Extracellular matrices for gastrointestinal surgery:Ex vivo testing and current applications

AIM:To assess the effects of bile and pancreatic juice on structural and mechanical resistance of extracellular matrices(ECMs) in vitro.METHODS:Small-intestinal submucosa(SIS),porcine dermal matrix(PDM),porcine pericardial matrix(PPM) and bovine pericardial matrix(BPM) were incubated in human bile and pancreatic juice in vitro.ECMs were examined by macroscopic observation,scanning electron microscopy(SEM) and testing of mechanical resistance.RESULTS:PDM dissolved within 4 d after exposure to bile or pancreatic juice.SIS,PPM and PDM retained their integrity for > 60 d when incubated in either digestive juice.The effect of bile was found to be far more detrimental to mechanical stability than pancreatic juice in all tested materials.In SIS,the loss of mechanical stability after incubation in either of the digestive secretions was less distinct than in PPM and BPM [mFmax 4.01/14.27 N(SIS) vs 2.08/5.23 N(PPM) vs 1.48/7.89 N(BPM)].In SIS,the extent of structural damage revealed by SEM was more evident in bile than in pancreatic juice.In PPM and BPM,structural damage was comparable in both media.CONCLUSION:PDM is less suitable for support of gastrointestinal healing.Besides SIS,PPM and BPM should also be evaluated experimentally for gastrointestinal indications.

No Intestinal Stem Cell Regeneration after Complete Progenitor Ablation in Drosophila Adult Midgut

Adult stem cells or progenitors are essential for maintaining the normal structure and function of adult tissues （i.e., ho- meostasis）. One of the best examples is the adult intestinal epithelium which is constantly renewed by the progeny of intestinal stem cells （ISCs）. The proliferation and differentiation of adult stem cells must be tightly controlled in order to maintain resident tissue homeostasis. Mis-regulation of stem cell proliferation and differentiation leads to depletion or excessive proliferation of stem cells, eventually resulting in severe diseases such as cancer （Radtke and Clevers, 2005; Morrison and Spradling, 2008）. Understanding the detailed regulatory mechanisms of stem cell proliferation and differ- entiation will shed insights into the causes of related human diseases.

Mechanism of Acupuncture and Moxibustion on Promoting Mucosal Healing in Ulcerative Colitis

The latest guideline about ulcerative colitis(UC) clinical practice stresses that mucosal healing, rather than anti-inflammation, is the main target in UC clinical management. Current mucosal dysfunction mainly closely relates to the endoscopic intestinal wall(mechanical barrier) injury with the imbalance between intestinal epithelial cells(IECs) regeneration and death, as well as tight junction(TJ) dysfunction. It is suggested that biological barrier(gut microbiota), chemical barrier(mucus protein layer, MUC) and immune barrier(immune cells) all take part in the imbalance, leading to mechanical barrier injury. Lots of experimental studies reported that acupuncture and moxibustion on UC recovery by adjusting the gut microbiota, MUC and immune cells on multiple targets and pathways, which contributes to the balance of IEC regeneration and death, as well as TJ structure recovery in animals. Moreover, the validity and superiority of acupuncture and moxibustion were also demonstrated in clinic. This paper aims to review the achievements of acupuncture and moxibustion on mucosal healing and analyse the underlying mechanisms.