Daichi Kawamura

Influence of aging on the quantity and quality of human cardiac stem cells.

Advanced age affects various tissue-specific stem cells and decreases their regenerative ability. We therefore examined whether aging affected the quantity and quality of cardiac stem cells using cells obtained from 26 patients of various ages (from 2 to 83 years old). We collected fresh right atria and cultured cardiosphere-derived cells (CDCs), which are a type of cardiac stem cell. Then we investigated growth rate, senescence, DNA damage, and the growth factor production of CDCs. All samples yielded a sufficient number of CDCs for experiments and the cellular growth rate was not obviously associated with age. The expression of senescence-associated b-galactosidase and the DNA damage marker, gH2AX, showed a slightly higher trend in CDCs from older patients (≥65 years). The expression of VEGF, HGF, IGF-1, SDF-1, and TGF-b varied among samples, and the expression of these beneficial factors did not decrease with age. An in vitro angiogenesis assay also showed that the angiogenic potency of CDCs was not impaired, even in those from older patients. Our data suggest that the impact of age on the quantity and quality of CDCs is quite limited. These findings have important clinical implications for autologous stem cell transplantation in elderly patients.

Increased plasma VEGF levels following ischemic preconditioning are associated with downregulation of miRNA-762 and miR-3072-5p

Ischemic preconditioning (IPC) has protective effects against ischemia-perfusion injury of organs. In the present study, we investigated the associated mechanisms after performing remote IPC (rIPC) of lower limbs by clamping abdominal aorta in mice. Subsequent experiments showed decreased damage and paralysis of lower limbs following spinal cord injury (SCI). Concomitantly, plasma vascular endothelial growth factor (VEGF) levels were increased 24 h after rIPC compared with those in sham-operated animals. In subsequent microRNA analyses, thirteen microRNAs were downregulated in exosomes 24 h after rIPC. Further studies of femoral CD34-positive bone marrow (BM) cells confirmed downregulation of these seven microRNAs 24 h after rIPC compared with those in sham-operated controls. Subsequent algorithm-based database searches suggested that two of the seven microRNAs bind to the 3′ UTR of VEGF mRNA, and following transfection into CD34-positive BM cells, anti-miR-762, and anti-miR-3072-5p inhibitors led to increased VEGF concentrations. The present data suggest that rIPC transiently increases plasma VEGF levels by downregulating miR-762 and miR-3072-5p in CD34-positive BM cells, leading to protection against organ ischemia.

Single-incision laparoscopic splenectomy and splenic autotransplantation for an enlarged wandering spleen with torsion.

A wandering spleen is a rare condition in which the spleen is not located in the left upper quadrant, but instead is found in the lower abdomen or in the pelvic region because of the laxity of the peritoneal attachments. The unusually long pedicle is susceptible to twisting, which can lead to ischemia, and eventually to necrosis. We herein report a case of an enlarged wandering spleen with torsion, successfully treated by single-incision laparoscopic splenectomy and autotransplantation. The transplanted splenic tissues could be identified on a spleen scintigram obtained 3 months after the surgery. Howell-Jolly bodies were not observed in blood specimens. This procedure is able to prevent an overwhelming postsplenectomy infection, and leads to satisfactory cosmetic results.

Loss of skeletal muscle mass after curative gastrectomy is a poor prognostic factor

Sarcopenia has been reported to relate to poor prognosis in various malignant cancer types. The present study aimed to clarify the prognostic impact of skeletal muscle mass (SMM) loss after curative gastrectomy in patients with gastric cancer. A total of 119 patients who underwent curative gastrectomy for gastric cancer between 2009 and 2016 were analyzed. The SMM loss at 6 months postoperatively compared with the SMM prior to surgery was calculated using the hospital records. The median loss of SMM was 3.8%. Multivariate logistic regression analysis demonstrated that total gastrectomy was a significant and independent risk factor for SMM loss of ≥5% (odds ratio=2.58; P=0.02). Results from multivariate analysis using stepwise Cox proportional hazards regression indicated that the following factors were significantly associated with shorter overall survival after curative gastrectomy: Age [>70 years; hazard ratio (HR)=2.46, P=0.04], TNM stage (≥2; HR=2.65, P=0.04) and loss of SMM (≥5%; HR=2.57, P=0.03). The present findings suggested that loss of SMM after curative gastrectomy for gastric cancer is an independent predictive factor for poor prognosis.

Laparoscopic low anterior resection for rectal cancer after Whitehead's hemorrhoidectomy: A case report

A 65‐year‐old man presented with bloody stool. Colonoscopy revealed a raised tumor in the rectum, above the peritoneal reflection. He underwent endoscopic mucosal resection, but the pathological findings suggested the possibility of residual cancer. We performed laparoscopic low anterior resection using a circular stapling instrument for additional curative surgery. However, we could not insert the shaft of the endoscopic circular stapler from the anus because of anal stenosis due to Whiteheads hemorrhoidectomy the patient had undergone 20 years earlier. Therefore, we planned to use a linear stapler to insert an anvil into the rectum. The cartridge‐carrying instrument was inserted from the sigmoidal side, and we performed a side‐to‐end anastomosis. The patient was discharged without anastomotic leakage or defecation disorder. We present this case because laparoscopic low anterior resection for rectal cancer with anal stenosis has not been previously reported.

Abstract 1072: Synergistic effect of gemcitabine and a Dclk1 inhibitor on pancreatic cancer cell survival

Pancreatic cancer has the highest mortality rate of all major cancers and is one of the most lethal malignancies. There is a constant upward trend in the number of patients diagnosed with pancreatic cancer and the number of deaths due to pancreatic cancer. Gemcitabine (GEM) is often used in the treatment of pancreatic cancer (PDAC), but has limited effects. Doublecortin-like kinase 1 (Dclk1) is important in the progression of early pancreatic neoplastic lesions and PDAC. However, the functional role of Dclk1 in PDAC is unknown. To identify the substrate protein phosphorylated by Dclk1, we performed a protein microarray analysis on Dclk1 knockdown cells. The results of this analysis directed our studies toward Chk1, which is known to be a potential regulator of the cell cycle and experiences upregulation of phosphorylation after GEM treatment. In general, GEM treatment results in DNA damage to pancreatic cancer cells, an increase in phosphorylated Chk1 (p-Chk1), and arrests the cell cycle progression to repair the damaged DNA. On the basis of the preliminary data, we hypothesized that the decrease in Chk1 phosphorylation by Dclk1 inhibition circumvents cell cycle arrest and impairs the subsequent DNA repair. The aim of this study was to evaluate the synergistic effect of Dclk1 inhibition and GEM treatment on pancreatic cancer cell survival. We used the human pancreatic cancer cell line MIA PaCa-2 and LRRK2-IN-1 (LRRK) as the Dclk1 inhibitor for this study. First, we examined the effects of GEM or the Dclk1 inhibitor or both on cancer cell proliferation and the expression of p-Chk1. Significantly decreased cell proliferation was observed on co-treatment of GEM and LRRK compared to GEM treatment alone. In addition, the expression of p-Chk1 significantly decreased on co-treatment compared to GEM treatment alone. Second, we used flow cytometry to analyze the cell cycle after treatment with GEM and/or LRRK. Almost all cancer cells treated with GEM alone were arrested in the S phase of the cell cycle. The addition of LRRK allows the cell cycle to proceed in the same manner as untreated control cancer cells do. We also evaluated DNA damage by measuring the intensity of gamma-H2AX. Cancer cells that were co-treated experienced more DNA damage than with GEM treatment alone. The co-treatment induced apoptosis without the repair of DNA damage in the cancer cells. In conclusion, the combined treatment with GEM and a Dclk1 inhibitor decreased the cell survival rate compared to treatment with GEM alone through the suppression of p-Chk1. Targeting Dclk1 in combination with GEM might offer an excellent opportunity for future pancreatic cancer treatments. Citation Format: Daichi Kawamura, Yoshihiro Takemoto, Arata Nishimoto, Toshiki Tanaka, Yukari Hironaka, Kumiko Yoshida, Junichi Murakami, Naruji Kugimiya, Eijiro Harada, Koji Ueno, Tohru Hosoyama, Kimikazu Hamano. Synergistic effect of gemcitabine and a Dclk1 inhibitor on pancreatic cancer cell survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1072. doi:10.1158/1538-7445.AM2017-1072