What is fibronectin?


After a spinal cord injury, a type of thick tissue forms at the place where the injury happened. This tissue has two main parts: one part is called the glial scar and the other is called the fibrotic scar. The glial scar surrounds the central area of the injury, and the fibrotic scar is found in the central part of the injury area, consisting of cells called fibroblasts and a thick structure of substances that support cells.

This scar tissue does two things: it helps protect the area by stopping the inflammation from spreading and causing more damage to nearby healthy tissue, but it also blocks the growth of nerve fibers which can hinder recovery. Recently, most research has been focused on the glial scar, with less focus on the fibrotic scar.

In laboratory experiments, models using a combination of two types of cells show that the fibrotic scar can block nerve fiber growth. Also, removing fibroblasts in live models shows that it can cause the tissue to lose its structure and form hollow areas at the injury site. Therefore, learning more about how the fibrotic scar forms might help us understand the disease process of spinal cord injuries better. In this article, I will focus on “Fibronectin” a vital player in fibrotic scar formation.


Fibronectin: The Body’s ‘Adhesive’ and How It Functions

Our bodies are composed of hundreds of different types of cells. What allows these cells to function as organized tissues and organs rather than just a ‘clump’? One of the answers lies in a protein called fibronectin.

Fibronectin plays many crucial roles in our body. In essence, this protein acts like an ‘adhesive,’ linking cells to each other and to their surrounding ‘matrix.’

Why Is This Topic Important?

In medicine, particularly in cancer research, wound healing, and immune response, fibronectin is an extremely important component. If the functions of fibronectin are disrupted, it can lead to various diseases due to disturbed cellular communication. Conversely, understanding how fibronectin works is leading to the development of new treatments and diagnostic methods.

What Will You Learn in This Article?

In this article, we’ll explore what fibronectin is, how it works, and why it’s crucial for our health. We will particularly focus on the multifunctionality of this protein and its implications for human health.

What is Fibronectin?

Basic Definition of Fibronectin

Fibronectin is a high-molecular-weight, multifunctional protein. This protein plays a role in ‘adhering’ cells to each other, which is crucial for maintaining tissue structure and function. The protein itself consists of various ‘domains,’ each with specific functions.

Where It Exists and Its Main Functions

Where It Exists

Fibronectin exists in various parts of the body but has significant functions particularly in the following areas:

  1. In the blood: Known as plasma fibronectin, it is involved in clotting and repair at wounded sites.
  2. Extracellular matrix: This is a complex network surrounding cells, where fibronectin anchors cells to other matrix components.
  3. Cell membrane: It also exists on the cell surface and is involved in cell-to-cell adhesion and signal transduction.

Main Functions

  1. Cell Adhesion: Fibronectin acts as a ‘foundation’ for cells to be precisely positioned.
  2. Tissue Repair: In cases of injury or damage, fibronectin helps in the growth of new cells and reconstruction of tissues.
  3. Immune Response: When pathogens invade, fibronectin also plays a role in directing immune cells to the precise locations.

Structure of Fibronectin

Amino Acid Composition

Fibronectin is a large protein made up of over 2,000 amino acid residues. This long chain of amino acids forms specific structures that allow it to perform a variety of functions. The types and sequences of amino acids are subtly adjusted depending on the functions and interactions fibronectin needs to perform.

Domain Structure

Fibronectin is divided into specific ‘domains,’ each functioning as independent units. These are involved in cell adhesion, protein interactions, and sugar chain binding, among others. Some of the main types of domains are:

  1. Type I, II, III Domains: These are the most common domains and are involved in cell adhesion and interactions with other proteins.
  2. Heparin-binding Domain: This domain binds with heparin, which is part of the extracellular matrix.

3D Structure

The 3D structure of fibronectin is exceptionally complex to accommodate its multifunctionality. Multiple domains can move flexibly with respect to each other, changing shape as required. This ‘variability’ contributes to the multifunctional nature of fibronectin.

Roles of Fibronectin

Cell Adhesion: The ‘Social Networking’ of Cells

How do individual cells form into tissues? One answer is through fibronectin-mediated cell adhesion. Fibronectin exists outside cells and connects cells to each other and to the ‘foundation’ around them, known as the extracellular matrix (ECM).

Tissue Repair: The ‘Handyman’ for Healing Wounds

When we get injured, how do our wounds heal? Fibronectin plays a critical role here as well. It gathers at the site of injury, promoting the growth of new cells and repairing the wound.

Immune Response: The ‘Defensive Wall’ Against Invaders

Fibronectin is closely involved in immune response. During an infection, fibronectin guides immune cells like white blood cells and macrophages to the site of infection, acting as a defense mechanism.

Fibronectin and Diseases: From Cancer to Inflammation and Tissue Disorders

Cancer: A Promoter of Metastasis?

Fibronectin levels are often high in the progression of cancer, suggesting that it may facilitate metastasis, the spread of cancer cells to other tissues and organs. Although the exact mechanism isn’t fully understood, ongoing research aims to find out more.

Inflammation: A Double-Edged Sword

Fibronectin is closely involved in inflammatory responses. On one hand, the protein guides white blood cells to the site of injury, aiding in the initial healing process. On the other hand, excessive accumulation of fibronectin could potentially prolong inflammation.

When inflammation becomes chronic, an excessive buildup of fibronectin may cause tissue hardening or dysfunction, which may, in turn, lead to fibrosis.

Tissue Disorders: The Breakdown of Structure

When fibronectin is lacking, the adhesion between cells, or between cells and the ECM, may weaken. This could potentially lead to the breakdown of tissue structure, affecting the function of organs such as the heart, liver, and lungs.

Specifically, a deficiency in fibronectin may slow wound healing, weaken the skin, or limit joint mobility, among other health issues.

Cutting-Edge Research on Fibronectin: Applications in Future Medicine and Unresolved Questions

Ongoing Research and Its Importance

Applications in Cancer Treatment

Given that fibronectin expression is often linked to cancer progression, research is underway to target this protein for new treatments. For instance, studies are looking at using antibodies against specific domains of fibronectin to inhibit the spread of cancer cells.

Controlling Inflammation

Because excessive accumulation of fibronectin can be problematic in chronic inflammation, research is exploring how to control this, through interactions with anti-inflammatory drugs and the discovery of new molecular targets.

Unresolved Issues

Clarifying Fine Mechanisms

The mechanisms and interactions of fibronectin are highly complex, and the detailed mechanisms are not yet fully understood.

Side Effects and Safety

Even if treatments targeting fibronectin prove to be effective, there is still insufficient data on their potential side effects and long-term safety.

Future Perspectives

The study of fibronectin holds enormous potential for breakthroughs in medicine, tissue engineering, and biotechnology. Understanding the multiple roles of this versatile protein not only answers fundamental biological questions but also opens the door to innovative therapies and diagnostic tools.

Next Steps in Research

Continued research into fibronectin’s domains, their interactions with other proteins, and their role in cellular behavior is critical. Such insights will pave the way for more targeted therapies for a range of conditions, from cancer and inflammatory diseases to tissue disorders.

Technological Advancements

With advancements in technologies like CRISPR for gene editing or improved imaging techniques, researchers will be able to study fibronectin and its interactions at an unprecedented resolution. This will likely speed up the rate of discovery and implementation of practical applications.

Challenges and Ethical Considerations

While the prospects are exciting, the manipulation of fibronectin in humans poses ethical and safety challenges. Rigorous clinical trials will be necessary to ensure that any therapies based on fibronectin are both effective and safe. Ethical considerations, especially when it comes to gene editing, will also need to be addressed.


Fibronectin is an integral part of the complex machinery that keeps our bodies running smoothly. Its roles in cell adhesion, tissue repair, and immune responses make it a subject of intense study. While research has illuminated some of its functions and potential applications, much remains to be discovered. The ongoing research and future studies promise to uncover even more about this fascinating protein, offering new possibilities for the medical field.