Repurposing a transplant drug for bone growth

The transplant immunosuppressant drug FK506, also known as tacrolimus or Prograf, can stimulate bone formation in both cell culture and animal Read more

Beyond the amyloid hypothesis: proteins that indicate cognitive stability

If you’re wondering where Alzheimer’s research might be headed after the latest large-scale failure of a clinical trial based on the “amyloid hypothesis,” check this Read more

Mother's milk is OK, even for the in-between babies

“Stop feeding him milk right away – just to be safe” was not what a new mother wanted to hear. The call came several days after Tamara Caspary gave birth to fraternal twins, a boy and a girl. She and husband David Katz were in the period of wonder and panic, both recovering and figuring out how to care for them. “A nurse called to ask how my son was doing,” says Caspary, a developmental Read more

gene editing

Viral vectors ready for delivery

The phrase “viral vector” sounds ominous, like something from a movie about spies and internet intrigue. It refers to a practical delivery system for the gene of your choice. If you are a biomedical researcher and you want to tweak genes in a particular part of the body in an experimental animal, viral vectors are the way to go.

Viral vector-transduced retinal ganglion cell; dendrites and axons labeled with GFP. Courtesy Felix Struebling via Xinping Huang

Emory’s Viral Vector Core was started when eminent neuroscientist Kerry Ressler was at Emory and is now overseen by geneticist Peng Jin. Technical director Xinping Huang and her colleagues can produce high-titer viral vectors, lentivirus and AAV. Discuss with her the best choice. It may depend on the size of the genetic payload you want to deliver and whether you want the gene to integrate into the genome of the target cell.

As gene therapy and CRISPR/Cas9-style gene editing research progresses, we can anticipate demand for services such as those provided by the Viral Vector Core. [Clinical applications are close, but will not be dealt with in the same place!] Read more

Posted on by Quinn Eastman in Neuro Leave a comment

CRISPR gene editing can miss its mark

Yanni Lin, TJ Cradick, Gang Bao and colleagues from Georgia Tech and Emory reported recently in Nucleic Acids Research on how the CRISPR/Cas9 gene editing system can sometimes miss its mark.

CRISPR/Cas9 has received abundant coverage from science-focused media outlets. Basically, it is a convenient system for cutting DNA in cells in a precise way. This paper shows that the CRISPR/Cas9 system can sometimes cut DNA in places that don’t exactly match the designed target.

Here we show that CRISPR/Cas9 systems can have off-target cleavage when DNA sequences have an extra base or a missing base at various locations compared with the corresponding RNA guide strand…Our results suggest the need to perform comprehensive off-target analysis by considering cleavage due to DNA and sgRNA bulges in addition to base mismatches.

CRISPR/Cas9 could be used to develop therapies for humans for genetic blood diseases such as sickle cell or thalassemia, and this paper does not change that potential. But the authors are cautioning fellow scientists that they need to design their tools carefully and perform quality control. Other investigators have made similar findings.

Posted on by Quinn Eastman in Uncategorized Leave a comment

Addendum on CRISPR

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.

Posted on by Quinn Eastman in Heart Leave a comment