Collagen Promotes The Repair Effect Of Adipose Mesenchymal Stem Cells On Dog Skin Damage

Skin is the largest organ of the body,which is mainly composed of epidermis,dermis and subcutaneous fat.It is the first line of defense to resist external infection and injury and protect the internal environment and tissues and organs of the body.The skin will be damaged by a variety of factors: surgical intervention,injury,external pressure,underlying diseases such as diabetes,vascular disease and so on.At the same time,pollutants in the air will also accelerate the aging of the skin,causing damage to the skin.The healing of skin injury is accomplished by the cooperation of several different cells,which can stop bleeding,reduce inflammation,promote angiogenesis,re-epithelialization and granulation tissue formation in the injured area.At present,the treatment of skin injury includes dressing,hyperbaric oxygen therapy(HBTO)and so on.The above methods have some shortcomings,such as high cost,injury tissue can not be removed in time,resulting in wound infection,scar tissue is difficult to repair and so on.Mesenchymal stem cells play a vital role in the field of regenerative medicine.They have great therapeutic potential and bring more cure opportunities for patients.Adipose mesenchymal stem cells(ADSC,Adispose-derived mesenchymal stem cells)is a special kind of stem cells,which can be isolated from adipose tissue and transferred to different tissues,such as fat,cartilage and muscle.ADSCs has many advantages in treatment.They can be purified from lipid cells,have higher collection efficiency,and have less antibody sensitivity.However,there are still some problems such as low survival rate and low cell viability of ADSC cultured in vitro,which affect the therapeutic effect of skin injury.Collagen can provide a more suitable 3D environment for ADSC,thus improving cell viability and promoting the proliferation and differentiation of ADSC.Therefore,to explore the most appropriate concentration of collagen to treat ADSC,let collagen effectively combine with canine ADSC,and form a more effective method for the treatment of skin injury.In this experiment,Collagen(Col)was added to dog ADSC medium,and ADSC and collagen(Col+ADSC)were cultured in vitro,and then transplanted into animal skin injury model by subcutaneous injection.Nine Kunming white mice and three Chinese garden dogs were used to establish skin injury models by routine operation,which were respectively set as PBS group,ADSC group and Col+ADSC3 group for treatment.After the model was established,PBS injection,ADSC transplantation and Col+ADSC transplantation were performed on the 1st and 5th day respectively.In addition,three diabetic dogs were selected,and each dog was randomly divided into three groups: PBS group,ADSC group,Col+ADSC group and Col group.Through HE staining,Masson staining,immunohistochemical staining and immunofluorescence staining of skin,the wound repair was observed clinically,and related tests were carried out to obtain detailed information about its rehabilitation,thus providing valuable reference for clinical medicine.(1)The effect of Collagen on canine mesenchymal stem cells: This experiment first explored the optimal concentration of col to promote the growth,development and proliferation of canine ADSC.After that,Ed U staining and cell scratch test were carried out on dog ADSC,and it was found that adding 10 μg Col per ml of culture medium could effectively promote the proliferation and migration of dog ADSC,thus improving the cell viability in vitro.(2)Analysis of the effect of collagen on the differentially expressed genes of canine ADSC: protein analysis of the supernatant of canine ADSC showed that Col was the largest component in the supernatant of canine ADSC,which was essential for cell growth.At the same time,the transcriptome analysis of ADSC showed that Col promoted the effect of ADSC in repairing skin injury by up-regulating the signal pathway of ADSC related to skin injury repair function,especially the coagulation cascade reaction pathway.(3)Evaluation of animal experiment: the round skin of diameter 1.1cm was removed from the back of mice,and the round skin of 1.5cm was removed from the abdomen of normal dogs and diabetic dogs for allogeneic control and autologous control experiments,combined with pet hospital to collect natural cases.Compared with the results of various tests and natural cases,the healing period of skin was shortened and the healing rate was accelerated after Col+ADSC transplantation.At the same time,Col can promote the role of ADSC in epidermis repair,hair follicle angiogenesis,collagen deposition,elimination of inflammation and scar tissue repair in mice and dogs.This study proved that collagen treatment increased the viability of canine ADSC cells cultured in vitro,and up-regulated the pathway of ADSC in promoting skin healing,which effectively promoted the effect of ADSC on the repair of canine skin injury,and provided a certain experimental basis and application basis for improving the application of ADSC in the treatment of skin injury.