Research On Platelet-rich Plasma Loaded Fiber Dressings For Diabetic Foot Ulcer

With the severe aging,the incidence and prevalence of diabetic foot ulcer(DFU)are greatly increased.Because platelet-rich plasma(PRP)contains a large number of growth factors that promote the rapid healing of chronic wounds,PRP has been widely used and studied in clinical orthopedics,dermatology,acute wounds and chronic refractory wounds.However,due to the limitation of low utilization of PRP,PRP treatment requires frequent administration,and the standard platelet used in clinical practice is stored at room temperature(20-24℃)under gentle stirring,and the storage time is limited to 5-7 days.Improving the sustained release and long-term activity of PRP remains a challenge.Therefore,this thesis proposes to use coaxial 3D bioprinting and freeze-drying technology to prepare long-release and long-term viability PRP fiber dressings(CCNG-P and CNG-P),and to explore the therapeutic effect of PRP in the mechanism of sustained release in fibers,the mechanism of maintaining long-term viability,and the promotion of wound healing.The specific research content and results are as follows:(1)Preparation and properties of CCNG-P fiber dressing:The multi-component and multi-functional CCNG fiber dressing was constructed by coaxial 3D printing technology.The morphology analysis showed that the cross section of the fiber showed a three-layer structure.The CCNG fiber dressing can achieve gel-sol intertransformation and has excellent moisture absorption(23 times)and moisture retention(16 times)properties.Controlling the content of the outermost chitosan could improve the antibacterial property of CCNG fiber dressing(≥97 %),and regulating the content of the outermost collagen could promote the proliferation,migration and adhesion of L929 cells on the fiber surface.CCNG-P shell-core fibers loading PRP can improve the utilization rate of PRP,which can not only reduce the number of administration by 50 %-75 %,but also show better therapeutic effect than clinical PRP-gel.It provides a new method for loading PRP to improve the utilization rate.(2)Preparation and properties of long-term viability CNG-P fiber dressings:The long-term viability CNG-P fiber dressing was constructed by coaxial 3D bioprinting combined with freeze-drying technology.Morphological analysis showed that after 6 months of storage,platelets were evenly dispersed and round in the nuclear layer of CNG-P fibers,and contained a large number of α-particles and dense particles.After 6 months of storage,the PRP activity of CNG-P only lost about 40 %.The optimal freezing and storage conditions were screened.Liquid nitrogen freezing and trehalose excipient could maintain the biological viability of platelets in the freezing process,and low temperature-20℃/-80℃ could reduce the loss of PRP during storage.Animal experiments showed that CNG-P could promote rapid wound healing.At 21 days,the epidermal healing effect,gland and hair follicle growth and other healing effects were more similar to normal tissue,collagen deposition was up to63.73 %,and new capillaries had entered the mature stage of blood vessels.After 6 months of storage,the CNG-P still has the potential to promote wound healing,which provides a new idea to solve the limitations of clinical PRP preparation.