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Stem cells that are temporarily in a "primed" state are more apt to differentiate when the balance is tipped. |
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How does a stem cell decide what specialized identity to adopt—or whether it should simply remain a stem cell? A new study from Vascular Biology suggests that the conventional view, in which cells are "instructed" to progress along prescribed pathways, is too simplistic. Instead, it supports a "systems" view—the idea that cells differentiate through the collective behavior of an entire network that ultimately produces just a few stable outcomes.
Sui Huang, MD, PhD, and Hannah Chang, an MD/PhD student, show that within populations of seemingly identical blood stem cells, some cells are "primed" to become red or white blood cells—and indeed may do so, given enough of the right signals. Cells slowly move in and out of this primed state, allowing them to change in response to their environment, in a random but controlled way. Above, stem cells (shown as green balls) move about in their valley, and at times have a greater "energy," priming them to go over the edge and fall into new valleys when the balance is tipped (here, by differentiation factors GATA1 or PU.1). Chang has shown that stem cell differentiation in the lab can be made far more efficient by selecting cells that are already primed and catching them before they revert to a more stem-like state. (Nature, May 22)
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A randomized study led by Tom Sandora, MD, MPH, medical director of Infection Control, shows that rigorous classroom sanitation can curb stomach bugs. Third- to fifth-grade teachers in Ohio received disinfecting wipes to clean students' desks after lunch, and students were asked to use alcohol-based hand sanitizer several times daily. During the next eight weeks, 16 percent of the students were home sick with gastrointestinal illness, as compared with 24 percent of their peers in other classrooms. In the classrooms with enhanced sanitation, less norovirus was detected on computer mice, desks and drinking fountains. Absenteeism due to respiratory illness didn't change. (Pediatrics, June)
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Renamed in Dr. Judah Folkman's honor, this year's expanded Research Day featured 104 posters and 11 presentations from young researchers around the hospital. Awards went to the following Children's Hospital Boston researchers: Chong Yung, PhD (Vascular Biology), who is developing a device to treat sepsis using magnetism to pull pathogens from the blood; Jonathan Meisel, MD (Surgery), who has shown that an angiogenesis inhibitor may prevent painful adhesions after surgery; Joshua Murtie, PhD (Neurobiology), who is developing a topical treatment for peripheral neuropathy, which affects millions of diabetics; and Richard White, MD, PhD (Hematology/Oncology), who has found embryonic cells in zebrafish that may help explain
melanoma's origins.
Houseofficer Development Awards went to: Rahul Rathod, MD (Cardiology), to compare different shunting approaches in patients with hypoplastic left heart syndrome; Michelle Ann Lee, MD, PhD (Hematology/Oncology), who will travel to Uganda to study how pediatric cancer care is delivered; and Alex Kentsis, MD, PhD (Medicine), to examine the protein composition of urine as a gauge of whether a child has appendicitis. Click here to see a slide show of the event.
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healthy infants and toddlers don't get enough vitamin D, finds a study led by Catherine Gordon, MD, MSc, director of the Bone Health Program. Blood testing of babies coming to Children's for well-care visits revealed that 40 percent had vitamin D levels below those optimal for bone health, and 12 percent were frankly deficient. Had it not been for the study, these deficiencies might well have been missed. A third of the deficient children had evidence of bone loss, and 7.5 percent had bone changes consistent with rickets. The main culprits were exclusive breastfeeding without vitamin D supplementation and (among toddlers) inadequate milk intake. (Archives of Pediatrics & Adolescent Medicine, June)
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