| Strenuous exercise,excessive fatigue,traffic accidents frequently lead to tendon injuries,tendon injuries after bleeding stage inflammation,hyperglycemia period,shape such as a continuous process and to heal.Despite the doctors have tried to optimize all kinds of surgery to repair,but the result is only to restore the continuity of the tendon tissue.Tendons play key roles in protection,movement andtransmitting muscular forces to bone.Repair of injured tendons has become a significant challenge in orthopedics.The process of regeneration in tendon is very difficult and slow compared with other connective tissues because of its poor vascularization and excessive load.Natural tendon healing often results in the formation of fibrotic scar tissue,which has poor tissue quality and inferior mechanical properties;the result is then healed tendons never reach the initial state.Collagen arrangement crisscross disorder,a significant change in composition of collagen,the toughness and strength of the tendon and flexibility are relatively lower,easy to break again.The structure and function change is due to the damaged parts replaced by scar tissue,rather than we hoped for tendon regeneration.In fact wound healing is a complex series of cell and biochemistry adjustment process,involving cell interactions and in contact with the substrate material.Tendon injuries healing quality has become the research hotspot and difficult problem in the field of sports medicine.Therefore,in order to improve the quality of tendon healing,to restore the normal function of tendon after healing,explore new method to promote tendon healing technology is particularly important.In recent years,tissue engineering has become a promising approach in tissue regeneration.Limited intrinsic regenerative capacity of tenocytes and inability of tendons to self-repair have generated a demand for the development of a tissue-engineering method to accelerate and optimize the healing of injured tendons.Treatments of tendon injury with tissueengineering procedures have been increasing.Bone marrow mesenchymal stromal cells and embryonic stem cells have been used in the repair of injured tendons.However,the implantation of bone marrow mesenchymal stromal cells and embryonic stem cells is associated with risks of ectopic bone formation in tendons or teratoma formation.Autologous tenocytes have also been used to repair injured tendons.However,tenocytes may not be an ideal source for tendon repair because of limited proliferative potential.Secondary lesion formation at the donor site after removal of tendon tissue for obtaining tenocytes is another problem.Tendon stem cells(TSCs),a new cell type,have been identified for several years.TSCs have been found to have higher expression of tenomodulin,type I collagen and scleraxis than bone marrow mesenchymalstromal cells.Also,TSCs possess clonogenicity,self-renewal and multi-differentiationthat TSCs could promote better restoration of structure and function after tendon injury.However,non-tenocyte differentiation of TSCs may occur after transplantation because osteocalcin and chondrogenic markers were also detected in the TSCs.It is important to promote proliferation and tenogenic differentiation of TSCs to obtain promising results after cell therapy.TSCs need appropriate scaffolds to keep their stemness or orient tenogenic differentiation.Extracellular matrix(ECM)is one of the most important factors for the growth and function of stem cells.More recently published results indicate that ECM proteins deposited by feeder cells are important for maintaining stem cell self-renewal or improving differentiation toward specific lineage.ECM from adipose tissue-derived stem cells and synovium-derived stem cells has been used to produce biologic scaffolds,enhance the bioactivities of seeded cells and promote reconstruction of injured tissue.Engineered tissue produced using this method is currently used in clinical studies.Acellular substrates generated from fibroblasts have also been used to construct various engineering tissues.This method used the capabilities of cells to produce their own ECM in vitro.The cell sheets are biocompatible and can be made from autologous cells.Skin-derived fibroblast is an easily accessible cell source,and no major tissue defect is caused at the donor site.Additionally,dermal fibroblasts and tenocytes both are derived from mesoderm and have similar cell morphology and ECM components.Skin-derived fibroblasts and acellular dermal matrix graft also have been used to repair tendon injury and have been used safely to treat tendinopathy.This study adopts the skin cultured fibroblasts from SD rats,observe the secretion of extracellular matrix for the various biological characteristics of tendon cells.To explore whether it can be to tendon stem cell proliferation,differentiation of tendon to have a positive role.As a further advancement,we sought to produce an engineered tendon using de-cellularized fibroblast-derived matrix(d FM).TSCs were seeded on these acellular sheets,and the tenogenic differentiation of TSCs was investigated in vitro.The effects of this engineered tendon tissue on tendon repair using a rat patellar tendon injury model were also characterized. |
