We at Webvision would like to wish you the very best this holiday season. As in past years, we like to post an image from retinal science that is somehow evocative of the Holiday Season and this year, Gabe Luna from the Steve Fisher / Geoff Lewis laboratory delivers a stunning image of astrocytes in a retinal flat mount, but with a twist… We think you’ll be seeing more of Gabe’s beautiful imagery, but for now, here is his description of how he made this image:
“I used a GFAP-GFP mouse to identify all the astrocytes in the retina and manually (at the time it was manual) annotate their coordinates, then we used a probabilistic random-walk algorithm to go to each “cell center” and perform a segmentation result of that one astrocyte. Once all the 5,000 or so cells are segmented as a greyscale image of the individual cell, then they are assigned various hues that are spectrally distinct and the montage is re-assembled into one large image. The image there is a grossly down-sized image of the original. The original was a seamless mosaic of 412 individual z-stacks of about 15 planes at 1 micron intervals, using a 40x oil immersion lens.”
We’ve talked about work out of the RIKEN Institute before here on Webvision. The work that comes out of there is clever and often unconventional. The latest work from the RIKEN that seems to have gotten a bit of attention is two recent papers from Haruko Obokata and colleagues, here and here that discuss almost inconceivably simple approaches to generating stem cells out of adult, differentiated blood, fat, muscle and brain mouse cells. The approach essentially immerses the cells in an acidic solution for a half hour to induce a state of cell stress and subsequent induced pluripotency allowing them to recapitulate mature, differentiated tissues of a variety of cell types, including a reported blastocyst. Granted, there are a variety of ways to collect and harvest stem cells, but these approaches present a variety of both ethical and logistical confounds. So, this approach could solve a number of problems related to collecting and harvesting stem cells.
The other notable thing about this study is how elegant the screening method was. The authors used GFP tagged Oct4 genes to note when cells had reached pluripotent status. These GFP expressing cells were then indicators of induced pluripotency in harvested, differentiated cells that underwent stress through acid immersion. Since only approximately 25% of the cells that underwent acid immersion survived, this approach allowed the investigators to see which of those remaining cells exhibited Oct4 gene expression revealing pluripotent stem cell status. Other assays backed up these determinations of pluripotency including teratoma assays as well as the creation of chimeras.
If this approach proves a viable technique to generating stem cells, work in stem cell based vision rescuing therapeutics (as well as many other therapeutic applications) could be dramatically facilitated as labs exploring stem cell therapies in vision rescue are currently having to invest large efforts in using existing approved stem cell stocks or isolating stem cells through labor intensive methods.
The Wall St. Journal is reporting that one of the co-authors of this study said the research contained “crucial mistakes” and RIKEN is weighing whether to retract the papers.
Nature has announced that the papers have been retracted.
The STAP approach has been completely refuted.
Continue reading “Notable Papers: An Easier Way To Make Stem Cells?”
This laser confocal image shows a GFP transgenic mouse retina under the control of the GFAP promoter stained with anti-Collagen IV (blue), anti-GFAP (red) and anti-GFP (green). These labels not only show the spatial relationship of individual astrocytes to one another, but also the vasculature. Image provided by Gabriel Luna out of the Steve Fisher and Geoff Lewis’s retinal cell biology group at UC Santa Barbara Neuroscience Research Institute.
This beautiful image is another by Gabriel Luna out of Steve Fisher and Geoff Lewis’s retinal cell biology group at UC Santa Barbara Neuroscience Research Institute that shows a small mosaic of the outer plexiform layer in mouse retina stained with anti-Calbindin D (green; horizontal cells) PNA (red; cone terminals) and GFP for bipolar cells (blue). I love the regular order that the retina shows, yet its beauty and regularity belie the complexity that is present.
Another amazing image sent to us by Gabriel Luna out of the Steve Fisher and Geoff Lewis’s retinal cell biology group at UC Santa Barbara Neuroscience Research Institute. This image is of the optic nerve head of a normal mouse retina displaying the “glial tubes” formed by the astrocytic network (anti-GFAP; red). Anti-GFP (green) and anti-Collagen IV (blue) which were used to determine numbers of astrocytes and relative locations in relation to blood vessels.