Monday, February 3, 2014

Stem cell stories that caught our eye: caveats on acid-bath stem cells, 3-D printing and lung disease

Blood cells were genetically modified to glow with green fluorecence when they converted to stem cells
Here are some stem cell stories that caught our eye this past week. Some are groundbreaking science, others are of personal interest to us, and still others are just fun.

A new type of stem cell and a new moniker: STAP cells. It seem like every news outlet in the county ran a story about Stimulus-Triggered Acquisition of Pluripotentcy (STAP) cells, which in essence are stem cells created by stressing adult cells. You probably remember the stories from the headlines which tended to mix bits of hype like “breakthrough” and “game-changer” with phrases like “cells given an acid bath” or “tortured cells.” Both halves of those headlines need a bit of a reality check.

Two great teams worked together on the research, one at the Riken Institute in Japan and one in Boston at Harvard affiliated Brigham and Women’s Hospital. They clearly created embryonic-like stem cells from adult tissue using a very novel method. It may turn out to be a game-changing breakthrough, but it is too early to tell. The touted increase in efficiency seems largely due to using cells from newborn mice. When they tried it with older adult tissue, it worked but the efficiency dropped greatly. Second, the cells could only be kept alive in the lab for a couple weeks, much different, and much less useful, than embryonic stem cells that can be kept alive forever. Last, the new process was much faster than traditional iPS type of reprogramming adult tissue, 30 minutes versus weeks, but we don’t know what additional changes or mutations the process created. Then there is the perennial issue that it is always hard to get the same results in human cells as in mice. So, much work remains to be done.

The cells were stressed, but hardly tortured. The acid was weaker than table vinegar and weaker than the acid in your stomach, which raises the issue of why don’t the cells in your stomach convert to stem cells.

The news section of the journal Science did a pretty lay-accessible analysis of the work that points out the reasons for the excitement as well as some of the caveats. Since the original paper appeared in Nature, the highly competitive Science feeling obligated to address it does lend credence to its potential importance. Most news outlets ran with the Associated Press version, and the writer at the Boston Globe found some interesting narrative about how the discovery happened.

If you want a refresher on the concept of reprogramming adult cells to become stem cells watch our video on creating iPS cells.

Could 2014 be the year of 3D bioprinting? Yahoo posted a story about a report from a market research firm that predicts 3D bioprinting of human organs will soon become a reality. By my definition of “soon” that is a gross overstatement, but the field is making more rapid progress than I would have guessed even a couple years ago. The piece does mention the work of Organovo that is not currently planning to make whole organs. They are making bits of organ, say some liver tissue that could be used to test drugs for liver toxicity. Liver cells created from iPS reprogramming have already proven better than mice at predicting drug toxicity. But those cells in a simple layer will, in turn, probably turn out to be inferior to complex 3D liver tissue created by a printer.

A better way to get the lung cells you want. An old colleague that wrote for me at Harvard posted a nice narrative on the Boston Children’s Hospital’s Vector blog about a team there solving a piece of the problem of how you get stem cells to become the desired cells in a complex tissue like lung. They did what many in the field now are doing: asked what happens in the body on a day-to-day basis. They isolated a pathway that is activated when the lung is injured. That pathway directs the native stem cells to become specific kinds of cells. They then took the next step of finding ways to manipulate the pathway to enhance the repair mechanism. Getting our own cells to do a better job often seems like a better option than giving donor cells.

Don Gibbons

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