Hyperbaric oxygen alters intracellular bioenergetics distribution in human dermal fibroblasts

AIMS

Hyperbaric oxygen therapy (HBOT), used to promote wound healing, has limited efficacy in many clinical conditions. Wound healing exerts bioenergetic demands on cells that can exceed their intrinsic bioenergetic capacity to proliferate and migrate. The aim of this investigation was to quantify the effects of HBOT on mitochondrial dynamics and bioenergetics functions in cells relevant to wound healing.

MAIN METHODS

High-resolution respirometry and fluorescence microscopy were used to quantify mitochondrial respiration, intermembrane potential, dynamics, including motility, and the intracellular distribution of mitochondrial bioenergetic capacity partitioned into perinuclear and cell peripheral regions in cultured human dermal fibroblasts. Cells were subjected to a range of gas mixtures and hyperbaric pressures, including conditions utilized in clinical care.

KEY FINDINGS

Motility was reduced immediately following all HBOT exposures utilized in experiments. Inhomogeneities in intermembrane potential and respiration parameters were produced by different HBOT conditions. The partitioning of ATP-linked respiration was also HBOT-condition dependent. Application of HBOT at common clinical pressure and oxygen conditions resulted in the largest immediate decrement in mitochondrial motility and reductions in ATP-linked respiration in both the cell periphery and perinuclear zones. Aberrations in motility and respiration were also present 6 h after exposure.

SIGNIFICANCE

HBOT produces intracellular distinctions and inhomogeneities in mitochondrial dynamics and bioenergetics. HBOT as is commonly applied in clinical medicine induced undesirable and persistent alterations in bioenergy function needed to support cell migration and/or proliferation. There may be alternative HBOT parameters that more effectively engender maintenance and adequacy of intracellular bioenergy supply to promote wound healing.

Prophylaxis of mitochondrial dysfunction caused by cellular decompression from hyperbaric exposure

Mitochondrial dysfunction occurring in response to cellular perturbations can include altered mitochondrial motility and bioenergetic function having intracellular heterogeneity. Exogenous mitochondrial directed therapy may correct these dysfunctions. Using in vitro approaches, we find that cell perturbations induced by rapid decompression from hyperbaric conditions with specific gas exposures has differential effects on mitochondrial motility, inner membrane potential, cellular respiration, reactive oxygen species production, impaired maintenance of cell shape and altered intracellular distribution of bioenergetic capacity in perinuclear and cell peripheral domains. Addition of a first-generation cell-permeable succinate prodrug to support mitochondrial function has positive overall effects in blunting the resultant bioenergy responses. Our results with this model of perturbed cell function induced by rapid decompression indicate that alterations in bioenergetic state are partitioned within the cell, as directly assessed by a combination of mitochondrial respiration and dynamics measurements. Reductions in the observed level of dysfunction produced can be achieved with application of the cell-permeable succinate prodrug.