The novel immunosuppressant FTY720 activates sphingosine 1-phosphate receptors (S1PRs) that affect responsiveness of lymphocytes to chemokines such as stromal cell-derived factor 1 (SDF-1), resulting in increased lymphocyte homing to secondary lymphoid organs. Since SDF-1 and its receptor CXCR4 are also involved in bone marrow (BM) homing of hematopoietic stem and progenitor cells (HPCs), we analyzed expression of S1PRs and the influence of FTY720 on SDF-1/ CXCR4-mediated effects in human HPCs. By reverse transcriptase-polymerase chain reaction (RT-PCR), S1PRs were expressed in mobilized CD34 ؉ HPCs, particularly in primitive CD34 ؉ /CD38 ؊ cells. Incubation of HPCs with FTY720 resulted in prolonged SDF-1-induced calcium mobilization and actin polymerization, and substantially increased SDF-1-dependent in vitro transendothelial migration, without affecting VLA-4, VLA-5, and CXCR4 expression. In nonobese diabeticsevere combined immunodeficient (NOD/ SCID) mice, the number of CD34 ؉ /CD38 ؊ cells that homed to the BM after 18 hours was significantly raised by pretreatment of animals and cells with FTY720, tending to result in improved engraftment. In addition, in vitro growth of HPCs (week-5 cobblestone area-forming cells [CAFCs]) was 2.4-fold increased. We conclude that activation of S1PRs by FTY720 increases CXCR4 function in HPCs both in vitro and in vivo, supporting homing and proliferation of HPCs. In the hematopoietic microenvironment, S1PRs are involved in mi IntroductionHoming of hematopoietic stem and progenitor cells (HPCs) to the bone marrow is an active and rapid process that takes place less than one day after transplantation, as demonstrated in the nonobese diabetic-severe combined immunodeficient (NOD/SCID) mouse model 1 as well as in recent in vivo tracking experiments using a bioluminescence technique. 2 In addition to adhesion molecules, proteolytic enzymes, and cytokines, especially chemokines such as stromal cell-derived factor 1 (SDF-1, CXCL12) are involved in HPC trafficking. CXCR4, the receptor for SDF-1, is expressed on HPCs and plays a central role in both progenitor cell homing and mobilization. [3][4][5][6][7][8][9] Blocking of CXCR4 with monoclonal antibodies has been shown to reduce homing of transplanted human progenitors to the bone marrow of NOD/SCID mice. 3 In the adult human bone marrow, SDF-1 was found to be expressed particularly by endothelial cells and along the endosteum region, suggesting SDF-1 mediates both early steps of HPC homing and final lodgement of stem cells in the niches of the bone marrow microenvironment. 10 Stimulation of CXCR4 by SDF-1 also activates adhesion molecules (eg, VLA-4) important for the homing process and may modulate proliferation of progenitors and stem cells. [11][12][13] In addition, there is indirect evidence that the SDF-1/ CXCR4 interaction is important for stem cell homing after transplantation in humans, since the migratory capacity of human progenitor cells in response to SDF-1 is correlated with hematopoietic recovery after stem cell tra...

Sphingosine 1-phosphate (S1P) is an ubiquitously present extracellular lipid mediator that is released by several cell types, particularly by activated platelets. The effects of S1P are mediated by a specific family of G protein-coupled sphingosine 1-phosphate receptors (S1P1-S1P5). We demonstrate that S1P acts on hematopoietic progenitor cells as a chemotactic factor, attracting peripheral blood CD34(+) cells in vitro. Furthermore, constant activation of S1P receptors augments CXCR4-mediated signal transduction induced by stromal cell-derived factor 1 (SDF-1). These effects are most likely mediated by the S1P1 receptor consistently expressed in both primitive and committed CD34(+) hematopoietic progenitor cells (HPCs). In vivo, sustained activation of S1P1 by a receptor agonist during the homing process resulted in increased engraftment. Given the fact that activated platelets represent a major source of extracellular S1P, SDF-1-mediated stem cell homing may occur at sites of tissue injury in addition to the bone marrow. This could explain the previously observed contribution of primary hematopoietic stem cells to tissue repair in myocardial infarction and other diseases.

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Background: Necrotizing enterocolitis (NEC) and focal intestinal perforation (FIP) are major causes of morbidity in infants with extremely low birth weight (ELBW). Objective: To evaluate the surgical procedures applied, and the survival and long-term outcome of ELBW infants with NEC and FIP in a single-center study. Methods: Inborn and outborn ELBW infants (<1000 g) with NEC and FIP were analyzed retrospectively from 2002 to 2007. Data collected include surgical procedures, survival as well as complications, length of partial parenteral nutrition and hospital stay. The short-term and long-term outcomes after 2–7 years were assessed and compared with a matched control group. Results: Out of 280 ELBW infants, 28 underwent surgery, 19 because of FIP and 9 for NEC. Fourteen infants in the FIP group were treated with primary laparotomy and 5 with peritoneal drainage (PD). In the NEC group, only 1 infant was treated with PD. PD was used for unstable patients and was always followed by secondary laparotomy after stabilization. Five of 28 (18%) surgically treated ELBW infants and 4 (14%) matched controls died. The following complications occurred in the surgical group: complete (n = 1) or minor wound dehiscence (n = 4), stoma prolapse (n = 5), parastomal hernia (n = 2), stoma fistula (n = 1), and wound infection (n = 2). Dependency on parenteral nutrition was significantly shorter in infants with FIP, while there were no differences in time to stoma closure and length of hospital stay between those with FIP and those with NEC. Eleven of 23 (47.8%) surviving patients with FIP or NEC showed developmental delay, compared with 9 of 24 (37.5%) in the controls. Conclusions: The management of EBLW infants with NEC and FIP remains challenging. Our treatment approach was associated with low mortality. Developmental delay seems to be caused by extreme prematurity rather than NEC- or FIP-related bowel perforation.

Background Rhabdomyosarcoma (RMS) diagnosed during the first year of life is reported to have poor outcome. Little is known about treatment and outcome data of relapsed disease (RD). Methods Characteristics, treatment, and outcome of 155 patients ≤ 12 months registered within the Cooperative Weichteilsarkom Studiengruppe (CWS) between 1981 and 2016 were evaluated. Results Localized disease (LD) was diagnosed in 144 patients and metastatic disease (MD) in 11. The histological diagnosis was alveolar (RMA) (n = 38, 23/25 examined patients PAX7/3:FOXO1‐positive), embryonal (RME) (n = 100), botryoid (n = 10), anaplastic (n = 1), and spindle‐cell RMS (n = 6). Multimodal treatment including conventional (age‐adjusted) chemotherapy (CHT) (n = 150), resection (n = 137), and radiotherapy (RT) (n = 37) was administered. Complete remission was achieved in 129 of 144 patients with LD. RD occurred in 51 infants at a median age of 1.7 years (range, 0.3–8.8). Sixty‐three percent of patients with RMA suffered RD, in contrast to 28% of patients with RME. Relapse treatment consisted of conventional CHT (n = 48), resection (n = 28), and RT (n = 21). The pattern of relapse and best resection were significant prognostic factors for patients with RD (P = 0.000 and P = 0.002). Late effects occurred as secondary malignancies in 6%, long‐term toxicity in 21%, and resection‐related impairment in 33% of the 105 surviving patients. The 5‐year event‐free survival and overall survival for infants with initial LD were 51% and 69%, 14% and 14% for patients with initial MD and 39% and 41% for relapsed patients, respectively. Conclusion Multimodal treatment including microscopically complete resection is strongly recommended to achieve a good prognosis in LD and RD of infants with RMS.

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The International Soft-Tissue Sarcoma Consortium (INSTRuCT) was founded as an international collaboration between different pediatric soft-tissue sarcoma cooperative groups (Children's Oncology Group, European Pediatric Soft-Tissue Sarcoma Group, and Cooperative Weichteilsarkom Studiengruppe). Besides other tasks, a major goal of INSTRuCT is to develop consensus expert opinions for best clinical treatment. This consensus paper for patients with rhabdomyosarcoma of the female genital tract (FGU-RMS) provides treatment recommendations for local treatment, long-term follow-up, and fertility preservation. Therefore, a review of the current literature was combined with recommendations of the treatment protocols of the appropriate

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