Coagulopathies in orthopaedics: links to inflammation and the potential of individualizing treatment strategies.

Orthopaedic patients are at risk for developing pathologic imbalances of coagulation factors characterized by phases of both hypocoagulability and hypercoagulability. Complications from "hypocoagulability" include life-threatening hemorrhage, wound hematoma, and poor wound healing. Complications due to "hypercoagulability" include deep venous thrombosis, pulmonary embolus, and disseminated intravascular coagulation. In addition, coagulation imbalance that favors the production of procoagulant factors may lead to excessive inflammation and contribute to systemic inflammatory response syndrome, acute respiratory distress syndrome, multiple organ dysfunction syndrome, and death. Optimally, the goal of individualized treatment of coagulopathies in orthopaedic patients should be to achieve efficient healing while avoiding the morbidities associated with imbalance of coagulation and inflammation. Such individualized and time-sensitive measures of coagulation status require rapid, accurate, qualitative, and quantitative assessment of the critical balance of the coagulation system. Commonly used coagulation tests (prothrombin time and activated partial thromboplastin time) are incapable of determining this balance. An alternative to is to perform thrombin generation assays. The greatest advantage of thrombin generation assays over traditional coagulation tests is their ability to detect hypercoagulability, the balance of procoagulant and anticoagulant factors, and the effect of all pharmaceutical anticoagulants. Further clinical investigations are warranted to develop and refine the thrombin generation assays to help predict clinical complications related to coagulation imbalances. In addition, future testing will help define the prothrombotic period allowing for appropriate initiation and cessation of anticoagulant pharmaceuticals. These subsequent studies have the potential to allow the development of a real-time coagulation monitoring strategy that could have paramount implications in the management of postoperative patients.

The α2ß1 integrin is a metastasis suppressor in mouse models and human cancer.

Integrins regulate cell-cell and cell-matrix adhesion and thereby play critical roles in tumor progression and metastasis. Although work in preclinical models suggests that ß1 integrins may stimulate metastasis of a number of cancers, expression of the ß1 subunit alone has not been shown to be a useful prognostic indicator in human cancer patients. Here we have demonstrated that the α2ß1 integrin suppresses metastasis in a clinically relevant spontaneous mouse model of breast cancer. These data are consistent with previous studies indicating high expression of α2ß1 integrin in normal breast epithelium and loss of α2ß1 in poorly differentiated breast cancer. They are also consistent with our systematic analysis of microarray databases of human breast and prostate cancer, which revealed that decreased expression of the gene encoding α2 integrin, but not genes encoding α1, α3, or ß1 integrin, was predictive of metastatic dissemination and decreased survival. The predictive value of α2 expression persisted within both good-risk and poor-risk cohorts defined by estrogen receptor and lymph node status. Thus, the α2ß1 integrin functionally inhibits breast tumor metastasis, and α2 expression may serve as an important biomarker of metastatic potential and patient survival.

Isolation and purification of C3 from human plasma.

The alternative pathway of complement shares its terminal components (C3 and C5 through 9) with the classical pathway, but has several unique components, including factors D, B, and P (properdin). This unit presents methods for assaying total alternative pathway activity and the activity of factors B and D. Radial immunodiffusion (RID) can also be used to measure factor D, B, and P concentrations.

Assays for membrane complement receptors.

Leukocytes express several types of receptors for activated products of the complement (C) system. This unit describes assays for a subset of these receptors: those specific for fixed fragments of C3 (CR1, CR2, CR3, and CR4). Although the assays have been designed for tests of human C receptors, they can often be carried out with rodent (e.g., mouse, rat, or guinea pig) cells by substitution of rodent-specific reagents. Two basic protocols are presented for rosette assay of CR1, CR2, CR3, and CR4 on adherent and nonadherent cells. Isolated leukocytes may be tested for rosette formation in suspension or adherent to a surface. Nonadherent cells such as lymphocytes, NK cells, or cells from an undifferentiated leukocyte cell line must be tested in suspension. The unit also contains three support protocols for formation and quantitation of sheep erythrocyte-C3 complexes for use in the two basic protocols.