What Are Fibroblasts?

Fibroblasts are specialized cells in the body essential for the structure of tissues. They produce proteins that make up the components of the extracellular matrix (ECM), which serves as a scaffolding for other cells. This makes fibroblasts important components of connective tissue, the fibrous material that holds organs and tissues in place.

These cells serve several important functions in every organ system and body part. Dermal fibroblasts (those in the skin) are essential for wound healing, while other fibroblasts are involved in inflammation, tissue growth and repair, regulating the heartbeat, and more. Other types of fibroblasts contribute to fibrosis (scarring), scleroderma (a skin disorder), and cancer.

This article provides an overview of fibroblasts' anatomy and function, and the conditions associated with them.   

Structure

Fibroblasts are the most common cells in the connective tissue and are present in many body parts. They are flat, branch-shaped cells characterized by a dark, oval nucleus. The structure of the cell can vary based on the stage of development and location. Fibroblasts are different from epithelial cells that line organs, tissues, and other surfaces in the body.

Unlike some other types of cells, fibroblasts can undergo development and transformation. The fibrocyte is an inactivated state of the cell associated with tissue generation. In wound healing or as part of the inflammatory response, fibroblasts transform to myofibroblasts, which are stiffer, crisscrossed with fibers, and provide more support.

Types of Fibroblasts

There are many types of fibroblasts involved in different body parts and systems. Among the primary subtypes are:

• Pericytes: This common type supports the structure of tiny blood vessels called capillaries by surrounding and holding them in place. They likely play a role in regulating circulation, especially in the brain.
• Cardiac fibroblasts: The walls of the heart have their own fibroblasts. These are associated with heart muscle function.
• Muscular fibroblasts: These contain three layers of fibroblasts (the endomysium, perimysium, and epimysium) that support skeletal muscles.
• Dermal fibroblasts: These play an essential role in wound healing. Several fibroblasts support the layers of skin and help in hair production. Papillary fibroblasts support the epidermis (outer layer of skin), while reticular fibroblasts are located in a deeper layer.
• Fat: Some fibroblasts turn into adipocytes, or fat cells, which make up the layer of cells that comprise body fat.
• Other types: Certain fibroblasts are associated with the structure and function of the colon, bladder, lungs, and digestive organs.    

Function

The primary function of fibroblasts is to provide support and structure to tissues in the body. They are associated with many body processes, which include:

• Extracellular matrix: Fibroblasts produce collagen and other proteins that make up the ECM. This is the network of fibers that support tissues in the body, such as the skin, organs, and blood vessels.
• Tendons and bones: The collagen protein produced by fibroblast cells is a critical component of cartilage (found in joints and between bones), tendons, and bone.  
• Wound healing: Dermal (skin) fibroblasts transform into myofibroblasts and play a crucial role in repairing tissues. They form the structural framework of the healing wound, facilitating healing and causing fibrosis, which is when tissues stiffen or scar.
• Immune response: These cells play a central role in inflammation, the physical response to injury, infection, or certain chronic diseases. They’re essential for immune function, providing support for blood cells fighting off infection, damage, or tumor development.  
• Tissue development and aging: In the inactivated (fibrocyte) state, fibroblasts play a central role in tissue development and growth in the womb and developmental stages of life. Fibroblasts are involved in the natural thickening and hardening of tissues associated with aging.   
• Heart function: As part of their role in supporting heart tissues, cardiac fibroblasts are also involved in regulating the heartbeat. They help make up the structure of cells that signal heart muscles to contract.  

Associated Conditions

Many conditions are associated with fibroblasts and fibroblast activity since they are an essential part of your body’s structure. These critical cells are involved in:

• Heart disease: Fibroblasts regulate the activity and structure of the heart. They’re associated with high blood pressure (hypertension) and heart failure, among other cardiac issues.    
• Scleroderma: This is a rare disease in which fibrosis occurs in the skin and ECM, more often seen in cisgender women. This leads to severe skin tightening, inflammation, and joint swelling.
• Inflammatory diseases: Inflammation is a component in various diseases and conditions. Fibroblasts are involved in inflammatory diseases such as autoimmune diseases and inflammatory bowel diseases.
• Cancer: Fibroblasts can also contribute to the spread of cancer cells and affect surrounding ECM and other structures, leading to the growth of tumors.

Summary

Fibroblasts are common cells that support tissues in the body. They’re typically flat in shape, with spindles. These cells produce the proteins that hold vessels, tissues, muscles, and other structures in place, serve a role in cell development and repair, and are essential for wound healing. Fibroblasts are involved in a wide range of diseases and conditions.

A Word From Verywell

Fibroblasts are an essential part of the body's delicate framework from the skin to the heart. It is important to understand these cells, their function, and their place in medicine. Knowing how you are put together is a big part of maintaining your health.