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The use of autologous (or syngeneic) cells derived from induced pluripotent stem cells (iPSCs) holds great promise for future clinical use in a wide range of diseases and injuries. It is expected that cell replacement therapies using autologous cells would forego the need for immunosuppression, otherwise required in allogeneic transplantations. However, recent studies have shown the unexpected immune rejection of undifferentiated autologous mouse iPSCs after transplantation. Whether similar immunogenic properties are maintained in iPSC-derived lineage-committed cells (such as neural precursors) is relatively unknown. We demonstrate that syngeneic porcine iPSC-derived neural precursor cell (NPC) transplantation to the spinal cord in the absence of immunosuppression is associated with long-term survival and neuronal and glial differentiation. No tumor formation was noted. Similar cell engraftment and differentiation were shown in spinally injured transiently immunosuppressed swine leukocyte antigen (SLA)-mismatched allogeneic pigs. These data demonstrate that iPSC-NPCs can be grafted into syngeneic recipients in the absence of immunosuppression and that temporary immunosuppression is sufficient to induce long-term immune tolerance after NPC engraftment into spinally injured allogeneic recipients. Collectively, our results show that iPSC-NPCs represent an alternative source of transplantable NPCs for the treatment of a variety of disorders affecting the spinal cord, including trauma, ischemia, or amyotrophic lateral sclerosis.

The signal transducer and activator of transcription 3 (STAT3) factor plays an important role in the tumorigenicity of cancer stem cells. The purpose of this study was to investigate the inhibitory mechanism of this pathway acting through the tumor suppressor von Hippel-Lindau (VHL) protein in glioma cancer stem cells. We isolated floating neurosphere-forming CD133+ cells as glioma stem-like cells (GSLCs) by the MACS method. Furthermore, we examined these cells for their growth rate, ability to form colonies and neurospheres in soft agar, capacity for implantation into SCID mice and expression of CD133, STAT3, JAK2, Elongin A, PTEN and VHL. Furthermore, we transferred the VHL gene, an inhibitor of STAT3, into GSLCs using an adenovirus vector and compared these transfectants with control vector-transfected GSLCs. GSLCs proved to be implantable and formed a tumor in the subcutaneous tissue of SCID mice, the histology of which was similar to that of human glioblastomas. In addition, GSLCs exhibited a high capacity for soft agar colony and neurosphere formation, nearly all of which were CD133 positive. The majority of GSLCs were immunopositive for STAT3, JAK2 and Elongin A, but immunonegative for PTEN and VHL. When the VHL gene was transferred to GSLCs and these cells were transplanted into SCID mice, they did not result in tumor formation. Their capacity for soft agar colony and neurosphere formation was significantly inhibited, although their proliferation was only moderately inhibited. Regarding the expression of various factors, that of CD133 was decreased in the VHL transfectants and those of STAT3, JAK2 and Elongin A were eliminated. However, the expression of PTEN and of VHL was upregulated. These findings suggest that VHL regulated the tumorigenicity and self-renewal ability of glioma cancer stem cells by inhibiting the JAK/STAT signaling pathway.

Key words: capecitabine; lymph node metastasis; lung metastasis; thymidine phosphorylase; rectal xenograft modelGastrointestinal cancer is one of the most common internal malignancies and is one of the leading causes of cancer-related morbidity and mortality in the world. The primary definitive treatment modality is surgical excision. Adjuvant therapies subsequent to surgery have been studied extensively in recent years because of the high incidence of postoperative recurrences. More than 40 years after its development, 5-FU remains the chemotherapeutic mainstay for the management of patients with many types of cancer. In recent years, several new approaches to the treatment of cancer have undergone examination. These include the introduction of 2 novel cytotoxic compounds. Another strategy that has received attention has been the development of several oral forms of fluoropyrimidine, offering an alternative route of administration to intravenous 5-FU 1 . Capecitabine (N 4 -pentyloxycarbonyl-5Ј-deoxy-5-fluorocytidine) is a new fluoropyrimidine carbamate, which is designed to be activated to 5-FU by 3 sequential steps of enzyme reactions. 1 In humans, it is sequentially converted first to 5Ј-deoxy-5-fluorocytidine by carboxylesterase located in the liver, then to 5Ј-deoxy-5-fluorouridine by cytidine deaminase also with high activity in the liver and in various solid tumors and finally to 5-FU by thymidine phosphorylase (dThdPase) with high activity in many types of tumors. [1][2][3] This oral fluoropyrimidine has an advantage over parental therapy with 5-FU in its potential for affording patients greater convenience and comfort. 4 -6 Randomized clinical trials that compared capecitabine with parenteral 5-FU/leucovorin against metastatic colorectal cancer demonstrated that capecitabine provides at least equivalence, a favorable benefit-risk ratio and greater patient preference making it an acceptable replacement for 5-FU/leucovorin. 4,5,7 Our interest focused on the possibility of capecitabine usage in the prevention of metastasis. Neoadjuvant or adjuvant chemotherapy to inhibit spontaneous metastasis or suppress occult micrometastasis may reduce the incidence of postoperative distant metastasis and improve survival. To confirm this possibility, large randomized clinical trials should be needed. These clinical trials are expensive and time consuming. Animal experiments may take their place to examine the efficacy of new therapeutic modalities. Here, we develop an animal model of gastrointestinal cancer by the intrarectal injection of tumor cells, which resulted in the formation of local tumors with lymph node and lung metastasis consistent with the progression of gastrointestinal cancer in humans.In our study, we examined the efficacy of capecitabine for the inhibition of metastasis and its mechanism for doing so by using a mouse metastasis model. MATERIAL AND METHODS AnimalsMale BALB/c-nu/nu mice aged 5 weeks were obtained from Charles River Japan, Inc. (Kanagawa, Japan). After at least 1 week of observation, th...

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