Cells in the umbilical cord stroma have gained attention in recent years; however, differentiation to certain lineages in humans has been demonstrated in few studies. Unlike bone marrow MSCs, human umbilical cord stroma cells (HUCSCs) are far from being well characterized. This study attempts to describe proliferation, structural, and differentiation properties of these cells to account for their exceptional nature in many aspects. Cellular dynamics, cellular structure, and the degree of transformations during expansion and differentiation into mesenchymal and neuronal lineages were examined in vitro over a 10-month period. Comparisons with human bone marrow MSCs regarding differentiation were performed. HUCSCs in culture revealed two distinct cell populations, type 1 and type 2 cells, that possessed differential vimentin and cytokeratin filaments. Corresponding cells were encountered in cord sections displaying region-specific localization. ␣-Smooth muscle actin and desmin filaments, which were evident in cord sections, diminished through passages. No difference was noted regarding type 1 and type 2 cells in differentiation to chondrogenic, adipogenic, and osteogenic lineages, whereas a preferential differentiation was noted in neuronal lineage. Relative success was achieved by production of chondrocytic spheres and osteogenic monolayers, whereas adipocytes were immature compared with bone marrow MSCs. The presence of neuronal markers suggests that they transform into a certain state of maturity under neurogenic induction. Conclusively, HUCSCs retain their original phenotype in culture without spontaneous differentiation, have a limited lifespan, and bear multipotent stem cell characteristics. Given these characteristics, they may be generally considered progenitor cells if manipulated under appropriate conditions and deserve further study to be potentially used in cell-based therapies. STEM CELLS 2007;25:319 -331

Summary:A retrospective analysis was made of 122 children who had received an allogeneic haematopoietic stem cell transplantation (HSCT) for autosomal recessive osteopetrosis between 1980 and 2001. The actuarial probabilities of 5 years disease free survival were 73% for recipients of a genotype HLA-identical HSCT (n ¼ 40), 43% for recipients of a phenotype HLA-identical or one HLAantigen mismatch graft from a related donor (n ¼ 21), 40% for recipients of a graft from a matched unrelated donor (n ¼ 20) and 24% for patients who received a graft from an HLA-haplotype-mismatch related donor (n ¼ 41). In the latter group, a trend towards improvement was achieved at the end of the study period (17% before 1994, 45% after 1994, P ¼ 0.11). Causes of death after HSCT were graft failure and early transplant-related complications. Severe visual impairment was present in 42% of the children before HSCT. Conservation of vision was better in children transplanted before the age of 3 months. Final height was related to height at the time of HSCT and better preserved in children transplanted early. Most children attended regular school or education for the visually handicapped. At present, HSCT is the only curative treatment for autosomal recessive osteopetrosis and should be offered as early as possible.

Summary:Neurological complications may occur in BMT recipients (11-59%), frequently contributing to morbidity or mortality. They are the main causes of death in 10-15%. Lifethreatening neurological complications were seen in 11 out of 113 (9.7%) children who underwent BMT from HLAmatched family (n ¼ 7) or mismatched donors (n ¼ 4) at our institution. Diagnoses of patients with neurological complications were acute myeloblastic leukemia (AML) (five), thalassemia major (two), Fanconi anemia (two), Omenn syndrome (one) and leukodystrophy (one), and the neurological events were seen between days þ 13 and þ 85 after transplantation. Minor symptoms including reversible, nonrepetitive seizures were excluded. Cyclosporine A toxicity was diagnosed in six children. The rest of the complications were brain abscess/meningoencephalitis (two), severe hypomagnesemia (one), busulfan toxicity (one), sustained hypertension (three), and intracranial hemorrhage (three). Six patients with neurological complications suffered from 4grade II graft-versus-host disease (GvHD), and all were high risk for transplantrelated complications. In this study, risk status of the underlying disease, mismatched transplantation, a diagnosis of AML (advanced stage), older age and 4grade II GvHD were important adverse factors for the development of severe life-threatening neurological complications. Bone Marrow Transplantation (2005) 35, 71-76.

Cross-linking of Fas (CD95, APO-1) and Fas ligand (FasL; CD95L) induces apoptosis of Fas-bearing cells. Recent evidence suggests that FasL. expression plays an important role in maintenance of immune privilege in murine testis and eye and in tumour escape from immune rejection in colon cancer, melanoma and hepatocellular carcinoma. Bcl-2 is a membrane protein that suppresses apoptosis in response to a variety of stimuli. In this paper we describe abundant expression of FasL protein and mRNA transcripts within the immune privileged environment of the placenta by immunohistochemistry and reverse transcription in-situ polymerase chain reaction methods. The syncytiotrophoblast layer, the main site of feto-maternal interface, and extravillous trophoblasts, demonstrated consistent immunoreactivity for FasL in term placentae. Co-occurrence of Fas and Bcl-2 were detected with a similar pattern of distribution with FasL. The TUNEL method revealed evidence of apoptosis in the placental tissues. We speculate that abundant presence of FasL in the trophoblast contributes to immune privilege in this unique environment, perhaps by fostering apoptosis of activated Fas-expressing lymphocytes of maternal origin. An apoptotic process mediated by FasL may also play a role in placental invasion during implantation and underscores similarities between the trophoblast and neoplastic cells.

ABSTRACT:We evaluated the potential therapeutic use of exogenous human bone marrow-derived mesenchymal stem cells (hBMMSCs) in an experimental rat model of necrotizing enterocolitis (NEC). Thirty-six newborn Sprague-Dawley rats were randomly divided into three groups: NEC, NEC ϩ hBM-MSC, and a control (control and control ϩ hBM-MSC). NEC was induced by enteral formula feeding, exposure to hypoxia-hyperoxia, and cold stress. After NEC was induced, iron-labeled hBM-MSCs were administered by intraperitoneal injection. All pups were killed on the fourth day following injection, and the terminal ileum was excised for a histopathological and immunohistochemical evaluation. The pups in the NEC ϩ hBM-MSC group showed significant weight gains and improvements in their clinical sickness scores (p Ͻ 0.01). Bowel damage severity observed in the histopathological evaluation was significantly lower in the NEC ϩ hBM-MSC group than that in the NEC group (p ϭ 0.012). The number of MSCs homing to the bowel was significantly higher in the NEC ϩ hBM-MSC group than that in the control ϩ hBM-MSC group. In conclusion, this is the first study that has evaluated the effectiveness of hBM-MSCs in a neonatal rat NEC model. MSCs reduced histopathological damage significantly. (Pediatr Res 70: 489-494, 2011) N ecrotizing enterocolitis (NEC) is the most common gastrointestinal emergency and a leading cause of mortality and morbidity in newborn infants. The etiology and pathophysiology of NEC remains unclear. Although prematurity is the most consistent risk factor, hypoxic-ischemic injury, formula feeding, abnormal bacterial colonization, antenatal and postnatal risk components, and genetic aspects comprise other potential risk factors (1-3). Medical management of severe cases is often inadequate, and surgical intervention may be warranted. Thus, ϳ20 -40% of neonates eventually require a surgical procedure (1,4,5). In addition, morbid sequelae among survivors include impaired growth, short bowel syndrome, prolonged neonatal hospitalization, and poor longterm neurodevelopment (1-5). Therefore, the introduction of new strategies for the prevention and/or therapy for this devastating disease is essential to increase the survival rate and to reduce significant complications.Mesenchymal stem cells (MSCs) are multipotent cells capable of differentiating into multiple cell types. In addition, MSCs secrete a wide variety of cytokines and chemokines that have beneficial paracrine actions during tissue repair (6 -11). Because of these unique properties, MSCs could be a future option for treating various diseases. Studies on the potential use of stem cells in pediatric diseases have recently aroused interest among clinicians (12-15), although stem cell therapy has not yet been studied as a treatment modality for neonatal intestinal disorders such as NEC. In this study, the therapeutic potential of exogenous human bone marrow-derived (hBM)-MSC therapy was evaluated in an experimental neonatal rat model of NEC. MATERIALS AND METHODSAnimal model. Fatih Uni...