Biostabilization: Many biomedical implants or tissue-engineered constructs contain biomolecules or cells, which are prone to degradation without adequate preservation strategies. Implants need to be readily available to treat patients. However, storage and transport of implants from the day of production until the application under physiological conditions is intricate and cost intensive. Therefore, preservation methods need to be established. Cryopreserved endothelialized biohybrid lung modules for example, enable long-term storage and availability on demand. Decellularized heart valves and pericardium patches can be freeze-dried allowing storage and transport at room temperature. Biostabilization is an integral step in the development of implants and tissue-engineered constructs that have cellular components or biomolecules to ensure availability off-the-shelf in acute situations and to enable intercontinental transport.
Group leader: Prof. Dr. Ir. Willem F. Wolkers / Unit for Reproductive Medicine / University of Veterinary Medicine Hannover
Keywords: bioheat and mass transfer, cryopreservation of cells and tissues, cryopreservation modeling, dry biobanking, freeze-drying, liposomes for drug delivery, macromolecular stability, membrane biophysics, molecular spectroscopy
The focus of the group is to develop preservation technologies for cells, tissues, and bodily fluids for disease diagnostics, therapies, genetic field studies, and genetic reserves. In order to have biological samples available for future use, they need to be preserved and stored in biobanks, which is usually done at ultra-low temperatures. Sample specific preservation technologies need to be custom-designed to avoid functionality losses. One of the central aims of the group is to move from cold biobanking to dry biobanking of biospecimens inspired by lessons from nature. Dry biobanking reduces the carbon footprint associated with cryogenic storage and transport, and has the additional benefit that it can be implemented in underdeveloped countries and in non-laboratory settings, where cryogenic storage is not an option.
Research interests include:
 Wolkers WF, Oldenhof H, Tang F, Han J, Bigalk J, Sieme H, Factors affecting the membrane permeability barrier function of cells during preservation technologies. Langmuir 35 (2019) 7520-7528.
 Vásquez-Rivera A, Oldenhof H, Hilfiker A, Wolkers WF, Spectral fingerprinting of decellularized heart valve scaffolds. Spectrochim Acta A Mol Biomol Spectrosc. 214 (2019) 95-102.
 Zouhair S, Aguiari P, Iop L, Vásquez-Rivera A, Filippi A, Romanato F, Korossis S, Wolkers WF, Gerosa G, Preservation strategies for decellularized pericardial scaffolds for off-the-shelf availibility. Acta Biomaterialia 84 (2019) 208-221.
 Goecke T, Theodoridis K, Tudorache I, Ciubotaru A, Cebotaria S, Ramm R, Höffler K, Sarikouch S, Vásquez-Rivera A, Haverich A, Wolkers WF, Hilfiker A, In vivo performance of freeze-dried decellularized pulmonary heart valve allo- and xenografts orthotopically implanted into juvenile sheep. Acta Biomaterialia 68 (2018) 41-52.
 Vásquez-Rivera A, Sommer KK, Oldenhof H, Higgins AZ, Brockbank KGM, Hilfiker A, Wolkers WF, Simultaneous monitoring of different vitrification solution components permeating into tissues. Analyst 143 (2018) 420-428.
 Vásquez-Rivera A, Oldenhof H, Dipresa D, Goecke T, Kouvaka A, Will F, Haverich A, Korossis S, Hilfiker A, Wolkers WF, Use of sucrose to diminish pore formation in freeze-dried heart valves. Scientific Reports 8 (2018) 12982.
 Sydykov B, Oldenhof H, de Oliveira Barros L, Sieme H, Wolkers WF, Membrane permeabilization of phosphatidylcholine liposomes induced by cryopreservation and vitrification solutions. Biochimica et Biophysica Acta 1860 (2018) 467–474.
 M Zhang, H Oldenhof, B Sydykov, J Bigalk, H Sieme H, WF Wolkers, Freeze-drying of mammalian cells using trehalose: preservation of DNA integrity. Scientific Reports 7 (2017) 6198.
 Zhang M, Oldenhof H, Sieme H, Wolkers WF, Freezing-induced uptake of trehalose into mammalian cells facilitates cryopreservation. Biochimica et Biophysica Acta 1858 (2016) 1400-1409.
 Wang S, Oldenhof H, Dai X, Haverich S, Hilfiker A, Harder M, WF Wolkers, Protein stability in stored decellularized heart valve scaffolds and diffusion kinetics of protective molecules. Biochimica et Biophysica Acta 1844 (2014) 430–438.