Combining bioengineered human skin with bioprinted cartilage for ear reconstruction.

Microtia is a congenital disorder that manifests as a malformation of the external ear leading to psychosocial problems in affected children. Here, we present a tissue-engineered treatment approach based on a bioprinted autologous auricular cartilage construct (EarCartilage) combined with a bioengineered human pigmented and prevascularized dermo-epidermal skin substitute (EarSkin) tested in immunocompromised rats. We confirmed that human-engineered blood capillaries of EarSkin connected to the recipient's vasculature within 1 week, enabling rapid blood perfusion and epidermal maturation. Bioengineered EarSkin displayed a stratified epidermis containing mature keratinocytes and melanocytes. The latter resided within the basal layer of the epidermis and efficiently restored the skin color. Further, in vivo tests demonstrated favorable mechanical stability of EarCartilage along with enhanced extracellular matrix deposition. In conclusion, EarCartilage combined with EarSkin represents a novel approach for the treatment of microtia with the potential to circumvent existing limitations and improve the aesthetic outcome of microtia reconstruction.

Liquid Poly-N-acetyl Glucosamine (sNAG) Improves Achilles Tendon Healing in a Rat Model.

The Achilles tendon, while the strongest and largest tendon in the body, is frequently injured. Even after surgical repair, patients risk re-rupture and long-term deficits in function. Poly-N-acetyl glucosamine (sNAG) polymer has been shown to increase the rate of healing of venous leg ulcers, and use of this material improved tendon-to-bone healing in a rat model of rotator cuff injury. Therefore, the purpose of this study was to investigate the healing properties of liquid sNAG polymer suspension in a rat partial Achilles tear model. We hypothesized that repeated sNAG injections throughout healing would improve Achilles tendon healing as measured by improved mechanical properties and cellular morphology compared to controls. Results demonstrate that sNAG has a positive effect on rat Achilles tendon healing at three weeks after a full thickness, partial width injury. sNAG treatment led to increased quasistatic tendon stiffness, and increased tangent and secant stiffness throughout fatigue cycling protocols. Increased dynamic modulus also suggests improved viscoelastic properties with sNAG treatment. No differences were identified in histological properties. Importantly, use of this material did not have any negative effects on any measured parameter. These results support further study of this material as a minimally invasive treatment modality for tendon healing.

The RDH bandage: hemostasis and survival in a lethal aortotomy hemorrhage model.

BACKGROUND: The Rapid Deployment Hemostat (RDH) Bandage has been designed in collaboration with the Office of Naval Research for the treatment of bleeding because of extremity trauma. It is intended as both a battlefield and civilian severe trauma wound dressing. It consists of a specific formulation of Marine Polymer Technologies' proprietary hemostatic polymer poly-N-acetyl glucosamine, and has received FDA clearance. This study compares the hemostatic capabilities of the RDH Bandage with the standard U.S Army First Aid Field Bandage (AFAFB), utilizing a controlled lethal aortotomy model of hemorrhage. MATERIALS AND METHODS: Aortic punch wounds 4 mm in diameter were made in the abdominal aortas of female Yorkshire White swine, and were allowed to bleed for 5 s before application of test materials. Test hemostats were applied to the wound with manual compression for 10 min. Total loss of blood was determined in each experiment. Bandages were removed at the end of 2 h, for those animals that survived, and the onset of re-bleeding was observed. Animals were monitored for an additional 30 min to assess survival following bandage removal. Hemostatic efficacy was judged by the total loss of blood, and the survival of the animals. RESULTS: Eighty percent of the animals treated with the RDH Bandage survived the study through the entire protocol, whereas only 40% of those treated with the Army First Aid Field Bandage survived the removal of manual compression step, and none survived following the removal of bandage after the 2 h observation/monitoring period. The average blood loss for the RDH Bandage treated animals was 234 ml, and the average blood loss for the Army First Aid Field Bandage treated animals was 1071 ml, through the observation/monitoring period. CONCLUSIONS: The RDH Bandage is significantly superior to the standard issue U.S. Army First Aid Field Bandage in the control of hemorrhage in a lethal swine abdominal aortotomy hemorrhage model, resulting in decreased blood loss and increased survival.