Effects of μCT radiation on tissue engineered bone-like constructs

Abstract

High-resolution, non-destructive imaging with micro-computed tomography (μCT) enables in situ monitoring of tissue engineered bone constructs. However, it remains controversial, if the locally imposed X-ray dose affects bone development and thus could influence the results. Here, we developed a model system for μCT monitoring of tissue engineered bone-like constructs. We examined the in vitro effects of high-resolution μCT imaging on the cellular level by using pre-osteoblastic MC3T3-E1 cells embedded into three-dimensional collagen type I matrices. We found no significantly reduced cell survival 2h after irradiation with a dose of 1.9Gy. However, 24h post-irradiation, cell survival was significantly decreased by 15% compared to non-irradiated samples. The highest dose of 7.6Gy decreased survival of the pre-osteoblastic MC3T3-E1 cells by around 40% at 2days post-irradiation. No significant increase of alkaline phosphatase (ALP) activity at 2days post-irradiation was found with a dose of 1.9Gy. However, ALP activity was significantly decreased after 7days. Using our model system, the results indicate that μCT imaging with doses as low as 1.9Gy, which is required to obtain a reasonable image quality, can induce irreparable damages on the cellular level