Bone Abstracts

Purpose: Osteoradionecrosis (ORN) of the mandible is a serious complication of radiation therapy, and preceded by soft tissue damage before bone loss appears. However, there is still no adequate treatment to heal the soft tissue damage of ORN. This study investigated the effect of PDGF-BB or mesenchymal stem cells (rMSCs) on radiation-induced soft tissue injury.

Methods: Rat model was designed to irradiate the skin of SD rats while sparing the body and internal organs by utilizing a non-occlusive skin clamp along with an X-ray image guided stereotactic irradiator. All wounds were created using the 50 Gy dose level both on the right and the left flank at a 100 cm source-to-surface distance. Next day, experimental groups were randomly divided into three groups (n=3–4, each group). Left side in a subject was administered by 8 μg PDGF-BB, rMSCs and combination of PDGF and rMSCs, while the right side was used as vehicle control. Each wound was analyzed by defining the percentage of the irradiated area ulcerated at given time points and histological observation.

Results: No systemic or lethal sequelae occurred in any animals, and all irradiated skin areas in the multi-dose trial underwent ulceration. Greater than 60% of skin within each irradiated zone underwent ulceration within 16 days. PDGF-BB treatment groups (only PDFG group or PDGF and rMSCs mixed group) improved healing quality more highly organized collagen fiber deposition in full-thickness compared with control group.

Experimental groups were all reached peak ulceration above 50%, with all healing significantly but incompletely by the 56-day endpoint compared with control group.

Conclusions: These results suggest that PDGF-BB or MSCs are an alternative as a treatment to heal soft tissue injury, highlighting future therapeutic options, particularly for patients suffering from an impaired capacity for ORN.