Balance of the prooxidant and antioxidant system is associated with mortality in critically ill patients.

It is well known that oxidative stress causes certain diseases and organ damage. However, roles of oxidative stress in the acute phase of critical patients remain to be elucidated. This study aimed to investigate the balance of oxidative and antioxidative system and to clarify the association between oxidative stress and mortality in critically ill patients. This cohort study enrolled 247 patients transported to our emergency department by ambulance. Blood was drawn on hospital arrival, and serum derivatives of reactive oxidant metabolites (dROMs, oxidative index) and biological antioxidant potential (BAP, antioxidative index) were measured. Modified ratio (MR) is also calculated as BAP/dROMs/7.51. There were 197 survivors and 50 non-survivors. In the non-survivors, dROMs were significantly lower (274 vs 311, p<0.01), BAP was significantly higher (2,853 vs 2,138, p<0.01), and MR was significantly higher (1.51 vs 0.92, p<0.01) compared to those in the survivors. The AUC of MR was similar to that for the APACHE II score. Contrary to our expectations, higher BAP and lower dROMs were observed on admission in non-survivors. This may suggest that the antioxidative system is more dominant in the acute phase of severe insults and that the balance toward a higher antioxidative system is associated with mortality.

E-PASS score as a useful predictor of postoperative complications and mortality after colorectal surgery in elderly patients.

PURPOSE: The aim of this study was to clarify whether a surgical-specific risk scoring system estimating the physiologic ability and surgical stress (E-PASS) score was useful for prediction of postoperative morbidity and mortality. METHODS: The E-PASS score consists of the preoperative risk score (PRS), surgical stress score (SSS), and the comprehensive risk score (CRS). Conventional scoring systems [colorectal physiologic and operative severity score for the enumeration of mortality (CR-POSSUM) and the prognostic nutritional index (PNI)] were also examined. We retrospectively compared these scores in patients with or without postoperative complications. We assessed the relationship between these scores, clinicopathological features and postoperative mortality. RESULTS: Postoperative complications developed in 78 patients (33%). American Society of Anesthesiologists score, performance status, PNI score, PRS, SSS, and CRS were significantly higher in patients with postoperative complications than in those without postoperative complications (p < 0.05). The area under the receiver operating characteristic curve (AUC) was highest for E-PASS [E-PASS (PRS, 0.74; SSS, 0.62; CRS, 0.78), PNI (0.62), CR-POSSUM (PS, 0.57; OSS, 0.52)]. Multivariate logistic analysis identified CRS ≥ 0.2 as a significant determinant of postoperative complications (p < 0.01; hazard ratio, 4.84). Overall survival was significantly better in the CRS < 0.2 group than in the CRS > 0.2 group (p < 0.01). CONCLUSIONS: The E-PASS score system was a useful predictor of postoperative complications and mortality, especially in patients with advanced age.

Down-Regulation of Nogo-B Expression as a Newly Identified Feature of Intrahepatic Cholangiocarcinoma.

Nogo-B, located in the endoplasmic reticulum, is an isoform belonging to the reticulon protein family, which is expressed specifically in cholangiocytes and non-parenchymal cells in the liver. Nogo-B expression is down-regulated with the progression of liver fibrosis, but its distinct function in liver malignancies has not been fully clarified. We have hypothesized that Nogo-B expression may be altered in intrahepatic cholangiocarcinoma (ICC), a relatively rare type of primary liver cancer with highly malignant behavior. The present study aimed to investigate the relationship between Nogo-B expression, assessed by immunohistochemical staining, and clinicopathological factors and prognosis in 34 ICC patients. Positive expression was observed in 19 (56%) of 34 ICC specimens: 6 patients (18%) with positivity levels of 1+ (positive cells in 10-50% of cancer cells) and 13 patients (38%) with 2+ (positive cells over 50%). Importantly, the remaining 15 patients (44%) were categorized as negative expression (Nogo-B-positive cells, less than 10%). Conversely, the mass-forming type of ICC tended to express Nogo-B with the degree of 2+ positivity, compared to the periductal infiltration type (p = 0.064), and the mass-forming type showed a better 5-year survival rate (66% vs. 5%) after hepatectomy (p < 0.05). However, the degree of positivity was not associated with tumor relapse rate, disease-free and overall survival, although each of the periductal infiltration type, intrahepatic metastasis, larger tumor size, and lower microvessel counts was associated with lower survival rates. We propose that Nogo-B expression is down-regulated in ICC, the implication of which, however, remains to be investigated.

Short-term outcomes of laparoscopic surgery for colorectal cancer in oldest-old patients.

BACKGROUND/AIMS: Oldest-old patients generally have several comorbidities, and laparoscopic-assisted colectomy (LAC) has not been performed on these patients. However, the surgical technique of LAC has improved, and its indications have been extended. The aim of this study was to evaluate the safety and effectiveness of LAC for patients over 85 years old. METHODS: Fifty-eight patients over 85 years old who underwent colectomy were retrospectively analyzed. The patients were divided into two groups (LAC group n = 15; open surgery group (Open group) n = 43), and clinicopathological features, surgical characteristics, and outcomes were compared. RESULTS: There were no significant differences in clinical background characteristics between the groups. The LAC group had longer operation time and greater lymph node dissection (both p < 0.01). Postoperatively, the use of analgesics (p = 0.01) was less and the start of oral liquid intake (p = 0.03) was faster in the LAC group. Postoperative complications occurred in 3 patients (20%) in the LAC group and 13 patients (30%) in the Open group (p = 0.66); delirium (n = 6) and sub-ileus (n = 4) developed only in the Open group. CONCLUSION: After LAC, elderly patients tended to have less postoperative pain and started oral liquid intake earlier. LAC can be safe and effective, preventing postoperative complications that occur specifically in oldest-old patients.

Novel diagnostic procedure for determining metastasis to sentinel lymph nodes in breast cancer using a semi-dry dot-blot method.

We developed an easy, quick and cost-effective detection method for lymph node metastasis called the semi-dry dot-blot (SDB) method, which visualizes the presence of cancer cells with washing of sectioned lymph nodes by anti-pancytokeratin antibody, modifying dot-blot technology. We evaluated the validity and efficacy of the SDB method for the diagnosis of lymph node metastasis in a clinical setting (Trial 1). To evaluate the validity of the SDB method in clinical specimens, 180 dissected lymph nodes from 29 cases, including breast, gastric and colorectal cancer, were examined. Each lymph node was sliced at the maximum diameter and the sensitivity, specificity and accuracy of the SDB method were determined and compared with the final pathology report. Metastasis was detected in 32 lymph nodes (17.8%), and the sensitivity, specificity and accuracy of the SDB method were 100, 98.0 and 98.3%, respectively (Trial 2). To evaluate the efficacy of the SDB method in sentinel lymph node (SLN) biopsy, 174 SLNs from 100 cases of clinically node-negative breast cancer were analyzed. Each SLN was longitudinally sliced at 2-mm intervals and the sensitivity, specificity, accuracy and time required for the SDB method were determined and compared with the intraoperative pathology report. Metastasis was detected in 15 SLNs (8.6%), and the sensitivity, specificity, accuracy and mean required time of the SDB method were 93.3, 96.9, 96.6 and 43.3 min, respectively. The SDB method is a novel and reliable modality for the intraoperative diagnosis of SLN metastasis.

Prediction of portal pressure from intraoperative ultrasonography.

BACKGROUND: Portal hypertension is a major risk factor for hepatic failure or bleeding in patients who have undergone hepatectomy, but it cannot be measured indirectly. We attempted to evaluate the intraoperative ultrasonography parameters that correlate with portal pressure (PP) in patients undergoing hepatectomy. METHODS: We examined 30 patients in whom PP was directly measured during surgery. The background liver conditions included chronic viral liver disease in seven patients, chemotherapy-associated steatohepatitis in four patients, fatty liver in one patient, hepatolithiasis in one patient, obstructive jaundice in one patient, and a normal liver in 16 patients. A multivariate logistic analysis and linear regression analysis were conducted to develop a predictive formula for PP. RESULTS: The mean PP was 10.4 ± 4.1 mm Hg. The PP tended to be increased in patients with chronic viral hepatitis. A univariate analysis identified the association of the six following parameters with PP: the platelet count and the maximum (max), minimum (min), endo-diastolic, peak-systolic, and mean velocity in the portal vein (PV) flow. Using multiple linear regression analysis, the predictive formula using the PV max and min was as follows: Y (estimated PP) = 18.235-0.120 × (PV max.[m/s])-0.364 × (PV min). The calculated PP (10.44 ± 2.61 mm Hg) was nearly the same as the actual PP (10.43 ± 4.07 mm Hg). However, there was no significant relationship between the calculated PP and the intraoperative blood loss and post hepatectomy morbidity. CONCLUSIONS: This formula, which uses ultrasonographic Doppler flow parameters, appears to be useful for predicting PP.

Usefulness of evaluating hepatic elasticity using artificial acoustic radiation force ultrasonography before hepatectomy.

AIM: To evaluate hepatic fibrosis and tumor diagnosis preoperatively, we investigated the elasticity calculated by the new parameter of ultrasonography, acoustic radiation force impulse (ARFI). METHODS: We examined ARFI of the non-tumorous right and left lateral liver and in the tumor by push pulse of probe in 95 patients with hepatic malignancies undergoing hepatectomy. Measurement of ARFI as hepatic stiffness was indicated as the Vs (m/s). RESULTS: Measuring the Vs in the non-tumor region was achieved in the right liver in 99% and at the left lateral liver in 94%. The Vs in the right liver was significantly lower than in the left lateral liver, and the Vs of the liver tumor was significantly higher than in the non-tumorous liver. The Vs in the right and left lateral liver was correlated with the platelet count, aspartate aminotransferase, fibrotic indices and indocyanine green test. The Vs in the right liver was significantly correlated with the fibrotic marker or index. The Vs of liver cirrhosis and histological stage 4 in the right and left liver was significantly the highest compared to the others. The Vs in the right liver showed a high area under the receiver-operator curve value predicting histological fibrosis. The Vs in the right was significantly correlated with blood loss and postoperative complications, particularly uncontrolled ascites. CONCLUSION: Non-invasive ARFI imaging elastography is useful in evaluating impaired liver function or in the differential diagnosis of liver malignancies, highly hepatic fibrosis and in predicting posthepatectomy morbidity.

Three-dimensional printing model of liver for operative simulation in perihilar cholangiocarcinoma.

3-dimensional printed liver was constructed using 3D vascular imaging in a patient with intrahepatic cholangiocarcinoma who underwent major hepatectomy. The reproducibility of 3D modeling by the latest imaging has been clarified and future preoperative simulation should be adramatically changed.

Clinicopathological parameters associated with surgical site infections in patients who underwent pancreatic resection.

BACKGROUND/AIMS: To clarify parameters associated with postoperative surgical site infection (SSI) after pancreatectomy, we examined clinicopathological and surgical records in 186 patients who underwent pancreatectomy at a single academic institute. METHODOLOGY: Patient demographics, liver functional parameters, histological findings, surgical records and post-hepatectomy outcomes during hospitalization were compared between the non-SSI and SSI group, in which SSIs included superficial and deep SSIs. RESULTS: The prevalence of SSI (29-35%) has not changed over an 18-year period. With respect to patient demographics and laboratory data, no parameters were associated with postoperative SSI. In surgical records, the operating time in the SSI group tended to be longer in comparison with that in the non- SSI group (618 vs. 553 minutes, respectively) but not significantly different (p=0.070). With respect to postoperative outcomes, time to oral intake in the SSI group was significantly longer than that in the non-SSI group (21.2 vs. 13.7 days, respectively) (p<0.01). Incidences of pancreatic fistula, postoperative bleeding, long-term ascites and re-operation were significantly more frequent in the SSI group in comparison with the non-SSI group (p<0.05). Decrease of body weight after surgery in the SSI group was significantly greater than that in the non- SSI group (-4.1 vs. -2.7kg, respectively) (p<0.05). Period of hospital stay in the SSI group was significantly longer than that in the non-SSI group (37 vs. 25 days) (p<0.05). Multivariate analysis showed that only postoperative pancreatic fistula was significantly associated with SSI (p<0.01). CONCLUSIONS: SSI is an important risk factor of longer hospital stay after pancreatectomy and prevention of pancreatic fistula through the future improvement of surgical procedures is necessary to decrease SSI rates.

Clinical significance of vessel-sealing device usage for pancreatectomy: a retrospective cohort study.

BACKGROUND/AIMS: We compared each vessel-sealing device to evaluate safety and efficacy for controlling surgical results in 200 patients undergoing pancreatectomy. METHODOLOGY: Sixty-seven patients applied the hemostatic devices (VS group) consisted of LigaSure™ (LS) or the Harmonic ultrasonic dissector (USD). Results were compared with that of a historical control group (n=134). RESULTS: In pancreaticoduodenectomy, the prevalence of lymph node dissection was high in the VS group. Blood transfusion was significantly less frequent in the VS group than in the control group (p<0.01). The prevalence of surgical site infection and systemic complications was significantly lower in the VS group than in the control group (p<0.05). The duration of hospitalization was significantly shorter in the VS group than in the control group (p<0.01). In distal pancreatectomy, the prevalence of cutting stapler usage for transection was low in the VS group. Postoperative weight loss and the prevalence of surgical site infections was higher in the VS group than in the control group but were more frequently observed in the USD group than in the LS group. CONCLUSIONS: Use of energy sealing devices improves surgical results and avoids pancreatectomy-related complications. These devices are safe and effective for use in pancreatic surgery.

Novel biodegradable powder for preventing postoperative pleural adhesion.

OBJECTIVES: Progress in medical technology and improvements in prognosis have led to an increase in polysurgery. However, postoperative pleural adhesion leads to poor visualization, bleeding, and lung and vascular trauma during subsequent surgeries. To date, there have been no appropriate anti-adhesive agents to prevent pleural adhesion. The aim of this study was to investigate the anti-adhesive effects of commercially available anti-adhesive agents and a newly developed powder-type anti-adhesive agent. METHODS: In 48 male rats, we performed thoracotomy at the fifth intercostal space. We randomized animals into four groups: normal saline, Seprafilm, Interceed, and aldehyde dextran and ε-poly(L-lysine) powder (D-L powder). W killed animals on Day 7 or 28 to evaluate the severity, length, gross appearance, and pathological appearance of adhesion formation. RESULTS: Adhesion length in the D-L powder group was significantly shorter than in the control group (P < 0.05) on both Days 7 and 28. Pathologically, all anti-adhesive materials remained on the lung surface on Day 7. On Day 28, only Interceed remained on the lung surface, in which small vessels were present. We also demonstrated the usage of D-L powder during video-assisted thoracic surgery in pigs, and found it easy to administer via the trocar sleeve. CONCLUSIONS: We found D-L powder to be effective for preventing postoperative pleural adhesion, although Seprafilm and Interceed are also somewhat effective. However, D-L powder is easier to administer during video-assisted thoracic surgery.

Novel powdered anti-adhesion material: preventing postoperative intra-abdominal adhesions in a rat model.

BACKGROUND: Although laparoscopic surgery has decreased postoperative adhesions, complications induced by adhesions are still of great concern. The aim of this study was to investigate the anti-adhesive effects of a novel powdered anti-adhesion material that can be applied during laparoscopic surgery in comparison with other anti-adhesion materials. METHODS: Our novel powdered anti-adhesion material is composed of aldehyde dextran and ε-poly(L-lysine). In 40 male rats, a 2.5×2.0-cm abdominal wall resection and cecum abrasion were performed. The rats were randomized into four groups based on the anti-adhesion treatments: normal saline; Seprafilm(®); Interceed(®); and novel powdered anti-adhesion material. The animals were euthanized on days 7 and 28 to evaluate the adhesion severity, area of adhesion formation, gross appearance, and pathological changes. RESULTS: The adhesion severities on both days 7 and 28 were significantly lower for all anti-adhesion material groups compared with the normal saline group (p<0.05). Pathologically, all groups showed inflammatory cell infiltration on day 7 and complete regeneration of the peritoneum on day 28. CONCLUSIONS: Our novel powdered anti-adhesion material was found to be effective for reducing postoperative intra-abdominal adhesions and showed equivalent efficacy to commercial anti-adhesion materials.

Regeneration of the ureter using a scaffold-free live-cell structure created with the bio-three-dimensional printing technique.

Ureteral strictures, which can be caused by ureteral injury, radiation therapy, ureterolithiasis, urinary tract infections, and ureteral endometriosis, typically require ureteral reconstruction. Although tissue engineering, autologous alternative tissue transplantation, and surgical techniques applying various flaps have been carried out for ureteral regeneration, all with some success, each method has its advantages and disadvantages. As an alternative, we created the first artificial ureter structures using only live cells and grafted them into healthy rat ureters. Spheroids were created using normal human dermal fibroblasts and human umbilical vein endothelial cells and subsequently laminated using a bio-three-dimensional printer. After molding the laminated spheroids into tubular structures, the artificial ureters were transplanted into live rats. After 2-12 weeks, the animals were sacrificed and their gross and pathological features were examined. In the artificial ureteral lumen of rats with Grade 0-1 hydronephrosis, regeneration of the ureteral epithelium was observed, the thickness of which increased over the course of the experiment. Regeneration of the muscular layer was also observed, extending from the normal ureteral side toward the artificial ureter structure over time. However, complete regeneration was not observed at the end of 12 weeks. Although ureteral peristalsis was noted in all cases, it was weaker than expected. Therefore, we achieved short-segment ureteral regeneration using a cell-only structure. This finding suggests that by applying alternative strategies to this method, such as changing the cell type and composition, regeneration over the entire length of the ureter may be possible in the future. STATEMENT OF SIGNIFICANCE: Until now, ureteral regeneration techniques have been dominated by the use of high-molecular-weight compounds and autologous tissues, and there have been no reports of regeneration using structures made entirely of cells. This is the first report of ureteral regeneration using a tubular structure made from stacked spheroids. Although this study only attained short-segment ureteral regeneration, regeneration of the ureter over a much longer proportion of its length can be achieved in the future by applying other strategies, such as changing the cell type. This study provides a foundation to achieve the future goal of complete regeneration.

Validation of the histone methyltransferase EZH2 as a therapeutic target for various types of human cancer and as a prognostic marker.

The emphasis in anticancer drug discovery has always been on finding a drug with great antitumor potential but few side-effects. This can be achieved if the drug is specific for a molecular site found only in tumor cells. Here, we find the enhancer of zeste homolog 2 (EZH2) to be highly overexpressed in lung and other cancers, and show that EZH2 is integral to proliferation in cancer cells. Quantitative real-time PCR analysis revealed higher expression of EZH2 in clinical bladder cancer tissues than in corresponding non-neoplastic tissues (P < 0.0001), and we confirmed that a wide range of cancers also overexpress EZH2, using cDNA microarray analysis. Immunohistochemical analysis showed positive staining for EZH2 in 14 of 29 cases of bladder cancer, 135 of 292 cases of non-small-cell lung cancer (NSCLC), and 214 of 245 cases of colorectal cancer, whereas no significant staining was observed in various normal tissues. We found elevated expression of EZH2 to be associated with poor prognosis for patients with NSCLC (P = 0.0239). In lung and bladder cancer cells overexpressing EZH2, suppression of EZH2 using specific siRNAs inhibited incorporation of BrdU and resulted in significant suppression of cell growth, even though no significant effect was observed in the normal cell strain CCD-18Co, which has undetectable EZH2. Because EZH2 expression was scarcely detectable in all normal tissues we examined, EZH2 shows promise as a tumor-specific therapeutic target. Furthermore, as elevated levels of EZH2 are associated with poor prognosis of patients with NSCLC, its overexpression in resected specimens could prove a useful molecular marker, indicating the necessity for a more extensive follow-up in some lung cancer patients after surgical treatment.

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.

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

[This corrects the article DOI: 10.1371/journal.pone.0211339.].

Indispensable Points for Research on Antiadhesion Materials.

To prevent postoperative abdominal adhesions, many new antiadhesion materials have been developed all over the world. Few studies have analyzed the thickness of antiadhesive materials, but it is an important factor in maximizing adhesion prevention. The aspect of material thickness will needed for the future studies. However, few materials proceeded further than animal experimentation. Comparison tests between the newly developed antiadhesion materials and products already on the market will make it easier to conduct clinical trials. Recently, many new technologies are developed in the field of engineering and medical-engineering collaboration achieved some results, such as electrospinning technique. Application of new technologies to the medical field must be accelerated.

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.