Fabrication Of Gradient Nanofibers For Directing Stem Cell Recruitmen As Wound Dressings

As the largest outer organ of the human body,the skin not only maintains the normal metabolism of the human body,but also plays a key role in combating ultraviolet radiation,fighting bacteria and viruses,and preventing foreign invasion and other harmful factors.However,external trauma often leads to skin damage to form a wound surface,normal tissue necrossion and destruction of the skin's defense function,prone to tissue fluid seepage,hydrolyte balance disorders and wound infection,and even worsen the harm to the lives of patients.The wound dressing creates an effective barrier to protect the wound from external harmful factors and plays a major role in the mechanical wound protection and accelerated wound healing.In recent years,with the increasingly diversified and complex clinical needs,the research on the fabric dressing is not satisfied with the isolation of the external environment,which promotes the development of the fabric dressing towards multi-functionalization.These new dressings use different pathological mechanisms to promote the healing of wound surfaces,and compared with conventional wound treatment materials(e.g.cotton,linen),new wound dressings often explore the control of drug release,the response to the microenvironment of the wound surface and the regulation of the body's self-healing.At present,domestic and foreign markets,although more and more enterprises began to develop and produce functional dressings,but the products are mostly poor,wound healing effect is limited,so the development of highly efficient and rapid wound healing materials are currently urgent problems at home and abroad.In recent years,driven by the great success of regenerative medicine stem cell therapy,it has been found that the collection ofendogenetic interstitity stem cells(MSCs)to the wound region can release biofactors to participate in and tissue reconstruction to promotewound healing,which is expected to become a strategy for the next generation of wound therapy.The study found that in ordinary wounds,stem cells migrate from the wound edge to the wound area to participate in the wound repair,and the distribution of the wound surface shows the tendency of more creation and less center of the wound,which causes the large area wound to close quickly.Other studies have shown that the substratecytogen derivative factor(SDF-1?)is a key kinetic factor involved in cell collection,showing adecreasing gradientdistribution of the genesis to the center at the wound site to induce the migration of stem cells around to the wound surface.Therefore,through the dressing as a carrier carrying the detobation factor SDF-1?,the recruitment of endo-source MSC to promote wound surface healing is a very effective method.However,it is difficult to simulate the gradient release of the chemicalation factor in the body.On the other hand,the inflammatory micro-environment of the invasion will also affect the activity of stem cells migrating to the invasional face.Therefore,in this study,we designed experiments to solve the above two problems:(1)model construction gradient distribution nanofiber membrane,to achieve SDF-1?gradient release,to exploreits induction effect on MSC migration;Electrostectrulation spinning technology has attracted wide attention as a method for the preparation of nanofibers.Electrospinning fiber membranes have unique characteristics such as microfibers,high porosity,interconnected micron/nanochannels,high-ratio surface area,etc.These excellent features have broad application prospects in the field of biomedicine.Electrostational spinning nanofibers can mimic natural extracellular substrates,support cell adhesion,migration,proliferation and differentiation,and promote wound healing.This topic uses gradient microarray as the receiving device,polyheigen esters(PCL)and collagen(Col)as raw materials,using classical spinning technology to prepare the PCL/Col nanofiber membrane of gradient distribution,and then table SDF-1? ? The formal structure,aesthetic properties,biocomponability,cell migration characteristics,and surface repair capabilities of gradient nanofibermembranes are further studied by applying a layer of methyl acrylic esterification gelatin(Gel MA)ofsodiumdichlorofenate(DS)to the fiber surface.This topic first determines the concentration of electrostectrical spinning polymer solution,and designs the ring electrode and the number of dot electrode arrays of 0,1,9,25 as receiving devices,and studies the shape of PCL/Colelectrospinningnanofiber membranes under different receiving devices.The results show that the fiber film prepared under the electrode receiving device with gradient distribution shows the "center-around" fiber density gradient distribution.In order to prepare a versatile dressing,we will prepare a gradient fiber membrane surface crosslink SDF-1 alpha,and further use photoconclinked Gel MA hydrogel coated with sodium dichlorofenate(DS)to prepare a load drug and activefactor gradient nanofiber membrane(SDF-1alpha/DS/GF-9).The appearance,structure,stem cell collection and healing properties of the prepared fiber membrane were characterized and tested.The results showed that the prepareddrug-carrying gradient electrospinning nanofiber membrane SDF-1alpha/DS/GF-9 can effectively raise MSCand accelerate the healing of the whole cortical skin damage model mice,which isexpected to be used as a new functional fabric dressing.