Surgical vacuum filter derived bone grafting substitute displays osteogenic microRNA and mRNA profiles

Abstract text (incl. references and figure legends)

Background Autograft is the golden standard in bone reconstruction, recently a surgical vacuum filter, BoneFlo (Curasan, Germany) was introduced that provides a bone grafting substitute (BGS).The osteogenic capacity of this grafting material, however, is unclear. The aim of this study was therefore to assess the osteogenic miRNA and mRNA expression of this BGS. Methods Samples were collected during non-union surgeries. A surgical vacuum filter (BoneFlo) containing Cerasorb (Curasan, Germany) was fitted to the general surgical vacuum system as soon as the bone was exposed during the surgical procedure. For control samples, whole blood was collected from 5 healthy volunteers and combined with Cerasorb. Subsequently, all samples were snap-frozen and mechanically disrupted. MiRNAs and mRNAs were isolated, transcribed, and pooled for qPCR analysis, followed by further in silico target analyses. Results In total, samples were collected in 7 patients during non-union surgery. From the qPCR data, distinct differences in miRNA and mRNA expression were found between the surgical vacuum filter BGS and the whole blood control samples. A total of 27 miRNAs were shown to be differentially expressed in BGS as compared to the whole blood control samples. Of these 27 miRNAs, six were down, and 21 upregulated. In silico target analyses revealed 116 mRNA targets for the 27 deregulated miRNAs. Discussion This study revealed distinct osteogenic miRNA and mRNA expression profiles in surgical vacuum filter derived human BGS, linked to important processes in the fracture healing cascade and inflammatory response. Most upregulated miRNAs showed to be involved in osteoblastogenesis, mineralization, and angiogenesis. The identified miRNA profiles in the graft material were not seen in samples with whole blood only, indicating that the derived material indeed displays osteogenic properties. Lastly, early osteogenic marker gene expression was upregulated in the BGS comapred to the control.

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This study was partly sponsored by Curasan, Germany.