Effect of pH on Wound Healing

Wound healing has always been a global public health problem. According to the healing time, wounds can be divided into acute wounds and chronic wounds. There are many factors that promote wound healing, including age, physical health, nutrition, infection, pressure, and other factors. Among them, pH has been shown to play a role in wound healing and treatment, especially for matrix metalloproteinases (MMPs), tissue inhibitors of MMPs (TIMMs), fibroblast activity, keratinocyte proliferation, microbial proliferation, and immune responses to wounds. Influence. This article will introduce the effect of microenvironmental pH on wound healing, and provide new ideas for wound repair.

What is pH?

pH is a measure of the concentration of hydrogen ions (H+). It is measured on a logarithmic scale, ranging from 0-14. The concentration of H+ in different liquids in living organisms is critical because small changes can alter the balance of chemical reactions.

A pH of 7 is considered neutral. If the H+ concentration increases, the pH will be below 7 which is called acidic. If the concentration decreases, the pH will be higher than 7, which is considered alkaline.

The pH value of the normal skin surface is 4.0-6.0, and the pH value of wounds at different depths and locations is different.

How does pH affect wound healing?

1. Affect bacterial growth: The optimum pH value for the growth and proliferation of most pathogenic bacteria is mostly 7.2-7.4, so when the pH value is low, the growth of these pathogenic bacteria is inhibited.

2. Affect the activity of enzymes: especially for matrix metalloproteinases (MMPs), which play an important role in the process of wound healing, and their activity is also affected by the pH value.

3. Affects oxygen release: pH can also affect oxygen release. When the pH value is lowered by 0.6, the oxygen release amount of oxyhemoglobin can be increased by 50%, and when the pH value is changed by 0.9, the oxygen release amount can be increased by 5 times. The pH value of the microenvironment can also affect the immune function by affecting the chemotaxis and migration of leukocytes.

pH has been shown to play a role in wound healing and healing. At present, the specific mechanism of pH value in the process of acute and chronic wound healing is still unclear, but it is generally accepted that the acidic microenvironment can promote wound healing.

Is the microenvironmental pH value of the wound constantly changing during the healing process?

Of wound healing, the pH value of the microenvironment of the wound will change continuously. Wound healing can be roughly divided into four stages: the coagulation stage, the inflammation stage, the proliferative stage, and the mature stage. In the beginning, the wound will enter the coagulation period, which will lead to an insufficient blood supply, which will lead to a decrease in oxygen content and an increase in glycolysis, thereby increasing PaCO2 and reducing the local pH of the wound. If the wound surface is infected, the local pH value will rise rapidly after a short-term decrease, releasing excess elastase, aggravating the damage of the wound surface, and making the wound surface protracted to healing.

Functional wound dressings on wound pH?

The following figure is a comparison of the effect of some functional wound dressings on the pH value of the wound:

It can be seen that the effect of pH on the performance of antimicrobial wound dressings is interesting as the most common pH range for chronic wounds is 6.5–8.5. The shift to higher pH values for chronic wounds compared to acute wounds is called "alkaline". transformation", thought to be due to tissue necrosis and the presence of microorganisms. The obtained results indicated that the release of silver and its antibacterial efficacy are partly dependent on pH. Additionally, the dressing itself may affect pH. From the results, it can be further speculated that the effect of the dressing on pH and silver ion release has a synergistic effect on antimicrobial efficacy. Therefore, silver-containing dressings alginate + ion-Ag and CMC with Ag + can be expected to help wound healing through the antibacterial effect of silver as well as establishing a low physiological pH.

refer to:

1. Wiegand C, Abel M, Ruth P, Elsner P, Hipler UC. In vitro assessment of the antimicrobial activity of wound dressings: influence of the test method selected and impact of the pH. J Mater Sci Mater Med. 2015 Jan;26(1 ):5343. doi: 10.1007/s10856-014-5343-9. Epub 2015 Jan 13. PMID: 25578697; PMCID: PMC4325976.

2. Qin Y. Silver-containing alginate fibers and dressings. Int Wound J. 2005;2(2):172–176. doi: 10.1111/j.1742-4801.2005.00101.x.

3. Eberlein T. Presented at DGfW conference. 2010.

4. Dissemond J, Witthoff M, Brauns TC, Haberer D, Goos M. pH-Wert des Milieus chronischer Wunden. Hautaz. Year 2003.

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Editor: kiki Jia

Date: February 16, 2023