The Process of Wound Healing and the Different Stages of Repair

The human body is a complex machine made up of many organ systems that work in combination with one another to keep you in good health. One of the biggest examples of the different and complex bodily systems in the process of wound healing. The process of wound healing, together with doctor-prescribed wound care products, works together to repair, replace, and heal damaged tissues. The big question here, though, is about how does all this happen to magically heal our body and keep us in good health. Read on to find out more about the process of wound healing and the different stages of repair.

Wound healing is a complicated process that the integumentary system carries out. During wound healing, it is actually the skin, the largest organ of the body that goes through the process of repairing the damage caused by the wounds. This is why it is first important to understand the makeup of the skin in order to understand the process of wound healing.^(1, 2)

The skin is the largest and heaviest organ of the body and it covers the entire external surface while forming the first line of defense against pathogens and harmful environmental factors such as ultraviolet (UV) rays from the sun. The skin is made up of three layers, which are the epidermis, dermis, and the hypodermis, or subcutaneous layer. The structure of the skin is composed of an intricate network that functions as the body’s first physical barrier to safeguard it from pathogens, chemicals, UV radiation, mechanical injuries, and also regulates temperature. The skin also monitors the amount of water that gets released into the environment.^(3, 4)

The process of wound healing actually refers to the healing of the skin since a wound occurs when there is a break or tear in the epidermal (outermost) layer of the skin. Wound healing begins immediately after there is an injury to the epidermal layer. It is a highly complex and dynamic process that includes many mechanisms, including organized cellular, molecular, and humoral mechanisms.⁽⁵⁾

Let us now look at the different stages of repair involved in wound healing.

When you suffer an injury, the body immediately sets into motion a series of automatic events, which is sometimes referred to as the cascade of healing. All wounds have to go through different processes of healing, which range from initial wound reaction to the advanced and final stages of producing new skin. Simple wounds, such as the ones that do not have extensive tissue damage or infection, may take around four to six weeks to heal. However, this does not include the healing time for scar tissue, which takes longer to form and heal.⁽⁶⁾

It is important to know that while scar tissue never returns to 100 percent of the original strength, it does manage to reach at least 80 percent strength in about 12 to 15 weeks after the initial injury.⁽⁷⁾

After the injury, the cascade of healing is typically divided into four overlapping stages or phases. These include hemostasis, inflammatory, proliferative, and maturation.

Let us take a closer look at the four stages/phases of wound healing:

1. Hemostasis Phase

   The hemostasis phase begins as soon as the injury takes place and it is the first response put forth by the body in response to the wound. The wound causes blood and other fluids to leave the body and in return, the body responds by making all attempts to stop the flow of blood.

   The affected blood vessels immediately constrict in order to reduce the blood flow. Some studies have shown that thrombocytes and platelets in the blood also almost immediately begin to clump together near the site of the open wound and they form a fibrin network.⁽⁸⁾ The fibrin network is responsible for thickening the blood in the affected area to stop the bleeding.^(9, 10)

   As the blood thickens, it forms a clot to prevent harmful germs from entering the body through the site of the injury. This also restores the skin’s ability to function as the first line of defense against dirt and pathogens in order to allow the healing process to begin. At the same time, the platelets release certain types of specialized chemicals that alert the surrounding cells to begin the next phase and to start healing the wound.

2. Inflammatory Phase

   The inflammatory phase is dedicated to the cleaning and healing of the injured area. After you get a wound, you will notice that there is some amount of inflammation in the area. This happens because the immune cells immediately rush to the damaged tissue and the white blood cells known as neutrophils enter the place to start cleaning up the wound. The white blood cells also move out any waste material away from the site of the injury and eventually out of the body. These neutrophils typically reach their peak population within 24 to 48 hours after the injury and by day three, they again reduce in number.⁽¹¹⁾

   After these white blood cells leave, specialized cells known as macrophages arrive at the injury site to continue cleaning of the debris. At the same time, these cells also release certain growth factors and proteins that work to attract the immune system cells to the injured area to enable tissue repair.⁽¹²⁾

   This phase is sometimes also known as the defensive phase since it focuses on destroying any bacteria and removing the debris. It can be said that phase two of wound healing involves preparing the wound bed for the growth of new tissue.

   The inflammatory phase lasts for four to six days and is commonly associated with reddening of the skin, heat, pain, and inflammation.

3. Proliferative Phase

   The proliferative phase occurs once the wound is relatively stable. The focus of the body in this stage of wound healing is to close the wound, manufacture new tissue, and also repair any damaged blood vessels in the area. The proliferative phase takes place over four different processes. These include:⁽¹³⁾

   • Apithelialization: This is the process where new skin tissue is produced in various layers of the damaged skin.
   • Angiogenesis: This process involves the creation of new blood vessels in the affected area.
   • Production of collagen: This process starts the production of collagen to strengthen the tissue of the wound.
   • Contraction: This part of the proliferative phase involves the reduction of the wound size and area and the eventual closing of the wound.

   The proliferative phase also witnesses the combination of blood vessels and connective tissue, to form something known as granulation tissue. This granulation tissue starts forming from about four to five days into the healing process of the wound.⁽¹⁴⁾

4. Maturation Phase

   During the last phase, known as maturation, the newly formed tissue begins to slowly gain strength and elasticity. The collagen fibers start to reorganize while the tissue remodels to become mature. There is also an overall increase in the tensile strength of the tissue, though this strength is restricted to around 80 percent of the pre-injury strength. The maturation phase tends to differ greatly depending on each type of wound, usually lasting for anywhere between 21 days to two years.⁽¹⁵⁾

The process of wound healing is a complex and remarkable one, but it can be susceptible to disruption owing to various local and systemic factors, including infection, age, nutritional intake, body type, moisture, and even environmental factors. When you give the right healing environment, your body will work properly towards healing the wound and replacing the damaged tissue.

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