ArtiBone: Cryopreservation of 3D tissue-engineered bone substitutes
The major innovation of the present project is the development of ready-to-use cryopreserved 3D tissue-engineered (TE) bone substitutes to facilitate their large-scale application in clinical practice for bone regeneration. Bone diseases, and, particularly injuries and large bone defects from traffic accidents or war conflicts, are significantly increasing nowadays. The first pre-vascularized 3D-bone substitutes are currently undergoing clinical trials. However, in most if not all publications addressing TE bone substitute, the necessity for short-term availability of bone grafts is ignored. Proposed solutions require extended time periods for manufacturing and cultivation. Establishing biobanks of ready-to-use bone grafts is a possible way to overcome these shortcomings and to meet patients’ needs. Therefore, while novel reliable and cost-effective methods for producing 3D-TE-bone are to be developed, there is also a growing need for new storage concepts specially tailored for bone grafts. This is a major prerequisite for successful translation into clinical use. The proposed project follows a two-way approach: a 3D tissue-engineered bone substitute is designed and specifically optimized for cryopreservation, and protocols for cryopreservation are matched to the specific requirements of bone substitute (cells, scaffold material). Proof-of-concept will be established using a collagen/chitosan/hydroxyapatite-matrix (scaffold) seeded with amnion-derived stem cells from a well characterized non-human primate preclinical model (common marmoset, Callithrix jacchus). In this project, fundamental factors of cryoinjury of stem cells within a 3D TE bone matrix will be examined for the first time. Moreover, guidelines for handling and storage will be provided. Exploring the efficiency of cryopreservation, we intend to reveal equilibration time, cooling/warming rates, and cryoprotective solutions suitable for storage of TE bone substitutes yielding high cell viability and metabolic activity after thawing. Finally, a new concept of cryopreservation of scaffolds seeded with MSCs pre-differentiated into osteogenic lineage will be evaluated in terms of preservation of differentiation potential of cells after cryopreservation.