In life, accidents happen and sometimes we may end up with injuries. Luckily, our body has its own ways to repair itself. Although we may not possess the body regeneration ability like Deadpool, the ability of our body to heal itself from injuries is certainly amazing.
How does a wound heal?
Our skin is made up of the epidermis and dermis. Within the epidermis, the key components responsible for wound healing are keratinocytes, dendritic cells and melanocytes. The deeper dermis layer consists of even more cells and structures that are essential to wound healing:
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fibroblasts for the production of collagen;
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endothelial cells to stimulate blood vessel growth;
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leukocytes such as lymphocytes, neutrophils and macrophages;
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smooth muscle cells;
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extracellular matrix
OpenStax College : J. Gordon Betts, Peter Desaix, Eddie Johnson., CC BY 3.0 , via Wikimedia Commons
These are the real heroes that help to ‘seal’ up your wound, thus preventing further blood loss and entry of pathogens, as well as restoring your skin's integrity.
In adults, a scar is the normal end product of most injuries, with occasionally excessive scarring that is hypertrophic or keloid, which can affect the appearance of the skin.
Stages of wound healing
Wound healing can be divided into four stages:
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Hemostasis — This phase is when your body tries to reduce blood loss from the injuries by constricting the blood vessels under your skin. Platelets in your blood would aggregate at the wound opening and a series of clotting cascades is set off to initiate wound healing.
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Inflammation — Now the loss of blood is less of a concern, your body starts to recruit various cells and substances to repair the damage of your skin. Generally, this stage lasts for three days and your wound may show redness, swelling, heat and pain, which is normal. However, in the case of impaired wound healing (which we will discuss below), this phase is exceptionally long and may backfire, causing health problems.
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Proliferation — At this stage, new blood vessels will be formed (a process called angiogenesis) to supply oxygen to the wound environment. With that, new collagen can be formed, which is essential to the wound healing process. The wound edges would also begin to contract, thus assisting in wound closure. Epithelialization may also start to occur, which allows the skin to regenerate. At this stage, the wound bed is still fragile and can be damaged by simple things, such as incorrect wound dressing choice. Using moist wound dressing is crucial at this stage to support the wound healing process.
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Remodelling or maturation — Finally, the initial collagen that has been laid down leads to a more ordered network of skin structure that gets stronger over time. Nonetheless, this repaired area is never as strong as normal tissue and is always at risk of breakdown. These final changes can take place for up to a year or more after the initial injury.
Factors affect wound healing
In a healthy, young person, wound healing should generally progress as mentioned above. However, numerous factors can affect how the wound heals.
Age
Older people tend to have a slower rate of wound healing because their body has decreased inflammatory response and delayed formation of new blood vessels, all of which are important for wound healing. The skin of older people is also slower at producing new collagen and skin cells, partly due to decreased amino acid, which makes the skin drier.
Diabetes
Impaired wound healing has always been a huge concern among patients with diabetes, especially if the patient also has diabetic neuropathy, peripheral arterial disease or skin infection at the same time. One of the most commonly seen wound healing problems among the diabetic patients is the diabetic foot ulcer. Having persistently high blood sugar levels affects how the cells function, which makes it harder for them to repair the wound.
BruceBlaus, CC BY-SA 4.0 , via Wikimedia Commons
Poor nutrition
A diet that is lacking in vital nutrients (such as proteins) can lead to delayed wound healing and wound breakdown. This is more commonly seen with critically-ill patients after surgery and those who are affected by concurrent medical conditions such as cancer, stroke and HIV/AIDS. Fortunately, such nutrition deficiency can be addressed by giving parenteral and enteral nutrition.
Smoking
We all know smoking is bad for health in every aspect imaginable; in addition, it is also bad for wound healing. This is because a good oxygen supply to the wound environment is crucial for wound healing, but nicotine and carbon monoxide in tobacco reduce the oxygen level and promote formation of thrombi, which may further deprive the wound environment of oxygen. A study that looks at subjects who received smoking cessation intervention after surgery found that quitting smoking helps to improve post-operative complications.
Medications
There are certain medications that may affect the wound healing process, such as:
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Non-steroidal anti-inflammatory drugs (NSAIDs) — commonly used in the treatment of pain and fever. E.g. ibuprofen, mefenamic acid, diclofenac
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Corticosteroids — commonly used in a wide range of medical conditions that have inflammation such as severe asthma and autoimmune disease. E.g. prednisolone, dexamethasone
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Chemotherapy — Commonly used in the treatment of cancer
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Radiation — Commonly used in the treatment of solid tumors
If you’re receiving any of these treatments on a long-term basis, discuss with your healthcare provider on what to do should you develop wounds that are difficult to heal.
Other factors
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Prolonged immobilization, such as stroke patients or those with spinal cord disease who have to stay in bed all day. Especially in the presence of urinary incontinence, it’s very common for patients to develop a pressure wound/ulcer at the lower back area known as sacrum.
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Persistent swelling (edema) at the hands and feets
A word from DOC2US
If you have any questions related to wound healing, you can consult our professional doctors and healthcare professionals on DOC2US. DOC2US is a mobile application that allows you to talk to a doctor or any healthcare professionals via text chat at any time and from anywhere. For better communication, you can even send our online doctor images or voice messages related to your medical inquiry.
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Disclaimer: As a service to our users and general public, DOC2US provides health education contents. Please note the date of last review or update on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.
References
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UpToDate - Risk factors for impaired wound healing and wound complications
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Whittlesea C, Hodson K. Clinical pharmacology and therapeutics. 6th ed. Amsterdam: Elsevier; 2019. P.1020-1022.
Cover image credit: Photo by Diana Polekhina on Unsplash
