Falsifying DNA- questioning the Gold Standard

August 21, 2009

Earlier this week, a group of scientists in Israel shook the world of forensic sciences and questioned the use of DNA testing as the “gold standard”.  In a paper published by the Forensic Science International: Genetics journal, researchers showed that it is possible to fabricate DNA evidence. In this paper, the scientists fabricated saliva and blood samples that contained DNA from a person other than the donor of that blood and saliva!  Also, the researchers showed that through the use of a DNA database, they could utilize a profile within that database and construct a sample of DNA to match that profile without needing any tissue from that person.  In the world of science, this makes a lot of sense, as many people use synthetic DNA oligos in almost every molecular laboratory!

Thankfully, Dr. Frumkin who is the lead author on the paper, has developed a test to distinguish real DNA samples from fake ones using epigenetic modifications, specifically DNA methylation.  In the human genome, 70% of the DNA is methylated, meaning that it contains methyl group modifications in a CpG dinucleotide context. Methylation at the promoter region is associated with gene silencing.  Synthetic DNA, however, would lack this specific epigenetic modification, and therefore can be distinguished from the real deal.

As our world becomes increasingly reliant on scientific technologies, the idea that DNA can be planted at a crime scene is very scary.  Hopefully with tests like the one generated by Dr. Frumkin will be common practice to ensure that science stays ahead of the game.

By Alisha Jamal, University of Toronto

Removal of the stem cell ban—what does it all mean for Science?

August 15, 2009

Earlier this year, U.S. President Obama lifted the restriction of federal funding of human embryonic stem cells—a controversial field of biomedical research. The ban, originally introduced by President Bush on August 9, 2001 in an effort to stop the destruction of embryos, banned scientists from making new embryonic stem cell lines, but allowed them to use the 21 lines already created. The band was frustrating for many scientists who argued that that the pre-existing lines were not diverse enough to study many diseases.   New stem cell lines, which may have disease-specific mutations, would have also allowed scientists to investigate a greater range of disease pathways. These new lines could yield fundamental insight into how diseases are caused and how they may be treated or cured. Further, many of the established lines were defective which could make them dangerous to transplant into people. Although laboratories still continued to use stem cells to study diseases, they had to find their own ways to fund their projects and often had to design separate lab areas.

Stem cells, which are derived from the inner cell mass of a developing blastocyst, are pluripotent, meaning they can differentiate into any cell of the three germ layers: endoderm, mesoderm and ectoderm. Scientists believe that stem cells hold the “key” for discovering why diseases occur, and will provide treatments for Alzheimer’s, Parkinson’s, diabetes and heart disease to name a few.

Opponents of the ban however, argue that stem cells are not even needed anymore to generate pluripotent cells since scientific advances have shown promise for the ability to induce adult cells to go back to the pluripotent state. These cells, known as induced pluripotent stem cells or iPS have recently begun to show a lot of promise. For example, one of our own, Dr. Andras Nagy, a Toronto researcher based out of Mount Sinai was the first to reprogram adult human cells into embryonic-like stem cells without using viruses that could potentially cause cancer. In a seminal Nature paper, Nagy’s group describes a new PiggyBac transposition system where they can insert the reprogramming factors and subsequently take them out. This discovery will change the face of stem cell therapies because in essence, we will be able to take a person’s own cell, reprogram it, lead it to differentiate into a necessary cell type, and put it back into them.

In any case, the field of pluripotent cells is a “hot” area of research with promise for advancing human health. With Obama overturning the ban, stem cell research will likely continue to advance with newly developed strong collaborations and likely the development of stem cell databases. This will hopefully get us one step closer to finding the cause, and perhaps the cure, for many diseases that affect human health.

By Alisha Jamal, University of Toronto