extracellular matrix
Capturing the Extracellular Matrix in 3D Color
Posted on by Dr. Francis Collins
For experienced and aspiring shutterbugs alike, sometimes the best photo in the bunch turns out to be a practice shot. That’s also occasionally true in the lab when imaging cells and tissues, and it’s the story behind this spectacular image showing the interface of skin and muscle during mammalian development.
Here you see an area of the mouse forelimb located near a bone called the humerus. This particular sample was labeled for laminin, a protein found in the extracellular matrix (ECM) that undergirds cells and tissues to give them mechanical and biochemical support. Computer algorithms were used to convert the original 2D confocal scan into a 3D image, and colorization was added to bring the different layers of tissue into sharper relief.
Skin tissue (bright red and yellow) is located near the top of the image; blood vessels (paler red, orange, and yellow) are in the middle and branching downward; and muscle (green, blue, and purple) makes up the bottom layer.
The image was created by Sarah Lipp, a graduate student in the NIH-supported tissue engineering lab of Sarah Calve. The team focuses on tissue interfaces to better understand the ECM and help devise strategies to engineer musculoskeletal tissues, such as tendon and cartilage.
In February 2020, Lipp was playing around with some new software tools for tissue imaging. Before zeroing in on her main target—the mouse’s myotendinous junction, where muscle transfers its force to tendon, Lipp snapped this practice shot of skin meeting muscle. After processing the practice shot with a color-projecting macro in an image processing tool called Fiji, she immediately liked what she saw.
So, Lipp tweaked the color a bit more and entered the image in the 2020 BioArt Scientific Image & Video Competition, sponsored by the Federation of American Societies for Experimental Biology, Bethesda, MD. Last December, the grad student received the good news that her practice shot had snagged one of the prestigious contest’s top awards.
But she’s not stopping there. Lipp is continuing to pursue her research interests at the University of Colorado, Boulder, where the Calve lab recently moved from Purdue University, West Lafayette, IN. Here’s wishing her a career filled with more great images—and great science!
Links:
Muscle and Bone Diseases (National Institute of Arthritis and Musculoskeletal and Skin Diseases/NIH)
Musculoskeletal Extracellular Matrix Laboratory (University of Colorado, Boulder)
BioArt Scientific Image & Video Competition (Federation of American Societies for Experimental Biology, Bethesda, MD)
NIH Support: National Institute of Arthritis and Musculoskeletal and Skin Diseases
Tackling Fibrosis with Synthetic Materials
Posted on by Dr. Francis Collins
When injury strikes a limb or an organ, our bodies usually heal quickly and correctly. But for some people, the healing process doesn’t shut down properly, leading to excess fibrous tissue, scarring, and potentially life-threatening organ damage.
This permanent scarring, known as fibrosis, can occur in almost every tissue of the body, including the heart and lungs. With support from a 2019 NIH Director’s New Innovator Award, April Kloxin is applying her expertise in materials science and bioengineering to build sophisticated fibrosis-in-a-dish models for unraveling this complex process in her lab at the University of Delaware, Newark.
Though Kloxin is interested in all forms of fibrosis, she’s focusing first on the incurable and often-fatal lung condition called idiopathic pulmonary fibrosis (IPF). This condition, characterized by largely unexplained thickening and stiffening of lung tissue, is diagnosed in about 50,000 people each year in the United States.
IPF remains poorly understood, in part because it often is diagnosed when the disease is already well advanced. Kloxin hopes to turn back the clock and start to understand the disease at an earlier stage, when interventions might be more successful. The key is to develop a model that better recapitulates the complexity and irreversibility of the disease process in people.
Building that better model starts with simulating the meshwork of collagen and other proteins in the extracellular matrix (ECM) that undergird every tissue and organ in the body. The ECM’s interactions with our cells are essential in wound healing and, when things go wrong, also in causing fibrosis.
Kloxin will build three-dimensional hydrogels, crosslinked sponge-like networks of polymers, peptides, and proteins, with structures that more accurately capture the biological complexities of human tissues, including the ECMs within fibrous collagen-rich microenvironments. Her synthetic matrices can be triggered with light to lock in place and stiffen. The matrices also will make it possible to culture the lung’s epithelium, or outermost layer of cells, and connective tissue that surrounds it, to study cellular responses as the model shifts from a healthy and flexible to a stiffened, disease-like state.
Kloxin and her team will also integrate into their model system lung cells that have been engineered to fluoresce or light up under a microscope when the wound-healing program activates. Such fluorescent reporters will allow her team to watch for the first time how different cells and their nearby microenvironment respond as the composition of the ECM changes and stiffens. With this system, she’ll also be able to search for small molecules with the ability to turn off excessive wound healing.
The hope is that what’s learned with her New Innovator Award will lead to fresh insights and ultimately new treatments for this mysterious, hard-to-treat condition. But the benefits could be even more wide-ranging. Kloxin thinks that her findings will have implications for the prevention and treatment of other fibrotic diseases as well.
Links:
Idiopathic Pulmonary Fibrosis (National Heart, Lung, and Blood Institute/NIH)
April Kloxin Group (University of Delaware, Newark)
Kloxin Project Information (NIH RePORTER)
NIH Director’s New Innovator Award (Common Fund)
NIH Support: Common Fund; National Heart, Lung, and Blood Institute
Snapshots of Life: Portrait of a Bacterial Biofilm
Posted on by Dr. Francis Collins
Credit: Scott Chimileski and Roberto Kolter, Harvard Medical School, Boston
In nature, there is strength in numbers. Sometimes, those numbers also have their own unique beauty. That’s the story behind this image showing an intricate colony of millions of the single-celled bacterium Pseudomonas aeruginosa, a common culprit in the more than 700,000 hospital-acquired infections estimated to occur annually in the United States. [1]. The bacteria have self-organized into a sticky, mat-like colony called a biofilm, which allows them to cooperate with each other, adapt to changes in their environment, and ensure their survival.
In this image, the Pseudomonas biofilm has grown in a laboratory dish to about the size of a dime. Together, the millions of independent bacterial cells have created a tough extracellular matrix of secreted proteins, polysaccharide sugars, and even DNA that holds the biofilm together, stained in red. The darkened areas at the center come from the bacteria’s natural pigments.
