miRNA analysis to discover fracture related biomarkers

Background

Biomarkers predictive of fracture healing outcomes would provide a useful tool to allow surgeons to proactively make patient based clinical decisions. Currently, even in high risk groups, there are no accurate ways to determine the potential of a particular patient to progress to delayed or non-union. Such a tool would enable more reliable patient stratification, thus allowing for earlier diagnosis and increasing the potential success of additional early interventions by the surgeon. Small non-coding RNA sequences, such as microRNA (miRNA) have been shown to be powerful regulators of cellular behavior in both healthy and diseased environments. They can function by interacting with messenger RNA sequences and thereby modifying protein expression. miRNAs normally act intracellularly, but due to the action of extracellular vesicles (EVs) released by cells they are able to signal over large distances and thus EVs are a critical signaling pathway between different cells. EVs and miRNA have the advantage of being extremely stable, detectable in complex body fluids such as serum, and provide information directly relating to cellular function. MicroRNA (miRNA) studies are already transitioning from basic research applications to clinical applications in areas such as cancer diagnosis. 

Goal

Within this project we aim to identify fracture related non coding RNA sequences, present in extracellular vesicles, in the serum of patients. Then establish their function within primary human mesenchymal stem cells and propose predictive markers that could be used to screen patients early after injury. In addition, functionally active miRNA species identified as lacking in non-healing patients can also be used as a potential off-the-shelf treatment to enhance fracture repair in patients shown to have a decreased level of expression. 

Results

Serum was obtained from patients at various times after injury day 0-3, day 5-12 and day 19-56 and whole non-coding RNA was sequenced. As a comparator, mesenchymal stromal cells (MSCs) were induced to undergo osteogenesis and compared to unstimulated controls. We have identified several miRNA targets that are regulated during early osteogenesis. We also identified the presence of some of these markers in serum taken from fracture patients within days after fracture (Figure). Furthermore, we are also one of the first groups to identify piRNA and circular RNA markers of osteogenesis. This work will be continued in a new follow up project.