An excellent example of the use of CRISPR gene editing technology came up at the Emory-Children’s Pediatric Research Center’s Innovation Conference this week.
Marcela Preininger, who is working with cardiomyocyte stem cell specialist Chunhui Xu, described her work (poster abstract 108) on cells derived from a 12 year old patient with an inherited cardiac arrhythmia syndrome: catecholaminergic polymorphic ventricular tachycardia or CPVT. Her team has obtained skin fibroblasts from the patient, and converted those cells into induced pluripotent stem cells, which can then be differentiated into cardiac muscle cells or cardiomyocytes.
Working with TJ Cradick, director of the Protein Engineering Facility at Georgia Tech, Preininger is testing out CRISPR gene editing as a means of correcting the defect in this patient’s cells, outside the body. Cradick says that while easy and efficient, RNA-directed CRISPR can be lower in specificity compared to the protein-directed TALEN technology.
From Preininger’s abstract:
Once the mutation has been corrected at the stem cell level, we will investigate whether the repaired (mutation-free) iPS cells can be differentiated into functional cardiomyocytes with normal Ca2+ handling properties, while closely monitoring the cells for mutagenic events. Pharmacological restoration of the normal myocardial phenotype will also be optimized and explored in our model.
Peng Jin and collaborators led by Da-Hua Chen from the Institute of Zoology, Chinese Academy of Sciences have a new paper in Stem Cell Reports. They describe a souped-up method for producing iPS cells (induced pluripotent stem cells).
Production of iPS cells in the laboratory is becoming more widespread. Many investigators, including those at Emory, are using the technology to establish â€œdisease in a dishâ€ models and derive iPS cells from patient donations, turning them into tools for personalized medicine research.
Pure cardiac muscle cells, ready to transplant into a patient affected by heart disease.
Thatâ€™s a goal for many cardiology researchers working with stem cells. Having a pure population of cardiac muscle cells is essential for avoiding tumor formation after transplantation, but has been technically challenging.
Fluorescent beacons that distinguish cardiac muscle cells
Researchers at Emory and Georgia Tech have developed a method for Cheap Oakleys purifying cardiac muscle cells from stem cell cultures using molecular beacons.
Molecular beacons are tiny “instruments” that become fluorescent only when they find cells that have turned on certain genes. In this case, they target instructions to make a type of myosin, a protein found in cardiac muscle cells.
Doctors could use purified cardiac muscle cells to heal damaged areas of the heart in patients affected by heart attack and heart failure. In addition, the molecular beacons technique http://www.lependart.com could have broad applications across regenerative medicine, because it could be used with other types of cells produced from stem cell cultures, such as brain cells or insulin-producing islet cells.
The results are published in the journal Circulation.
“Often, we want to generate a particular cell population from stem cells for introduction into patients,” says co-senior author Young-sup Yoon, MD, PhD, professor of medicine (cardiology) and director of stem cell biology at Emory University School of Medicine. “But the desired cells often lack a readily accessible surface marker, or that marker is not specific enough, as is the case for cardiac muscle cells. This technique could allow us to purify almost any type of cell.”
The 2012 Nobel Prize in Medicine was awarded to Shinya Yamanaka and John Gurdon for the discovery that differentiated cells in the body can be reprogrammed. This finding led to the development of â€œinduced pluripotent stem cells.â€
These cells were once skin or blood cells. Through a process of artificial reprogramming in the lab, scientists wipe these cellsâ€™ slates clean and return them to a state very similar to that of embryonic stem cells.Â But not exactly the same.
It has become clear that iPS cells can retain some memories of their previous state. This can make it easier to change an iPS cell that used to be a blood cell (for example) back into a blood cell, compared to turning it into another type of cell. The finding raised questions about iPS cellsâ€™ stability and whether http://www.troakley.com/ iPS cell generation â€“ still a relatively new technique â€“ would need some revamping for eventual clinical use.
Chromosomal hotspots where iPS cells differ from ES cells
It turns out that iPS cells and embryonic stem cells have differing patterns of methylation, a modification of DNA that can alter how genes behave even if the underlying DNA sequence remains the same. Some of these differences are the same in all iPS cells and some are unique for each batch of reprogrammed cells.
University of Georgia researchers recently reported on their work to create pigs with induced pluripotent stem cells. This type of cell, first developed about five years ago, has the ability to turn into any other kind of cell in the body.
An Emory transplant team, working with the UGA group, hopes to use this technology to develop pig islet cells as an alternative to human islets to treat patients with Type 1 diabetes. Type 1 diabetes usually occurs early in life and affects more than one million Americans who are unable to manufacture their own insulin because their pancreatic islets do not function.
Emory islet transplant team
The Emory Transplant Center has conducted clinical trials since 2003 transplanting human pancreatic islet cells into patients with Type I diabetes. Some of these patients have been able to give up insulin injections, either temporarily or permanently. Other sources of islets are needed for transplant though because of the large number of potential patients and because each transplant typically requires islets from several pancreases.
To create pigs using pluripotent stem cells, the UGA team injected new genes into pig bone marrow cells to reprogram the cells into functioning like embryonic stem cells. The resulting pluripotent cells were inserted into blastocysts (developing embryos), and the embryos were implanted into surrogate mothers. The resulting pigs had cells from the stem cell lines as well as the embryo donor in multiple tissue types.
The pluripotent stem cell process could allow researchers to make genetic changes to dampen or potentially eliminate the rejection of the pig islets by the human immune system.
Posted on May 13, 2010