Neuronal apoptosis after hypothermia circulatory arrest and intermittent antegrade cerebral perfusion

Objective To observe the influence of hypotherrnic circulatory arrest （HCA） on the apoptotic processes of neurons in the hippocampus and the expression of the related genes Bcl-2 and Bax, and compare to the intermittent antegrade cerebral perfusion. Methods Eighteen dogs were randomly divided into three groups： control group （6 animals, underwent normal temperature cardiopulmonary bypass, NCPB）, HCA group （6 animals, underwent HCA for 1 h）, and HCA ＋ IACP group （6 animals, underwent HCA for 1 h, combined with intermittent antegrade cerebral perfusion （IACP） every 15 min）. The hippocampus tissue was retrieved 2h after the CPB discontinued The expression of Bcl-2 and Bax were examined with immunohistochemistry method. The cytomorphologic changes of the hippocampus tissue were investigated with transmission electron microscopy （TEM）. Results The immunohistochemical staining showed that Bax protein levels were significantly higher in HCA group than in the other two groups （P〈0.01）, while Bcl-2 protein levels were significantly higher in HCA ＋ IACP group than that of the other two groups （P〈0.01）. Meanwhile, the TEM results showed that there was no apoptosis of neurons in control group, but neuronal apoptotic changes could be clearly observed in HCA group, and only a small amount of apoptotic neurons were seen in HCA ＋ IACP group. Conclusions HCA alone can induce neuronal apoptosis in the hippocampus. IACP during the HCA period has a protective effect on the cerebral tissue through suppressing apoptosis by decreasing Bax expression and increasing Bcl-2 expression.

Crosslinking and functionalization of acellular patches via the self-assembly of copper@tea polyphenol nanoparticles

Decellularization is a promising technique to produce natural scaffolds for tissue engineering applications.However,non-crosslinked natural scaffolds disfavor application in cardiovascular surgery due to poor biomechanics and rapid degradation.Herein,we proposed a green strategy to crosslink and functionalize acellular scaffolds via the self-assembly of copper@tea polyphenol nanoparticles(Cu@TP NPs),and the resultant nanocomposite acellular scaffolds were named as Cu@TP-dBPs.The crosslinking degree,biomechanics,denaturation temperature and resistance to enzymatic degradation of Cu@TP-dBPs were comparable to those of glutaraldehyde crosslinked decellularized bovine pericardias(Glut-dBPs).Furthermore,Cu@TP-dBPs were biocompatible and had abilities to inhibit bacterial growth and promote the formation of capillary-like networks.Subcutaneous implantation models demonstrated that Cu@TP-dBPs were free of calcification and allowed for host cell infiltration at Day 21.Cardiac patch graft models confirmed that Cu@TP-dBP patches showed improved ingrowth of functional blood vessels and remodeling of extracellular matrix at Day 60.These results suggested that Cu@TP-dBPs not only had comparable biomechanics and biostability to Glut-dBPs,but also had several advantages over Glut-dBPs in terms of anticalcification,remodeling and integration capabilities.Particularly,they were functional patches possessing antibacterial and proangiogenic activities.Thesematerial properties and biological functionsmade Cu@TP-dBPs a promising functional acellular patch for cardiovascular applications.