Biomedical subjects

Maria Lucia Scaldaferri

Publications and source records attributed to Maria Lucia Scaldaferri.

4 recordsLinked to original sources

PubMed2005

Growth factors sustain primordial germ cell survival, proliferation and entering into meiosis in the absence of somatic cells.

It is known that mammalian primordial germ cells (PGCs), the precursors of oocytes and prospermatogonia, depend for survival and proliferation on specific growth factors and other undetermined compounds. Adhesion to neighboring somatic cells is also believed to be crucial for preventing PGC apoptosis occurring when they lose appropriate cell to cell contacts. This explains the current impossibility to maintain isolated mouse PGCs in culture for periods longer than a few hours in the absence of suitable cell feeder layers producing soluble factors and expressing surface molecules necessary for preventing PGTC apoptosis and stimulating their proliferation. In the present paper, we identified a cocktail of soluble growth factors, namely KL, LIF, BMP-4, SDF-1, bFGF and compounds (N-acetyl-L-cysteine, forskolin, retinoic acid) able to sustain the survival and self-renewal of mouse PGCs in the absence of somatic cell support. We show that under culture conditions allowing PGC adhesion to an acellular substrate, such growth factors and compounds were able to prevent the occurrence of significant levels of apoptosis in PGCs for two days, stimulate their proliferation and, when LIF was omitted from the cocktail, allow most of them to enter into and progress through meiotic prophase I. These results consent for the first time to establish culture conditions for purified mammalian PGCs in the absence of somatic cell support and should make easier the molecular dissection of the processes governing the development of such cells crucial for early gametogenesis.

Acetylcysteine↗

PubMed2005

Adhesion molecules for mouse primordial germ cells.

In the present article we will focus on the adhesion molecules expressed by mouse primordial germ cells (PGCs) and will discuss the role that they play, or are believed to play, in two crucial processes of PGC development, namely cell lineage specification and migration into the gonadal ridges. Recent findings indicate that the adhesion-dependent allocation of the PGC precursors to a niche within the epiblast and the forming extraembryonic mesoderm during the pre-gastrulation period is crucial for their commitment. Subsequently, PGC migration and homing within the gonadal ridges require integrated signals involving contact of PGCs with extracellular matrix molecules and cellular substrates or repulsion from them, adhesion among PGCs themselves and attraction by the developing gonads. A number of adhesion, or putative adhesion molecules, have been identified in mammalian PGCs, mainly in the mouse. These molecules belong to three adhesion molecule families such as cadherins (E-P- and N-cadherins), integrins and the IgG superfamily (PECAM-1). Moreover oligosaccarides (LewisX) and growth factor receptors (c-Kit) can also play adhesive roles in some stages of PGC development. An understanding of how genes encoding adhesive molecules are regulated in PGCs and the molecular pathways associated with the functions of adhesion receptors is crucial in furthering our knowledge of PGC biology. Adhesion molecules might once again turn out to be crucial in controlling not only the germ cell lineage and PGC migration but also the PGC differentiation fate itself.

Animals↗

PubMed2005

Establishment of oocyte population in the fetal ovary: primordial germ cell proliferation and oocyte programmed cell death.

Strict control of cell proliferation and cell loss is essential for the coordinated functions of different cell populations in complex multicellular organisms. Oogenesis is characterized by a first phase occurring during embryo-fetal life and in common with spermatogenesis, during which mitotic proliferation of the germline stem cells, the primordial germ cells (PGC), prevails over germ cell death. The result is the formation of a relatively high number of germ cells depending on the species, ready to enter sex specific differentiation. In the female, PGC enter into meiosis and become oocytes, thereby ending their stem cell potential. After entering into meiosis in the fetal ovary, oocytes pass through leptotene, zygotene and pachytene stages before arresting in the last stage of meiotic prophase I, the diplotene or dictyate stage at about the time of birth. The most part of oocytes die during the fetal period or shortly after birth. It is widely accepted that in mammals a female is born with a fixed number of oocytes within the ovaries, which over the years progressively decreases without possibility for renewal. Once the oocyte reserve has been exhausted, ovarian senescence, driving what is referred to as the menopause in women, rapidly ensues. The fertile lifespan of a female depends by the size of the oocyte pool at birth and the rapidity of the oocyte pool depletion. Which mechanisms control PGC proliferation? Why do most of the oocytes die during fetal life and what are the mechanisms of such massive degeneration? Is it possible to prolong the lifespan of a female by reducing oocyte lost during the fetal life? This review reports some of the most recent results obtained in an attempt to answer these questions.

Animals↗

PubMed2005

In vitro restoration of functional SMN protein in human trophoblast cells affected by spinal muscular atrophy by small fragment homologous replacement.

The majority of patients affected by spinal muscular atrophy (SMA) have deletion of the survival of motor neuron 1 (SMN1) gene, but they retain a "nonfunctional" copy of the duplicate gene (SMN2) in their genome. SMN2 produces defective SMN protein because of a C --> T transition in exon 7, which causes the skipping of exon 7 during SMN mRNA maturation. Many attempts have been made to correct altered SMN gene expression and to increase the level of normal SMN protein, but to date an effective treatment for this disease has not been established. Small Fragment Homologous Replacement (SFHR) is a site-specific gene modification approach that has the potential to maintain the genomic organization necessary for expression. The target modification in the genome is mediated by small DNA fragments (SDFs) 400-800 bp in length. In this study we used SFHR to induce a T --> C transition at codon 280 in exon 7 of the SMN2 gene in order to produce an increase in functional SMN protein. SDFs were transfected in vitro into cells obtained from five human fetal chorionic villi of embryos, homozygous for the SMN1 deletion, by either electroporation or microinjection. Transfected SMA cells showed an increase of up to 53% in full-length SMN mRNA compared with untransfected controls, as detected by real-time polymerase chain reaction. Consistent with the RNA data, immunocytochemistry and immunoblotting revealed a significant 2-fold increase in wild-type SMN protein. Furthermore, genotype and phenotype of transfected cells remained stable after several in vitro passages, demonstrating the stability of the correction over time.

Cells, Cultured↗