DOS BULLETIN - Dansk Ortopædisk Selskab

2010-378_DOS nr. 3 2010 29/09/10 10:08 Side 127
Differences in expression of microRNA in human
lumbar discs
Benny Dahl, Søren Ohrt-Nissen, Kristina Døssing,
Maria Rossing, Lennart Friis-Hansen, Finn Cilius Nielsen
Department of Orthopaedic Surgery, Rigshospitalet;
Department of Clinical Biochemistry, Rigshospitalet
Background: Recent studies have pointed towards a genetic contribution
to the development of disc degeneration. In spite of identification of
candidate genes, the complete understanding of the genetic role in disc
degeneration has not been obtained. MicroRNA's (miRNA's) regulate
protein translation through mRNA binding, and more than 800 miRNA's
have been identified in humans.
Purpose: The purpose of the present study was to isolate miRNA from
human lumbar intervertebral discs and assess the difference in miRNA
expression between the annulus fibrosus and nucleus pulposus.
Methods: Intervertebral discs were obtained from twelve patients undergoing
anterior interbody fusion for degenerative disc disease of the lumbar
spine. The interverbral discs were immediately stored in RNA-Later,
and frozen at -80 degrees Celcius. After RNA extraction, global miRNA
expression analysis was performed using the Affymetrix GeneChip®
miRNA array.
Findings: From 100 mg tissue it was possible to extract 2 microg RNA.
27 miRNA's had a higher expression in the fibrosus and 10 had the highest
expression in the pulposus. One miRNA, 147b, was highly expressed
in annulus fibrosus. One target gene for this miRNA is brain derived
neurotrophic factor (BDNF), a member of the "neurotrophin" family of
growth factors that has been associated with degeneration of human
intervertebral discs.
Conclusion: To our knowledge, this is the first time miRNA´s have been
demonstrated in human intervertebral lumbar discs. Furthermore we
found differences in expression of miRNA between the nucleus pulposus
and annulus fibrosus. In vitro transfection studies in untransformed
fibroblasts will determine the functional role of these miRNA´s.
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