Promoting a Cobalt Complex of Qingzhuan Dark Tea Polysaccharides on Fracture Healing in Rats

Fractures occur commonly with multiple injuries, and their incidence has increased in recent years. Trace amounts of cobalt are necessary for many living organisms as it stimulates hematopoiesis and improves bone health. However, cobalt is also toxic, as it might cause allergic reactions and tissue destruction. These factors limit the application of cobalt in some medical fields. We studied the tea polysaccode-cobalt complex (TPS-Co) prepared from Qingzhuan Dark Tea polysaccharides. We used 6-week-old Sprague-Dawley rats to establish a femoral fracture model and evaluated the effects of CoCl2 and TPS-Co on the healing of femoral fractures. In this study, treatment with TPS-Co for the same content of cobalt intake decreased the side effects associated with CoCl2 treatment and accelerated the healing of femoral fractures in rats. This treatment method promoted angiogenesis by upregulating the expression of vascular endothelial growth factor and hypoxia-inducible factor. Bone formation was promoted via the upregulation of the expression of bone morphogenetic protein 2 and serum bone alkaline phosphatase. TPS-Co was found to actively regulate bone and vascular systems, resulting in significant bone regeneration effects. Therefore, the Qingzhuan Dark Tea polysaccharide cobalt complex might be used as an additive or drug to promote fracture healing, and thus, it might have a huge market value. Impact statement At present, the application of cobalt in the medical field is limited because it causes a series of adverse reactions in the human body. To find a way to retain the excellent active function of cobalt while mitigating its adverse reactions, we prepared the Qingzhuan dark tea polysaccode-cobalt complex (TPS-Co). The effects of cobalt compounds and organocobalt complexes on femoral fractures in rats were also evaluated. Our results showed that TPS-Co positively regulated the vascular and skeletal system and had a significant promoting effect on bone regeneration. These results may have positive implications for future cobalt applications.