Sodium Alginate/Chitosan/Tannic Acid Composite Hydrogel Microspheres Promote Osteogenic Differentiation In Vitro And In Vivo

Objectives:Bones are a critical component of the human body’s structural framework,and damage to bone tissue can have a profound impact on a patient’s daily activities and even pose a threat to their life.Traditional treatment methods for bone defects have several limitations,such as limited availability of autologous bone,extended reconstruction time,risk of infection at the donor site,among others.In bone tissue engineering,new grafts with tissue-inducing activity have been designed using biological scaffolds,cells,and active molecules.Bone marrow mesenchymal stem cells(BMSCs)are the most commonly used seed cells,and their effects on osteogenic differentiation very important.It has been reported that sodium alginate/chitosan hydrogel can effectively promote bone repair,and tannic acid as an active substance can effectively improve the performance of hydrogel and promote osteogenic differentiation,but for tannic acid(TA)The role of microspheres combined with sodium alginate(SA)/chitosan(Chitosan,CS)in the osteogenic differentiation of BMSCs and the promotion of bone healing is still remain unknown.In this paper,a preliminary study was carried out on the effect of TA-loaded SA/CS composite hydrogel microspheres on the osteogenic differentiation of BMSCs.Methods:(1)Use a UV spectrophotometer to draw the standard curve of TA and detect the release law of TA(2)Staining of living cells and dead cells to observe the effect of SA/CS/TA microspheres on the viability of BMSCs(3)Real-time quantitative polymerase chain reaction(qPCR),Western blotting,and immunofluorescence techniques were used to analyze the expression of osteogenic-specific genes and proteins,in order to validate the promotion of BMSCs osteogenic differentiation by SA/CS/TA microspheres(4)The impact of SA/CS/TA microspheres on the osteogenic differentiation of BMSCs was further confirmed by using alkaline phosphatase(ALP)staining to detect the effect of microspheres on ALP activity and Alizarin Red S(ARS)staining to assess their effect on extracellular matrix mineralization.(5)Investigate the promoting effect of SA/CS/TA microspheres on bone defect healing by constructing rat tibial bone defect model in vivoResults:(1)SA/CS/TA can release TA slowly(2)SA/CS/TA microspheres had no significant effect on the activity of BMSCs(3)SA/CS/TA microspheres can promote the expression of genes and proteins related to osteogenic differentiation(4)SA/CS/TA microspheres can increase ALP activity and increase extracellular matrix mineralization(5)SA/CS/TA can effectively promote the healing of tibial bone defects in vivoConclusion:SA/CS/TA microspheres can effectively promote the osteogenic differentiation of BMSCs and accelerate the healing of bone defects,and can be used as a new type of graft with inductive activity,providing a new direction for the repair and reconstruction of bone tissue.