The initial events after fracture seem to be essential for fast and uneventful bone healing. Tissue organization (e.g. invasion of vessels) starts early, leading to a restructuring of the hematoma. Interestingly, almost all accounts of the fracture healing process begin with the discussion of the invasion of inflammatory cells to the wound site as the first event. However, this starting point ignores the important fact that the initial fracture hematoma already contains inflammatory cells. The initial cell composition and its particular microenvironment could be among the factors, which crucially determine whether fracture healing proceeds effectively.
This talk aims to give a detailed overview, beginning with the first events in fracture healing and bone regeneration, followed by a description of the close interplay between bone and the immune system, which already implicates an important role for immune cells in fracture healing. Bone healing in knockout mice devoid of mature T and B cells is compared with the healing in mice depleted of cytotoxic (CD8) T cells at the time of injury. The data is considered in the context of in vitro results and compared to a large animal model as well as clinical studies. Results focus on aspects of the early fracture hematoma with special regard to the initial immunologic features. We will demonstrate the importance of immune cells for the cellular composition in the injured region dictating the healing course and progression.
This research seems to be of vital importance, especially in immunologically suppressed patients, suffering from delayed healing or non-union situations. The understanding of the initial phase of healing could play a pivotal role in future fracture treatment strategies and allow us to differentiate between aspects of inflammation that are essential for bone healing and those that delay bone healing.
Disclosure of Interest None Declared