**4.1 Functional assays**

Pathophysiology and Clinical Aspects of 10 Venous Thromboembolism in Neonates, Renal Disease and Cancer Patients

bearing MP being about 34% (Thaler, 2011). In contrast those who did not develop

There are a number of conditions associated with elevated MP. Most of these disease states are associated with an increased risk of thrombosis. They essentially seem to reflect the health and pathophysiology of the endovascular system. Table 3 below gives a list of

**Condition** Specific example where MP were elevated

(reference)

(Ahn, 2002)

Pereira, 2006)

Stroke (Merten, 2004) Diabetes (Alkhatatbeh)

Thromboembolism (Cimmino)

Myelofibrosis (Villmow, 2002)

2005 )

Myocardial infarct/angina (Nagy) (Exner,

Essential Thrombocytosis (Villmow, 2002)

Pre-eclampsia of pregnancy (Aharon)

(Combes, 1999;Dignat-George, 2004) Systemic lupus erythematosis (Nielsen;

Neoangiogenesis (Goon, 2006 )

Chemotherapy induced (Kim, 2002; Kim)

thrombosis did not have a detectable level of tissue factor bearing microparticles.

**3.1.4 Disease groups associated with venous or arterial thrombosis** 

**Cardiovascular disease** Hypertension (Boulanger)

**Myeloproliferative Disorder** Polycythemia vera (Duchemin)

**Thrombotic Microangiopathies** Thrombotic thrombocytopaenic purpura

**Autoimmune diseases** Antiphopholipid antibody syndrome

**Cancer related** Metastatic solid tumours (Dass, 2007)

Table 3. List of conditions associated with thrombosis and elevated MPs in circulation.

The role of MP in promoting atherothrombosis has also been another area of study (Cimmino). In one report, shed membrane microparticles were seen to be produced in human atherosclerotic plaques and were a critical determinant of thrombogenecity after plaque rupture (Mallat, 1999). The apoptosis occurring after plaque disruption or rupture was closely associated with TF expression on cell membranes leading to thrombogenecity. These MP were observed to express phosphotidylserine and some expressed CD11a which is an adhesion molecule (Martinez, 2005) (Morel, 2006). Given the links between inflammation and thrombosis, the emerging role of MP in atherothrombosis is not

conditions where they have been found to be elevated.

**3.2 Microparticles and atherothrombosis** 

surprising (McGregor, 2006; Meerarani, 2007).

Most of the assays under this section relate to either the prothrombotic function of MP or measuring the phospholipid content of MP. This can be done in the liquid phase e.g. a clot based assay such as the XACT test or by estimation of prothrombinase activity using an ELISA (Exner, 2003). The advantages of these approaches are that they provide an indication of the procoagulant activity of MP. The drawback is that the cell of origin for the MP cannot be determined.
