Lung and heart-lung transplantation

Normothermic Ex Vivo Heart Perfusion With Exosomes From Human Umbilical Cord Mesenchymal Stem Cells Improves Graft Function in Donation After Circulatory Death Hearts

BACKGROUND

This study aimed to investigate the cardioprotective effect of exosomes derived from human umbilical cord mesenchymal stem cells on donation after circulatory death (DCD) hearts preserved with normothermic ex vivo heart perfusion (EVHP) in a rat heart transplantation model.

METHODS

Thirty-two male Lewis rats were divided into 2 groups: the control group and the exosome group. The donor-heart rats were subjected to the DCD procedure by suffering a 15-min warm ischemia injury, subsequently preserved with EVHP for 90 min, and then transplanted into recipients via abdominal heterotopic heart transplantation. Vehicle or exosome was added into the perfusate of normothermic EVHP in the control or exosome group. We evaluated left ventricular graft function, myocardial inflammation, and myocardial apoptosis of the donor heart 1.5 h after heart transplantation. Furthermore, we investigate the alternation of myocardial gene expression in the donor hearts between both groups by transcriptome sequencing.

RESULTS

The treatment with exosome significantly enhanced cardiac function through increasing left ventricular developed pressure, dp/dtmax, and dp/dtmin of DCD hearts at 90 min after heart transplantation compared with the control group. The myocardial cells in the exosome group exhibited an orderly arrangement without obvious edema. Furthermore, exosome added into perfusate in the exosome group significantly attenuated the level of inflammatory response and apoptosis. Transcriptome sequencing and RT-qPCR showed the phosphoinositide 3-kinase/protein kinase B pathway was activated after exosome treatment.

CONCLUSIONS

Normothermic EVHP combined with exosome can be a promising and novel DCD heart preservation strategy, alleviating myocardial ischemia-reperfusion injury in the DCD heart.

Effects of hypothermia and hyperpotassium on alveolar fluid clearance in the resected human lung

The effect of hypothermia and hyperpotassium on alveolar fluid clearance in the resected human lung was examined by instilling an isosmotic albumin solution with a potassium concentration of 0.3 mEq/l or 20 mEq/l into one segment of a resected lobe within 10 min of surgical removal for bronchogenic carcinoma. The experiments were carried out at 37 degrees C, 25 degrees C, and and 8 degrees C over 4 hr, after which the alveolar fluid was aspirated. Alveolar fluid clearance was calculated by a simple equation using the changes in the albumin concentration of the alveolar fluid. It was found that although hypothermia at 8 degrees C abolished alveolar fluid clearance completely, alveolar fluid clearance at 25 degrees C was not different from that at 37 degrees C. Moreover, although the potassium concentration increased in the alveolar fluid at 37 degrees C and 8 degrees C, hyperpotassium did not affect the alveolar fluid clearance. These findings indicate that the net transport of potassium leans to influx from the alveolar epithelial cells into the alveolar spaces when the alveolar potassium concentration is low, and to efflux from the alveolar spaces when the alveolar potassium concentration is high. Thus, we conclude that hypothermia abolishes alveolar fluid clearance in resected human lungs, but that the potassium concentration in alveolar fluid does not affect alveolar fluid clearance.

Endoscopic management of bronchial stenosis after double lung transplantation

Double lung transplantation with bilateral bronchial sutures is an increasingly popular therapeutic alternative for endstage, bilateral, septic pulmonary disease; however, surgical outcome has been hampered by mechanical complications at the level of the airway anastomoses. In our institution, therefore, the protocol for surveillance includes frequent flexible fiberoptic and rigid bronchoscopy under general anesthesia in all patients. Since 1988, there were 24 double lung transplantations (mean age, 19 yr) performed at the University of Marseille Hospitals using bilateral sutures without omental wrapping. Nineteen patients had cystic fibrosis; of the ten individuals (53 percent) with cystic fibrosis who ultimately developed bronchial stenosis, six required therapeutic endoscopic intervention including dilatation or Nd:YAG laser resection. Five patients required endobronchial silicone stents. Statistically significant risk factors for postsurgical airway narrowing included young age (mean, 14.3 yr vs 24.0 yr in patients without stenosis) and prolonged mechanical ventilation prior to transplant (all five patients ventilated before surgery developed stenosis). Results of interventional bronchoscopy were good, and an excellent level of physical activity was maintained in most patients. A team familiar with all aspects of therapeutic bronchoscopy is essential to ensure proper management of airway complications in patients after lung transplantation.