Gene expression analysis of neurogenic heterotopic ossification around the hip joint of spine injury patients by microarray technique

Status:

completed 08/2017

Aims:

It was the purpose of this study to provide evidence for an early development of a neurogenic heterotopic ossification (NHO) by radiologic as well as histologic and scanning electron microscopic analyses. NHO-affected and healthy tissue samples from nine paraplegic patients should be evaluated by microarray-gene chip analysis to get maximal information on the molecular pathomechanisms. Additionally, quantification of IL-1ß, IL-6, IL-8, IL-10 as well as the neuropeptide substance P in the sera of the patients should be performed.

Activities/Methods:

The early development of NHO was identified primarily by sonography and verified by MRT or CT. For the first time bioptic specimen were taken from the early NHO tissue and from healthy muscle as control (same patient) from nine paraplegic patients and were analyzed by histology and transmission electron microscopy. Additionally, the mostly up- or down-regulated genes were determined as possible marker for an early recognition of NHO. The inflammatory mediators IL-1ß, IL-6, IL-8, IL-10 as well as the neuropeptide substance P in patients’ sera and in a pool-serum from healthy donors (control) were analyzed by ELISA technique.

Results:

Edema formation and/or calcification were detected by all sonographic examinations, which were taken as beginning NHO. NHO development was subsequently confirmed by MRT or CT. Compared to the healthy control tissue several phases of NHO within the affected tissue were determined among these an initial inflammatory reaction, edema formation, bleeding and leucocyte infiltration with subsequent muscle hypotrophy and necrosis. Progressive fibrosis and subsequent chondrogenesis was detected as beginning enchondral ossification and intermediate form of NHO.

The microarray gene chip analysis showed striking values for phospholipase A2 group 7 (PLA2G7), the interferon gamma inducible protein 30 (IFI30) and the trans-2,3-enoyl-CoA reductase like protein (TECRL). In the sera of the patients a 15-fold increase in IL-6 concentration was detected compared to the pool serum. Value for the cytokines IL-1ß, IL-8, IL-10 and the neuropeptide substance P showed only minor differences compared to the pool serum.

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