Effect of interferon on heterotopic new bone formation in mice

To study the effect of interferon (IFN) on bone induction and new bone formation, heterotopic bone was induced by implanting pieces of demineralized bone matrix in soft tissue of mice. Mouse IFN was given as daily subcutaneous injections of 2 X 10(5) IU/mouse. Treatment was started one week before bone matrix implantation and continued until sacrifice. As a measure of chondrogenesis in the implants short-term incorporation of 35sulphur administered 11 days after implantation was measured. The amount of mineralized tissue formed in connection with the implant was estimated by 45calcium incorporation 20 days after implantation. There was no indication of a negative effect of IFN on bone induction, new bone formation, or metabolism of orthotopic bone. This is in agreement with our findings in the clinical use of IFN after reconstructive surgery in osteosarcoma.