Human neural stem cells enhance structural plasticity and axonal transport in the ischaemic brain

Stem cell transplantation promises new hope for the treatment of stroke although significant questions remain about how the grafted cells elicit their effects. One hypothesis is that transplanted stem cells enhance endogenous repair mechanisms activated after cerebral ischaemia. Recognizing that bilateral reorganization of surviving circuits is associated with recovery after stroke, we investigated the ability of transplanted human neural progenitor cells to enhance this structural plasticity. Our results show the first evidence that human neural progenitor cell treatment can significantly increase dendritic plasticity in both the ipsi- and contralesional cortex and this coincides with stem cell-induced functional recovery. Moreover, stem cell-grafted rats demonstrated increased corticocortical, corticostriatal, corticothalamic and corticospinal axonal rewiring from the contralesional side; with the transcallosal and corticospinal axonal sprouting correlating with functional recovery. Furthermore, we demonstrate that axonal transport, which is critical for both proper axonal function and axonal sprouting, is inhibited by stroke and that this is rescued by the stem cell treatment, thus identifying another novel potential mechanism of action of transplanted cells. Finally, we established in vitro co-culture assays in which these stem cells mimicked the effects observed in vivo. Through immunodepletion studies, we identified vascular endothelial growth factor, thrombospondins 1 and 2, and slit as mediators partially responsible for stem cell-induced effects on dendritic sprouting, axonal plasticity and axonal transport in vitro. Thus, we postulate that human neural progenitor cells aid recovery after stroke through secretion of factors that enhance brain repair and plasticity.

In pediatric lymphoblastic leukemia of B-cell origin, a small population of primitive blast cells is noncycling, suggesting them to be leukemia stem cell candidates

Kinetic investigations in pediatric acute lymphoblastic leukemia (ALL) are based on all blast cells and, therefore, reflect the proliferative characteristics of the predominant immunophenotype of leukemic cells. Nothing is known about proliferation of immunologically defined rare subpopulations of leukemic cells. In this study, mononuclear cells from the bone marrow of 15 children with untreated CD19 B-cell precursor ALL were examined for proliferative features according to the immunophenotype. After exclusion of highly proliferating residual normal hematopoietic cells, ∼ 3% of blast cells were CD19 and showed a low percentage of cells in S-phase assessed by the bromodeoxyuridine labeling index (BrdU-LI): median BrdU-LI, 0.19% [interquartile range (IQR), 0.15-0.40%]. In contrast, a median BrdU-LI of 7.2% (IQR, 5.7-8.8%) was found for the major CD19 blast cell compartment. Staining smears of sorted CD19 cells for CD10 or CD34 revealed a small fraction of CD19CD10 or CD19CD34 blast cells. These cells were almost nonproliferating with a median BrdU-LI of <0.1% (IQR, 0-0.2%). This proliferative behavior is suggestive of a stem/progenitor cell function and, in addition, the low proliferative activity might render them more resistant to an antiproliferation-based chemotherapy. However, xenotransplantation experiments will be necessary to demonstrate a possible stem cell function.

Influence of pregnancy on the adipocytokine and peroxisome proliferator-activated receptor pathways in peripheral blood mononuclear cells from healthy donors and rheumatoid arthritis patients

To identify candidate genes that are regulated by human pregnancy and have the potential to modulate rheumatoid arthritis (RA) disease activity.

Expression profiling of stem cell-related genes in neoadjuvant-treated gastric cancer: a NOTCH2, GSK3B and β-catenin gene signature predicts survival

Cancer stem cell (CSC) based gene expression signatures are associated with prognosis in various tumour types and CSCs are suggested to be particularly drug resistant. The aim of our study was first, to determine the prognostic significance of CSC-related gene expression in residual tumour cells of neoadjuvant-treated gastric cancer (GC) patients. Second, we wished to examine, whether expression alterations between pre- and post-therapeutic tumour samples exist, consistent with an enrichment of drug resistant tumour cells. The expression of 44 genes was analysed in 63 formalin-fixed, paraffin embedded tumour specimens with partial tumour regression (10-50% residual tumour) after neoadjuvant chemotherapy by quantitative real time PCR low-density arrays. A signature of combined GSK3B(high), β-catenin (CTNNB1)(high) and NOTCH2(low) expression was strongly correlated with better patient survival (p<0.001). A prognostic relevance of these genes was also found analysing publically available gene expression data. The expression of 9 genes was compared between pre-therapeutic biopsies and post-therapeutic resected specimens. A significant post-therapeutic increase in NOTCH2, LGR5 and POU5F1 expression was found in tumours with different tumour regression grades. No significant alterations were observed for GSK3B and CTNNB1. Immunohistochemical analysis demonstrated a chemotherapy-associated increase in the intensity of NOTCH2 staining, but not in the percentage of NOTCH2. Taken together, the GSK3B, CTNNB1 and NOTCH2 expression signature is a novel, promising prognostic parameter for GC. The results of the differential expression analysis indicate a prominent role for NOTCH2 and chemotherapy resistance in GC, which seems to be related to an effect of the drugs on NOTCH2 expression rather than to an enrichment of NOTCH2 expressing tumour cells.

Functional characterization of stem cell-derived cardiomyocytes

Conference Proceedings of ICGEB/CVR Symposium

Intervertebral disc regeneration or repair with biomaterials and stem cell therapy--feasible or fiction?

The "gold standard" for treatment of intervertebral disc herniations and degenerated discs is still spinal fusion, corresponding to the saying "no disc - no pain". Mechanical prostheses, which are currently implanted, do only have medium outcome success and have relatively high re-operation rates. Here, we discuss some of the biological intervertebral disc replacement approaches, which can be subdivided into at least two classes in accordance to the two different tissue types, the nucleus pulposus (NP) and the annulus fibrosus (AF). On the side of NP replacement hydrogels have been extensively tested in vitro and in vivo. However, these gels are usually a trade-off between cell biocompatibility and load-bearing capacity, hydrogels which fulfill both are still lacking. On the side of AF repair much less is known and the question of the anchoring of implants is still to be addressed. New hope for cell therapy comes from developmental biology investigations on the existence of intervertebral disc progenitor cells, which would be an ideal cell source for cell therapy. Also notochordal cells (remnants of the embryonic notochord) have been recently pushed back into focus since these cells have regenerative potential and can activate disc cells. Growth factor treatment and molecular therapies could be less problematic. The biological solutions for NP and AF replacement are still more fiction than fact. However, tissue engineering just scratched the tip of the iceberg, more satisfying solutions are yet to be added to the biomedical pipeline.

Gene expression by human monocytes from peripheral blood in response to exposure to metals

With increasing life expectancy and active lifestyles, the longevity of arthroplasties has become an important problem in orthopaedic surgery and will remain so until novel approaches to joint preservation have been developed. The sensitivity of the recipient to the metal alloys may be one of the factors limiting the lifespan of implants. In the present study, the response of human monocytes from peripheral blood to an exposure to metal ions was investigated, using the method of real-time polymerase chain reaction (PCR)-based low-density arrays. Upon stimulation with bivalent (Co2+ and Ni2+) and trivalent (Ti3+) cations and with the calcium antagonist LaCl3, the strength of the elicited monocytic response was in the order of Co2+ > or = Ni2+ > Ti3+ > or = LaCl3. The transcriptional regulation of the majority of genes affected by the exposure of monocytes to Co2+ and Ni2+ was similar. Some genes critically involved in the processes of inflammation and bone resorption, however, were found to be differentially regulated by these bivalent cations. The data demonstrate that monocytic gene expression is adapted in response to metal ions and that this response is, in part, specific for the individual metals. It is suggested that metal alloys used in arthroplasties may affect the extent of inflammation and bone resorption in the peri-implant tissues in dependence of their chemical composition.

Longitudinal data on telomere length in leukocytes from newborn baboons support a marked drop in stem cell turnover around 1 year of age

Stem cells of various tissues are typically defined as multipotent cells with 'self-renewal' properties. Despite the increasing interest in stem cells, surprisingly little is known about the number of times stem cells can or do divide over a lifetime. Based on telomere-length measurements of hematopoietic cells, we previously proposed that the self-renewal capacity of hematopoietic stem cells is limited by progressive telomere attrition and that such cells divide very rapidly during the first year of life. Recent studies of patients with aplastic anemia resulting from inherited mutations in telomerase genes support the notion that the replicative potential of hematopoietic stem cells is directly related to telomere length, which is indirectly related to telomerase levels. To revisit conclusions about stem cell turnover based on cross-sectional studies of telomere length, we performed a longitudinal study of telomere length in leukocytes from newborn baboons. All four individual animals studied showed a rapid decline in telomere length (approximately 2-3 kb) in granulocytes and lymphocytes in the first year after birth. After 50-70 weeks the telomere length appeared to stabilize in all cell types. These observations suggest that hematopoietic stem cells, after an initial phase of rapid expansion, switch at around 1 year of age to a different functional mode characterized by a markedly decreased turnover rate.

Drug treatment is superior to allografting as first-line therapy in chronic myeloid leukemia

Early allogeneic hematopoietic stem cell transplantation (HSCT) has been proposed as primary treatment modality for patients with chronic myeloid leukemia (CML). This concept has been challenged by transplantation mortality and improved drug therapy. In a randomized study, primary HSCT and best available drug treatment (IFN based) were compared in newly diagnosed chronic phase CML patients. Assignment to treatment strategy was by genetic randomization according to availability of a matched related donor. Evaluation followed the intention-to-treat principle. Six hundred and twenty one patients with chronic phase CML were stratified for eligibility for HSCT. Three hundred and fifty four patients (62% male; median age, 40 years; range, 11-59 years) were eligible and randomized. One hundred and thirty five patients (38%) had a matched related donor, of whom 123 (91%) received a transplant within a median of 10 months (range, 2-106 months) from diagnosis. Two hundred and nineteen patients (62%) had no related donor and received best available drug treatment. With an observation time up to 11.2 years (median, 8.9 years), survival was superior for patients with drug treatment (P = .049), superiority being most pronounced in low-risk patients (P = .032). The general recommendation of HSCT as first-line treatment option in chronic phase CML can no longer be maintained. It should be replaced by a trial with modern drug treatment first.