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.

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.