The cryopreservation of solid tissues is still a key challenge. In a tissue-like matrix made of proteins or carbohydrates cells grow flattened, spindle- or star-shaped and form with ´the matrix and intercellular contacts a highly organized 3-dimensional network. In this state the cells are, due to their unfavorable surface to volume ratio and their high metabolic activity, far more susceptible to thermal stress then spherical single-cells in a cell suspension. Because the tissue matrix represents a diffusion barrier, the gas- and material exchange as well as the access of cryoprotective substance to the cells in the centre of the tissue is limited. The removal of heat is aggravated by the thermal resistance of the tissue contrary to a cell suspension. Inhomogenous conditions are formed, which often lead to a loss in vitality in the cryopreserved tissue.
Development of Cryoprotocols for the gentle preservation of solid tissue
The most important factors for a vital cryopreservation of cell structures and functional tissues are an optimal match between freezing hardware and freezing technique, a thereon aligned time-temperature-regime and a defined addition of one or more cryopretectants. The whole of this tissue-specific coordinated technical and biological methods is known as cryoprotocoll. With the goal of optimal preservation of cell viability, metabolic status and tissue integrity, we develop your cryoprotocoll for mammalian and plant cells. For example, tissue cryopreservation according to GMP guidelines or cell and tissue cryopreservation in multiwell and multititer plates are possible.
Endogenous cryoprotectives for medical applications
A huge problem for transplant medicine is the required renunciation on toxic cryoprotectivs. Implantable donor tissue, like cornea or implantable tissue replacements, must not be treated with classical antifreeze additives to protect the patient.
We do research on natural, non-toxic alternatives. The human body itself provides the natural, biodegradable polysaccharides hyaluronan, chondroitin and dermatan sulfate, which can provide inter- as well as extracellular protection against cold damage within the scope of a perfectly balanced cryoprotocol. In tissue engineering we are going to use this tissue components to built cryoprotectant-free, cryopreservable tissue constructs