Stem cells with the capacity to form any type of tissue can be created from adult cells without destroying embryos, according to a new research that suggests a way of sidestepping ethical controversy over the field.
Embryonic stem cells (ESCs) are found only in early embryos and are attractive to medical researchers as they are ‘pluripotent’ – they can give rise to all the 200 or so tissue types found in the human body. The goal is to find ways of directing their growth as they can be used to provide replacement tissue for treating conditions such as Parkinson’s, diabetes, and spinal paralysis. They are also the source of ethical controversy: the cells are derived from excess human embryos discarded after in vitro fertilization and obtaining them requires destruction of the embryos.
Two groups – one led by Shinya Yamanaka at Kyoto university in Japan and one led by Thompson and Junying Yu at the University of Wisconsin – separately engineered human skin cells to express 4 different genes. For reasons not yet clear, exposing cells to these genes appears to turn back the developmental clock. Both groups found that the resulting cells exhibit two major properties that define ESC’s – pluripotency divide indefinitely in their undifferentiated state. While the new cells look and act like ESCs, it is not yet clear just how similar they are. A screen of the expression of 30,000 genes showed that the pluripotent cells are similar but not identical to ESCs.
Both teams used viral DNA to introduce genes for 4 transcription factors – proteins that turn on other genes in the cell – into fibroblasts – a type of skin cell. Two of these transcription factors were the same in both groups; two were different. Scientists theorize that when expressed in adult cells. The transcription factors activate a genetic cascade that returns the cell and its DNA to an embryonic–like state. When implanted into mice, the cells generated a ball of tissue containing multiple differentiated cell types, a standard test for cell pluripotency. Yamanaka’s team also showed that the cells could differentiate into muscle and nerve cells, employing the same protocols used with ESCs.
Before these cells can be considered for human therapeutics, the researchers will need to develop an alternative way to express the transcription factors. The viruses currently used can integrate into genome and pose potential safety concerns. Germline transmission is the final and definitive proof that these cells can do anything a traditionally derived ESC can do.
There is still a long way to go, however!
Source:
http://www.technologyreview.com/biotech/19742
http://www.timesonline.co.uk/tol/news/uk/health/article1895546.ece
Dec 5, 2007
Nov 24, 2007
Life minus Nine
We define life in many ways. All the research in the world is aimed primarily at only one target - improving human lives. The past steps lead us to a new gate called ‘nanotechnology'. Although research in this field has been going on for decades, it is only now that the focus light is turned on. It will be worthwhile to spend some time on it.
Nanotechnology, like life, can be defined in many ways, its areas extending far beyond just physics, chemistry, or biology. Here, I try to relate these hard-to-define terms, "life" and "nano". What would life be 'minus nine'? I would rather prefer to talk about life 'plus' nine.
It is customary to define nanoparticles or nanostructures as entities in the range of sizes from 1 - 100 nm, thus many biological materials can be classified as nanoparticles. Considering a gradation in this range, we can include, viruses, which range in size between 10 to 200 nm, in the upper part of the nanoparticle range. Proteins, ranging between 4 and 50 nm, are in the low nanometer range, while the building blocks of proteins, the amino acids - each about 0.6 nm in size - are below the lower limit of a nanoparticle. These are a few of the examples that could be considered in the nanoscale. The structures made up by these particles sometimes end up in the same range too.
A protein is a combination of any of the 20 amino acids, bound together one after the other by strong peptide chemical bonds. These chains called polypeptides contain hundreds, and in some cases thousands of amino acids; hence they correspond to "nanowires". The polypeptide nanowires further undergo twistings and turnings to compact themselves into a relatively small volume forming a polypeptide nanoparticle, with a diameter that is typically in the range of 4 - 50 nm. Thus a protein is a nanoparticle consisting of a compacted polypeptide nanowire.
The genetic material deoxyribonucleic acid (DNA) has the structure of a compacted nanowire. It is made up of 4 nucleotide molecules that bind together in a long double helix to form chromosomes. Thus the DNA molecule is a double-nanowire, with the strands twisted around each other with a repeat unit every 3.4 nm, and a diameter of 2 nm.
Another biological structure made up of subunits in the nanometer range size is the human tendon. The function of a tendon is to attach a muscle to a bone. The fundamental building block of a tendon is the assemblage of amino acids that form a gelatin- like protein called 'collagen' (1 nm), which coils into a triple helix (2 nm). Further arrangement then follows a three-fold sequence of fibrillar nanostructures: a microfibril (3 - 5 nm), a subfibril (10 - 20 nm), and a fibril itself (50 - 500 nm). These nanostructures then make up the macroscopic tendon.
A view of these biological nanostructures would give us an idea what role the study of nanoparticles plays in biology. Taken to the scrap, many important biomolecules may end up in nanoparticles. Since the smallest amino acid, glycine is 0.42 nm in size, and some viruses reach 200 nm, it will be appropriate to define a biological nanostructure as being in the nominal range from 0.5 to 200 nm. It is our discretion to study them as a separate class, to place them in a separate group, or to create a new field called 'nanobiotechnology'.
Remember, best things come in small packages!
Nanotechnology, like life, can be defined in many ways, its areas extending far beyond just physics, chemistry, or biology. Here, I try to relate these hard-to-define terms, "life" and "nano". What would life be 'minus nine'? I would rather prefer to talk about life 'plus' nine.
It is customary to define nanoparticles or nanostructures as entities in the range of sizes from 1 - 100 nm, thus many biological materials can be classified as nanoparticles. Considering a gradation in this range, we can include, viruses, which range in size between 10 to 200 nm, in the upper part of the nanoparticle range. Proteins, ranging between 4 and 50 nm, are in the low nanometer range, while the building blocks of proteins, the amino acids - each about 0.6 nm in size - are below the lower limit of a nanoparticle. These are a few of the examples that could be considered in the nanoscale. The structures made up by these particles sometimes end up in the same range too.
A protein is a combination of any of the 20 amino acids, bound together one after the other by strong peptide chemical bonds. These chains called polypeptides contain hundreds, and in some cases thousands of amino acids; hence they correspond to "nanowires". The polypeptide nanowires further undergo twistings and turnings to compact themselves into a relatively small volume forming a polypeptide nanoparticle, with a diameter that is typically in the range of 4 - 50 nm. Thus a protein is a nanoparticle consisting of a compacted polypeptide nanowire.
The genetic material deoxyribonucleic acid (DNA) has the structure of a compacted nanowire. It is made up of 4 nucleotide molecules that bind together in a long double helix to form chromosomes. Thus the DNA molecule is a double-nanowire, with the strands twisted around each other with a repeat unit every 3.4 nm, and a diameter of 2 nm.
Another biological structure made up of subunits in the nanometer range size is the human tendon. The function of a tendon is to attach a muscle to a bone. The fundamental building block of a tendon is the assemblage of amino acids that form a gelatin- like protein called 'collagen' (1 nm), which coils into a triple helix (2 nm). Further arrangement then follows a three-fold sequence of fibrillar nanostructures: a microfibril (3 - 5 nm), a subfibril (10 - 20 nm), and a fibril itself (50 - 500 nm). These nanostructures then make up the macroscopic tendon.
A view of these biological nanostructures would give us an idea what role the study of nanoparticles plays in biology. Taken to the scrap, many important biomolecules may end up in nanoparticles. Since the smallest amino acid, glycine is 0.42 nm in size, and some viruses reach 200 nm, it will be appropriate to define a biological nanostructure as being in the nominal range from 0.5 to 200 nm. It is our discretion to study them as a separate class, to place them in a separate group, or to create a new field called 'nanobiotechnology'.
Remember, best things come in small packages!
Oct 7, 2007
Take a closer look
This is perhaps the smallest toilet in the world!
This nanotoilet is the winner of the Most Bizarre prize at The 49th International Conference on Electron, Ion and Photon Beam Technology and Nanofabrication Bizarre/Beautiful Micrograph Contest.
Here is the 2004 winner...
Fishing with Nanotubes – These micro fish appear hooked on nanotubes with a catalyst bait.
Check out the rest of the images here.
Oct 2, 2007
Flying Nano Wonders
Butterflies are probably the most beautiful creatures on earth. Those colorful wings captivates you with its beauty.
Have you ever thought whether those magical patterns are formed by true colors??? In fact, these clever insects trick you into believing that their wings possess true colors. The wings have what can be called biophotonic crystals that scatter light in some intriguing ways. Something our 21st century physicists have hard time replicating in labs!
These are some ridges of nano dimensions found on the surface of the wings. These creatures have been exploiting the potentials of nanotechnology for the past 30 million years!!!!
What you see here is not some fabric... but the wings of a butter fly.
I found more details about this here. You may want to take a look at this site!
Have you ever thought whether those magical patterns are formed by true colors??? In fact, these clever insects trick you into believing that their wings possess true colors. The wings have what can be called biophotonic crystals that scatter light in some intriguing ways. Something our 21st century physicists have hard time replicating in labs!
These are some ridges of nano dimensions found on the surface of the wings. These creatures have been exploiting the potentials of nanotechnology for the past 30 million years!!!!
What you see here is not some fabric... but the wings of a butter fly.
I found more details about this here. You may want to take a look at this site!
Nano in the Eyes
At John Hopkins, researchers have developed a nanoparticle as a new biosensor to treat damaged retinal cells.
Biosensor detects oxidative stress inside the cells. It responds by regulating therapeutic gene expression. This reduces the damage caused by the free radicals.
Biosensor has an outer lipid layer. This layer also has some targeting proteins. These proteins recognize the endothelial cells lining the eye's blood vessels. The lipid outer layer ensures easy entry of the biosensor into the cell.
Once inside the cells, the DNA is exposed. If there is oxidative stress, the promoters are activated and two proteins are expressed. One, a fluorescent protein that helps in detection of the damaged cells; two, a therapeutic protein that reduces the damage.
They have tested the biosensor in animal models like mouse, rabbits, and dogs. These nanoparticles were also found to be nontoxic on cells but animals showed varied levels of toxicity.
You will find more info here.
Biosensor detects oxidative stress inside the cells. It responds by regulating therapeutic gene expression. This reduces the damage caused by the free radicals.
Biosensor has an outer lipid layer. This layer also has some targeting proteins. These proteins recognize the endothelial cells lining the eye's blood vessels. The lipid outer layer ensures easy entry of the biosensor into the cell.
Once inside the cells, the DNA is exposed. If there is oxidative stress, the promoters are activated and two proteins are expressed. One, a fluorescent protein that helps in detection of the damaged cells; two, a therapeutic protein that reduces the damage.
They have tested the biosensor in animal models like mouse, rabbits, and dogs. These nanoparticles were also found to be nontoxic on cells but animals showed varied levels of toxicity.
You will find more info here.
Toxin - Nanoparticle Combine Defeats Cancer
Diptheria toxin is a protein secreted by Corynebacterium diphtheriae.
The protein has three domains - A, B and T. The B domain is believed to be responsible for recognizing the cell surface receptors. The toxin is found to show affinity for heparin binding epidermal like growth factor like precursors, which are found on the cell surface. T domain aids the protein to gain entry into the cell.
The A chain has the enzymatic activity. It catalyzes the ADP ribosylation of eukaryotic aminoacyl transferase II. This prevents protein biosynthesis in the cells leading to cell death.
The diphtheria toxin A (DT - A) chain's toxic properties can be exploited by properly guiding them to the cells that need to be killed.
This is exactly what the researchers have done using nanotechnology.
A nanoparticulate system made of Poly(beta amino ester) polymer and poly( butane diol diacrylate co amino pentanol) was used to deliver the diphtheria toxin A (DT - A) gene. This gene is linked to a regulatory sequence that gets activated only in prostate cancer cells. While the specificity is taken care of by the gene regulator, safe delivery of the toxin into these cells is the responsibility of the nanoparticulate system. Now, the diphtheria toxin does the rest.
Studies in the laboratory show promising results. Well, I guess we can expect efficient nano based injectable or ingestible drugs to treat cancer in the near future.
The protein has three domains - A, B and T. The B domain is believed to be responsible for recognizing the cell surface receptors. The toxin is found to show affinity for heparin binding epidermal like growth factor like precursors, which are found on the cell surface. T domain aids the protein to gain entry into the cell.
The A chain has the enzymatic activity. It catalyzes the ADP ribosylation of eukaryotic aminoacyl transferase II. This prevents protein biosynthesis in the cells leading to cell death.
The diphtheria toxin A (DT - A) chain's toxic properties can be exploited by properly guiding them to the cells that need to be killed.
This is exactly what the researchers have done using nanotechnology.
A nanoparticulate system made of Poly(beta amino ester) polymer and poly( butane diol diacrylate co amino pentanol) was used to deliver the diphtheria toxin A (DT - A) gene. This gene is linked to a regulatory sequence that gets activated only in prostate cancer cells. While the specificity is taken care of by the gene regulator, safe delivery of the toxin into these cells is the responsibility of the nanoparticulate system. Now, the diphtheria toxin does the rest.
Studies in the laboratory show promising results. Well, I guess we can expect efficient nano based injectable or ingestible drugs to treat cancer in the near future.
Subscribe to:
Posts (Atom)