The authors have previously shown that acellular (AC) trachea-lung scaffolds can (1) be produced from natural rat lungs, (2) retain critical components of the extracellular matrix (ECM) such as collagen-1 and elastin, and (3) be used to produce lung tissue after recellularization with murine embryonic stem cells. The aim of this study was to produce large (porcine or human) AC lung scaffolds to determine the feasibility of producing scaffolds with potential clinical applicability. We report here the first attempt to produce AC pig or human trachea-lung scaffold. Using a combination of freezing and sodium dodecyl sulfate washes, pig trachea-lungs and human trachea-lungs were decellularized. Once decellularization was complete we evaluated the structural integrity of the AC lung scaffolds using bronchoscopy, multiphoton microscopy (MPM), assessment of the ECM utilizing immunocytochemistry and evaluation of mechanics through the use of pulmonary function tests (PFTs). Immunocytochemistry indicated that there was loss of collagen type IV and laminin in the AC lung scaffold, but retention of collagen-1, elastin, and fibronectin in some regions. MPM scoring was also used to examine the AC lung scaffold ECM structure and to evaluate the amount of collagen I in normal and AC lung. MPM was used to examine the physical arrangement of collagen-1 and elastin in the pleura, distal lung, lung borders, and trachea or bronchi. MPM and bronchoscopy of trachea and lung tissues showed that no cells or cell debris remained in the AC scaffolds. PFT measurements of the trachea-lungs showed no relevant differences in peak pressure, dynamic or static compliance, and a nonrestricted flow pattern in AC compared to normal lungs. Although there were changes in content of collagen I and elastin this did not affect the mechanics of lung function as evidenced by normal PFT values. When repopulated with a variety of stem or adult cells including human adult primary alveolar epithelial type II cells both pig and human AC scaffolds supported cell attachment and cell viability. Examination of scaffolds produced using a variety of detergents indicated that detergent choice influenced human immune response in terms of T cell activation and chemokine production.

Care of burn-injured patients requires knowledge of the pathophysiologic changes affecting virtually all organs from the onset of injury until wounds are healed. Massive airway and/or lung edema can occur rapidly and unpredictably after burn and/or inhalation injury. Hemodynamics in the early phase of severe burn injury are characterized by a reduction in cardiac output, increased systemic and pulmonary vascular resistance. Approximately 2–5 days after major burn injury, a hyperdynamic and hypermetabolic state develops. Electrical burns result in morbidity much higher than expected based on burn size alone. Formulae for fluid resuscitation should serve only as guideline; fluids should be titrated to physiologic end points. Burn injury is associated basal and procedural pain requiring higher than normal opioid and sedative doses. Operating room concerns for the burn-injured patient include airway abnormalities, impaired lung function, vascular access, deceptively large and rapid blood loss, hypothermia and altered pharmacology.

Preoperative anxiety and emergence delirium in children continue to be common even with midazolam premedication. Midazolam is unpleasant tasting even with a flavored vehicle and as a result, patient acceptance is sometimes poor. As an alternative, we evaluated dexmedetomidine administered intranasally. Dexmedetomidine an alpha-2 adrenergic agonist is tasteless, odorless, and painless when administered by this route. Alpha-2 adrenergic agonists produce sedation, facilitate parental separation, and improve conditions for induction of general anesthesia, while preserving airway reflexes. Institutional review board approval was obtained to study 100 pediatric patients randomized to intranasal dexmedetomidine (2 microg/kg) or oral midazolam (0.5 mg/kg) administered 30 to 45 minutes before the surgery. Subjects received general anesthesia with oxygen, nitrous oxide, isoflurane, and analgesics (0.05-0.1 mg/kg morphine or 0.1 mg/kg methadone). Nurses and anesthetists were blinded to the drug administered and evaluated patients for preoperative sedation, conditions for induction of general anesthesia, emergence from anesthesia, and postoperative pain. Responses of 100 patients (50 dexmedetomidine and 50 midazolam) were analyzed. Dexmedetomidine (P=.003) was more effective than midazolam at inducing sleep preoperatively. Dexmedetomidine and midazolam were comparable for conditions at induction (P>0.05), emergence from anesthesia (P>0.05), or postoperative pain (P>0.05). Both drugs were equieffective in these regards. In pediatric patients, dexmedetomidine 2 microg/kg administered intranasally and midazolam 0.5 mg/kg administered orally produced similar conditions during induction and emergence of anesthesia. Intranasal administration of dexmedetomidine is more effective at inducing sleep and in some circumstances offers a useful alternative to oral midazolam in children.

The inability to produce perfusable microvasculature networks capable of supporting tissue survival and of withstanding physiological pressures without leakage is a fundamental problem facing the field of tissue engineering. Microvasculature is critically important for production of bioengineered lung (BEL), which requires systemic circulation to support tissue survival and coordination of circulatory and respiratory systems to ensure proper gas exchange. To advance our understanding of vascularization after bioengineered organ transplantation, we produced and transplanted BEL without creation of a pulmonary artery anastomosis in a porcine model. A single pneumonectomy, performed 1 month before BEL implantation, provided the source of autologous cells used to bioengineer the organ on an acellular lung scaffold. During 30 days of bioreactor culture, we facilitated systemic vessel development using growth factor-loaded microparticles. We evaluated recipient survival, autograft (BEL) vascular and parenchymal tissue development, graft rejection, and microbiome reestablishment in autografted animals 10 hours, 2 weeks, 1 month, and 2 months after transplant. BEL became well vascularized as early as 2 weeks after transplant, and formation of alveolar tissue was observed in all animals ( = 4). There was no indication of transplant rejection. BEL continued to develop after transplant and did not require addition of exogenous growth factors to drive cell proliferation or lung and vascular tissue development. The sterile BEL was seeded and colonized by the bacterial community of the native lung.

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