Biomedical subjects

Uma Lakshmipathy

Publications and source records attributed to Uma Lakshmipathy.

3 recordsLinked to original sources

PubMed2005

Stem cell plasticity.

The central dogma in stem cell biology has been that cells isolated from a particular tissue can renew and differentiate into lineages of the tissue it resides in. Several studies have challenged this idea by demonstrating that tissue specific cell have considerable plasticity and can cross-lineage restriction boundary and give rise to cell types of other lineages. However, the lack of a clear definition for plasticity has led to confusion with several reports failing to demonstrate that a single cell can indeed differentiate into multiple lineages at significant levels. Further, differences between results obtained in different labs has cast doubt on some results and several studies still await independent confirmation. In this review, we critically evaluate studies that report stem cell plasticity using three rigid criteria to define stem cell plasticity; differentiation of a single cell into multiple cell lineages, functionality of differentiated cells in vitro and in vivo, robust and persistent engraft of transplanted cells.

Adult↗

PubMed2004

Efficient transfection of embryonic and adult stem cells.

The ability of embryonic stem cells and adult stem cells to differentiate into specific cell types holds immense potential for therapeutic use in cell and gene therapy. Realization of this potential depends on efficient and optimized protocols for genetic manipulation of stem cells. In the study reported here, we demonstrate the use of nucleofection as a method to introduce plasmid DNA into embryonic and adult stem cells with significantly greater efficiency than electroporation or lipid-based transfection methods have. Using enhanced green fluorescent protein (eGFP) as a reporter gene, mouse embryonic stem cells were transfected both transiently and stably at a rate nearly 10-fold higher than conventional methods. The transfected cells retained their stem cell properties, including continued expression of the stem cell markers SSEA1, Oct4, and Rex1; formation of embryoid bodies; differentiation into cardiomyocytes in the presence of appropriate inducers; and, when injected into developing blastocysts, contribution to chimeras. Higher levels of transfection were also obtained with human embryonic carcinoma and human embryonic stem cells. Particularly hard-to-transfect adult stem cells, including bone marrow and multipotent adult progenitor cells, were also transfected efficiently by the method of nucleofection. Based on our results, we conclude that nucleofection is superior to currently available methods for introducing plasmid DNA into a variety of embryonic and adult stem cells. The high levels of transfection achieved by nucleofection will enable its use as a rapid screening tool to evaluate the effect of ectopically expressed transcription factors on tissue-specific differentiation of stem cells.

Animals↗

PubMed2002

Expression of bacterial endonucleases in Saccharomyces cerevisiae mitochondria.

Expression vectors were created in which the 5' end of the Saccharomyces cerevisiae CDC9 gene, which encodes a mitochondrial targeting peptide, was cloned in-frame with the coding regions of the EcoR I, Hind III, and Pst I endonuclease genes. Expression of the EcoR I and Hind III fusion proteins inhibited growth of yeast on glycerol-containing media and resulted in the nearly quantitative restriction digestion of their mitochondrial DNA. In contrast, expression of Pst I, which does not recognize any sites within yeast mitochondrial DNA, had no effect on growth in glycerol-containing media, and did not affect the integrity of the mitochondrial genome.

Journal Article↗