Stem-cell Technology Advances 0
Abstract
Un-differentiates cells are called blank cells. Grown in cell culture for few generations, they remain un-differentiated. How to know they are un-differentiated has been discussed in this paper. The embryonic stem cells have been used to recover many diseases by direct differentiation. Various mechanisms and methods described. The planning and policy situation of Stem Cell Technology in its country of origin has been reviewed. The pituitary hypoplasia diagnosis to be a stem cell defect. Foreign gene expression in embryos, transgenic and animal modeling for disease cure has been postulated, on the basis of research results reported. Various embryo manipulation, transfer of gene, nuclear injection, gene mapping, isolation and analysis of gene in future have been reported and discussed. Embryonic Stem Cell Therapeutics, Gene targeting, cell death, cell differentiation, programming molecules research has been reviewed. Mutation defects in mice have been related to stem cell defects. A 2 step process of gene targeting mechanism has been developed which help a lot in gene therapy and animal genetic manipulations.
Gene trap strategies and mechanism of its use for human and animal good has been briefly hinted at for future researchers to initiate new research mechanism.
5. Embryonic stem cell:
Foetal tissues- a source of embryonic stem cell can too differentiate into various cell types through three germ layers.
Embryonic stem cells (ESC) can be had from inner cell mass of pre implantation embryo and cultured in mouse embryonic feeder cells. Embryonic development after fertilization has been detailed ( Wani, 1996). After fertilization within 30 hrs zygote divides and becomes a morula in 3-4 days post coitus. A blastocyst is seen within 5-6 days, p. c. The 150µ blastocyst (1/7 th of a mm) has already differentiated into outer trophoblast (70 cells and inner cell mass, cluster of 30 cells). They are multipotent and rise to germ layers ectoderm, mesoderm and endoderm. Maintenance of ICM cell lines, culture feeder layers under undifferentiated state in now possible by Leukemia Inhibitory Factors (LIF) addition to growth culture. Some of the figures 1-5 show schematic development of fertilized eggs. The research has entered an advance phase and we have many tests which can differentiate stem cell from differentiated cells. Various details are shown in table 1 and this phenomenon briefly represented in Figure 2. The Embryoid bodies are graphically represented in Figure 3.
Differentiation
ICM cell proliferate and undergo differentiation. The activity of lineage specific genes is the evidence of differentiation. Lineage commitment is infact the beginning of the differentiation. Thus totipotencey is infact multilineage expression now. The trancriptosome activity is thus a signal. Its minimal activity maintains the cell in open state. The levels are low but in detectable levels, so its standardization could help to maintain them?
Programming Molecules
A broad review of about 100 research publications in presented in these pages, under various heads.
Stem -Cell –Technology
Stem- cells are undifferentiated cells. The embryo at morulla stages has undifferentiated blastomers. These cells can transform themselves into 200 or more cell type, which could be used to repair or regenerate new desired cells. This advanced cell research may help diseased people like those suffering from cancer, Alzheimer’s disease syndrome, Parkinson’s disease and even paralysis.
The stem cells are derived from 4-5 days old embryos or fertilized cells. The stem-cell- technology has a new role to play in animal reproduction.
Firstly, the stem cell source could be pooled out of slaughter house oocytes or from the vast pool of embryos hatching out in many animal species.
Secondly, the cell source could be obtained from foetal culture and if new-grown-–immunoprotectant cell of foetus could help or provide germ-cell specific to any particular organ, the repair of organs could be a new revolution.
The Demethylases- reprogramming molecules present in blastocyst cytoplasm may be a positive factor for maintenance of open transcriptosome activity. Similarly, heterochromatin modeling and regulation could be negative mechanism. The inadequate knowledge of regulatory gene today hamper our understanding but tomorrow we could know switch off and on of these regulators & various interfering mechanism like methylation effects and SIRNA (Small Interfering RNA). In future, we dream for Genome shuffling i. e. shape of the genome profile. The gene profile like October 4 embryos & BMP4 etc. has already been identified. More identification is on; solutions are expected, through research.
U. K Cabinet decisions in 1990
Biotechnology in general and stem-cell-nanotechnology in particular is still not in its applied stage even in U. K. A balanced information system, inter-research council is suggested. Cabinet office (1990) U. K Govt. has started supporting embryonal stem cell technology. Manpower shortage in Embryo manipulation in cattle, protein engineering, animal trans genesis, stem cell biology is felt. Thus these fields are future emerging technologies to enhance livestock and agri-productivity. More and more researchers shall be attracted to this area, as more jobs securities are evident in industry related to stem cell technologies.
Mutation defects investigated
Agricultural and food research council of UK has stressed some of the scientific thrust areas like molecular biology, biochemistry, intracellular signaling stem cell biology, global climatic change and agro-based food production & safety. The transgenic animal modeling to develop disease targeting as reviewed (Wani, 2007) has been the main focus of human disease cure models in centre of genomic research university of Edinburgh. The focus has been on use of transgenic in the fields of toxicology, cardiovascular diseases, pulmonary diseases, inflammatory and immunological diseases. Many neuropsychiatries, reproductive, endocrinological, embryological disorders could be evaluated and studied through these animal transgenic models. High priority in funding in suggested for initiating these areas. (Lathe & Mullins, 1993, Wani, 2008).
Animal breeding has entered an era of embryo manipulation, transfer of genes, nuclear injections, gene mapping, isolation and analysis of genes for future genetic gains. (Bul field et. al. , 1994). This would have tremendous impact on animal related development. The detailed procedures have been described (Houdebine. 1992). Insertional mutagenesis and mouse development have been reported ( Kuelin et. al. , (1992). Various mice were generated with disrupted TAPS gene using embryonic stem cell Technology (Kaer-L-Van et al, 1992). Ruminant microbial degradation using stem cells were used to improve ruman feed degradability. (Goto et. al. , 1993). Embryonic stem cells were used in embryonic stem therapeutics to generate various modes of Trypanosoma cruzi, parasitaemia, CD4 or CD8 molecules differed in interferon mRNA contents. This mechanism when moduled into theraphy modes may yield resistance, against Trypanosama cruzi or brucei (Rottenberg et. al. , 1993). Bone healing was achieved through Bone morphogenetic proteins (BMPS). These are differentiative factors whose principal function is to induce transformation of undifferentiated mesenchymal cells into chondroblasts and osteoblasts in dose-dependent manner. (Kirker et. al. , 1995). Germ- line chimeras have been produced in mice. (Uchida et al 1995)
Gene Targeting-2 step process
Gene targeting strategy was developed. This was used to develop many mice strains. The so called double replacement gene targeting is a 2-step process in which a region of the gene of interest is first replaced with a selectable marker. An inactivated allele so formed is retargeted with another vector to yield or reconstruct the inactivated allele. (Moore et. al. , 1995). Pierre-Robin Syndrome in human signaling skeletal and facial abnormalities is of great importance. Similar abnormalities reminiscent of this disease was generated using activin receptor type II. This Act Rc II was found to signal pituitary gonadotrophins and reproductive performance was defective. All Act Rc II deficient mice did not show the skeletal or facial abnormalities, but showed pituitary release or FSH suppression defects. (Matzuk et al, 1995).
Gene Therapy
Embryonic Stem Cell Technology uses have been discussed in theraphy of human diseases. (Ramirez & Bradley, 1994). Inhibin deficient mice are prone to gonadal cancers. (Mutzuk et. al. , 1994). Livestock transgenesis and potentiality of stem-Cell Technology use is reviewed (Seemark, 1994).
Gene transgetting in reproductive studies has been reported as earlier as 1995. (Camper et al, 1995). Experiment on laboratory Animal, has been concern of animal welfare associations. Transgenic technology can reduce animal use in future. (Gordon et al, 1997). Procine Chimeras have been produced using primodial germ cell derived colonies. (Piedrahita et. al. , 1998). Introducing mutations using gene targeting technique in mice has been reported. (Torres & Kulin, 1997). A detailed review covering transgenic animal modeling has been reviewed. The technologies like DNA microinjection, embryonic stem cell technology, traits affecting domestic animal.
Productivity, animal bioreactors have been discussed (Pinkert et al, 1996).
Directed differentiation
New concept on FSH , mechanism action using embryonic stem cell technologyhas been studied. FSH is needed for follicle maturation in females. Its role in male fertility, as was not established (Kumar et. al. , 1997).
Stem cell biology has revealed that stem cells have the capacity to renew their self. Some stem cells can been directed to choose a selected pathway. It means they can differentiate into particular cells only. One can use growth factors cell lineage identification mechanism is needed to achieve a break through. Various questions are still not clear like regeneration in response to injury. The system recognition and regeneration manipulative mechanisms are being searched. (Morrison at al, 1997).
Embryonic stem cell lines has been established in many specie besides mice like cattle, rats etc (stranzinger,1996).
Various reviews on reproductive physiological research and future prospects have been reported. (Foote, 1996) more recent reviews have been published (Wani, 2007, 2008). New techniques, describing gene trap strategies or embryonic nervous systems have been in use since last one decade in Japan (Shiraieh et. al. , 1996). Yamada et. al. (1994) described gene targeting approaches. His review describes methods of using embryonic stem cells for gene targeting growth and differentiation studies. Hair development is now possible using keratinocyte- growth factors isolates. (Muridae et. al. , 1996). Using stem cell factor melanoma in gray horses was investigated. No such association with coat colour was established (Rieder et. al. , 1999). Embryonic sex was determined in pre-implantation embryos, using green fluorescent protein (GFP) gene on X chromosome. (Little 1998).
A stem cell defect in mice has been related to mutations that cause pituitary dwarfism. The cause lies in the gene encoding the transcription of growth hormone factor 1. (GHF 1 or pit 1). The dwarf mice were found to be deficient in growth hormone (GH), prolactin synthesis. Thus they exhibit pituitary hypolasia -a- stem cell defect. Tolipotent embryonic stem cells can be identified by the methods described (Reddy et. al. 1992). Foreign gene expression in embryos had been described (Kondoh et. al. ,1991)This has resulted in success of transgenesis of mice,fowls and fishes.
Stem cells are blanks cells, which can be cultured and give rise to any kind of cells and tissues. They are ploripotent cells, which proliferate and can be differentiated into different cells types. Various other cells have this capacity which is briefly explained (Puri 2003). They have a capacity to revitalize diseased tissue and can replace organ transplantation. Stem cell technology, promise safety against life threatening diseases and organ replacements. This is possible by creating identified cell lines which will give rise to tissue and organs for replacing diseased parts, thus we see a futuristic replacement of blood bank with stem cell bank.
Stem cell line availability may help cloning. The evidence of such miracle was born in February, 1997 named “Dolly the Sheep. ” Dolly came into existence by fusion of an adult mammary cell nucleus of a pregnant Finn Dorset White Sheep with enucleated Oocyte of Scottish black Face Ewe. The embryo so developed invitro was reared to birth in the uterus of a black faced ewe. Since then cloning of pets and animals is in practice and even human clones are the fantary of HBO film displays. This has brought home many realities of spiritualism like birth of Christ and above all the birth of Isaq. A hope to infertile couple to have babies of their own origin. Here genetic make up is not borrowed but is ones own. Unlike invotro- fertilization the need of sperm cell too is warded off. So a baby to a virgin is a reality. It has many benefits, risks and applications too. A brief is as:-
Advantages
Organ replacement, no illegal sale of organs and exploitations.
Drug sensitivity test- animal friendly- animal welfare approach.
Genomic research possible- many unanswered questions shall be replied.
Risks
Oncogenic potential and ethical conflicts
Applications
Animal with higher yield could be produced.
Gene mapped animals may be possibility with simple means.
Embryonic development solutions could be found.
Aging research may reveal many secrets of longevity. Models for diseases investigations with cells and tissue can save animals and humans. Drug sensitivity tests shall be simpler. Gene targeting will be possible.
Cell Death Warded Off
The Somatic cells have DNA polymerase activity which is unable to replicate the end of a linear molecule, so it is unable to make up for the ends of eukaryotic chromosomes, which shorten at ends so the aging effect. This is why chromosome becomes progressively instable and thus leads to cell death. This formative defect is awarded off in stem cell. These cells are toti potent and hence have no chromosomal abrasion possibilities, nicely passaged germ cells without having clubbing into Embryoid.
2. Stem Cell Technology
The concerns shadowing our livestock improvements are poor zoo- sanitation. Our huge products humps needs export market. Our poor disease safety procedures need to be sharpened. Our milk products at present are imported by Bangladesh and Sri- Lanka alone leaving a huge surplus in our Gowdowns. International zoo sanitary conditions need products from disease- free animals. This is possible by preventing animal disease. Therefore a new thrust on immunological studies like stem cell, primodial Germ Cell, fetal and cord blood cells shall be our endeavor to discuss in these pages.
1. Introduction
