“CRISPR” stands for Clustered Regularly Interspaced Short Palindromic Repeats, which are the hallmark of a bacterial defense system which forms the basis for the popular CRISPR-Cas9 genome editing technology.
CRISPR-Cas9 is a genome editing tool that is creating a buzz in the science world. It is faster, cheaper and more accurate than previous techniques of editing DNA and has a wide range of potential applications.
A few months back, China’s Scientist He Jiankui had announced that he was successfully edited the genes of Twins named Lulu and Nana so that they won’t get affected by HIV virus which causes AIDS. He used CRISPR gene editing tool for achieving this.
Since this kind of Gene-editing is illegal in most of the Countries including China, He Jiankui was put under house arrest by the Chinese Government.
Scientists from the German Cancer Research Center (DKFZ) and the stem cell institute HI-STEM in Heidelberg have succeeded for the first time in directly reprogramming human blood cells into a previously unknown type of neural stem cell. These induced stem cells are similar to those that occur during the early embryonic development of the central nervous system. They can be modified and multiplied indefinitely in the culture dish and can represent an important basis for the development of regenerative therapies.
Stem cells are considered to be the all-rounders of our tissues: they
can multiply indefinitely and then – if they are pluripotent embryonic
stem cells – generate all conceivable cell types. In 2006, the Japanese
scientist Shinya Yamanaka recognized that such cells could also be
produced in the laboratory – from mature body cells. Four genetic
factors alone are sufficient to reverse the course of development and
produce so-called induced pluripotent stem cells (iPS) that have
identical properties to embryonic stem cells. Yamanaka was awarded the
Nobel Prize for Medicine in 2012 for this discovery.
“This was a major breakthrough for stem cell research,” said
Andreas Trumpp, German Cancer Research Center (DKFZ) and Director of
HI-STEM in Heidelberg. “This applies in particular to for research in
Germany, where the generation of human embryonic stem cells is not
permitted. Stem cells have enormous potential both for basic research
and for the development of regenerative therapies that aim to restore
diseased tissue in patients. However, reprogramming is also associated
with problems: For example, pluripotent cells can form germ line tumors,
Biomedical engineers at Duke University have used a CRISPR/Cas9 genetic engineering technique to turn off a gene that regulates cholesterol levels in adult mice, leading to reduced blood cholesterol levels and gene repression lasting for six months after a single treatment.
This marks the first time researchers have delivered CRISPR/Cas9 repressors for targeted therapeutic gene silencing in adult animal models.
The CRISPR/Cas9 system is based on an antiviral defense mechanism in bacteria in which the Cas9 enzyme recognizes the viral DNA sequences of previous infections and cuts up invading DNA during re-infection.
Researchers have engineered the CRISPR/Cas9 system to not only locate and cut specific sequences of DNA, but to also turn on or off the expression of targeted genes without making permanent changes to the DNA sequence.
While this CRISPR/Cas9 repressor technique has emerged as a robust tool for disrupting gene regulation in cell culture models, it had not yet been adapted for delivery to adult animals for applications such as gene therapy.
The Duke Researchers develop an approach to efficiently package and deliver the CRISPR/Cas9 repressor system to mice. They tested their delivery system by silencing Pcsk9, a gene that regulates cholesterol levels.
While several drugs have been developed to treat high cholesterol and cardiovascular disease by blocking the activity of Pcsk9, this new approach would prevent Pcsk9 from being made.
The team that first unveiled the rapid, inexpensive, highly sensitive CRISPR-based diagnostic tool called SHERLOCK has greatly enhanced the tool’s power, and has developed a miniature paper test that allows results to be seen with the naked eye — without the need for expensive equipment.
The work, led by researchers from the Broad Institute of MIT and Harvard and from MIT, has the potential for a transformative effect on research and global public health.
The SHERLOCK team developed a simple paper strip to display test results for a single genetic signature, borrowing from the visual cues common in pregnancy tests. After dipping the paper strip into a processed sample, a line appears, indicating whether the target molecule was detected or not.
The team has also increased the sensitivity of SHERLOCK and added the capacity to accurately quantify the amount of target in a sample and test for multiple targets at once.
The researchers previously showcased SHERLOCK’s utility for a range of applications. In the new study, the team uses SHERLOCK to detect cell-free tumor DNA in blood samples from lung cancer patients and to detect synthetic Zika and Dengue virus simultaneously, in addition to other demonstrations.
At the core of SHERLOCK’s success is a CRISPR-associated protein called Cas13, which can be programmed to bind to a specific piece of RNA.
SHERLOCK’s diagnostic potential relies on additional strands of synthetic RNA that are used to create a signal after being cleaved. Cas13 will chop up this RNA after it hits its original target, releasing the signaling molecule, which results in a readout that indicates the presence or absence of the target.
The SHERLOCK platform can now be adapted to test for multiple targets. SHERLOCK initially could only detect one nucleic acid sequence at a time, but now one analysis can give fluorescent signals for up to four different targets at once — meaning less sample is required to run through diagnostic panels.