11月7日-9日，聚焦东莞，姚睿/王立强/韩晓筱/雷一霆/吴洋/朱卉等众多专家，带你了解生物3D打印技术

1

3D bioprinting technology shows unique technical advantages in organoid and in vitro tissue construction, regenerative medicine, drug testing and other fields. At this stage, cell printing technology needs to solve the key theoretical and technological problems, such as stem cell-printing compatibility, new technology of spatio-temporal iteration, and stable construction of multicellular organoid and bionic tissues. Rui Yao has long been engaged in the research of "3D printing of stem cells and organ reconstruction", focusing on the regulation mechanism of stem cell fate determination and tissue and organ function reconstruction by engineering factors. This discuss will focus on the achievements of Yao Rui's group in recent years in (1) breaking through the printing technology of human induced pluripotent stem cells and maintaining cell self-renewal ability and pluripotency; (2) constructing multicellular organoids based on hiPSCs and printing technology, and discovering the high genetic background correlation of microplastic toxicity; (3) establishing the digital stem cell expansion and non-destructive collection technology based on 3D printing; (4) proposing the mechanically enhanced hydrogel-based tissue delivery method for minimally invasive delivery of large-size printed tissues for transplantation. The above studies show that a variety of in vitro tissues with physiological functions can be formed based on cell 3D printing technology and stem cell differentiation regulation, laying the foundation for the in vitro construction of complex organs.

2

Bioprinting is an emerging multidisciplinary technology that can be used for organ manufacturing, tissue repair, and drug screening. Layer-by-layer manufacturing of organs is a major feature of bioprinting technology, which also determines the accuracy of structures limited by printing resolution.  Insufficient resolution will lead to defects in the printing process and cannot complete the manufacture of complex organs. This study proposes a method based on computer vision to detect the deviation between the printing helix and the reference trajectory, and calculate the modified reference trajectory through error vector compensation. The new printed spiral trajectory generated by the corrected reference trajectory error is significantly reduced compared with the original spiral trajectory, and the correction efficiency is more than 90%.

3

The advancement of tissue engineering and regenerative medicine heavily relies on the development of effective scaffolds that can support cell growth and mimic the natural extracellular matrix. Traditional approaches have struggled with creating large, complex cell-laden constructs due to challenges such as weak mechanical stability, poor vascularization, slow printing speeds, and high cell death rates. In this study, we present a novel methodology combining Performance-to-Structure Design (PoD) with Precision High-fidelity Fabrication (HfF) through advanced 3D printing techniques to address these issues. Our approach involves using a biomimetic scaffold design based on Triply Periodic Minimal Surface (TPMS) unit cells, which provide excellent permeability, mechanical integrity, and support for cell growth. By leveraging high-resolution 3D printing, we achieve precise fabrication, enhancing the structural and functional properties of the constructs. The resulting cell-laden constructs demonstrate improved oxygen diffusion, high cell viability, and efficient nutrient transport, making them suitable for applications such as liver tumor models and potentially other complex tissue structures. This work represents a significant step towards the goal of printing entire organs, offering a promising solution to the current limitations in soft tissue construct fabrication.

4

In the realm of bone and joint diseases, conditions such as osteoarthritis pose significant challenges to both patients and healthcare systems. These diseases are characterized by the degradation of cartilage and underlying bone, leading to pain, stiffness, and reduced mobility. Hydrogel microspheres, a novel class of polymer materials, have emerged as promising agents in the therapeutic landscape of these conditions due to their unique properties, including biocompatibility, tunable mechanical properties, and the capacity for controlled release of therapeutic agents. This report will delve into the application of hydrogel microspheres in the treatment of osteoarthritis, illustrating their potential to improve clinical outcomes and enhance the quality of life for affected individuals. Furthermore, we will explore the burgeoning field of 3D printing, which offers unprecedented opportunities for the fabrication of complex and patient-specific hydrogel microsphere-based scaffolds, paving the way for regenerative medicine and personalized therapeutic interventions.

5

Damages of cartilage, tendon, and other soft tissues are common sports injuries, which cover a wide range of patient ages. 3D bioprinting has the ability to prepare artificial tissues, which can control the distribution of cells, extracellular matrix, and other bioactive compounds in different locations of the engineered tissues.

In a series of studies, we focus on the development of bioprinting techniques such as extrusion-based bioprinting, aspiration-assisted bioprinting, and electrohydrodynamic jet printing, etc. We have investigated the major issues on biofabrication, including: 1) the control and optimization of the bioprinting processes, 2) preparation and characterization of bioink with high cell density, 3) fabrication of artificial tissues with anatomically relevant structures and functions, 4) induction of bioprinted tissue in terms of biological functions and physical properties, 5) multi-scale biofabrication and regeneration of soft tissues.

Regarding biomedical applications, we explore a novel support bath that can be crosslinked with a bioink through the Schiff base reaction, and further developed a numerical model to evaluate the extrusion process and support bath dynamics, establishing essential parameters for consistent fiber formation and structural integrity. This led to the creation of a zonally stratified cartilage with a complex three-layer structure, promoting cellular integration, proliferation, and characteristic protein presence. In addition, a composite tendon construct was developed by integrating the electrohydrodynamic jet 3D printing technique and the fabrication of tissue strands, which exhibited fibrous arrangement, high cell density, and enhanced cell alignment. With the presence of cyclic stretching, the expression of tendon-specific proteins and cellular orientation in the tissue strands showed significant enhancement. In another study, we built a DLP-based multi-material bioprinter based on the liquid vat switching mechanism, which included a bottom-up cleaning nozzle with a drying fan, and enabled the printing of complex structures with multiple popular biomaterials. Through these studies, we use different biofabrication technologies creatively to construct artificial tissues that can be potentially applied for the repair of human tissue defects, which aims to realize the integration of structural mimicry and bio-functionalization.

6

Bioprinting has seen significant progress in recent years in the fabrication of bionic tissues with high complexity. Multiple disciplines have been involved such as biomaterials, mechanical engineering, life science, and medicine. However, it remains challenging to develop cell-laden living constructions exhibiting diverse bio-functionalities to satisfy the unique architectural, physicochemical and physiological requirements of different tissues. Bioink is one of the key aspects of bioprinting, which needs to be designed for advanced bio-functionalities for specific organ requirements. Hybrid printing techniques should also be adopted for fabricating multi-scale living consturcts with in vivo-like and functional tissue-mimic microenvironment. We envision that the synergy of the advanced bioinks and 3D printing techniques will make it possible to engineer functional living tissue constructs with promising physical, structural and biological properties.