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.
Mimicking human air sacs – a new lab tool for studying respiratory disease
Studying a flat lawn of cells in a petri dish is so old fashioned these days. The current trend is to use stem cells to create mini-organs called organoids that more closely mimic the actual three dimensional structures that you would find in the human body. We’ve written about the creation of mini-brains, livers, pituitary glands and several other organoids. Now, a UCLA research team has added lung organoids to the list.
Reported yesterday in Stem Cells Translational Medicine, the CIRM-funded study describes the technique of nudging lung stem cells, collected from patients’ lung tissue, to self-assemble into 3D structures that resemble air sacs found in the human lung. This technique will surely usher in a better understanding of idiopathic pulmonary fibrosis, a disease that causes scarring of the lungs, leading to shortness of breath and depriving the organs of oxygen. The cause of the disease isn’t known in most cases and, sadly, people usually die within five years of their initial diagnosis.
One of the main challenges in the lab has been reproducing the tale tell scarring seen in this chronic lung disease. When lung cells are taken from pulmonary fibrosis patients and grown as a flat layer, the cells look healthy. But with this novel lung organoid technique, the researchers were able to manipulate the cells to develop the types of scars seen in actual diseased lungs. Better yet, the methodology is very straight-forward, as Dan Wilkinson described in a university press release:
“The technique is very simple. We can make thousands of reproducible pieces of tissue that resemble lung and contain patient-specific cells.”
Now the researchers are in a position to better understand the cellular and molecular basis of the disease and to test out possible treatments that would work best in each individual.
A common thread running through all Parkinson’s cases
The cause of Parkinson’s disease seems straight-forward enough: nerve cells that produce dopamine – a chemical signal that helps generate smooth body movements – progressively die leading to body stiffness, uncontrollable shaking in the limbs and weakened coordination, just to name a few symptoms.
But the underlying genetics of Parkinson’s is anything but simple. Mutations in several genes are associated with family histories of the disease while other mutations in other genes are known to indirectly increase the risk of developing Parkinson’s. These familial forms of Parkinson’s, however, only make up about 15% of all cases; the remaining are so-called sporadic, meaning there’s no obvious family history. So, treating Parkinson’s disease involves treating each of its many forms. But in a CIRM-funded study, published late last week in Cell Stem Cell, Stanford researchers reported on a common thread that appears to run through all forms of Parkinson’s disease.
The team focused on a known mutation in the LRRK2 gene, found in about 1 out of 20 cases of familial Parkinson’s and which pops up in 1 out of 50 cases of sporadic Parkinson’s. The link between LRRK2 and Parkinson’s had not been understood. The Stanford researchers found it plays an important role in the maintenance of mitochondria, structures that produce a cell’s energy needs.
When mitochondria become damaged or old they begin spewing out molecules that are toxic to the cell. In response, the cell gobbles up these mitochondria but only after the LRRK protein interacts with and removes a protein called Miro which normally anchors the mitochondria to the cell’s internal structures. The mutated form of LRRK2 doesn’t interact with Miro very well and, as a result, Miro holds on to the toxic mitochondria which in turn are not dismantled as rapidly.
You’d think this mechanism of action would to be specific to the LRRK2-mutant Parkinson’s but to the scientists’ pleasant surprise, it wasn’t. They discovered this result by creating induced pluripotent stem cells from skin samples collected from twenty different subjects: four healthy subjects; five with the sporadic Parkinson’s; six with familial Parkinson’s from LRRK2 mutations and five with familial patients from other mutations. The iPS cells were grown into dopamine-producing nerve cells, the kind that die off in Parkinson’s disease. With these cells in hand, they observed the impact of intentionally damaging the mitochondria.
As expected, this damage to the nerve cells from the healthy subjects led to the breakdown of Miro which in turn allowed the detachment and degradation of mitochondria. Also as expected, the nerve cells from patients with the LRRK2 mutant showed delays in the release and degradation of mitochondria. But when the team looked at the other Parkinson’s nerve cells not associated with the LRRK2 mutant, they found the same delay in the release of Miro and degradation of mitochondria.
This result points to Miro as a common player in all forms of Parkinson’s. Xinnan Wang, the team’s leader, spoke about the exciting implications of these findings in a university press release:
“Existing drugs for Parkinson’s largely work by supplying precursors that faltering dopaminergic nerve cells can easily convert to dopamine. But that doesn’t prevent those cells from dying, and once they’ve died you can’t bring them back. Measuring Miro levels in skin fibroblasts from people at risk of Parkinson’s might someday prove beneficial in getting an accurate, early diagnosis. And medicines that lower Miro levels could prove beneficial in treating the disease.”
A cautionary tale about science communication
What to leave in, what to leave out: it’s the continual dilemma (I must add a fun dilemma) for a science writer. When writing for a general audience, if you describe a research report in too much detail you’re likely to quickly lose your reader. But not adding enough detail can lead the reader to draw conclusions that aren’t accurate. And just a like a game of telephone, as the story is passed along from one source to another, the resulting storyline has little resemblance to the original research.
Research published this week in Nature Communications provides a case in point. Many of news outlets that picked up the research story which involved the successful production of mouse pups from mixing sperm with an novel type of egg cell that had been induced to divide before fertilization. The resulting headlines suggested that scientists had identified an end run around the need for a female’s egg to produce offspring. Based on a quick glance at these condensed summaries of the research report, you’d think motherless babies were just around the corner.
Gretchen Vogel at Science Magazine wrote a terrific autopsy of this news story, describing in five steps how it took on a life of its own. It’s a humorous (I personally LOL’d when I read it) yet serious cautionary tale of how science communication can go awry. I highly recommended the short piece. For a sneak peek, here’s her “five easy steps to create a tabloid science headline”:
Take one jargon-filled paper title: “Mice produced by mitotic reprogramming of sperm injected into haploid parthenogenotes“
- Distill its research into more accessible language. Text of Nature Communications press release: Mouse sperm injected into a modified, inactive embryo can generate healthy offspring, shows a paper in Nature Communications. And add a lively headline: “Mouse sperm generate viable offspring without fertilization in an egg“
- Enlist an organization to invite London writers to a press briefing with paper’s authors.
Headline of Science Media Centre press release: “Making embryos from a non-egg cell“
- Have same group distribute a laudatory quote from well-known and respected scientist:
“[It’s] a technical tour de force.”
- Bake for 24 hours and present without additional reporting. Headline in The Telegraph: “Motherless babies possible as scientists create live offspring without need for female egg,” and in The Guardian: “Skin cells might be used instead of eggs to make embryos, scientists say.”