Establishment and evaluation of an improved rat model of open abdomen

Introduction:This study aimed to establish an animal model of open abdomen(OA)through temporary abdominal closure via different techniques.Methods:Adult male Sprague-Dawley rats were randomly divided into three groups:group A(OA with polypropylene mesh alone);group B(OA with polypro-pylene mesh combined with a patch);and group C(OA with polypropylene mesh and a sutured patch).Vital signs,pathophysiological changes,and survival rates were closely monitored in the rats for 7 days after surgery.Abdominal X-rays and histopathological examinations were performed to assess abdominal organ changes and wound healing.Results:The results showed no significant difference in mortality rates among the three groups(p>0.05).However,rats in group B exhibited superior overall condi-tion,cleaner wounds,and a higher rate of wound healing compared to the other groups(p<0.05).Abdominal X-rays indicated that varying degrees of distal intestinal obstruction in all groups.Histopathological examinations revealed fibrous hyperpla-sia,inflammatory cell infiltration,neovascularization,and collagen deposition in all groups.Group B demonstrated enhanced granulation tissue generation,neovasculari-zation,and collagen deposition compared to the other groups(p<0.05).Conclusions:Polypropylene mesh combined with patches is the most suitable method for establishing an animal model of OA.This model successfully replicated the patho-logical and physiological changes in postoperative patients with OA,specifically the progress of abdominal skin wound healing.It provides a practical and reliable animal model for OA research.

Interaction between internal solitary waves and the seafloor in the deep sea

Internal solitary wave(ISW),as a typical marine dynamic process in the deep sea,widely exists in oceans and marginal seas worldwide.The interaction between ISW and the seafloor mainly occurs in the bottom boundary layer.For the seabed boundary layer of the deep sea,ISW is the most important dynamic process.This study analyzed the current status,hotspots,and frontiers of research on the interaction between ISW and the seafloor by CiteSpace.Focusing on the action of ISW on the seabed,such as transformation and reaction,a large amount of research work and results were systematically analyzed and summarized.On this basis,this study analyzed the wave–wave interaction and interaction between ISW and the bedform or slope of the seabed,which provided a new perspective for an in‐depth understanding of the interaction between ISW and the seafloor.Finally,the latest research results of the bottom boundary layer and marine engineering stability by ISW were introduced,and the unresolved problems in the current research work were summarized.This study provides a valuable reference for further research on the hazards of ISW to marine engineering geology.

Microfluidic intestinal organoid-on-a-chip uncovers therapeutic targets by recapitulating oxygen dynamics of intestinal IR injury

Increasing evidence demonstrates that mammals have different reactions to hypoxia with varied oxygen dynamic patterns.It takes~24 h for tri-gas incubator to achieve steady cell hypoxia,which fails to recapitulate ultrafast oxygen dynamics of intestinal ischemia/reperfusion(IR)injury.Inspired from the structure of native intestinal villi,we engineered an intestinal organoid chip embedded with engineered artificial microvessels based on coaxial microfluidic technology by using pH-responsive ZIF-8/sodium alginate scaffold.The chip was featured on:(i)eight times the oxygen exchange efficiency compared with the conventional device,tri-gas incubator,(ii)implantation of intestinal organoid reproducing all types of intestinal epithelial cells,and(iii)bio-responsiveness to hypoxia and reoxygenation(HR)by presenting metabolism disorder,inflammatory reaction,and cell apoptosis.Strikingly,it was found for the first time that Olfactomedin 4(Olfm4)was the most significantly downregulated gene under a rapid HR condition by sequencing the RNA from the organoids.Mechanistically,OLFM4 played protective functions on HR-induced cell inflammation and tissue damage by inhibiting the NF-kappa B signaling activation,thus it could be used as a therapeutic target.Altogether,this study overcomes the issue of mismatched oxygen dynamics between in vitro and in vivo,and sets an example of next-generation multisysteminteractive organoid chip for finding precise therapeutic targets of IR injury.

Rock Climbing‑Inspired Electrohydrodynamic Cryoprinting of Micropatterned Porous Fiber Scaffolds with Improved MSC Therapy for Wound Healing

Impaired wound healing imposes great health risks to patients.Recently,mesenchymal stem cell(MSC)therapy has shown potential to improve the healing process,but approaches to employ MSCs in the treatment of wounds remain elusive.In this study,we reported a novel electrohydrodynamic(EHD)cyroprinting method to fabricate micropatterned fiber scaffolds with polycaprolactone(PCL)dissolved in glacial acetic acid(GAC).Cyroprinting ensured the formation of a porous struc-ture of PCL fibers by preventing the evaporation of GAC,thus increasing the surface roughness parameter Ra from 11 to 130 nm.Similar to how rough rocks facilitate easy climbing,the rough surface of fibers was able to increase the adhesion of adipose-derived MSCs(AMSCs)by providing more binding sites;therefore,the cell paracrine action of secreting growth factors and chemokines was enhanced,promoting fibroblast migration and vascular endothelial cell tube formation.In rat models with one-centimeter wound defects,enhanced MSC therapy based on porous PCL fiber scaffolds improved wound healing by augmenting scarless collagen deposition and angiogenesis and reducing proinflammatory reactions.Altogether,this study offers a new and feasible strategy to modulate the surface topography of polymeric scaffolds to strengthen MSC therapy for wound healing.

Marine-inspired molecular mimicry generates a drug-free, but immunogenic hydrogel adhesive protecting surgical anastomosis

Herein,we report the synthesis of a biomimic hydrogel adhesive that addresses the poor healing of surgical anastomosis.Dopamine-conjugated xanthan gum(Da-g-Xan)is fabricated using deep insights into the molecular similarity between mussels'adhesive and dopamine as well as the structural similarity between barnacle cement proteins and xanthan gum.The hydrogel mimics marine animals’adherence to wet tissue surfaces.Upon applying this adhesive to colonic anastomosis in a rat model,protective effects were shown by significantly improving the bursting pressure.Mechanistically,the architecture of Da-g-Xan hydrogel is maintained by dynamic intermolecular hydrogen bonds that allow the quick release of Da-g-Xan.The free Da-g-Xan can regulate the inflammatory status and induce type 2 macrophage polarization(M2)by specifically interacting with mannose receptors(CD206)revealed by RNA-sequencing and molecular binding assays.Consequently,an appropriate microenvironment for tissue healing is created by the secretion of chemokines and growth factors from M2 macrophages,strengthening the fibroblast migration and proliferation,collagen synthesis and epithelial vascularization.Overall,this study demonstrates an unprecedented strategy for generating an adhesive by synergistic mimicry inspired by two marine animals,and the results show that the Da-g-Xan adhesive augments native tissue regenerative responses,thus enabling enhanced recovery following surgical anastomosis.

Damps’role in inflammatory bowel disease:a paradoxical player of mtDNA-STING signaling pathway in gut homeostasis

The inflammatory bowel disease(IBD),including Crohn’s disease(CD)and ulcerative colitis,are chronic,relapsing immune mediated disorders of the gastrointestinal homeostasis and intestinal inflammation[1].Failure to resolve mucosal inflammation and maintain gut barrier are notable shared clinical challenges in IBD,in particular when they activate immune cells within the gut lamia propria.Clinical trials and animal model studies aiming towards DAMPs have demonstrated that they can be effective therapeutic targets in mucosal inflammation of IBD.

Applications of four-dimensional printing in emerging directions:Review and prospects

Four-dimensional(4 D) printing technology is an extension of three-dimensional(3 D) printing technology that enables a 3 D-printed static structure to dynamically change its shape with time. Therefore, the resulting structure can undergo self-folding/unfolding assisted by some stimuli. This technology has made much initial progress in many industrial fields. Aiming to investigate the in-depth application value of4 D printing, this study reviews the recent research and application breakthroughs of 4 D printing in several emerging directions, including the simulation of plant and animal behaviors, smart tissue scaffolds and biomedical devices, food printing, digitalization of industrial art design, renewable energy, intelligent communication, soft electronics and robots, vehicle optimization, textile customization, and flexible machinery and mechanical structure. Based on the analyses of specific cases and processes, we present the current obstacles to large-scale applications and the future prospects.