"What are stem cells? How many kinds of stem cells are there? Do they have to come from embryos? Will stem cells keep me from getting ugly/old/sick?"

I get asked a lot of questions when I tell people I'm involved in stem cell research. There's clearly a lot of excitement and curiosity about stem cells, and an important part of being a stem cell scientist is telling the broader public about the value of your research and explaining how it might improve public health someday.

Every October, the global stem cell community comes together to promote appreciation and understanding of stem cell research on Stem Cell Awareness Day, which is being celebrated today, October 12. At Cell Stem Cell, we're marking the occasion by highlighting the voices and stories of the young scientists behind the papers in our October 6 issue, with videos and article summaries that they put together to give a short explanation of their work and what it could mean for human health. We hope they're useful to help a wider audience than we usually reach understand and appreciate the exciting work that we're publishing this month.

Dedifferentiated Schwann Cell Precursors Secreting Paracrine Factors Are Required for Regeneration of the Mammalian Digit Tip

Although chronic disease and traumatic injury often lead to irreparable damage, there are some tissues, such as the end of the fingertip, that have a surprising ability to completely regenerate following injury, even in humans. Here, we show that the nervous system plays a vital role in this process through Schwann cells, which normally act to support nerves by coating them with myelin, taking on a different role in guiding repair through release of factors that promote regeneration. Hopefully, by continuing to uncover the factors involved in regeneration, we can work toward new ways to promote tissue repair after injury or during disease.

Read more from Miller and colleagues



Conversion of Human Gastric Epithelial Cells to Multipotent Endodermal Progenitors using Defined Small Molecules

Visceral endodermal diseases, such as liver failure or diabetes, are becoming increasingly prevalent all over the world. Cell-based therapy with liver, pancreas, or intestinal cells would bring new hope for patients suffering with these diseases. We showed that we could convert human stomach cells into induced endodermal progenitor cells (hiEndoPCs) by growing them in a chemical cocktail with supporting cells. The hiEndoPCs can be maintained and expanded in a dish and make functional liver, pancreas, and intestinal cells, providing a new cell source for future use in cell therapies for liver failure and diabetes, as well as models for personalized drug screening.

Read more from Pei and colleagues



Tissue Mechanics Orchestrate Wnt-Dependent Human Embryonic Stem Cell Differentiation

The way cells are organized within regions of the developing embryo controls how they change over time to form tissues and organs. We grew human embryonic stem cells on soft hydrogels that simulated the mechanical environment of an early embryo and found that multiple signaling pathways were activated to elicit efficient, highly coordinated generation of a particular tissue called mesoderm. By demonstrating how mechanical environments can control tissue-level organization and synchronize with other signals to dictate how stem cells form tissues, we identified a tunable parameter to optimize stem cell protocols and improve tissue engineering for future application in regenerative medicine.

Read more from Weaver and colleagues



Glycolytic Metabolism Plays a Functional Role in Regulating Human Pluripotent Stem Cell State

We looked at the role of sugar metabolism in human embryonic stem cells. We found that human stem cells corresponding to an earlier (naive) stage of development consume more sugar than cells from a later (primed) stage. This is surprising, because primed cells were already known for high sugar consumption, which we found is important for naive cell growth. How we grew stem cells in the lab influenced their metabolism, and we could nudge stem cells toward neural cells by manipulating their sugar metabolism, which might be a viable strategy for helping make specific types of cells that are useful in the clinic.

Read more from Christofk and colleagues



Dnmt3a and Dnmt3b Associate with Enhancers to Regulate Human Epidermal Stem Cell Homeostasis

Our skin renews, heals wounds, and regenerates the hair that covers it, thanks to a small group of stem cells. In our recent paper, we identified a crucial role for two proteins, Dnmt3a and Dnmt3b, that preserve the stem cells in skin. Dnmt3a and Dnmt3b are essential for activating the stem cell program, and without them, this program fails and the stem cells collapse and disappear from the tissue. Dnmt3a and Dnmt3b trigger the expression of essential genes for skin stem cell identity; without their proper activation, the skin stem cells are not functional anymore.

Read more from Benitah and colleagues

Molecular Criteria for Defining the Naive Human Pluripotent State

The ability to convert human pluripotent stem cells into a "naive" state that resembles the earliest stages of human development may allow researchers to study some aspects of early human development in a dish. This study provides a set of criteria to assess the similarity between stem cells generated in the laboratory and their counterparts in the early human embryo. Our tests show that current naive human pluripotent stem cells are similar to early-stage embryos but do not resemble the in vivo context completely. We offer guidelines for future optimization of naive human stem cells, which potentially have a greater capacity to generate different tissue types.

Read more from Jaenisch and colleagues



3D Culture Supports Long-Term Expansion of Mouse and Human Nephrogenic Progenitors

Technologies for growing of mini-organs in the lab provide a useful tool for looking at how organs develop and what goes wrong in disease. We developed a 3D culture platform that allows us to grow nephron progenitor cells (NPCs), the precursors of nephrons that make up the kidney's filtration system, in an almost unlimited way. Cultured NPCs have broad applications. In the short term, we can use them to make nephron mini-organs that we can use to model kidney development and disease. In the longer term, human NPCs could also be a source of material for cell replacement therapies for kidney repair.

Read more from Belmonte and colleagues



Proximity-Based Differential Single-Cell Analysis of the Niche to Identify Stem/Progenitor Cell Regulators

Stem cells maintain tissues and rebuild them after injury. However, we still don't have the tools to harness these unique properties of stem cells in order to fully exploit them for medical purposes. By identifying the molecular signature of cells which support blood stem cells in the bone marrow, we found several molecules which enhance their ability to make new blood. In principle, researchers could use a similar approach to look for specific signals that promote growth and repair of other normal tissues or could apply it to cancer, where blocking the signals that drive cancer stem cells would create new opportunities to eradicate the disease.

Read more from Scadden and colleagues



Transplanted Human Stem Cell-Derived Interneuron Precursors Mitigate Mouse Bladder Dysfunction and Central Neuropathic Pain after Spinal Cord Injury

Although they are less obvious consequences than impaired movement, chronic pain and poor bladder control are two symptoms of spinal cord injury that have a significant quality of life impact for patients. These issues are caused in part by overactive neural networks in the injured spinal cord. In our paper, we show that human stem cells transplanted into the mice with injured spinal cords were able to dampen these defective neural networks and alleviate the injury effects. Although there was no effect on movement ability, this type of approach could be a way to address two other negative effects of spinal cord injury and thus improve patient quality of life.

Read more from Kriegstein and colleagues

With these short summaries, we're building on a lead set by other journals in our family—Cancer Cell's Significance box and Chem's The Bigger Picture box. If these summaries are popular, we might introduce them on a more regular basis, so we'd love to know what you think! Do you like them? Dislike them? Why? Which is more useful, the the video or the written summary? What could make them better? Please let us know by commenting here or messaging us on Twitter. Remember also that you can follow this and other Stem Cell Awareness Day events with #StemCellAwarenessDay.