Natural killer (NK) cells constitute our bodies' frontline defense system, guarding against tumors and launching attacks against infections. The activities of NK cells are regulated by the interaction of various receptors expressed on their surfaces with cell surface ligands. While the role of NK cells in controlling tumor activity is relatively clear, the fact that they are also linked to various other disease conditions is now being highlighted. Here, we present an overview of the role of NK cells during normal body state as well as under diseased state. We discuss the possible utilization of these powerful cells as immunotherapeutic agents in combating diseases such as asthma, autoimmune diseases, and HIV-AIDS. This review also outlines current challenges in NK cell therapy.

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Human embryonic stem cells (hESCs) offer new avenues for studying human development and disease progression in addition to their tremendous potential toward development of cell-replacement therapies for various cellular disorders. We have earlier reported the derivation and characterization of Relicell(®) hES1, the first fully characterized hESC line generated from the Indian subcontinent. Recent studies have demonstrated discrete differences among hESC lines, in terms of both their growth properties and their differentiation propensity. To address some of these issues in the context of hESC research in India, we have recently generated two new hESC lines: Relicell(®) hES2 and Relicell(®)hES3. Both these cell lines were derived using a combinatorial approach of immunosurgery followed by mechanical surgery for inner cell mass isolation. The cell lines exhibit the usual hESC characteristics including their ability to differentiate both in vitro and in vivo to yield the three germinal layers. Whole genome microarray analysis of these cell lines was compared with Relicell(®)hES1 and it showed that approximately 9000 genes were expressed by these lines. As expected the expression pattern of these new cell lines bore close resemblance to that of Relicell(®)hES1. A majority of the pluripotency genes and the genes known to inhibit various differentiation pathways were also expressed by these cell lines. We also observed that each of these cell lines expressed a unique set of genes that are mutually exclusive from each other. These results represent the first detailed characterization of a set of hESC lines originating from India.

Human embryonic stem cells offer a renewable source of a wide range of cell types for use in research and cell-based therapies. Characterizing these cells provides important information about their current state and affords relevant details for subsequent downstream manipulation. Prior to considering therapeutic applications, it is crucial that the cells are surveyed at a genetic and proteomic level during the extensive propagation, expansion and differentiation. Hence, a set of characterization tests to measure stem cell stability and identity--genomic, epigenomic and mitochondrial markers, as well as functional measures of utility, need to be developed. Thus, we outline a plan of standard assays that can be afforded by multiple laboratories to unambiguously test the quality of human embryonic stem cells. In this manuscript, we describe a comprehensive characterization of ReliCell hES1, the only human embryonic stem cell line reported from the Indian subcontinent. Our study employs gene expression analysis using quantitative reverse transcription-polymerase chain reaction and microarray, mitochondrial DNA sequencing, microRNA analysis, immunophenotyping and teratoma formation, in addition to demonstrating its capacity to propagate under feeder-free conditions.