title: Isolated metaphyseal injury influences unrelated bones.
abstract: Background and purpose - Fracture healing involves different inflammatory cells, some of which are not part of the traditional bone field, such as B-cells and cytotoxic T-cells. We wanted to characterize bone healing by flow cytometry using 15 different inflammatory cell markers in a mouse model of metaphyseal injury, and incidentally discovered a previously unknown general skeletal reaction to trauma. Material and methods - A bent needle was inserted and twisted to traumatize the cancellous bone in the proximal tibia of C57/Bl6 female mice. This is known to induce vivid bone formation locally in the marrow compartment. Cells were harvested from the injured region, the uninjured contralateral tibia, and the humerus. The compositions of the immune cell populations were compared to those in untraumatized control animals. Results - Tibial metaphyseal injury led to substantial changes in the cell populations over time. Unexpectedly, similar changes were also seen in the contralateral tibia and in the humerus, despite the lack of local trauma. Most leukocyte subsets were affected by this generalized reaction. Interpretation - A relatively small degree of injury to the proximal tibia led to systemic changes in the immune cell populations in the marrow of unrelated bones, and probably in the entire skeleton. The few changes that were specific for the injury site appeared to relate to modulatory functions.
authors.affiliation: a Department of Clinical and Experimental Medicine , Orthopaedics.
authors.forename: Love
authors.initials: L
authors.lastname: Tätting
authors.affiliation: a Department of Clinical and Experimental Medicine , Orthopaedics.
authors.forename: Olof
authors.initials: O
authors.lastname: Sandberg
authors.affiliation: a Department of Clinical and Experimental Medicine , Orthopaedics.
authors.forename: Magnus
authors.initials: M
authors.lastname: Bernhardsson
authors.affiliation: b Department of Clinical and Experimental Medicine and Department of Clinical Immunology and Transfusion Medicine , Linköping University , Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Ernerudh
authors.affiliation: a Department of Clinical and Experimental Medicine , Orthopaedics.
authors.forename: Per
authors.initials: P
authors.lastname: Aspenberg
mesh_terms: D000818:Animals; D001402:B-Lymphocytes / Q000276:immunology*; D001853:Bone Marrow / Q000276:immunology; D001854:Bone Marrow Cells / Q000276:immunology*; D000071556:Cancellous Bone / Q000293:injuries*; D016022:Case-Control Studies; D005260:Female; D005434:Flow Cytometry; D017102:Fracture Healing / Q000276:immunology*; D006098:Granulocytes / Q000276:immunology*; D006811:Humerus / Q000276:immunology; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D009000:Monocytes / Q000276:immunology*; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*; D013977:Tibia / Q000276:immunology / Q000293:injuries; D013978:Tibial Fractures / Q000276:immunology*