Hyaluronan in the Bone Marrow of Healthy Individuals and Patients with Acute Myeloid Leukaemia.

In the connective tissues the two major structural components are collagens and glycosaminoglycans (GAGs). When assessing pathological processes in the extracellular matrix, e.g. fibrosis, attention is primarily directed to the collagens. Hyaluronan (HYA) is a GAG of great interest not only as a tentative marker of early fibrosis but also of importance for the disease process in various malignancies.

Acute myeloid leukaemia (AML) is a clonal disorder characterised by abnormal proliferation of myeloid cell precursors. Research has mainly focused on the cellular events but the bone marrow matrix has attracted minor interest.

In this study bone marrow biopsies were obtained from 35 newly diagnosed AML patients and 30 healthy individuals. The bone marrow sections were analysed histochemically for HYA and reticulin (type III collagen).

The HYA staining was significantly stronger, p=0.003, in the AML patients compared to the healthy controls. Only one patient demonstrated abnormal reticulin staining score, but in the group of 8 patients with antecedent myelodysplastic syndrome (MDS), the reticulin staining score was significantly higher, p=0.003, compared to the patients with de novo AML. There was a significant correlation between the HYA and reticulin staining scores, p=0.005, in the AML patients as was seen in the control group, p=0.0005, indicating that the variables HYA and reticulin are not independent. No correlation was found between HYA grading and lactate dehydrogenase (LDH), number of blast cells, sex, age or antecedent blood disease before AML diagnosis. In the control group there was a significant correlation, p=0.042, between HYA and age.

Our findings establish that there is a deposition of HYA in bone marrow in healthy individuals and that HYA is increased in AML patients. It is discussed whether HYA could be an early marker of impending fibrosis and also exert important effects on cellular events in the disease process.