fibroblast
Meaning of fibroblast: The cell that builds the body's structural framework, and the same cell that closes a wound by making a scar.
Definition of fibroblast
A fibroblast is the main working cell of connective tissue. It manufactures collagen and the other fibers, along with the gel-like material between them, that hold organs in place and give skin, tendon and bone their structure. After an injury, fibroblasts multiply, move into the wound and lay down the framework that becomes a scar.
What does a fibroblast make?
It secretes the extracellular matrix, the material filling the space between cells. Collagen is the largest component, a rope-like protein that provides tensile strength. Elastin supplies recoil, so skin springs back after stretching. Fibronectin acts as a glue that other cells grip. Large sugar-protein molecules hold water and give the matrix its cushioning. The fibroblast also makes enzymes that break the matrix down again, so the framework is continually rebuilt rather than laid once and left alone. The balance between building up and breaking down decides whether a tissue holds its shape, thickens, or is slowly lost.
How does it heal a wound?
Healing runs through overlapping stages, and the fibroblast dominates the middle one.
| Stage | What happens |
|---|---|
| Clotting | A plug seals the breach and traps platelets |
| Inflammation | White cells clear bacteria and dead tissue |
| Rebuilding | Fibroblasts arrive, multiply and lay down collagen |
| Remodeling | Collagen is reorganized and the scar slowly strengthens |
Some fibroblasts convert into myofibroblasts, which contain muscle-like filaments and pull the wound edges toward each other. Once the wound is closed those cells normally die off. Where they do not, collagen keeps accumulating, giving a thick raised scar on the skin or fibrosis inside an organ. Excess scar tissue in the lung, liver or kidney stiffens the organ and interferes with how it works, and the same cell type is responsible.
Where are they found?
Everywhere connective tissue exists, which means almost everywhere: the deep layer of skin, tendons and ligaments, the sheets wrapping muscle, the framework inside organs, and the coverings of bone. Fibroblasts differ from site to site, and one taken from a tendon behaves unlike one taken from lung. They grow easily in a laboratory dish, so they have long served as a standard research cell, and a small skin sample can be grown and reprogrammed into other cell types for study.
Used in a sentence
The culture was established from skin fibroblasts taken at biopsy.
Good to know
The same cell that closes a wound also drives fibrosis, so scarring in the lung, liver or kidney reflects fibroblast activity that failed to switch off.
Word origin
Where “fibroblast” comes from
Fibro- comes from the Latin fibra, meaning fiber; blast comes from the Greek blastos, meaning a sprout or germ.