Bone is one of the few tissues in the body that has the general capability of scar-less, endogenous regeneration, resulting in complete functional and structural reconstitution. If an otherwise uneventful healing is altered by aging, the underlying mechanism may be substantial also to tissues that have already in young individuals only limited regenerative capacity. Thus, bone is an ideal model system to evaluate the effect of stress factors or constraints of healing on a cellular and tissue level.

Key elements of the regenerative healing process were proposed when this Research Unit was established and have been proven to be correct during the first funding period. (A) The finely tuned mechano-biological regulation of cell and tissue organization during structural re-constitution is altered in aged (by a shift in mechano-sensitivity). (B) An orchestrated regulation of the inflammatoryreaction, indicating long-term dynamics within the immune and the mesenchymal compartments is shifted in aged. During this second funding period, we aim to further the understanding of the mechanisms underlying the age related modulations of endogenous regeneration and how these coincide with alterations due to the metabolic syndrome. We will keep our focus on the three keyelements proposed in the first funding period: a) mechano-sensation in structural reconstitution, b) inflammation, and c) cell lineage commitment upon aging. The overall goal of our Research Unit is to investigate the influence of aging on the bone healingprocesses from the sub-cellular to the organ level, by focusing on well-characterized mechanosensation and immune pathways in age and pathology induced clinical challenges. This allows us to analyse signalling pathways involved in compromised conditions to gain a more detailed understanding of the altered processes that need consideration in the development of new treatment approaches.