Wound-induced calcium waves in alveolar type II cells

Area of Science:

• Cell biology
• Pulmonary medicine
• Wound healing

Background:

• Alveolar type II epithelial (ATII) cells are vital for lung repair after injury.
• Cellular communication mechanisms following acute lung injury are not fully understood.

Purpose of the Study:

• To investigate the signaling response of ATII cells to mechanical injury.
• To determine the role of intracellular calcium ([Ca2+]i) in cell survival and communication post-injury.

Main Methods:

• Created wounded rat ATII cell monolayers.
• Measured intracellular calcium ([Ca2+]i) dynamics using fluorescent indicators.
• Utilized calcium chelators (EGTA, Gd3+) and store-depleting agents (cyclopiazonic acid) to probe calcium sources.
• Assessed the role of extracellular factors released from injured cells.

Main Results:

• Wounding induced a propagating calcium wave originating from the wound edge, extending over 300 microns.
• The calcium wave resulted from both extracellular calcium influx and intracellular calcium store release.
• Inhibition of calcium influx reduced wave amplitude and speed.
• Depletion of intracellular calcium stores abolished the wave.
• Extracellular factors from injured cells also elevated [Ca2+]i in adjacent uninjured cells.

Conclusions:

• Mechanical injury to ATII cells initiates a rapid intracellular calcium ([Ca2+]i) wave in surrounding cells.
• This calcium wave is critically dependent on intracellular calcium stores and influx from extracellular sources.
• Soluble factors released during injury contribute to intercellular calcium signaling, potentially coordinating the repair response.