Fractures in cryopreserved elastic arteries

Area of Science:

• Biomedical Engineering
• Cryobiology
• Vascular Tissue Engineering

Background:

• Cryopreservation of vascular tissues is crucial for transplantation and research.
• Macroscopic fractures are a significant challenge, compromising tissue viability and function.
• Existing cryopreservation protocols often lead to structural damage.

Purpose of the Study:

• To identify the conditions causing macroscopic fractures in cryopreserved vascular tissue.
• To develop an optimized cryopreservation method preventing such fractures.
• To maintain the in vitro function and cytological structure of the common carotid artery.

Main Methods:

• Cryopreservation of rabbit common carotid arteries using dimethyl sulfoxide (DMSO).
• Systematic variation of cooling and warming rates to pinpoint fracture occurrence.
• Differential scanning calorimetry (DSC) to identify thermal events.
• Controlled addition/removal of DMSO to minimize osmotic injury and toxicity.

Main Results:

• Seventy-five percent of arteries fractured under standard cryopreservation.
• Fractures consistently occurred during warming between -150°C and -100°C.
• The glass transition temperature (Tg) of the cryoprotectant solution was -123°C.
• Reducing warming rate to <50°C/min between -180°C and -100°C prevented fractures.

Conclusions:

• Macroscopic fractures result from thermal stresses during rapid warming of vitrified solutions.
• Slow warming to -100°C allows vitrified material to soften, mitigating stress.
• This optimized method enables safe, rapid thawing of cryopreserved vascular tissue.