Derivation of 30 human embryonic stem cell lines—improving the quality

We have derived 30 human embryonic stem cell lines from supernumerary blastocysts in our laboratory. During the derivation process, we have studied new and safe method to establish good quality lines. All our human embryonic stem cell lines have been derived using human foreskin fibroblasts as feeder cells. The 26 more recent lines were derived in a medium containing serum replacement instead of fetal calf serum. Mechanical isolation of the inner cell mass using flexible metal needles was used in deriving the 10 latest lines. The lines are karyotypically normal, but culture adaptation in two lines has been observed. Our human embryonic stem cell lines are banked, and they are available for researchers.     

A role for the androgen receptor in follicular atresia of estrogen receptor beta knockout mouse ovary.

Estrogen receptor beta (ERbeta) is highly expressed, but ERalpha is not detectable in granulosa cells in the mouse ovary. In ERbeta knockout (BERKO) mice, there is abnormal follicular development and very reduced fertility. At 3 wk of age, no significant morphologic differences were discernable between wild type (WT) and BERKO mouse ovaries, but by 5 mo of age, atretic follicles were abundant in BERKO mice and there were very few healthy late antral follicles or corpora lutea. At 2 yr of age, unlike the ovaries of their WT littermates, BERKO mouse ovaries were devoid of healthy follicles but had numerous large, foamy lipid-filled stromal cells. The late antral and atretic follicles in BERKO mice were characterized by a high level of expression of the androgen receptor (AR) and IGF-1 receptor. These proteins were abundantly expressed in granulosa cells of preantral and early antral follicles in both genotypes, but their expression was extinguished in late antral follicles of WT mice. Healthy late antral follicles and corpora lutea were restored in BERKO ovaries after 15 days of treatment of mice with the antiandrogen flutamide. The results suggest that in the absence of ERbeta there was a loss of regulation of AR. Because androgens enhance recruitment of primordial follicles into the growth pool and cause atresia of late antral follicles, the inappropriately high level of AR probably is related to the follicular atresia and to the early exhaustion of follicles in BERKO mice.     

CD marker expression profiles of human embryonic stem cells and their neural derivatives,determined using flow-cytometric analysis,reveal a novel CD marker for exclusion of pluripotent stem cells

Human embryonic stem cells (hESCs) are pluripotent cells that can differentiate into neural cell lineages. These neural populations are usually heterogeneous and can contain undifferentiated pluripotent cells that are capable of producing teratomas in cell grafts. The characterization of surface protein profiles of hESCs and their neural derivatives is important to determine the specific markers that can be used to exclude undifferentiated cells from neural populations. In this study, we analyzed the cluster of differentiation (CD) marker expression profiles of seven undifferentiated hESC lines using flow-cytometric analysis and compared their profiles to those of neural derivatives. Stem cell and progenitor marker CD133 and epithelial adhesion molecule marker CD326 were more highly expressed in undifferentiated hESCs, whereas neural marker CD56 (NCAM) and neural precursor marker (chemokine receptor) CD184 were more highly expressed in hESC-derived neural cells. CD326 expression levels were consistently higher in all nondifferentiated hESC lines than in neural cell derivatives. In addition, CD326-positive hESCs produced teratomas in SCID mouse testes, whereas CD362-negative neural populations did not. Thus, CD326 may be useful as a novel marker of undifferentiated hESCs to exclude undifferentiated hESCs from differentiated neural cell populations prior to transplantation.     

Fibrillar β‐amyloid 1‐42 alters cytokine secretion,cholinergic signalling and neuronal differentiation

Adult neurogenesis is impaired by inflammatory processes, which are linked to altered cholinergic signalling and cognitive decline in Alzheimer's disease. In this study, we investigated how amyloid beta (Aβ)‐evoked inflammatory responses affect the generation of new neurons from human embryonic stem (hES) cells and the role of cholinergic signalling in regulating this process. The hES were cultured as neurospheres and exposed to fibrillar and oligomeric Aβ_1‐42 (Aβf, AβO) or to conditioned medium from human primary microglia activated with either Aβ_1‐42 or lipopolysaccharide. The neurospheres were differentiated for 29 days in vitro and the resulting neuronal or glial phenotypes were thereafter assessed. Secretion of cytokines and the enzymes acetylcholinesterase (AChE), butyrylcholinesterase (BuChE) and choline acetyltransferase (ChAT) involved in cholinergic signalling was measured in medium throughout the differentiation. We report that differentiating neurospheres released various cytokines, and exposure to Aβf, but not AβO, increased the secretion of IL‐6, IL‐1β and IL‐2. Aβf also influenced the levels of AChE, BuChE and ChAT in favour of a low level of acetylcholine. These changes were linked to an altered secretion pattern of cytokines. A different pattern was observed in microglia activated by Aβf, demonstrating decreased secretion of TNF‐α, IL‐1β and IL‐2 relative to untreated cells. Subsequent exposure of differentiating neurospheres to Aβf or to microglia‐conditioned medium decreased neuronal differentiation and increased glial differentiation. We suggest that a basal physiological secretion of cytokines is involved in shaping the differentiation of neurospheres and that Aβf decreases neurogenesis by promoting a microenvironment favouring hypo‐cholinergic signalling and gliogenesis.     

Contractility and structure of adult rat seminiferous tubules in organ culture

Summary Isolated pieces of seminiferous tubules of adult rats were grown in organ culture for up to 8 weeks in Petri dishes on the surface of nutrient agar. The medium consisted of newborn calf serum, Eagle's minimum essential medium, glutamate and antibiotics. This method allowed observation of the contractions of the seminiferous tubules in the culture. Contractility, light and electron microscopic structure and histochemically demonstrable activities of alkaline phosphatase and ATPase of the tubule walls were studied at 1-week intervals. The contractility and alkaline phosphatase activity were maintained in the tubule wall for 3 weeks, and the activity of ATPase was maintained for 5 weeks. The thin filaments of the myoid cells, which are responsible for the contractility, were seen with the electron microscope in tubules cultured for 5 weeks. The organ culture method described in the present paper seems to be valuable for studies concerning the functioning of the myoid cells of the seminiferous tubules and the possibility that this is regulated by hormones.     

The derivation of clinical-grade human embryonic stem cell lines

The pluripotent nature of human embryonic stem cells (hESC) has attracted great interest in using them as a source of cells or tissue in cell therapy. However, in order to be used in regenerative medicine, the pluripotent hESC lines should be established and propagated according to good manufacturing practice quality requirements. The cultures should be animal substance free in order to exclude the risk of infections and immunogenity. They should also be genetically and epigenetically normal. The detailed molecular mechanisms of their pluripotency are still not defined. Using human feeder cells, a medium containing only human proteins, the mechanical isolation of the inner cell mass and mechanical passaging of hESC, is a safe option until a functional defined medium containing physiological concentrations of regulatory factors is available.     

Assignment of the locus for PLO-SL, a frontal-lobe dementia with bone cysts, to 19q13.

PLO-SL (polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy) is a recessively inherited disorder characterized by systemic bone cysts and progressive presenile frontal-lobe dementia, resulting in death at <50 years of age. Since the 1960s, approximately 160 cases have been reported, mainly in Japan and Finland. The pathogenesis of the disease is unknown. In this article, we report the assignment of the locus for PLO-SL, by random genome screening using a modification of the haplotype-sharing method, in patients from a genetically isolated population. By screening five patient samples from 2 Finnish families, followed by linkage analysis of 12 Finnish families, 3 Swedish families, and 1 Norwegian family, we were able to assign the PLO-SL locus to a 9-cM interval between markers D19S191 and D19S420 on chromosome 19q13. The critical region was further restricted, to approximately 1.8 Mb, by linkage-disequilibrium analysis of the Finnish families. According to the haplotype analysis, one Swedish and one Norwegian PLO-SL family are not linked to the chromosome 19 locus, suggesting that PLO-SL is a heterogeneous disease. In this chromosomal region, one potential candidate gene for PLO-SL, the gene encoding amyloid precursor-like protein 1, was analyzed, but no mutations were detected in the coding region.