Tissue cryopreservation according to GMP guidelines

⇒ Successful cryopreservation of tissue transplants

⇒ Temperature controlled biobanking

⇒ Demand-oriented provision of vital tissue for surgical treatment

All-in-one system for the medical tissue cryopreservation

The Center of Cryo Competence in Life Science has developed an unique system for the successful cryopreservation of living tissue, the cryogenic storage (cryobanking) for an arbitrary time span as well as for the demand-oriented provision of the revitalized tissue, e. g. for in vitro testing or surgery.

The core component of the system is the mediRACK. This RACK serves as a heat exchanger for a controlled cryopreservation and as a cold reservoir for the uninterrupted cold transport to the biobank. During the storage in the biobank the mediRACK serves as a stackable storage system with integrated temperature control. In conjunction with a mobile thawing station it enables the revitalization of the frozen tissue samples at its point of destination.

As cryogenic package for use with the mediRACK we developed our dish-hedgehog-system with tissue fixator.

A compact rising station enables the replacement of the culture medium by a special medium for the tissue cryopreservation as well as the rinsing of this cryopreservation medium before usage respectively implantation ─ at any place, aseptically and in a few simple steps.

The development of a mobile thawing station permits the revitalization of the cryopreserved tissue at its point of destination ─ whether in the scientific lab, hospital or at the surgeon’s practice.



The freezing system for succesful tissue cryopreservation

The mediRACK allows a successful cryopreservation of solid tissue with a standard bio-freezer (liquid nitrogen-operated controlled rate freezer.


During the cryopreservation process the mediRACK works as a heat exchanger which manages the heat transfer between the freezing chamber and tissue samples. The thermal management allows an exact sample specific application of the freezing program. The mediRACK has a unique design of three separate, thermally decoupled sample units which are linearly arranged in a framework. By a uniform distribution of the cooling gas the open design allows an identical temperature control at each of the 3 sample positions and thus, ensures a reproducible cryopreservation success for tissue implants and in vitro generated tissue constructs.

Guidance of the cooling gas flow through the mediRACK by vertical alignment of the freezing system in relation to the flow direction in the cooling chamber.

Cryopreservation performance of the mediRACK with tissue engineered mucosa (processed in the SY-LAB IceCube 14M biofreezer):

  • Simultaneous cryopreservation of up to 3 tissue patches with a maximum size of 4 cm² in appropriate packages
  • Accurate sample-specific application of defined cooling rates and complex temperature programs

  • Position-dependent temperature deviations below 2 K during the whole cryopreservation procedure
  • Position-dependent deviation of the freezing rate below 0.1 K/min respectively 5 % of the target freezing rate
  • Reproducible cell viability in the cryopreserved tissue constructs significantly higher than 80 %

Transport and storage

During the transportation of the cryopreserved tissue samples the mediRACK serves as a cold reservoir and thus, prevents an impairment of the samples even at temporary interruptions of the cold chain, for example during the sample transfer from the transport vessel to the storage location. The stackable design and the development of an unequivocal electronic determinability of the mediRACK enable an efficient and confusion-proof handling in the biobank. The integrated temperature measuring technology enables an interruption-free sample specific temperature monitoring from cryopreservation until revitalization.


The mediRACK is equipped with a rewarming system for the automated revitalization of the cryopreserved tissue within a mobile, autonomous working thawing station with an implemented hot steam generator. The quick and temperature controlled thawing of the samples with hot steam prevents recrystallization processes and thus, ensures an optimum maintenance of vitality.

Proof of vitality for a human mucosa construct by fluorescence microscopy: bottom side with vital fibroblasts
Proof of vitality for a human mucosa construct by fluorescence microscopy: top side with vital keratinocytes




Wide variety of specialized sample packages

As cryopreservation vessel for tissue and tissue constructs with the mediRACK we provide the unique dish-hedgehog-system with optional tissue fixators. It consists of lockable dishes from stable and temperature-resistant medical high performance plastic in various versions which provide aseptic working conditions. The main characteristics of the dishes are:

Confusion-proof tissue fixation

Before cryopreservation the tissue is transferred into the dish. And if necessary, the tissue can be easily centered and fixed by a tissue holder, made from stainless steel. A confusion of the bottom side and the top side of the transplant can be safely ruled out by this measure.

A: Colored model wth tissue holder ‚Hedgehog‘ for the confusion-proof fixation e.g. of human cornea and media adapters for perfusion culture
B: Transparent model with fixator for mucosa constructs and quick connectors for aseptic media exchange

Suited for the in vitro cultivation

All dishes can be used as vessels for the incubation or pre-cultivation of the tissue under in vitro conditions. Besides the static tissue culture (batch process) they even can be used for the perfusion culture with continuous medium exchange (flow culture). The tissue engineered or pre-cultured tissue patches can be cryopreserved directly within the culturing vessel after an aseptic medium exchange. An extension of the portfolio with membrane microreactors is planned.

Aseptic media exchange

All dishes are equipped with two liquid-tight ports which can be closed by a blind plug or equipped with application specific Luer-Lock connections, if needed. Besides the use of the dishes as microreactor vessels for the perfusion culture the connections enable an aseptic replacement of the cell culture medium inside of the closed dish even in a non-sterile environment.

Packages from different biocompatible and low temperature resistant plastics with different self-sealing port systems and external seal ring

Optimized thermal transfer properties

Design and thermal properties of the sample dishes allow an optimal temperature management in the cryopreservation process. The plano-parallel, flat surfaces of bottom and top side provide a perfect thermal contact between the package and the heat exchanger and therefore, impede the formation of hoarfrost during transportation and cryogenic storage. This enables a gentle automated thawing of the cryopreserved tissue in the mediRACK.

Overall benefits of the dish-hedgehog system:

  • Optional tissue fixator for a construct size of up to 4 cm²
  • Suitability for batch-culture and perfusion culture
  • Optimal cryopreservation and automated thawing with the mediRACK
  • Quick connectors for sterile media exchange
  • Transparent or colored design




Aseptic media exchange at the mobile rinsing station

The ultracompact design of the mobile rinsing station enables an uncomplicated and aseptic media exchange at any time and any place. The exchange of the cell culture medium by a cryoprotective medium for the cryopreservation as well as the rinsing of the cryoprotective agents with a cultural medium after the revitalization of the tissue can be performed with a few simple steps in a non-sterile environment. The gravity-driven replacement of the medium from a sterile infusion bag is possible without a pump and power supply and causes no cleaning effort.

Mobile rinsing station: Aseptic exchange of the cryomedium at a working area of 0.1 m² by perfusion of the tissue samples with a maintenance medium after the successful cryopreservation




Revitalization with the mobile thawing station

The mobile thawing station works autonomous because of its equipment with an integrated hot steam generator. Via a quick connector the mediRACK including the frozen samples gets coupled to the media supply of the thawing station and is thawed program-controlled by pulsed steam to achieve the maximum viability (controlled rapid thawing).

Thawing station with connected mediRACK, equipped with three cryopreserved tissue constructs (A) and control unit for the program-controlled permanent temperature monitoring (B)

The easy transport and the autonomous operation of the thawing station enable a revitalization of cryopreserved tissue samples at its point of destination. The cryopreserved tissue can be removed from the cooling unit as required and prepared for implantation within a very short time span. This offers a high planning certainty for the transplantation e. g. of cornea as well as an ambulatory wound care with tissue implants according to demand.