Each month CIRM President Alan Trounson gives his perspective on recently published papers he thinks will be valuable in moving the field of stem cell research forward. This month’s report, along with an archive of past reports, is available on the CIRM website.
The first section of my report this month focuses on trends spotted at this year’s annual meeting of the International Society for Stem Cell Research in Yokohama, Japan, June 13-16. The meeting showed a field that is clearly maturing both as a basic discipline helping us understand the underpinnings of life, but also as a field revealing ways to move stem cell science toward therapies.
At least three teams presented work in which they matured stem cells into complex tissues, not just various end stage cell types. One group showed they could grow gastric units they called organoids that could be transplanted into mice and integrated into the animal’s intestine. Another’s project resulted in what they called the first functional organ with networks of blood vessels, in this case a small piece of liver that was able to metabolize some drugs like a normal liver. The third team presented work that replicated in human tissue their work of a year ago in mouse cells. They coaxed stem cells into forming the multiple cells layers that make up the optic cup. Our full report here goes into each study in more detail, and our report from last April discussed the earlier optic cup work.
The remainder of this month’s report highlights four significant papers from research journals this month, but I want to discuss just one in some detail here. It could be a major advance in producing the types of cells needed for therapy in sufficient quantities and without fear of causing tumors. Traditionally researchers create a desired adult cell either by maturing pluripotent, embryonic or iPS, cells into that cell type, or by isolating adult stem cells from that lineage and maturing them into the desired cell. More recently, teams have been perfecting the art of direct reprogramming that turns one adult tissue directly into a different type of functional adult tissue. All three methods have obstacles in using them for clinical therapy. Starting with pluripotent cells results in lingering concern of a stray starter cell causing a tumor. With adult stem cells, most are difficult to isolate in usable quantities, and with direct reprogramming the end stage adult tissue produced generally is insufficient for therapy.
A UCSF team at the Gladstone Institutes seems to have gotten around all three issues by reprogramming skin cells to become neural stem cells instead of fully mature adult cells. This allows them to produce large quantities of their starting material, the neural stem cells, which can then be matured into various types of brain cells. They showed their neural stem cells could indeed produce multiple types of neurons as well as other types of brain cells and over time form neural networks in culture.
The other papers in this month’s report describe how a Swedish team used tissue engineering to give a young girl a new portal vein, and detail a potentially game changing theory on the origins of blood vessel disease, suggesting a newly found stem cell may be the culprit. My colleague blogged about this work earlier this month here.
My full report is available online, along with links to my reports from previous months.
A.T.
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