High-dose irradiation of bone chips preserves the <i>in vitro</i> activity of bone-conditioned medium

Abstract

Extracorporeal irradiation sterilizesresected tumor bone used as autografts in reconstruction surgery. Therapeutic irradiation is a standard technique in head and neck cancer therapy that aims to preserve organ function. Bone irradiation has a complex, mostly inhibitory, effect on remodeling and regeneration, although the underlying mechanisms are still not fully understood. It remains unclear if extracorporeal irradiation affects the paracrine-like activity of the corresponding autografts. We recently reported that bone-conditioned medium from autogenous bone chips contains a number of factors that might affect cell activity. In the present study, we investigated the effects of extracorporeal irradiation of porcine cortical bone chips on the activity of the corresponding bone-conditioned medium. The effects of bone-conditioned medium on the expressions of transforming growth factor-beta (TGF-β) target genes in oral fibroblasts were assessed. Bone-conditioned medium from bone chips exposed to a total radiation dose up to 120 Gy did not affect expressions of TGF-β target genes, including adrenomedullin, BTB/ POZ domain-containing protein 11, proteoglycan 4, NADPH oxidase 4, and interleukin 11, in oral fibroblasts. In conclusion, bone irradiation does not alter the capability of the corresponding bone-conditioned medium to provoke a robust fibroblastic cell response in vitro. (J Oral Sci 58, 325-331, 2016)

Bone-Conditioned Medium Obtained From Calvaria, Mandible, and Tibia Cause an Equivalent TGF-β1 Response In Vitro

“…Together, these findings establish that the paracrine-like activity of bone chips is independent of embryological origin and the ossification process of the donor site and the graft morphology. If we relate the findings to those of others, we can refer to our own data on BCM, all representing bone chips from pig mandible [15][16][17][18][19][20] and mixed samples from human bone. 30 Others have focused on the cellular aspects related to bone chips from different sources including from the mandibles.…”

“…In our previous studies, we have introduced a bioassay to evaluate the paracrine-like activity of bone chips, 15,16 in addition to proteomic analysis of the conditioned medium. 17 This bioassay reflects the activity of TGF-b released from freshly prepared bone chips or from bone chips undergoing heating, 18 radiation, 19 and exposure to antiseptic solutions. 20 The TGF-b activity is represented by the expression of TGF-b target genes including interleukin 11 (IL-11), proteoglycan 4 (PRG4), and NADPH oxidase 4 (NOX4), all of which play a possible role during bone regeneration and thus graft consolidation.…”