Monya Baker

A new zinc finger protein, perhaps the first of many, silences integrated viruses

When induced pluripotent stem cells were first made, keen-eyed researchers rejoiced that the viruses required to reprogram the cells did not need to stay active indefinitely. As the cells reprogram, the viruses are silenced. That opened the door to reprogramming cells without genetic engineering, which meant that the resultant cells would be more applicable to drug screening and cell therapies.

Monya Baker

Strategies for moving embryonic stem cells toward pancreatic or blood cells

Embryonic stem cells are, for most scientists, a means to an end. The cells themselves matter less than the cells they can produce, but making them differentiate into the desired quantities of particular cell types is easier said than done. That is especially true for tissues of the two inner germ layers, the endoderm (which forms most glands) and the mesoderm (which forms the muscles and cardiovascular system). Now, two new protocols promise more efficient ways to generate these tissues from embryonic stem cells.

Monya Baker

Six reprogramming factors in a plasmid reach a holy grail

For the first time, human skin cells have been reprogrammed to pluripotency without requiring genetic elements to insert themselves into the reprogrammed cells. Though so-called induced pluripotent stem cells promise to be as powerful as embryonic stem cells in their ability to differentiate into all cell types, standard techniques use viruses to insert multiple copies of reprogramming genes into the cells; this makes the cells less predictable, and it creates a higher risk of a cancerous growth. As a result, many laboratories have been racing to publish techniques to reprogram cells without permanent genetic modification.

Monya Baker

Electron microscopy reveals functioning synapses

[Editor's note: It's not easy to assess a study's ramifications from press releases, three of which caught my eye this month. I asked Phil Schwartz, a neural stem cell expert at Children's Hospital of Orange County, California, to help me understand the gap between study and therapy. I also asked authors from each paper to respond. This article is one of three resulting from this process.]

Research summary by Nature Reports Stem Cells: For many types of cell therapy, getting transplanted cells to integrate into a patient's tissue will be harder than making the cells. Researchers led by Leyan Xu of Johns Hopkins Medical Institutions, in Baltimore, Maryland had previously shown that grafts of human neural stem cells (NSCs) could relieve symptoms in a rat model of amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease).

Monya Baker

Ascl2, a transcription factor and Wnt target, switches on a stem cell program in the gut

In the search for what makes a stem cell a stem cell, Hans Clevers and colleagues at Hubrecht Institute-KNAW, the Netherlands, have found a transcription factor expressed uniquely in the gut1. Deletion of the gene, called Achaete scute-like 2 (Ascl2), completely ablates stem cell activity. Activating the gene in non-stem cells causes the cells to take on stem cell characteristics, including making stem cell markers and reproducing the structures and specialized cell types that normal intestinal stem cells produce.

Megan Scudellari

In a field rife with dissension, four recent papers may resolve one of the haematopoietic community's greatest disputes

Shortly after fertilization, a group of rare but nondescript cells begin to form in the mammalian embryo. They are the haematopoietic stem cells, able both to self-renew and differentiate into the entire blood system of an animal. Since their discovery almost 50 years ago, haematopoietic stem cells have been studied by legions of researchers, quickly becoming the best characterized of all known stem cells. Today, these regenerative cells are a mainstay therapy for cancers, genetic disorders and bone marrow diseases.

But despite the wealth of information on haematopoietic stem cells (HSCs) and their widespread use in clinics and labs, their origins remain a mystery. And researchers aren't happy about it. Throughout the haematopoietic community, a contentious debate persists over the birth of these cells.

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