Regenerative medicine: How cryotechnology is advancing tissue transplants and organ preservation

The vision: tissue and organs on demand

Regenerative medicine pursues an ambitious goal: to repair or replace damaged or destroyed tissue and entire organs with biotechnologically produced or preserved replacement materials. From skin transplants for burn victims and cartilage implants for arthritic joints to the long-term vision of organ preservation for transplant medicine - cryopreservation is a key enabler of these developments.

While individual cells are already routinely cryopreserved, the preservation of entire tissues and even more so entire organs poses fundamentally different challenges for cryotechnology. In this article, we highlight the current state of research and the role that Consarctic® plays in this pioneering field.

Single cells vs. tissue: Why the difference is so big

When cryopreserving a single cell suspension, all cells are in a homogeneous environment. They are cooled evenly, the CPA (cryoprotectant) reaches every cell and the phase transition takes place simultaneously everywhere.

The challenge of the masses

The situation is completely different for a piece of tissue or an organ:

• Thermal inhomogeneity: The surface of the fabric cools faster than the inside. This can lead to thermal stresses that damage the fabric mechanically.
• CPA diffusion: The cryoprotectant must diffuse into every single cell of the tissue. With thicker tissue, this takes significantly longer and requires adapted protocols.
• Vascular structure: In organs, the CPA can be perfused via the vascular system. Maintaining this delicate vascular structure during freezing and thawing is one of the greatest challenges.

Current applications in practice

Skin and calluses

The cryopreservation of skin pieces (allografts) for burn patients is already clinical routine. Corneal transplants (corneal grafts) are also successfully cryopreserved. These relatively thin tissues are comparatively manageable for cryotechnology.

Cartilage and bone

Cryopreserved allogenic cartilage and bone are used in orthopaedic surgery. The challenge here lies in preserving the chondrocytes (cartilage cells) within the extracellular matrix.

Heart valves and blood vessels

Cryopreserved heart valves have been successfully transplanted for decades. They are stored in nitrogen tanks at -196°C after the valves have been frozen in a controlled rate freezer.

The vision of the future: organ preservation

The ultimate goal of cryobiological research is the successful cryopreservation of whole organs. This would revolutionize transplantation medicine: Donor organs would no longer have to be transplanted within hours, but could be stored in stock and thawed when needed. The waiting lists for organ transplants could be drastically shortened.

Current research approaches include:

• Vitrification of entire organs: Perfusion with highly concentrated CPA solutions and ultra-fast cooling are intended to transform the entire organ into a vitreous state without ice crystals forming.
• Nanowarming: A promising approach to thawing in which magnetic nanoparticles are distributed in the organ and heated evenly and quickly by an external magnetic field. This solves the problem of thermal inhomogeneity during thawing.

The role of Consarctic® in tissue preservation

Consarctic® provides the technical basis for research institutions and tissue banks working on the preservation of tissues:

• BIOFREEZE® Controlled Rate Freezers: With their freely programmable freezing curves, they offer the flexibility needed for the development of new tissue preservation protocols.
• BSD+ and BSF+ storage tanks: For the safe long-term storage of cryopreserved tissue in the gas phase.
• ASR+ transport container: For the validated shipment of tissue transplants between tissue banks and clinics.

Cryogenics as a bridge to the medicine of the future

Regenerative medicine is still in its infancy. Every research breakthrough brings the vision of tissue and organs on demand closer. Cryopreservation is not just a tool, but an indispensable prerequisite.

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