.44%) characteristics. This hydrogel composite demonstrates exceptional biocompatibility and angiogenesis, enhances osteogenic development in bone marrow mesenchymal stem cells (BMSCs), and dramatically increases the expression of critical osteogenic markers such as ALP, RUNX2, and OPN. The composite hydrogel significantly improves bone regeneration (25.08 ± 1.08%) in non-healing calvaria defects and promotes the increased expression of both osteogenic marker (OPN) and angiogenic marker (CD31) in vivo. The expression of OPN and CD31 in the composite hydrogel was up to 5 and 1.87 times higher than that of the control group at 12 weeks. We successfully prepared a novel injectable composite hydrogel, and the design of the composite hydrogels shows significant potential for enhancing biocompatibility, angiogenesis, and improving osteogenic and angiogenic marker expression, and has a beneficial effect on producing an optimal microenvironment that promotes bone repair.

Although the distribution of Giardia duodenalis genotypes in humans has been increasingly reported in recent years, data on possible differences in pathogen transmission between age groups and virulence between genotypes are scarce. The purpose of this study is to investigate the genetic diversity of G. duodenalis in humans in Spain and compare the distribution of G. duodenalis assemblages A and B between children and adults and clinical presentations between the two genotypes. In the present study, 125 microscopy-positive fecal samples were collected from humans in Spain over a 7-year period. PCR and sequence analyses of the triosephosphate isomerase, β-giardin and glutamate dehydrogenase genes were used to identify the multilocus genotypes of G. duodenalis. Sequence analysis of three genetic loci identified both G. duodenalis assemblages A (29) and B (66), with co-infections of the two in two patients. Among the sequences obtained in this study, four multilocus genotypes (MLGs) of the sub-assemblage AII were observed within assemblage A. In contrast, 19 MLGs were detected within assemblage B due to the high sequence diversity at each locus. One MLG, however, was found in 51.9% (27/52) of assemblage B samples. Children were more commonly infected by assemblage B (44/53 or 83%) than adults (22/42 or 52.4%; χ2 = 10.371, df = 1, P = 0.001). Asymptomatic infection was more common in patients with assemblage A (4/29 or 13.8%) than in those with assemblage B (1/66 or 1.5%; χ2 = 6.091, df = 1, P = 0.029), and the frequency of abdominal pain occurrence was higher in assemblage B patients (65/66 or 98.5%) than assemblage A patients (25/29 or 86.2%; χ2 = 6.091, df = 1, P = 0.029). These results illustrate the existence of differences in genotype distribution between children and adults and clinical presentations between G. duodenalis genotypes. They are useful in understanding the transmission of G. duodenalis in humans in Spain.

Excessive scarring can impede the normal skin movement, resulting in decreased body flexibility and functional abnormalities. These issues, in turn, impact patients’ daily lives and comfort. To prevent the pathological healing of infected wounds, this study developed a composite hydrogel microneedle that possesses stable mechanical properties and favorable biocompatibility. The microneedles, composed of gelatin methacryloyl hydrogels, were integrated with curcumin-loaded PLGA microparticles to promote wound healing and allow the controlled release of curcumin within a suitable timeframe, thereby minimizing the formation of hypertrophic scars. Zinc oxide nanoparticles were integrated into the base layer of the microneedle, forming a physical barrier and exhibiting significant antibacterial activity against both Staphylococcus aureus and Escherichia coli. Due to the unique structural and functional design, we demonstrated that this class of microneedles could accelerate the healing of infected wounds and downregulate the expression of α-SMA and collagen I in scar fibroblasts, thereby showing potential to inhibit scar formation. In vivo investigations further validated the effective repair of infected wounds in rat skin and demonstrated the inhibition of pathological scars using hypertrophic scar models in rabbit ears. Altogether, these materials exhibit promising potential to provide a new option for preventing pathological scarring in the treatment of infected wounds.