Regeneration of esophagus using a scaffold-free biomimetic structure created with bio-three-dimensional printing.

Various strategies have been attempted to replace esophageal defects with natural or artificial substitutes using tissue engineering. However, these methods have not yet reached clinical application because of the high risks related to their immunogenicity or insufficient biocompatibility. In this study, we developed a scaffold-free structure with a mixture of cell types using bio-three-dimensional (3D) printing technology and assessed its characteristics in vitro and in vivo after transplantation into rats. Normal human dermal fibroblasts, human esophageal smooth muscle cells, human bone marrow-derived mesenchymal stem cells, and human umbilical vein endothelial cells were purchased and used as a cell source. After the preparation of multicellular spheroids, esophageal-like tube structures were prepared by bio-3D printing. The structures were matured in a bioreactor and transplanted into 10-12-week-old F344 male rats as esophageal grafts under general anesthesia. Mechanical and histochemical assessment of the structures were performed. Among 4 types of structures evaluated, those with the larger proportion of mesenchymal stem cells tended to show greater strength and expansion on mechanical testing and highly expressed α-smooth muscle actin and vascular endothelial growth factor on immunohistochemistry. Therefore, the structure with the larger proportion of mesenchymal stem cells was selected for transplantation. The scaffold-free structures had sufficient strength for transplantation between the esophagus and stomach using silicon stents. The structures were maintained in vivo for 30 days after transplantation. Smooth muscle cells were maintained, and flat epithelium extended and covered the inner surface of the lumen. Food had also passed through the structure. These results suggested that the esophagus-like scaffold-free tubular structures created using bio-3D printing could hold promise as a substitute for the repair of esophageal defects.

Replacement of Rat Tracheas by Layered, Trachea-Like, Scaffold-Free Structures of Human Cells Using a Bio-3D Printing System.

Current scaffold-based tissue engineering approaches are subject to several limitations, such as design inflexibility, poor cytocompatibility, toxicity, and post-transplant degradation. Thus, scaffold-free tissue-engineered structures can be a promising solution to overcome the issues associated with classical scaffold-based materials in clinical transplantation. The present study seeks to optimize the culture conditions and cell combinations used to generate scaffold-free structures using a Bio-3D printing system. Human cartilage cells, human fibroblasts, human umbilical vein endothelial cells, and human mesenchymal stem cells from bone marrow are aggregated into spheroids and placed into a Bio-3D printing system with dedicated needles positioned according to 3D configuration data, to develop scaffold-free trachea-like tubes. Culturing the Bio-3D-printed structures with proper flow of specific medium in a bioreactor facilitates the rearrangement and self-organization of cells, improving physical strength and tissue function. The Bio-3D-printed tissue forms small-diameter trachea-like tubes that are implanted into rats with the support of catheters. It is confirmed that the tubes are viable in vivo and that the tracheal epithelium and capillaries proliferate. This tissue-engineered, scaffold-free, tubular structure can represent a significant step toward clinical application of bioengineered organs.

Initial experience with a 3D printed model for preoperative simulation of the Nuss procedure for pectus excavatum.

The incidence of pectus excavatum has been estimated to be between 0.1% and 0.8% though a large autopsy series reports. After publication of the Nuss procedure for pectus excavatum, it became widely accepted. However, there are still some complications, such as over-correction and recurrence. To reduce differences in the procedure due to surgeons' experience level, preoperative simulation may be useful. Thus, we performed simulated surgery using a specific patient's three-dimensional (3D) chest wall model made by a 3D printer before operation. A 13-year-old male patient with a severe deformity of the chest underwent the Nuss procedure. As in the simulation, bars were inserted into the 5th and 7th intercostal spaces (ICS), leading to improvement of the chest wall. This simulation can increase surgeons' confidence to improve the deformity by determination of the number and insertion sites of bars.

Scaffold-free trachea regeneration by tissue engineering with bio-3D printing.

OBJECTIVES: Currently, most of the artificial airway organs still require scaffolds; however, such scaffolds exhibit several limitations. Alternatively, the use of an autologous artificial trachea without foreign materials and immunosuppressants may solve these issues and constitute a preferred tool. The rationale of this study was to develop a new scaffold-free approach for an artificial trachea using bio-3D printing technology. Here, we assessed the circumferential tracheal replacement using scaffold-free trachea-like grafts generated from isolated cells in an inbred animal model. METHODS: Chondrocytes and mesenchymal stem cells were isolated from F344 rats. Rat lung microvessel endothelial cells were purchased. Our bio-3D printer generates spheroids consisting of several types of cells to create 3D structures. The bio-3D-printed artificial trachea from spheroids was matured in a bioreactor and transplanted into F344 rats as a tracheal graft under general anaesthesia. The mechanical strength of the artificial trachea was measured, and histological and immunohistochemical examinations were performed. RESULTS: Tracheal transplantation was performed in 9 rats, which were followed up postoperatively for 23 days. The average tensile strength of artificial tracheas before transplantation was 526.3 ± 125.7 mN. The bio-3D-printed scaffold-free artificial trachea had sufficient strength to transplant into the trachea with silicone stents that were used to prevent collapse of the artificial trachea and to support the graft until sufficient blood supply was obtained. Chondrogenesis and vasculogenesis were observed histologically. CONCLUSIONS: The scaffold-free isogenic artificial tracheas produced by a bio-3D printer could be utilized as tracheal grafts in rats.

Yolk sac tumor of the vulva: a case report with recurrence after long-term follow-up.

A yolk sac tumor (YST) of the vulva is extremely rare and highly malignant with recurrence frequently occurring within a year. This report presents the 13th known case of vulvar YST, with recurrence occurring after the longest known follow-up period so far reported in the literature.

Pancreatic head resection preserving the main pancreatic duct for congenital hyperinsulinism of infancy.

Surgical intervention for congenital hyperinsulinism with an unclear focal lesion in the pancreatic head sometimes require the resection of most of the pancreas head and pancreaticojejunotomy. This report presents the case of a patient that underwent pancreatic head resection preserving the main pancreatic duct to avoid pancreaticojejunostomy.

A modified Foker's technique for long gap esophageal atresia.

External traction using the Foker's technique enables elongation in the esophageal segments within days, and allows the primary repair of the long gap. This article presents our modified Foker's technique which was easily applicable for long-gap esophageal atresia.

A gallstone in the Roux-en Y limb during pregnancy in a female patient with biliary atresia.

A 28-year-old female developed liver dysfunction at the 13th gestation week of her second pregnancy. A postpartum radiological examination revealed a stone in the Roux-en Y (RY) limb. She underwent surgical removal of the gallstone in the RY limb. Bile congestion during pregnancy led to the development of a gallstone.