Culture under low physiological oxygen conditions improves the stemness and quality of induced pluripotent stem cells.

The ex vivo expansion of stem cells under low physiological oxygen (O2 ) conditions has been demonstrated to improve the stemness and genomic stability of the cells. We investigated whether low-oxygen culture would be beneficial for the culture of induced pluripotent stem (iPS) cells. Two human iPS cell lines (201B7 and 253G1) were used for the experiments. Cells expanded from a single colony of each cell line were initiated for culture in 2.5% O2 , 5% O2 , or 20% O2 and maintained for 2 months in parallel. The levels of intracellular and mitochondrial reactive oxygen species did not differ between the cells cultured under different conditions. More colonies of uniformly smaller size were observed at 2.5% and 5% O2 than at 20% O2 . All of these iPS colonies that expanded under the various oxygen conditions stained positively for Oct3/4, Nanog, SSEA-4, and ALP. However, Western blot analysis showed that the iPS cells cultured at 2.5% and 5% O2 expressed significantly more Nanog but less 53BP1 than those cultured at 20% O2 . Data from an array CGH showed no significant chromosomal abnormalities, although some genes involved in cellular and metabolic processes were amplified in the low oxygen culture, particularly at 2.5% O2 . Our data suggest that low physiological oxygen culture could improve the stemness and quality of iPS cells, a result that might be associated with the amplification of genes involved in metabolic and cellular processes. Long-term culture will be necessary to confirm whether low physiological oxygen levels also improve genomic stability.

Additional superdrainage reduces anastomotic fistula and stenosis after gastric tube reconstruction with cervical anastomosis for esophageal cancer.

Objective: Gastric pull-up is a common procedure to reconstruct the continuity of the upper digestive tract after esophagectomy. However, this technique sometimes causes postoperative anastomotic leakage or stricture, resulting from congestion of the gastric tube. We performed additional microvascular venous anastomoses to solve this problem. The purpose of this study was to compare postoperative anastomotic leaks and strictures in cases with or without additional venous superdrainage after gastric tube reconstruction. Methods: A total of 117 consecutive patients with cervical and thoracic esophageal cancer who underwent thoracoscopic esophagectomy with gastric tube reconstruction in the National Nagasaki Medical Center between 2011 and 2021 were analyzed retrospectively. Of these patients, 46 did not undergo additional venous anastomoses (standard group), and 71 who underwent gastric pull-up surgery after November 2014 have added this surgical procedure to their routine (superdrainage group). We compared the frequency of postsurgical leakage and stricture in the 2 groups retrospectively. Results: Fifteen patients (32.6%) developed postoperative leakage in the standard group and 6 (8.5%) did so in the superdrainage group. Twelve patients (26.1%) showed postoperative anastomotic stricture in the standard group and 7 (9.9%) did so in the superdrainage group. Patients who did not undergo additional venous superdrainage were significantly more likely to develop postsurgical leakage (χ2 test P < .01) and anastomotic stricture (χ2 test P < .05). The mean time taken to perform additional venous anastomoses was 54.2 minutes. Conclusions: Our study revealed that performing additional venous anastomosis for as little as 1 hour can significantly reduce the incidence of postoperative leakage and stenosis. This procedure is of merit to perform after total esophagectomy with gastric tube reconstruction.