Multimaterial Printing of Serpentine Microarchitectures with Synergistic Mechanical/Piezoelectric Stimulation for Enhanced Cardiac-Specific Functional Regeneration.

Recreating the natural heart's mechanical and electrical environment is crucial for engineering functional cardiac tissue and repairing infarcted myocardium in vivo. In this study, multimaterial-printed serpentine microarchitectures are presented with synergistic mechanical/piezoelectric stimulation, incorporating polycaprolactone (PCL) microfibers for mechanical support, polyvinylidene fluoride (PVDF) microfibers for piezoelectric stimulation, and magnetic PCL/Fe3O4 for controlled deformation via an external magnet. Rat cardiomyocytes in piezoelectric constructs, subjected to dynamic mechanical stimulation, exhibit advanced maturation, featuring superior sarcomeric structures, improved calcium transients, and upregulated maturation genes compared to non-piezoelectric constructs. Furthermore, these engineered piezoelectric cardiac constructs demonstrate significant structural and functional repair of infarcted myocardium, as evidenced by enhanced ejection and shortening fraction, reduced fibrosis and inflammation, and increased angiogenesis. The findings underscore the therapeutic potential of piezoelectric cardiac constructs for myocardial infarction therapy.

Consecutive multimaterial printing of biomimetic ionic hydrogel power sources with high flexibility and stretchability.

Electric eel is an excellent example to harness ion-concentration gradients for sustainable power generation. However, current strategies to create electric-eel-inspired power sources commonly involve manual stacking of multiple salinity-gradient power source units, resulting in low efficiency, unstable contact, and poor flexibility. Here we propose a consecutive multimaterial printing strategy to efficiently fabricate biomimetic ionic hydrogel power sources with a maximum stretchability of 137%. The consecutively-printed ionic hydrogel power source filaments showed seamless bonding interface and can maintain stable voltage outputs for 1000 stretching cycles at 100% strain. With arrayed multi-channel printhead, power sources with a maximum voltage of 208 V can be automatically printed and assembled in parallel within 30 min. The as-printed flexible power source filaments can be woven into a wristband to power a digital wristwatch. The presented strategy provides a tool to efficiently produce electric-eel-inspired ionic hydrogel power sources with great stretchability for various flexible power source applications.

Testing the Associations Between Attachment Anxiety, Relational Aggression and Depressive Symptoms in Romantic Relationships: Actor-Partner Interdependence Model and Actor-Partner Interdependence Mediator Model.

Emerging adulthood is a pivotal period for romantic relationships, yet the specific mechanisms through which attachment anxiety influences relationship dynamics and psychological outcomes in this phase are poorly understood. Particularly, in the context of romantic dyads, understanding how partners' behaviors and emotional patterns reciprocally influence each other remains underexplored. This study utilizes the Actor-Partner Interdependence Model and Actor-Partner Interdependence Mediator Model to explore the relationship between attachment anxiety,relational aggression (both perpetration and victimization), and depressive symptoms among emerging adults. A sample of 138 mixed-sex emerging adulthood couples from China, was recruited (Mage = 21.40, SD = 2.54; 50% female, 62.6% reporting that this relationship was ongoing for more than a year). Attachment anxiety significantly predicted relational aggression in both partners, with male attachment anxiety also significantly predicted female relational aggression. Significant indirect effects of both partners' relational aggression perpetration and victimization on their own and each other's relationship between attachment anxiety and depressive symptoms. These findings contribute to understanding the intricate dynamics of attachment anxiety and relational aggression in romantic relationships during emerging adulthood, emphasizing the need for targeted interventions to mitigate these risks.

[Development and Challenges of Additive Manufactured Customized Implant].

Additive manufacturing (3D printing) technology aligns with the direction of precision and customization in future medicine, presenting a significant opportunity for innovative development in high-end medical devices. Currently, research and industrialization of 3D printed medical devices mainly focus on nondegradable implants and degradable implants. Primary areas including metallic orthopaedic implants, polyether-ether-ketone (PEEK) bone implants, and biodegradable implants have been developed for clinical and industrial application. Recent research achievements in these areas are reviewed, with a discussion on the additive manufacturing technologies and applications for customized implants. Challenges faced by different types of implants are analyzed from technological, application, and regulatory perspectives. Furthermore, prospects and suggestions for future development are outlined.

Association between problematic social networking use and anxiety symptoms: a systematic review and meta-analysis.

A growing number of studies have reported that problematic social networking use (PSNU) is strongly associated with anxiety symptoms. However, due to the presence of multiple anxiety subtypes, existing research findings on the extent of this association vary widely, leading to a lack of consensus. The current meta-analysis aimed to summarize studies exploring the relationship between PSNU levels and anxiety symptoms, including generalized anxiety, social anxiety, attachment anxiety, and fear of missing out. 209 studies with a total of 172 articles were included in the meta-analysis, involving 252,337 participants from 28 countries. The results showed a moderately positive association between PSNU and generalized anxiety (GA), social anxiety (SA), attachment anxiety (AA), and fear of missing out (FoMO) respectively (GA: r = 0.388, 95% CI [0.362, 0.413]; SA: r = 0.437, 95% CI [0.395, 0.478]; AA: r = 0.345, 95% CI [0.286, 0.402]; FoMO: r = 0.496, 95% CI [0.461, 0.529]), and there were different regulatory factors between PSNU and different anxiety subtypes. This study provides the first comprehensive estimate of the association of PSNU with multiple anxiety subtypes, which vary by time of measurement, region, gender, and measurement tool.

TCL1A-expressing B cells are critical for tertiary lymphoid structure formation and the prognosis of oral squamous cell carcinoma.

BACKGROUND: Oral squamous cell carcinoma (OSCC) is a malignant tumor with a poor prognosis. Traditional treatments have limited effectiveness. Regulation of the immune response represents a promising new approach for OSCC treatment. B cells are among the most abundant immune cells in OSCC. However, the role of B cells in OSCC treatment has not been fully elucidated. METHODS: Single-cell RNA sequencing analysis of 13 tissues and 8 adjacent normal tissues from OSCC patients was performed to explore differences in B-cell gene expression between OSCC tissues and normal tissues. We further investigated the relationship between differentially expressed genes and the immune response to OSCC. We utilized tissue microarray data for 146 OSCC clinical samples and RNA sequencing data of 359 OSCC samples from The Cancer Genome Atlas (TCGA) to investigate the role of T-cell leukemia 1 A (TCL1A) in OSCC prognosis. Multiplex immunohistochemistry (mIHC) was employed to investigate the spatial distribution of TCL1A in OSCC tissues. We then investigated the effect of TCL1A on B-cell proliferation and trogocytosis. Finally, lentiviral transduction was performed to induce TCL1A overexpression in B lymphoblastoid cell lines (BLCLs) to verify the function of TCL1A. RESULTS: Our findings revealed that TCL1A was predominantly expressed in B cells and was associated with a better prognosis in OSCC patients. Additionally, we found that TCL1A-expressing B cells are located at the periphery of lymphatic follicles and are associated with tertiary lymphoid structures (TLS) formation in OSCC. Mechanistically, upregulation of TCL1A promoted the trogocytosis of B cells on dendritic cells by mediating the upregulation of CR2, thereby improving antigen-presenting ability. Moreover, the upregulation of TCL1A expression promoted the proliferation of B cells. CONCLUSION: This study revealed the role of B-cell TCL1A expression in TLS formation and its effect on OSCC prognosis. These findings highlight TCL1A as a novel target for OSCC immunotherapy.

Microphysiological systems inspired by leaf venation.

Nature-inspired microfluidic networks are revolutionizing microphysiological systems, allowing for the precise emulation of human physiology. This article delves into the fabrication techniques of leaf-venation-inspired (LVI) microfluidic networks and explores their transformative applications in organ-on-a-chip and tissue engineering, showcasing their pivotal role in advancing biomedical research.

Bioactive 3D Electrohydrodynamic Printed Lattice Architectures Augment Tenogenesis of Tendon Stem/Progenitor Cells.

Tendon defect repair remains a tough clinical procedure that hinders functional motion in patients. Electrohydrodynamic (EHD) three-dimensional (3D) printing, as a novel strategy, can controllably fabricate biomimetic micro/nanoscale architecture, but the hydrophobic and bioinert nature of polymers might be adverse to cell-material interplay. In this work, 3D EHD printed polycaprolactone (PCL) was immobilized on basic fibroblast growth factor (bFGF) using polydopamine (PDA), and the proliferation and tenogenic differentiation of tendon stem/progenitor cells (TSPCs) in vitro was researched. A subcutaneous model was established to evaluate the effects of tenogenesis and immunomodulation. We then investigated the in situ implantation and immunomodulation effects in an Achilles tendon defect model. After immobilization of bFGF, the scaffolds profoundly facilitated proliferation and tenogenic differentiation; however, PDA had only a proliferative effect. Intriguingly, the bFGF immobilized on EHD printed PCL indicated a synergistic effect on the highest expression of tenogenic gene and protein markers at 14 days, and the tenogenesis may be induced by activating the transforming growth factor-ß (TGF-ß) signal pathway in vitro. The subcutaneous engraftment study confirmed a tendon-like structure, similar to that of the native tendon, as well as an M2 macrophage polarization effect. Additionally, the bioactive scaffold exhibited superior efficacy in new collagen formation and repair of Achilles tendon defects. Our study revealed that the topographic cues alone were insufficient to trigger tenogenic differentiation, requiring appropriate chemical signals, and that appropriate immunomodulation was conducive to tenogenesis. The tenogenesis of TSPCs on the bioactive scaffold may be correlated with the TGF-ß signal pathway and M2 macrophage polarization.

Heart-on-a-chip systems with tissue-specific functionalities for physiological, pathological, and pharmacological studies.

Recent advances in heart-on-a-chip systems hold great promise to facilitate cardiac physiological, pathological, and pharmacological studies. This review focuses on the development of heart-on-a-chip systems with tissue-specific functionalities. For one thing, the strategies for developing cardiac microtissues on heart-on-a-chip systems that closely mimic the structures and behaviors of the native heart are analyzed, including the imitation of cardiac structural and functional characteristics. For another, the development of techniques for real-time monitoring of biophysical and biochemical signals from cardiac microtissues on heart-on-a-chip systems is introduced, incorporating cardiac electrophysiological signals, contractile activity, and biomarkers. Furthermore, the applications of heart-on-a-chip systems in intelligent cardiac studies are discussed regarding physiological/pathological research and pharmacological assessment. Finally, the future development of heart-on-a-chip toward a higher level of systematization, integration, and maturation is proposed.

Calcium phosphate coating enhances osteointegration of melt electrowritten scaffold by regulating macrophage polarization.

The osteoimmune microenvironment induced by implants plays a significant role in bone regeneration. It is essential to efficiently and timely switch the macrophage phenotype from M1 to M2 for optimal bone healing. This study examined the impact of a calcium phosphate (CaP) coating on the physiochemical properties of highly ordered polycaprolactone (PCL) scaffolds fabricated using melt electrowritten (MEW). Additionally, it investigated the influence of these scaffolds on macrophage polarization and their immunomodulation on osteogenesis. The results revealed that the CaP coated PCL scaffold exhibited a rougher surface topography and higher hydrophilicity in comparison to the PCL scaffold without coating. Besides, the surface morphology of the coating and the release of Ca2+ from the CaP coating were crucial in regulating the transition of macrophages from M1 to M2 phenotypes. They might activate the PI3K/AKT and cAMP-PKA pathways, respectively, to facilitate M2 polarization. In addition, the osteoimmune microenvironment induced by CaP coated PCL could not only enhance the osteogenic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) in vitro but also promote the bone regeneration in vivo. Taken together, the CaP coating can be employed to control the phenotypic switching of macrophages, thereby creating a beneficial immunomodulatory microenvironment that promotes bone regeneration.

The effects of self-esteem and parental phubbing on adolescent internet addiction and the moderating role of the classroom environment: a hierarchical linear model analysis.

BACKGROUND: With the advent of the new media era, the understanding of adolescent internet addiction needs to be enriched. It is also necessary to distinguish the related factors of adolescent internet addiction at different levels to clarify the mechanisms of this phenomenon. METHODS: This study used hierarchical linear model analysis to explore the effects of student-level factors and school-level factors on adolescent internet addiction, along with cross-level moderating effects. A total of 1,912 students between the 4th and 8th grades in China participated in the study. Participants completed the Self-Esteem Scale, Parents Phubbing Scale, Classroom Environment Scale, and the Diagnostic Questionnaire of Internet Addiction. RESULTS: Correlational analyses revealed that internet addiction was found to be negatively correlated with both self-esteem and the teacher-student relationship (p < 0.01), while father phubbing, mother phubbing, and learning burden were shown to positively correlate with internet addiction (p < 0.01). Hierarchical linear model analysis suggested that student-level variables, including self-esteem, and mother phubbing, were significant predictors of internet addiction (ß = -0.077, p < 0.001 and ß = 0.028, p < 0.01, respectively). At the school level, learning burden significantly and negatively predicted internet addiction (ß = 0.073, p < 0.05). Furthermore, the relationship between self-esteem and internet addiction was significantly moderated by learning burden (ß = -0.007, p < 0.05). Meanwhile, the teacher-student relationship also had a significant moderating effect on the association between mother phubbing and internet addiction (ß = -0.005, p < 0.01). CONCLUSIONS: This study revealed the relationships between self-esteem, parental phubbing, and classroom environment with adolescent internet addiction, and these findings could provide insights into reducing adolescent internet addiction from the perspective of individuals, families, and schools.

Sleep health and associated factors among undergraduates during the COVID-19 in China: A two-wave network analysis.

Using network analysis, the current study investigated the pathways that underlie selected components of sleep health and their changes over time. Undergraduates (N = 1423; 80.60% female) completed a two-wave survey, sleep health (i.e. chronotypologies (CTs), sleep procrastination (SP), sleep quality (SQ)), psychological distress (PD), emotion regulation (ER), self-control (SC), problematic smartphone use (PSU) were measured. CTs, SP, and SQ formed a spatially contiguous pattern that remained unchanged in both waves. ER and PD node increased its strength, betweenness, and closeness in the network, while the link between the two was strengthened at T2. PSU was connected to SP, but not to CTs and SQ during both waves. In the context of the network approach, SP had the highest strength, and its associations with other dimensions of individual sleep may represent key factors in understanding the influence of exposure to the COVID-19 outbreak on sleep health.

Are "night owls" or "morning larks" more likely to delay sleep due to problematic smartphone use? a cross-lagged study among undergraduates.

Sleep is an important physiological process, but staying up late has become a worldwide problem, particularly among university students. Sleep procrastination has been found to associated with sleep biorhythms and problematic smartphone use ("PSU") in previous studies. This two-wave study examines the longitudinal reciprocal relationship between PSU and sleep procrastination, together with the moderating role of sleep biorhythms. Participants comprised 1,423 Chinese university students. The results revealed that PSU and sleep procrastination are reciprocally related. Additionally, sleep biorhythms moderated this relationship, as PSU at T1 significantly predicted sleep procrastination at T2 for the morning larks group but not the night owls group. Accordingly, both PSU and sleep biorhythms should be considered when developing interventions for sleep procrastination.

Coaxial Electrohydrodynamic Printing of Microscale Core-Shell Conductive Features for Integrated Fabrication of Flexible Transparent Electronics.

Reliable insulation of microscale conductive features is required to fabricate functional multilayer circuits or flexible electronics for providing specific physical/chemical/electrical protection. However, the existing strategies commonly rely on manual assembling processes or multiple microfabrication processes, which is time-consuming and a great challenge for the fabrication of flexible transparent electronics with microscale features and ultrathin thickness. Here, we present a novel coaxial electrohydrodynamic (CEHD) printing strategy for the one-step fabrication of microscale flexible electronics with conductive materials at the core and insulating material at the outer layer. A finite element analysis (FEA) method is established to simulate the CEHD printing process. The extrusion sequence of the conductive and insulating materials during the CEHD printing process shows little effect on the morphology of the core-shell filaments, which can be achieved on different flexible substrates with a minimum conductive line width of 32 ± 3.2 µm, a total thickness of 53.6 ± 4.8 µm, and a conductivity of 0.23 × 107 S/m. The thin insulating layer can provide the inner conductive filament enough protection in 3D, which endows the resultant microscale core-shell electronics with good electrical stability when working in different chemical solvent solutions or under large deformation conditions. Moreover, the presented CEHD printing strategy offers a unique capability to sequentially fabricate an insulating layer, core-shell conductive pattern, and exposed electrodes by simply controlling the material extrusion sequence. The resultant large-area transparent electronics with two-layer core-shell patterns exhibit a high transmittance of 98% and excellent electrothermal performance. The CEHD-printed flexible microelectrode array is successfully used to record the electrical signals of beating mouse hearts. It can also be used to fabricate large-area flexible capacitive sensors to accurately measure the periodical pressure force. We envision that the present CEHD printing strategy can provide a promising tool to fabricate complex three-dimensional electronics with microscale resolution, high flexibility, and multiple functionalities.

Occupational stress and mental health among civil servants during COVID-19 in China: The mediation effect of social support and work-family conflict.

Mental health problems of various populations during the COVID-19 pandemic have received high attention, but there is little research on the mental health of Chinese civil servants. The present study investigated occupational stress, mental health problems (i.e., anxiety, depression, and insomnia), social support, and work-family conflict in Chinese civil servants during the COVID-19 pandemic. A total of 327 civil servants in Wenzhou city, China, participated in an online survey, which collected data on socio-demographic characteristics, occupational stress, mental health problems (i.e., anxiety, depression, and insomnia), social support, and work-family conflict. Data were analyzed using non-parametric tests and a multiple mediation model. Self-reported risk at work and support from mental health workers were relatively low. Anxiety, depression, and insomnia prevalence were 49.24 %, 47.1 %, and 20.48 %, respectively. Those who held higher ranks at work had lower levels of anxiety and depression. In addition, those who felt bad about their health status had more mental health problems. Social support and work-family conflict mediated the relationship between occupational stress and mental health problems significantly. Stress management training, organizational-level improvement in work arrangements, and professional mental health services are warranted for Chinese civil servants during the pandemic.

Advancing Intelligent Organ-on-a-Chip Systems with Comprehensive In Situ Bioanalysis.

In vitro models are essential to a broad range of biomedical research, such as pathological studies, drug development, and personalized medicine. As a potentially transformative paradigm for 3D in vitro models, organ-on-a-chip (OOC) technology has been extensively developed to recapitulate sophisticated architectures and dynamic microenvironments of human organs by applying the principles of life sciences and leveraging micro- and nanoscale engineering capabilities. A pivotal function of OOC devices is to support multifaceted and timely characterization of cultured cells and their microenvironments. However, in-depth analysis of OOC models typically requires biomedical assay procedures that are labor-intensive and interruptive. Herein, the latest advances toward intelligent OOC (iOOC) systems, where sensors integrated with OOC devices continuously report cellular and microenvironmental information for comprehensive in situ bioanalysis, are examined. It is proposed that the multimodal data in iOOC systems can support closed-loop control of the in vitro models and offer holistic biomedical insights for diverse applications. Essential techniques for establishing iOOC systems are surveyed, encompassing in situ sensing, data processing, and dynamic modulation. Eventually, the future development of iOOC systems featuring cross-disciplinary strategies is discussed.

Graphene-Based Material-Mediated Immunomodulation in Tissue Engineering and Regeneration: Mechanism and Significance.

Tissue engineering and regenerative medicine hold promise for improving or even restoring the function of damaged organs. Graphene-based materials (GBMs) have become a key player in biomaterials applied to tissue engineering and regenerative medicine. A series of cellular and molecular events, which affect the outcome of tissue regeneration, occur after GBMs are implanted into the body. The immunomodulatory function of GBMs is considered to be a key factor influencing tissue regeneration. This review introduces the applications of GBMs in bone, neural, skin, and cardiovascular tissue engineering, emphasizing that the immunomodulatory functions of GBMs significantly improve tissue regeneration. This review focuses on summarizing and discussing the mechanisms by which GBMs mediate the sequential regulation of the innate immune cell inflammatory response. During the process of tissue healing, multiple immune responses, such as the inflammatory response, foreign body reaction, tissue fibrosis, and biodegradation of GBMs, are interrelated and influential. We discuss the regulation of these immune responses by GBMs, as well as the immune cells and related immunomodulatory mechanisms involved. Finally, we summarize the limitations in the immunomodulatory strategies of GBMs and ideas for optimizing GBM applications in tissue engineering. This review demonstrates the significance and related mechanism of the immunomodulatory function of GBM application in tissue engineering; more importantly, it contributes insights into the design of GBMs to enhance wound healing and tissue regeneration in tissue engineering.

COVID-19 symptoms, internet information seeking, and stigma influence post-lockdown health anxiety.

Background: With the lifting of Zero-COVID policies in China, rapid transmission of the virus has led to new challenges for patients' health anxiety. This study aimed to evaluate the relationship between COVID-19 symptoms and health anxiety, as well as the mediation paths between them in individuals infected with COVID-19. Method: A cross-sectional study was conducted in December 2022, following the relaxation of anti-COVID measures in China. A validated online questionnaire was used to collect data from COVID-19 patients on the number and severity of symptoms, health anxiety, internet health information-seeking behavior (IHISB), and perceived stigma. Structural equation modeling was used to examine the mediation model in which COVID-19 symptoms would affect health anxiety via IHISB and perceived stigma. Results: Overall, 1,132 participants (women, 67.6%) were included, with a mean (SD) age of 28.12 (10.07) years. Participants had an average of seven COVID-19 symptoms, with cough (91.3%), nasal congestion (89.1%) and fatigue (87.8%) being the most common. The number and severity of COVID-19 symptoms, IHISB, perceived stigma, and health anxiety were positively correlated with each other after adjusting for covariates (r ranging from 0.10 to 0.81, all p < 0.05). IHISB (effect = 0.14, p < 0.001) and perceived stigma (effect = 0.04, p < 0.001) fully mediated the relationship between COVID-19 symptoms and health anxiety. Conclusion: Interventions for health anxiety reduction during and after pandemics should target improving the quality of online health information, enhancing individuals' online healthy literacy, and reducing stigma.

Biomimetic three-dimensional glioma model printed in vitro for the studies of glioma cells and neurons interactions.

1The interactions between glioma cells and neurons are important for glioma progression but are rarely mimicked and recapitulated in in vitro three-dimensional (3D) models, which may affect the success rate of relevant drug research and development. In this study, an in vitro bioprinted 3D glioma model consisting of an outer hemispherical shell with neurons and an inner hemisphere with glioma cells is proposed to simulate the natural glioma. This model was produced by extrusion-based 3D bioprinting technology. The cells survival rate, morphology, and intercellular Ca2+ concentration studies were carried out up to 5 days of culturing. It was found that neurons could promote the proliferation of glioma cells around them, associate the morphological changes of glioma cells to be neuron-like, and increase the expression of intracellular Ca2+ of glioma cells. Conversely, the presence of glioma cells could maintain the neuronal survival rate and promote the neurite outgrowth. The results indicated that glioma cells and neurons facilitated each other implying a symbiotic pattern established between two types of cells during the early stage of glioma development, which were seldom found in the present artificial glioma models. The proposed bioprinted glioma model can mimic the natural microenvironment of glioma tissue, provide an in-depth understanding of cell-cell interactions, and enable pathological and pharmacological studies of glioma.

A cell-free tissue-engineered tracheal substitute with sequential cytokine release maintained airway opening in a rabbit tracheal full circumferential defect model.

In this study, a cell-free tissue-engineered tracheal substitute was developed, which is based on a 3D-printed polycaprolactone scaffold coated with a gelatin-methacryloyl (GelMA) hydrogel, with transforming growth factor-ß1 (TGF-ß) and stromal cell-derived factor-1α (SDF-1) sequentially embedded, to facilitate cell recruitment and differentiation toward chondrocyte-phenotype. TGF-ß was loaded onto polydopamine particles, and then encapsulated into the GelMA together with SDF-1, and called G/S/P@T, which was used to coat 3D-printed PCL scaffold to form the tracheal substitute. A rapid release of SDF-1 was observed during the first week, followed by a slow and sustained release of TGF-ß for approximately four weeks. The tracheal substitute significantly promoted the recruitment of mesenchymal stromal cells (MSCs) or human bronchial epithelial cells in vitro, and enhanced the ability of MSCs to differentiate towards chondrocyte phenotype. Implantation of the tissue-engineered tracheal substitute with a rabbit tracheal anterior defect model improved regeneration of airway epithelium, recruitment of endogenous MSCs and expression of markers of chondrocytes at the tracheal defect site. Moreover, the tracheal substitute maintained airway opening for 4 weeks in a tracheal full circumferential defect model with airway epithelium coverage at the defect sites without granulation tissue accumulation in the tracheal lumen or underneath. The promising results suggest that this simple, cell-free tissue-engineered tracheal substitute can be used directly after tracheal defect removal and should be further developed towards clinical application.