Promoting Effect On Wound Healing By Using Concentration Gradient Of Basic Fibroblast Growth Factor In Diabetic Porcine Model

BackgroundChronic wound is defined as skin tissue defect which failed to heal in an orderly set of stages and in a predictable amount of time as most of the wounds do.Diabetic ulcer is one of the most common complications of inpatients with diabetes mellitus,and the wound healing process of diabetes ulcer is delayed or even remain unhealed.With the growth of diabetes population,the diabetes-related ulcer gradually draws attention from the public.Researches have shown that diabetic peripheral neuropathy,poor local blood supply,reduction of endogenous growth factors,abnormal microenvironment and infection are the major causes of the delayed wound healing.Studies indicates that basic fibroblast growth factor promote proliferation and differentiation of multiple cells as an important mitogenic factor.Basic fibroblast growth factor was used to treat peripheral neuropathy and to modified the microenvironment of the wound by promoting nerve regeneration,angiogenesis and epithelization,thus reduced the risk of infection,and accelerate the process of wound healing.Basic fibroblast growth factor plays an important role in promoting granulation formation,epithelial migration and local microenvironment improvement.Within a certain range of concentration,the degree of cell proliferation and migration was proportional to the basic fibroblast growth factor.We suppose that cell has the tendency to migrates toward higher concentration of growth factor.We are here to investigate if the concentration gradient of basic fibroblast growth factor would effectively promote the healing of diabetic wound.ObjectiveAnnular concentration gradient of basic Fibroblast growth factor was combined with collagen fibers to make a scaffold and was applied to porcine diabetic wound to investigate if the fibroblasts would migrate toward the center of the wound by using concentration gradient bFGF scaffold,which promote epithelization and the formation of granulation that shorten the period acquired to heal.Using concentration gradient of bFGF to treat diabetic wound may provide a new concept that would enhance the quality and reducing the period of wound healing.MethodThe experiment group was divided into blank group,control group,constant concentration(low,medium,and high)group and concentration gradient group.Based on the result of wound healing assay,we first select the ideal concentration of bFGF.Then,the collagen fiber scaffold was cut into three co-centre circles(inner,middle,and outer).We combined the scaffold with different gradient of bFGF(inner-high,middle-medium,and outer-low)to make concentration gradient of bFGF.After the characteristics of the scaffold including absorption rate,combination rate,and releasing rate was measure,we applied the scaffold to diabetic porcine model.When it comes to animal model,six minipigs were injected with different amount of streptozotocin according to their weight.Diabetic porcine model was established as the blood glucose remain from 13 to 27 mmol/L for one week.36 round wounds were made to each minipig and were randomly divided into six groups.Samples were obtained on the 7th,14th,and 21st days.On the 21st day,samples were harvest after we gave euthanization to the minipigs.Samples acquired were examined by electron microscopy and immunohistochemistry to measure the granulation thickness,the number of blood vessels and the expression of bFGF.ResultAll female diabetic porcine models were successfully established,and a total of three wounds were infected.On the 21st day,there is a significant difference between the concentration gradient group and the blank,control,low and medium groups.However,compared to the constant high concentration group,no significant difference was found.ConclusionTreating diabetic wound with both constant concentration of bFGF and concentration gradient of bFGF improved the healing of diabetic wound.However,when it comes to the 21st day,the result showed significant difference between the blank group,control group,constant low concentration group,constant medium concentration group and the concentration gradient group.It indicated that the concentration gradient of basic fibroblast growth factor has a targeting effect on cell migration,which can induce the orderly growth of the wound,and then promote the healing of diabetic wound.The result told us that the effect of concentration gradient of bFGF on promoting diabetic wound healing was similar to using constant high concentration,which indicated that the concentration gradient basic fibroblast growth factor could promote the wound healing of diabetes more efficiently and achieve better effect with less amount of growth factors.