Mice cloned from white adipose tissue-derived cells

Technical advances contribute to the study of genomic imprinting

Genomic imprinting in mammals was discovered over 30 years ago through elegant embryological and genetic experiments in mice. Imprinted genes show a monoallelic and parent of origin-specific expression pattern; the development of techniques that can distinguish between expression from maternal and paternal chromosomes in mice, combined with high-throughput strategies, has allowed for identification of many more imprinted genes, most of which are conserved in humans. Undoubtedly, technical progress has greatly promoted progress in the field of genomic imprinting. Here, we summarize the techniques used to discover imprinted genes, identify new imprinted genes, define imprinting regulation mechanisms, and study imprinting functions.

Conversion of Adipose Tissue-Derived Mesenchymal Stem Cells to Neural Stem Cell-Like Cells by a Single Transcription Factor, Sox2

Adipose tissue is an attractive source of easily accessible adult candidate cells for regenerative medicine. Adipose tissue-derived mesenchymal stem cells (ADSCs) have multipotency and strong proliferation and differentiation capabilities in vitro. However, as mesodermal multipotent stem cells, whether the ADSCs can convert into induced neural stem cells (NSCs) has so far not been demonstrated. In this study, we found that normally the naïve ADSCs cultured as either monolayer or spheres in NSC medium did not express Sox2 and Pax6 genes and proteins, and could not differentiate to neuron-like cells. However, when we introduced the Sox2 gene into ADSCs by retrovirus, they exhibited a typical NSC-like morphology, and could be passaged continuously, and expressed NSC specific markers Sox2 and Pax6. In addition, the ADSC-derived NSC-like cells displayed the ability to differentiate into neuron-like cells when switched to the differentiation culture medium, expressing neuronal markers, including Tuj1 and MAP2 genes and proteins. Our results suggest the ADSCs can be converted into induced NSC-like cells with a single transcription factor Sox2. This finding could provide another alternative cell source for cell therapy of neurological disorders.

Generation of embryonic stem cells from mouse adipose-tissue derived cells via somatic cell nuclear transfer

Somatic cells can be reprogrammed into embryonic stem cells (ESCs) by nuclear transfer (NT-ESCs), or into induced pluripotent stem cells (iPSCs) by the "Yamanaka method." However, recent studies have indicated that mouse and human iPSCs are prone to epigenetic and transcriptional aberrations, and that NT-ESCs correspond more closely to ESCs derived from in vitro fertilized embryos than iPSCs. In addition, the procedure of NT-ESCs does not involve gene modification. Demonstration of generation of NT-ESCs using an easily-accessible source of adult cell types would be very important. Adipose tissue is a source of readily accessible donor cells and can be isolated from both males and females at different ages. Here we report that NT-ESCs can be generated from adipose tissue-derived cells (ADCs). At morphological, mRNA and protein levels, these NT-ESCs show classic ESC colonies, exhibit alkaline phosphatase (AP) activity, and display normal diploid karyotypes. Importantly, these cells express pluripotent markers including Oct4, Sox2, Nanog and SSEA-1. Furthermore, they can differentiate in vivo into various types of cells from 3 germinal layers by teratoma formation assays. This study demonstrates for the first time that ESCs can be generated from the adipose tissue by somatic cell nuclear transfer (SCNT) and suggests that ADCs can be a new donor-cell type for potential therapeutic cloning.

Citalopram increases the differentiation efficacy of bone marrow mesenchymal stem cells into neuronal-like cells

Several studies have demonstrated that selective serotonin reuptake inhibitor antidepressants can promote neuronal cell proliferation and enhance neuroplasticity both in vitro and in vivo. It is hypothesized that citalopram, a selective serotonin reuptake inhibitor, can promote the neuronal differentiation of adult bone marrow mesenchymal stem cells. Citalopram strongly enhanced neuronal characteristics of the cells derived from bone marrow mesenchymal stem cells. The rate of cell death was decreased in citalopram-treated bone marrow mesenchymal stem cells than in control cells in neurobasal medium. In addition, the cumulative population doubling level of the citalopram-treated cells was significantly increased compared to that of control cells. Also BrdU incorporation was elevated in citalopram-treated cells. These findings suggest that citalopram can improve the neuronal-like cell differentiation of bone marrow mesenchymal stem cells by increasing cell proliferation and survival while maintaining their neuronal characteristics.

The adipose-derived lineage-negative cells are enriched mesenchymal stem cells and promote limb ischemia recovery in mice

White adipose tissue (WAT) is a very attractive source of mesenchymal stem cells (MSCs) because of its availability and ease of harvest. However, the current method of isolating adipose tissue-derived MSCs often relies on the adhesiveness of the cultured stromal-vascular fraction (SVF). Unfortunately, the SVF is a heterogeneous cell population containing many cell types, including adipocyte precursor cells, endothelial cells, pericytes, multipotent MSCs, erythrocytes, and hematopoietic cells. Here we systematically characterized the adipose tissue-derived lineage-negative (Lin(-)) cell population using various surface markers and a set of cell proliferation and differentiation assays. We demonstrate clearly that the Lin(-) cell population represents enriched MSCs, which were identified by their high expression of MSC surface markers, and that these cells are a robust population with a vigorous growth capability and delayed aging. This cell population also demonstrated a much higher capacity for differentiation into osteogenic, chondrogenic and adipogenic cell lineages related to MSCs than did the SVF. These cells promoted recovery from limb ischemia, likely via production of vascular endothelial growth factor, an angiogenic factor. Our study demonstrates that Lin(-) cells are enriched in MSCs and provides a reliable method for isolating purer MSCs than SVF cells from the WAT, especially for obtaining fresh MSCs for clinical applications. In summary, this study identified a new, reliable method for enrichment of WAT MSCs with regenerative repairing features.