The Biocompatibility Reserarch And Constructing Tissue Engineered Bone By Three-dimensional Printed Polylactic Acid-hydroxyapatite Composite Scaffolds

Objective:The exploration of biocompatibility of three-dimensional printed polylactic acid-hydroxyapatite composite scaffolds(3D printed PLA-HA)combined with bone marrow stromal cells.To observe the osteogenesis capability of 3D printed PLA-HA composite scaffolds in vivo and to enhance the theoretical basis of repairing the large segmental bone defect for clinical.Methods:Bone marrow stromal cells labeled by green fluorescent protein(GPF)were seeded on three-dimensional printed PLA-HA composite scaffolds and beta-tricalcium phosphate(β-TCP).The state of adhesion and proliferation as well as alkaline phosphatase(ALP)activity were detected by fluorescence microscope,scanning electron microscopy,Cell Counting Kit 8(CCK8)and ALP activity experiment,respectively.The model of vivo bioreactor on adult New Zealand rabbits inside the unilateral tibial was constructed.The experimental research was divided into two groups: the experimental group included bone marrow stromal cells,three-dimensional printed PLA-HA composite scaffolds,periosteum and saphenous arteriovenous blood bundles;and the control group consisted of bone marrow stromal cells,three-dimensional printed PLA-HA composite scaffolds and tibial periosteum.After the samples were collected,osteogenic related genes,bone morphology measurement and histological examination stained were evaluated by polymerase chain reaction(PCR),micro-Computed Tomography(micro-CT)and hematoxylin and eosin(HE).Results:The adhesion rate of three-dimensional printed PLA-HA composite scaffolds could rise to 60% in 12 hour.Compared with the group of β-TCP,the amount of cell proliferation of three-dimensional printed PLA-HA composite scaffolds had significant differences in 4 and 7 days.The activity of ALP of three-dimensional printed PLA-HA composite scaffolds,compared to β-TCP,had significant differences in 3,7 and 14 days and the secretion of ALP was higher than the group of β-TCP in the following 7 days.The outcomes in vivo indicated that the amount of osteopontin(OPN)and collagen type Ⅰ(COLⅠ)expressed by the experimental group was higher than that in control group.The results from Micro-CT analysis revealed newly formed bone volume and bone trabecula had the higher amount than control group.Histological observation results showed the newly formed bone,partial newborn bone growing into woven bone,the larger volume and the much more osteocytes and higher density of newborn vascular in experimental group,while partial newborn bone and partial mature bone cell differentiation in control group.Conclusions:Three-dimensional printed PLA-HA composite scaffolds have fine biocompatibility and can be used as scaffolds in bone tissue engineering.Three-dimensional printed PLA-HA composite scaffolds can fulfill the requirements to construct tissue engineering bone with functional outcome.