Reconstituted Bone Xenograft Of Inbred Line Small-ear Pig Repaired The Segmental Defect Of Radius In Canine

Objective To assess the effect of small-ear porcine massive reconstituted bone xenograft to repair segmental bone defect with the 20mm segmental radius bone/periosteum defect model.Methods With modified Urist method to extract small-ear porcine bone morphogenetic protein(sepBMP) and then combine with small-ear porcine massive cancellous granules deproteinized systematically to develop massive reconstituted bone xenograft(MRBX), also bovine MRBX made as sepMRBX as control .The 20mm segmental radius bone/periosteum defect, a predictable non-union model, was created in twenty-seven dogs. Adult dogs were randomly divided into 3 groups. Small-ear porcine MRBX was used in 15 dogs of Group A for the treatment of the left segmental radius defect, while 6 dogs was kept untreated as a control ; whereas bovine MRBX was used in 6 dogs of Group B. The formation and healing of bones were determined by a serial radiographic, histological and by RT-PCR at 1, 2 , and 4 weeks post-implanted. Alkaline phisphatase(ALP) and bone sialoprotein(BSP) mRNA expression were measured by graphic analysis system. The levels of specific serum IgG were determined using PJA. The various criteria of observation were analyzed statistically.Results Serial Roentgenogram showed the constinuous image at the defects in MRBX group, while the image in control defects was located only at the two cut ends of the section. A large amount cartilage and bone-like tissue were formed 2 weeks post-implanted and bone island within 4 weeks. The levels of specific serum IgG were not found to be significantly different(P>0.05) in sepMRBX and bMRBX groups with pre-implantation. ALP mRNA expression in sepMRBX or bMRBX group was significantly higher than that of the control (P<0.05) after 2 weeks and BSP mRNA expression in sepMRBX group was significantly different(P<0.05) compared with bovine group and control.Conclusions The new type sepMRBX used hi the study has great potentials for repairing with barely immune rejection when segmental bone defect exists and local bone formation and minerilization is needed, especially considering its purified gene and genetic background. It opens a prospect to be the bone graft in the clinical application.