Monitoring Regeneration of Complex Tissue Defects Using High Resolution In-Vivo Micro-CT

Complex bone grafts are in great demand for the reconstruction of major hard tissue defects, such as those caused by severe trauma or oncogenic ablation. Numerous bone scaffolds combined with different cell populations and bone repair-enhancing signaling molecules, have been investigated for this purpose. However, vascularization and delivery of oxygen and nutrients to engrafted bone constructs pose a major hurdle in optimal bone-defect healing. The harvest of muscular and/or subcutaneous tissue flaps for vascular support of bone regeneration has been previously reported. However, the donor site morbidity associated with these grafts highlights the need for a different approach. We have recently engineered vascularized tissue constructs both in-vitro and in-vivo. Following implantation, these constructs undergo extensive vascular development, and have been shown to support healing of soft tissue defects. After the creation of non-union bone defects, Wistar rats were treated with biocompatible bone scaffolds seeded with osteoblasts and supported by an engineered vascular construct. Four weeks after surgery, rats were sedated using 3% Isoflurane inhalation and subjected to imaging. A high-resolution micro-CT scanner (Bruker Skyscan 1276, Kontich, Belgium) was used to longitudinally track bone healing in vivo, while minimizing radiation dose and specimen numbers. Throughout the experiment, both bone mineral density and morphometric parameters were successfully measured as indicators of the extent of bone repair. Therefore, high resolution in-vivo micro-CT can be used to track healing of bone defects supported by engineered vascular constructs.