(WHS-P60) EXPLORING THE POTENTIAL OF COLLAGEN SCAFFOLDS IN CALVARIAL BONE REGENERATION
Friday, May 17, 2024
7:30 AM – 5:00 PM East Coast USA Time
Autologous bone grafts are widely used to repair bone defects, such as craniofacial abnormalities. However, procedures involving alveolar bone grafts are invasive and there is risk for donor site infection and morbidity. Bone tissue engineering, which incorporates stem cells, scaffolds, and biological factors, is a promising alternative to current repair methods for cleft palate and other bone defects. In our study, we assess the impact of several scaffolds, including collage sponge implant, collagen gel with superficial silicone sheet, and collagen gel only on bone regeneration in a calvarial defect. Natural polymers, such as collagen, can be a useful material in bone tissue engineering. At 5 weeks of age, we created a 3 mm diameter calvarial defect in the parietal bone of mice. We implanted a collagen sponge pre-loaded with 20 microliters of PBS, a collagen gel with a silicone sheet, collagen gel only, or no intervention at all (control). At 4 or 12 weeks, we harvested the mice calvaria for analysis. We performed 3D-reconstruction volumetric analysis using the Amira software. For immunostaining, we cryosectioned the bone samples at a thickness of 30 um. We used immunostaining to characterize the components of the osteoconductive environment. At 4 and 12 weeks, collagen gel implant with overlying silicone sheet had the highest percent of bone growth in the defect, 24.7% and 30.9%, respectively. Collagen gel and collagen sponge implants had similar percentages of bone growth at 12 weeks, 25%, and 25.6%, respectively. All scaffold implants had a higher percentage of bone growth in the defect compared to the control condition (2% at 4 weeks and 7.8% at 12 weeks). Immunostaining analysis for the collagen gel and silicone sheet implants showed endomucin and CD31 staining for blood vessels within the fibrous bridge that connects the newly generated bone in the defect area to the surrounding intact bone. We also observed endomucin and CD31 signal in the periosteum at the edge of the defect and surrounding the new bone marrow. The superior bone growth at 4 and 12 weeks in the collagen gel and silicone sheet condition suggests that these materials foster an enhanced osteoconductive environment. The prominent presence of endomucin and CD31 staining marks neovascularization, a vital component for sustainable bone regeneration, and continuity between new and intact bone, across the fibrous bridge and into the intact bone. In the future, understanding the mechanisms involved in bone regeneration, and identifying key cells, can help optimize scaffold treatment options for bone defects for applications in bone tissue engineering procedures in pediatric cases, such as cleft lip and palate disorders.