Donkey pericardium as a select sourcing to manufacture percutaneous heart valves:Decellularization has not yet demonstrated any clear cut advantage to glutaraldehyde treatment

Background:The donkey pericardium is considered a good candidate to manufacture percutaneous heart valves based upon its thinness,low cellularity and undulating collagen bundles and laminates.Decellularization represents an avenue worth exploring,should its superiority to glutaraldehyde-treated pericardium be demonstrated.Materials and methods:Donkey pericardium was divided into two groups:regular glutaraldehyde fixation and mild decellularization.The treated pericardia were observed using scanning electron microscopy,histology and transmission electron microscopy.Tensile tests were performed along the axial and perpendicular directions,with the data fitted into both the Gasser–Ogden–Holzapfel(GOH)material model and the Fung’s anisotropic one.Results:The microstructures of the pericardia processed by the two protocols were similar,showing collagen bundles and laminates free of flaws.The decellularization eliminated most of the cells,however leaving the structure somehow compressed.The collagen filaments in bundles were slightly blurry.The anisotropy rates of the non-decellularized specimens were almost identical to the decellularized ones.The decellularized pericardium appeared stiffer.Conclusion:The decellularization proved to be effective.However,it makes the tissue stiffer,which may lead to higher shear concentration during cardiac cycles and reduce its wavy microstructure.Therefore,it appears premature to select decellularized donkey pericardium to manufacture heart valves.

Microarchitecture of titanium cylinders obtained by additive manufacturing does not influence osseointegration in the sheep

Large bone defects are a challenge for orthopedic surgery.Natural(bone grafts)and synthetic biomaterials have been proposed but several problems arise such as biomechanical resistance or viral/bacterial safety.The use of metallic foams could be a solution to improve mechanical resistance and promote osseointegration of large porous metal devices.Titanium cylinders have been prepared by additive manufacturing(3D printing/rapid prototyping)with a geometric or trabecular microarchitecture.They were implanted in the femoral condyles of aged ewes;the animals were left in stabling for 90 and 270 days.A double calcein labeling was done before sacrifice;bones were analyzed by histomorphometry.Neither bone volume,bone/titanium interface nor mineralization rate were influenced by the cylinder’s microarchitecture;the morphometric parameters did not significantly increase over time.Bone anchoring occurred on the margins of the cylinders and some trabeculae extended in the core of the cylinders but the amount of bone inside the cylinders remained low.The rigid titanium cylinders preserved bone cells from strains in the core of the cylinders.Additive manufacturing is an interesting tool to prepare 3D metallic scaffolds,but microarchitecture does not seem as crucial as expected and anchoring seems limited to the first millimeters of the graft.