Comparing the regeneration potential between PLLA/Aragonite and PLLA/ Vaterite pearl composite scaffolds in rabbit radius segmental bone defects

Mussel-derived nacre and pearl,which are natural composites composed CaCO3 platelets and interplatelet organic matrix,have recently gained interest due to their osteogenic potential.The crystal form of CaCO3 could be either aragonite or vaterite depending on the characteristics of mineralization template within pearls.So far,little attention has been paid on the different osteogenic capacities between aragonite and vaterite pearl.In the current work,aragonite or vaterite pearl powders were incorporated into poly-L-lactic acid(PLLA)scaffold as bio-functional fillers for enhanced osteogenesis.In intro results revealed that PLLA/aragonite scaffold possessed stronger stimulatory effect on SaOS-2 cell proliferation and differentiation,evidenced by the enhanced cell viability,alkaline phosphatase activity,collagen synthesis and gene expressions of osteogenic markers including osteocalcin,osteopotin and bone sialoprotein.The bone regeneration potential of various scaffolds was evaluated in vivo employing a rabbit critical-sized radial bone defect model.The X-ray and micro-CT results showed that significant bone regeneration and bridging were achieved in defects implanted with composite scaffolds,while less bone formation and non-bridging were found for pure PLLA group.Histological evaluation using Masson's trichrome and hematoxylin/eosin(H&E)staining indicated a typical endochondral bone formation process conducted at defect sites treated with composite scaffolds.Through three-point bending test,the limbs implanted with PLLA/aragonite scaffold were found to bear significantly higher bending load compared to other two groups.Together,it is suggested that aragonite pearl has superior osteogenic capacity over vaterite pearl and PLLA/aragonite scaffold can be employed as a potential bone graft for bone regeneration.

Powder metallurgical Ti-Mg metal-metal composites facilitate osteoconduction and osseointegration for orthopedic application

In this work,TieMg metal-metal composites(MMCs)were successfully fabricated by spark plasma sintering(SPS).In vitro,the proliferation and differentiation of SaOS-2 cells in response to TieMg metal-metal composites(MMCs)were investigated.In vivo,a rat model with femur condyle defect was employed,and TieMg MMCs implants were embedded into the femur condyles.Results showed that TieMg MMCs exhibited enhanced cytocompatibility to SaOS-2 cells than pure Ti.The micro-computed tomography(Micro-CT)results showed that the volume of bone trabecula was significantly more abundant around TieMg implants than around Ti implants,indicating that more active new-bone formed around TieMg MMCs implants.Hematoxylin-eosin(H&E)staining analysis revealed significantly greater osteointegration around TieMg implants than that around Ti implants.