Effects of Hyperbaric Oxygen on Wound Healing
Fibroblasts have an important structural role in the body’s tissues, responsible for depositing the extracellular matrix (ECM) and collagen necessary for connective tissue support and tissue repair. In the context of skin injuries, dermal fibroblasts, which are the main cellular component of the skin, are critical in wound healing and function by contracting the wound and depositing new ECM components and collagen to replace materials lost during injury as well as modulating the functions of immune cells, keratinocytes, endothelial cells and mast cells needed for wound healing.
Adequate oxygenation is essential for all of the stages of wound healing. Oxygen is necessary to support the increased metabolic demand for proper angiogenesis, normal fibroblast function, and epithelial cell migration for tissue repair. Clinical strategies such as hyperbaric oxygen therapy (HBOT) look to increase tissue oxygenation in order to accelerate wound healing. However, clinical efficacy in patient treatment has been variable, with mixed results, which has led researchers to look more closely at the mechanism by which HBOT affects wound healing.
The Lifeline® catalog includes fibroblasts from multiple tissue sources including:
Recent Research Using Lifeline Dermal Fibroblasts
The site of tissue injury presents with inflammation, damaged vasculature, and decreased blood flow, which limits oxygen supply to the cells. HBOT, as a clinical strategy to treat refractory wounds, is thought to “supersaturate” blood with oxygen, which is transported to the site of tissue injury, to provide the oxygen supply needed to meet the increased bioenergy demands of the cells involved in wound healing. Often, wound healing exerts bioenergetic demands on cells that exceed their normal, intrinsic bioenergetic capacity to proliferate and migrate. The aim of a recent study by Green and Colleagues was to quantify the effects of HBOT on mitochondrial dynamics and bioenergetics functions in cells relevant to wound healing. Potential adverse or toxic effects of HBOT at the tissue, cellular, organelle, and molecular levels may be responsible for the variable clinical responses.
The researchers selected Lifeline’s dermal fibroblast cells cultured in FibroLife™ culture medium for their studies because of their demonstrated utility in the study of wound healing. These cells were exposed to a range of gas mixtures and hyperbaric pressures similar to those used in the clinic to treat various conditions before mitochondrial attributes were assessed. High-resolution respirometry and fluorescence microscopy were used to quantify mitochondrial respiration (respiration assay quantified by the Seahorse Analyzer), intermembrane potential, motility, and the zone-based mitochondrial dynamics (nucleus and cell periphery).
In the context of wound healing, an increase in mitochondrial motility to acquire and utilize substrate for the additional ATP production would be expected (and needed) to support the greater metabolic activity needed within the cell nucleus as well as throughout the cell body to fuel cell division and migration. Differences observed in intermembrane potential and respiration parameters were found to be HBOT-condition dependent. Surprisingly, the researchers found that the HBOT at common clinical pressure and oxygen conditions used for wound healing – Cycle 3 at 97.9% O2, 0.0% N2, and 2.1% CO2 at 2.4 atmospheric absolute pressure (ATA) – induced the largest decrease in mitochondrial function. Compared to baseline, suppression of mitochondrial motility lowered levels of ATP-linked respiration in both the cell periphery and perinuclear zones were observed culminating in a reduction of overall intracellular bioenergetic capacity. These surprising results are countered to what is expected to support increase cellular activity at the site of injury to promote wound healing.
Ultimately the data presented in this publication may help to explain how and why the clinical efficacy of HBOT in chronic wound treatment is mixed and why it has limited efficacy to treat certain types of patient wounds, including diabetes and lower extremity ischemia based on energy partitioning within the cells. Data acquired from the other HBOT conditions suggest that alternative pressure and oxygen settings need to be investigated further to find settings that promote (rather than diminish) mitochondrial motility and bioenergy capabilities. As an example, Cycle 1 conditions of 95.0% O2, 0.0% N2 and 5.0% CO2 at 1 atmosphere was able to provide a mitochondrial dynamics and energetics profile that aligns with enhancing the ability of cells to proliferate and migrate that is more suitable for wound healing applications instead of current clinical practices.
Have you used Lifeline’s dermal fibroblasts or other cell types for your research? If so, we’d love to hear from you!