Cryopreservation of composite tissue transplants

Area of Science:

• Regenerative Medicine
• Transplantation Biology
• Vascular Surgery

Background:

• Composite tissue allotransplantation is crucial for upper extremity reconstruction.
• Donor tissue availability is a significant limitation in allotransplantation.
• Cryopreservation offers a potential solution to increase donor tissue availability and reduce antigenicity.

Purpose of the Study:

• To evaluate the viability of cryopreserved composite tissues.
• To demonstrate the feasibility of microvascular isotransplantation of cryopreserved composite flaps.

Main Methods:

• Harvested Lewis rat epigastric flaps; analyzed fresh and cryopreserved samples.
• Cryopreservation involved perfusion with dimethyl sulfoxide/trehelose, controlled cooling to -140°C, and 2-week storage.
• Evaluated flap viability using Factor VIII endothelial staining and MTT tetrazolium salt assay; performed in vivo isotransplantation.

Main Results:

• Cryopreserved samples showed intact vascular endothelia via Factor VIII staining.
• Epithelial viability index in cryopreserved samples was not significantly different from fresh controls (p=0.12).
• In vivo, 10/10 fresh transplants, 9/10 perfused transplants, and cryopreserved transplants (5-60 days survival) were viable.

Conclusions:

• Composite tissue flaps retain viability after cryopreservation.
• Long-term survival of cryopreserved composite tissue transplants is feasible.
• Flap loss is likely due to indirect injury, not direct freezing or cryoprotectant damage.