Bone Union Enhancement by bFGF-Containing HAp/Col in Prefabricated Vascularized Allo-Bone Grafts

Abstract

Background We have developed a prefabricated vascularized allo-bone graft (PVAG) by implanting the saphenous vascular bundles of recipient rats into transplanted donor bones in a flow-through manner. We previously demonstrated that the angiogenetic and bone formative abilities of the PVAG are stimulated by the addition of a basic fibroblast growth factor (bFGF)-containing hydroxyapatite/collagen (HAp/Col). This study aimed to demonstrate that the bone union ability of the PVAG is similarly stimulated by the bFGF-containing HAp/Col composite. Methods Sprague-Dawley donor rats (n = 32) and Wistar recipient rats (n = 32) were used in this study. The PVAG was fixed to the femur of the recipient rat using K-wire (dimeter: 0.7 mm) pinning, followed by suturing with a 4–0 nylon suture. Recipients were divided into four groups: with or without vascular bundles, and with or without bFGF-containing HAp/Col. Rats were sacrificed 6 weeks after transplantation, and bone union, bone resorption, and angiogenesis were radiologically and histologically evaluated. Results Radiological analysis revealed a significant increase in callus formation and union rate, while histological analysis showed a significant increase in bone formation and angiogenesis in the group treated with both vascular bundles and bFGF. Bone resorption did not significantly increase in any of the evaluated groups. Conclusion Osteogenic cells, osteoconductive scaffolds, growth factors, and mechanical environment are known to be important factors in the process of fracture healing. The PVAG developed herein contains osteogenic cells, osteoconductive scaffolds, and growth factors. In addition, the PVAG is rigidly fixed to the fracture site, providing a stable mechanical environment. Together, these four factors contributed to a good bone union. Furthermore, this method did not promote bone resorption. Thus, the addition of a vascular bundle and bFGF-containing HAp/Col makes it possible to create an ideal vascularized allo-bone graft for the reconstruction of massive bone defects.

Addition of a Vascular Bundle Accelerates Bone Union in Femoral Bone Defects

“…Therefore, in our previous studies, we have used flowthrough vascular axes, which prevented the occurrence of thrombus formation. [12][13][14]32 Tanaka et al reported that arteriovenous loops and distal ligation type arteriovenous bundles are more effective in achieving angiogenesis in the introduced tissues than flow-through vascular axes. 31 Although flow-through vascular axes may be inferior to other methods in their ability to induce angiogenesis, the technique is simpler to apply in clinical practice.…”

Progress of Wnt Signaling Pathway in Osteoporosis

“…As a potential mitogen, it can accelerate cartilage repair in vivo and promote the proliferation, differentiation, and maturation of chondrocytes in vitro [ 68 , 69 ]. The basic fibroblast growth factor (BFGF) is released from necrotic tissue when the body suffers from a fracture or tissue injury [ 70 ]. It participates in the self-repair process of bone tissue and promotes osteoblast proliferation and collagen formation.…”