Embedded Bioprinting of Tissue-like Structures Using κ-Carrageenan Sub-Microgel Medium.

Embedded three-dimensional (3D) bioprinting utilizing a granular hydrogel supporting bath has emerged as a critical technique for creating biomimetic scaffolds. However, engineering a suitable gel suspension medium that balances precise bioink deposition with cell viability and function presents multiple challenges, particularly in achieving the desired viscoelastic properties. Here, a novel κ-carrageenan gel supporting bath is fabricated through an easy-to-operate mechanical grinding process, producing homogeneous sub-microscale particles. These sub-microgels exhibit typical Bingham flow behavior with small yield stress and rapid shear-thinning properties, which facilitate the smooth deposition of bioinks. Moreover, the reversible gel-sol transition and self-healing capabilities of the κ-carrageenan microgel network ensure the structural integrity of printed constructs, enabling the creation of complex, multi-layered tissue structures with defined architectural features. Post-printing, the κ-carrageenan sub-microgels can be easily removed by a simple phosphate-buffered saline wash. Further bioprinting with cell-laden bioinks demonstrates that cells within the biomimetic constructs have a high viability of 92% and quickly extend pseudopodia, as well as maintain robust proliferation, indicating the potential of this bioprinting strategy for tissue and organ fabrication. In summary, this novel κ-carrageenan sub-microgel medium emerges as a promising avenue for embedded bioprinting of exceptional quality, bearing profound implications for the in vitro development of engineered tissues and organs.

Bioprinted biomimetic hydrogel matrices guiding stem cell aggregates for enhanced chondrogenesis and cartilage regeneration.

Articular cartilage tissue has limited self-repair capabilities, with damage frequently progressing to irreversible degeneration. Engineered tissues constructed through bioprinting and embedded with stem cell aggregates offer promising therapeutic alternatives. Aggregates of bone marrow mesenchymal stromal cells (BMSCs) demonstrate enhanced and more rapid chondrogenic differentiation than isolated cells, thus facilitating cartilage repair. However, it remains a key challenge to precisely control biochemical microenvironments to regulate cellular adhesion and cohesion within bioprinted matrices simultaneously. Herein, this work reports a bioprintable hydrogel matrix with high cellular adhesion and aggregation properties for cartilage repair. The hydrogel comprises an enhanced cell-adhesive gelatin methacrylate and a cell-cohesive chitosan methacrylate (CHMA), both of which are subjected to photo-initiated crosslinking. By precisely adjusting the CHMA content, the mechanical stability and biochemical cues of the hydrogels are finely tuned to promote cellular aggregation, chondrogenic differentiation and cartilage repair implantation. Multi-layer constructs encapsulated with BMSCs, with high cell viability reaching 91.1%, are bioprinted and photo-crosslinked to support chondrogenic differentiation for 21 days. BMSCs rapidly form aggregates and display efficient chondrogenic differentiation both on the hydrogels and within bioprinted constructs, as evidenced by the upregulated expression of Sox9, Aggrecan and Collagen 2a1 genes, along with high protein levels. Transplantation of these BMSC-laden bioprinted hydrogels into cartilaginous defects demonstrates effective hyaline cartilage repair. Overall, this cell-responsive hydrogel scaffold holds immense promise for applications in cartilage tissue engineering.

Cation-crosslinkedκ-carrageenan sub-microgel medium for high-quality embedded bioprinting.

Three-dimensional (3D) bioprinting embedded within a microgel bath has emerged as a promising strategy for creating intricate biomimetic scaffolds. However, it remains a great challenge to construct tissue-scale structures with high resolution by using embedded 3D bioprinting due to the large particle size and polydispersity of the microgel medium, as well as its limited cytocompatibility. To address these issues, novel uniform sub-microgels of cell-friendly cationic-crosslinked kappa-carrageenan (κ-Car) are developed through an easy-to-operate mechanical grinding strategy. Theseκ-Car sub-microgels maintain a uniform submicron size of around 642 nm and display a rapid jamming-unjamming transition within 5 s, along with excellent shear-thinning and self-healing properties, which are critical for the high resolution and fidelity in the construction of tissue architecture via embedded 3D bioprinting. Utilizing this new sub-microgel medium, various intricate 3D tissue and organ structures, including the heart, lungs, trachea, branched vasculature, kidney, auricle, nose, and liver, are successfully fabricated with delicate fine structures and high shape fidelity. Moreover, the bone marrow mesenchymal stem cells encapsulated within the printed constructs exhibit remarkable viability exceeding 92.1% and robust growth. Thisκ-Car sub-microgel medium offers an innovative avenue for achieving high-quality embedded bioprinting, facilitating the fabrication of functional biological constructs with biomimetic structural organizations.

Engineered muscle from micro-channeled PEG scaffold with magnetic Fe3O4 fixation towards accelerating esophageal muscle repair.

Engineered scaffolds are used for repairing damaged esophagus to allow the precise alignment and movement of smooth muscle for peristalsis. However, most of these scaffolds focus solely on inducing cell alignment through directional apparatus, often overlooking the promotion of muscle tissue formation and causing reduced esophageal muscle repair effectiveness. To address this issue, we first introduced aligned nano-ferroferric oxide (Fe3O4) assemblies on a micropatterned poly(ethylene glycol) (PEG) hydrogel to form micro-/nano-stripes. Further modification using a gold coating was found to enhance cellular adhesion, orientation and organization within these micro-/nano-stripes, which consequently prevented excessive adhesion of smooth muscle cells (SMCs) to the thin PEG ridges, thereby effectively confining the cells to the Fe3O4-laid channels. This architectural design promotes the alignment of the cytoskeleton and elongation of actin filaments, leading to the organized formation of muscle bundles and a tendency for SMCs to adopt synthetic phenotypes. Muscle patches are harvested from the micro-/nano-stripes and transplanted into a rat esophageal defect model. In vivo experiments demonstrate the exceptional viability of these muscle patches and their ability to accelerate the regeneration of esophageal tissue. Overall, this study presents an efficient strategy for constructing muscle patches with directional alignment and muscle bundle formation of SMCs, holding significant promise for muscle tissue regeneration.

Biological importance of human amniotic membrane in tissue engineering and regenerative medicine.

The human amniotic membrane (hAM) is the innermost layer of the placenta. Its distinctive structure and the biological and physical characteristics make it a highly biocompatible material in a variety of regenerative medicine applications. It also acts as a supply of bioactive factors and cells, which indicate the advantages over other tissues. In this review, we firstly discussed the biological properties of hAM-derived cells in vivo or in vitro, along with their stemness of markers, pointing out a promising source of stem cells for regenerative medicine. Then, we systematically summarized current knowledge on the collection, preparation, preservation, and decellularization of hAM, as well as their characteristics helping to improve the understanding of applications in tissue engineering. Finally, we highlighted the recent advances in which hAM has undergone additional modifications to achieve an adequate perspective of regenerative medicine applications. More investigations are required in utilizing appropriate modifications to enhance the therapeutic effectiveness of hAM in the future.

Repairing gastric ulcer with hyaluronic acid/extracellular matrix composite through promoting M2-type polarization of macrophages.

The treatment of gastric ulcer and perforation using synthetic and biomaterials has been a clinical challenge. In this work, a drug-carrying layer of hyaluronic acid was combined with a gastric submucosal decellularized extracellular matrix called gHECM. The regulation of macrophage polarization by the extracellular matrix's components was then investigated. This work proclaims how gHECM responds to inflammation and aids in the regeneration of the gastric lining by altering the phenotype of surrounding macrophages and stimulating the body's whole immune response. In a nutshell, gHECM promotes tissue regeneration by changing the phenotype of macrophages around the site of injury. In particular, gHECM reduces the production of pro-inflammatory cytokines, decreases the percentage of M1 macrophages, and further encourages differentiation of macrophage subpopulation to the M2 phenotype and the release of anti-inflammatory cytokines, which could block the NF-κB pathway. Activated macrophages are capable of immediately delivering through spatial barriers, modulating the peripheral immune system, influencing the inflammatory microenvironment, and ultimately promoting the recovery of inflammation and healing of ulcers. They contribute to the secreted cytokines that act on local tissues or enhance the chemotactic ability of macrophages through paracrine secretion. In this study, we focused on the immunological regulatory network of macrophage polarization to further develop the mechanisms behind this process. Nevertheless, the signaling pathways involved in this process need to be further explored and identified. We think that our research will encourage more investigation into how the decellularized matrix affects immune modulation and will help the decellularized matrix perform better as a new class of natural biomaterials for tissue engineering.

Biologic Mechanisms of Macrophage Phenotypes Responding to Infection and the Novel Therapies to Moderate Inflammation.

Pro-inflammatory and anti-inflammatory types are the main phenotypes of the macrophage, which are commonly notified as M1 and M2, respectively. The alteration of macrophage phenotypes and the progression of inflammation are intimately associated; both phenotypes usually coexist throughout the whole inflammation stage, involving the transduction of intracellular signals and the secretion of extracellular cytokines. This paper aims to address the interaction of macrophages and surrounding cells and tissues with inflammation-related diseases and clarify the crosstalk of signal pathways relevant to the phenotypic metamorphosis of macrophages. On these bases, some novel therapeutic methods are proposed for regulating inflammation through monitoring the transition of macrophage phenotypes so as to prevent the negative effects of antibiotic drugs utilized in the long term in the clinic. This information will be quite beneficial for the diagnosis and treatment of inflammation-related diseases like pneumonia and other disorders involving macrophages.

CARD9 in host immunity to fungal, bacterial, viral, and parasitic infections: An update.

Microbial infection, caused by fungi, bacteria, viruses, and parasites, significantly contributes to the global death burden and health costs. The innate and adaptive immune systems orchestrate a multifaceted signaling response to invading pathogens as the human antimicrobial system. In this process, caspase recruitment domain-containing protein 9 (CARD9) emerges as a critical intermediary adaptor molecule to participate in regulating a series of antimicrobial immune reactions. Previous publications have confirmed that CARD9 plays a crucial role in fungal, bacterial, viral, and parasitic infections. In this study, we aim to provide an update on the recent clinical and basic studies where the mechanism and function of CARD9 have been further studied and understood. In addition, we summarize the latest treatment and prevention strategies based on CARD9 and discuss the current perspectives and future direction of CARD9.

Diagnosis of Esophageal Lesions by Multi-Classification and Segmentation Using an Improved Multi-Task Deep Learning Model.

It is challenging for endoscopists to accurately detect esophageal lesions during gastrointestinal endoscopic screening due to visual similarities among different lesions in terms of shape, size, and texture among patients. Additionally, endoscopists are busy fighting esophageal lesions every day, hence the need to develop a computer-aided diagnostic tool to classify and segment the lesions at endoscopic images to reduce their burden. Therefore, we propose a multi-task classification and segmentation (MTCS) model, including the Esophageal Lesions Classification Network (ELCNet) and Esophageal Lesions Segmentation Network (ELSNet). The ELCNet was used to classify types of esophageal lesions, and the ELSNet was used to identify lesion regions. We created a dataset by collecting 805 esophageal images from 255 patients and 198 images from 64 patients to train and evaluate the MTCS model. Compared with other methods, the proposed not only achieved a high accuracy (93.43%) in classification but achieved a dice similarity coefficient (77.84%) in segmentation. In conclusion, the MTCS model can boost the performance of endoscopists in the detection of esophageal lesions as it can accurately multi-classify and segment the lesions and is a potential assistant for endoscopists to reduce the risk of oversight.

Metformin exerts anti-tumor effects via Sonic hedgehog signaling pathway by targeting AMPK in HepG2 cells.

Metformin, a traditional first-line pharmacological treatment for type 2 diabetes, has recently been shown to have anti-cancer effects on hepatocellular carcinoma (HCC). However, the molecular mechanism underlying the anti-tumor activity of metformin remains unclear. The Sonic hedgehog (Shh) signaling pathway is closely associated with the initiation and progression of HCC. Therefore, the aim of the current study was to investigate the effects of metformin on the biological behavior of HCC and the underlying functional mechanism of metformin in the Shh pathway. HCC was induced in HepG2 cells using recombinant human Shh (rhShh). The effects of metformin on proliferation and metastasis were evaluated using in vitro proliferation, wound healing, and invasion assays. The mRNA and protein expression levels of proteins related to the Shh pathway were measured using western blotting, quantitative PCR, and immunofluorescence staining. Metformin inhibited rhShh-induced proliferation and metastasis. Furthermore, metformin decreased the mRNA and protein expression of Shh pathway components, including Shh, Ptch, Smo, and Gli-1. Silencing of AMPK in the presence of metformin revealed that metformin exerted its inhibitory effects via AMPK. Our findings demonstrate that metformin suppresses the migration and invasion of HepG2 cells via AMPK-mediated inhibition of the Shh pathway.

Late-Onset Ileocutaneous Fistula Eight Years After Plug Repair With Polypropylene Mesh: A Case Report.

Introduction: As one of the short-term complications after inguinal hernia repair, mesh infection frequently occurs but rarely leads to ileocutaneous fistula. We present a rare case of ileocutaneous fistula 8 years after inguinal hernia plug repair with polypropylene mesh. Case Presentation: The patient was a 67-year-old male who underwent a plug repair with polypropylene mesh of the right inguinal hernia. Eight years after the primary repair, skin ulceration with pus presented in the right groin area, and the final diagnosis was enterocutaneous fistula. According to laparoscopic exploration, the ileum below the fistula closely adhered to the abdominal wall. After gently separating the bowel loop, a defect area of about 2 × 3 cm was observed on the surface of the ileum. In laparotomy, the plug was found embedded in the ileum and then was completely removed, and an ileum side-to-side anastomosis was performed. The patient was discharged 2 weeks after the surgery, and follow-up at the sixth month revealed complete healing of the wound and no evidence of hernia recurrence. Conclusion: Late-onset ileocutaneous fistula should be considered in the differential diagnosis in patients who present inflammation and abscess formation after hernia repair. Besides, for patients with suspected intestinal fistula after hernia repair, laparoscopic exploration should be given priority, and the mesh removal approach should be tailored according to the results of laparoscopic exploration.

Case Report: Isolated Cystic Dilatation of the Cystic Duct: A Misdiagnosed Case Preoperatively.

A 33-year-old female with a mild elevation of liver transaminase was sent to the general surgery department for medical services due to upper-right abdominal pain for 2 weeks. A liquid dark area ~4 × 3 × 3 cm in size in the theoretical location of the pancreatic segment of the common bile duct was detected by abdominal CT with no enhancement of the cystic wall found in the enhanced CT scan. The patient was then diagnosed with a choledochal cyst based on the results of the radiological images preoperatively. During the operation, the isolated cystic dilatation was found in the middle part of the cystic duct, and its caudal portion was found behind the head of the pancreas and converged into the common bile duct at an acute angle and low insertion. According to the intraoperative evaluation, the female was then diagnosed with a cystic duct cyst (CDC). The surgery was converted to a laparotomy for the unclear structure and the possibility of anatomic variation of the bile duct. The caudal portion of the cystic duct was found communicated with the common bile duct with a narrow base, and the extrahepatic bile duct was not cystic. The CDC was removed in the surgery. One week later, the patient was discharged from the hospital for the disappearance of abdominal pain and normal liver transaminase and did not report any discomfort in the 1-month-long follow-up. The lessons drawn from this case were as follows: (1) the distinction between the relatively frequent choledochal cyst and the isolated CDC should always be taken in mind; (2) a surgical strategy should be given priority for an intraoperatively confirmed CDC; (3) a common bile duct exploration is recommended for patients with choledocholithiasis or jaundice.

Combined hepatocellular carcinoma-cholangiocarcinoma: A misdiagnosed case preoperatively.

Combined hepatocellular carcinoma-cholangiocarcinoma (cHCC-CC) is a rare subtype in primary liver cancer, which is difficult to diagnose in clinics. In this report, we present a case of a 62-year-old male with abdominal pain and slightly elevated alpha-fetoprotein. The contrast-enhanced computed tomography scans showed a left liver mass, which showed adherence to the imaging characteristics of hepatocellular carcinoma. However, with the treatment of laparoscopic liver resection, the following histological examination displayed two distinct components, which were consistent with the diagnosis of cHCC-CC.

MicroRNA-182 promotes epithelial-mesenchymal transition by targeting FOXN3 in gallbladder cancer.

Increasing evidence has suggested an association between the expression profiles of microRNAs (miRs) and gallbladder cancer (GBC). Recently, miR-182 has been demonstrated to exert tumor-promoting effects. However, the biological activity and molecular mechanisms of miR-182 in GBC remain unclear. The results of the present study demonstrated that miR-182 expression was significantly upregulated in GBC tissues and cell lines (GBC-SD and SGC-996). In addition, miR-182-knockdown attenuated epithelial-mesenchymal transition (EMT) in GBC cells, as indicated by decreased cell migratory and invasive abilities, decreased vimentin expression, and increased E-cadherin expression. The activities of ß-catenin and its downstream factors, Cyclin D1 and c-Myc, were also demonstrated to decrease following miR-182-knockdown. Forkhead box N3 (FOXN3) was identified as the direct target of miR-182. Overexpression of FOXN3 ameliorated EMT and the ß-catenin pathway. Taken together, the results of the present study suggested that miR-182 promotes EMT in GBC cells by targeting FOXN3, which suppresses the Wnt/ß-catenin pathway.

Silencing glioma-associated oncogene homolog 1 suppresses the migration and invasion of hepatocellular carcinoma in vitro.

Hepatocellular carcinoma (HCC) is the fourth most common cause of cancer-associated death worldwide. Glioma-associated oncogene homolog 1 (Gli1) is a key component and functions as a reliable marker of Hedgehog signaling pathway activation. Previous studies have demonstrated that Gli1 serves important roles in the progression of various types of cancer, including HCC. However, its effect on HCC invasion and metastasis and the underlying mechanism remain to be elucidated. Small interference RNA was employed to silence the Gli1 gene in liver cancer cells. Reverse transcription-quantitative PCR and western blot analysis were performed to evaluate the mRNA and protein expression of Gli1, respectively. A series of assays, including Cell Counting Kit-8, adhesion, wound healing and Matrigel invasion were performed to investigate cell viability, adhesive, migratory and invasive capabilities of liver cancer cells, respectively. In addition, immunofluorescence staining was performed to determine the cellular localization of focal adhesion kinase (FAK), phosphorylated (p-)FAK and p-AKT. The mRNA and protein expression of Gli1 in liver cancer cells (HepG2 and SK-Hep1) were markedly decreased in a dose-dependent manner following Gli1-knockdown. Gli1 silencing significantly inhibited the adhesion, migration and invasion of SK-Hep1 cells. Additionally, knockdown of Gli1 markedly suppressed the expression of metalloproteinase (MMP)-2 and MMP-9. Furthermore, downregulation of Gli1 blocked the FAK/AKT signaling pathway. Gli1 serves significant roles in the migration and invasion of HCC cells through activation of the FAK/AKT signaling pathway and subsequent upregulation of MMP-2 and MMP-9 expression. Thus, Gli1 may be a potential protein target for the regulation of HCC migration and invasion.