Tissue‐Engineered Tracheal Reconstruction Using Three‐Dimensionally Printed Artificial Tracheal Graft: Preliminary Report

Three‐dimensional printing has come into the spotlight in the realm of tissue engineering. We intended to evaluate the plausibility of 3D‐printed (3DP) scaffold coated with mesenchymal stem cells (MSCs) seeded in fibrin for the repair of partial tracheal defects. MSCs from rabbit bone marrow were expanded and cultured. A half‐pipe‐shaped 3DP polycaprolactone scaffold was coated with the MSCs seeded in fibrin. The half‐pipe tracheal graft was implanted on a 10 × 10‐mm artificial tracheal defect in four rabbits. Four and eight weeks after the operation, the reconstructed sites were evaluated bronchoscopically, radiologically, histologically, and functionally. None of the four rabbits showed any sign of respiratory distress. Endoscopic examination and computed tomography showed successful reconstruction of trachea without any collapse or blockage. The replaced tracheas were completely covered with regenerated respiratory mucosa. Histologic analysis showed that the implanted 3DP tracheal grafts were successfully integrated with the adjacent trachea without disruption or granulation tissue formation. Neo‐cartilage formation inside the implanted graft was sufficient to maintain the patency of the reconstructed trachea. Scanning electron microscope examination confirmed the regeneration of the cilia, and beating frequency of regenerated cilia was not different from those of the normal adjacent mucosa. The shape and function of reconstructed trachea using 3DP scaffold coated with MSCs seeded in fibrin were restored successfully without any graft rejection.     

Development of Conductive Boron-Doped Diamond Electrode: A microscopic,Spectroscopic, and Voltammetric Study

Building on diamond characteristics such as hardness, chemical inertness and low electron emission threshold voltage, the current microscopic, spectroscopic and voltammetric investigations are directed towards improving the properties of electrode coating materials for their future use in clinical studies of deep brain stimulation via fast-scan cyclic voltammetry (FSCV). In this study we combine the capabilities of confocal Raman mapping in providing detailed and accurate analysis of local distributions of material constituents in a series of boron-doped polycrystalline diamond films grown by chemical vapor deposition, with information from the more conventional techniques of scanning electron microscopy (SEM) and infrared absorption spectroscopy. Although SEM images show a uniform distribution of film crystallites, they have the limitation of being unable to differentiate the distribution of boron in the diamond. Values of 10¹⁸–10²¹ atoms/cm³ of boron content have been estimated from the absorption coefficient of the 1290 cm⁻¹ infrared absorption band and from the 500 cm⁻¹ Raman vibration. The observed accumulation of boron atoms and carbon sp² impurities at the grain boundaries suggests that very high doping levels do not necessarily contribute to improvement of the material’s conductivity, corroborating with voltammetric data. FSCV results also indicate an enhanced stability of analyte detection.     

Response to pretransplant hypomethylating agents influences the outcome of allogeneic hematopoietic stem cell transplantation in adults with myelodysplastic syndromes

This study describes a retrospective analysis on the transplant outcome of 56 consecutive patients with myelodysplastic syndrome (MDS) according to their response to hypomethylating agents (HMA). While 2‐yr disease‐free survival (DFS) of patients who transformed to acute myeloid leukemia (n = 12) was 25%, that of the remaining patients with MDS according to response to HMA was 73.1%, 68.1%, 50.0%, and 20.8% in G‐COR (group of continuous response, n = 19), G‐NoC (group of no change, n = 15), G‐LOR (group of loss of response, n = 6), and G‐DP (group of disease progression, n = 4), respectively. When dichotomized as G‐COR/G‐NoC versus G‐LOR/G‐DP, significantly different 2‐yr DFS (71.0% vs. 33.3%; P = 0.004) and relapse (14.1% vs. 46.7%; P = 0.016) were demonstrated. On multivariate analysis, G‐LOR/G‐DP [hazard ratio (HR), 3.91; P = 0.008] and poor karyotype at transplantation (HR, 2.69; P = 0.017) were the significant predictors for poor DFS, as G‐LOR/G‐DP was for relapse (HR, 6.28; P = 0.011). DFS was significantly poor in patients with any of the two predictors in all MDS (81.5% vs. 34.9%; P = 0.001) or higher‐risk MDS (HrMDS) at the time of HMA (80.7% vs. 29.2%; P = 0.005). G‐COR showed a trend of better DFS compared with G‐NoC among HrMDS (74.6% vs. 36.5%; P = 0.090). These results implicate the significance of response to HMA on hematopoietic stem cell transplantation (HSCT) outcomes and support the need for future study to verify the suggested strategy of proceeding to transplantation before LOR or DP, especially for HrMDS.