| The formation of adhesion after tendon injury is a common clinical complication.Given the lack of effective adhesion prevention measures,treatment often falls into the vicious circle of adhesion-release-adhesion,which seriously affects the functional rehabilitation of patients.In the United States,more than 320,000 cases of tendon injuries are caused by trauma and excessive exercise each year,resulting in billions of dollars in medical expenses.Moreover,30%–40% of patients have complications,such as limited joint activity due to tendon adhesion.In this study,we focused on reducing the incidence of tendon adhesion and promoting the healing of the tendon.Through an in-depth study of tendon structure and adhesion mechanism,many methods and materials for preventing tendon adhesion have been explored.Natural material amnion derived from living organisms has a semi-permeable membrane and is rich in collagen,cytokines,enzymes,and other active ingredients,allowing nutrient penetration.Moreover,its unique structure makes it an ideal biological material.In clinical application,the amnion lacks mechanical strength,and dissolves very quickly,which causes slippage.To overcome the above limitations of amniotic materials,other materials should be introduced to improve the strength of the amnion,and moderate hydrophobicity for maximizing the potential of amniotic materials.In this study,fresh amnion was treated by freezing and vacuum drying.By utilizing electrospinning technology,PCL nanofibers were received on the two surfaces of the lyophilized amnion to form an amnion/PCL Nanofiber Composite Membrane,and a growth factor-sustained release system was constructed to meet the tendon healing cycle.The characterization of the composite membrane,the effect of the composite membrane on the biological behavior of tenocytes and fibroblasts were evaluated and measured.A rabbit toe tendon injury model was established to evaluate the effect of prevention and treatment of tendon injury in vivo.The findings of this study are as follows: 1.Most of the cell components in fresh amnion were effectively removed after freezing and vacuum drying,and the fibrous reticular structure of the basement membrane and dense layer was retained.After receiving the PCL nanofiber,the tensile strength of the amniotic membrane was strengthened.2.The 3D porous structure provided sufficient space for cell growth,which promoted the proliferation of tenocytes and fibroblasts,upregulated the phosphorylation of ERK1/2 and SMAD2/3,and promoted the synthesis of type I collagen.The nanofiber composite membrane of the shell-core structure slowly released bioactive components such as TGF-?1 into the tendon repair area,which conformed to the tendon healing repair cycle.3.In the rabbit model of tendon repair,compared with the control and amnion groups,the nanofiber membrane isolated the exogenous invasive tissue,promoted the endogenous healing of tendon,and inhibited tendon adhesion.In this experiment,the Nanofiber Composite Membrane effectively isolated exogenous adhesion tissue and promoted the endogenous healing of tendons.This study provides a new treatment strategy to solve the clinical problem of tendon adhesion and has broad application prospects.Part One A Multicenter Prospective,Cohort Study of Lyophilized Amnion for Prevention of Flexor Tendon Adhesion in Zone II of the FingerObjective: Tendon adhesion to surrounding tissues is the most common complication reported after tendon repair.To date,effective solutions to prevent tendon injury are still lacking.Methods: A total of 89 patients with flexor tendon injury in zone II were recruited.The patients were divided into a control group,a poly-DL-lactic acid(PDLLA)group and an amnion group according to the different tendon treatments applied.The control group was not subjected to other treatments.PDLLA and bioamniotic membranes were respectively used to wrap broken ends in the PDLLA and amnion membrane groups.The patients were followed at 1,2,3,and 6 months after surgery and the ranges of active flexion and extension lag in the proximal and distal interphalangeal joints were evaluated.Results: The means of total active ranges of motion of the interphalangeal joints(excluding rupture cases)in the PDLLA and amnion groups did not significantly differ between each other but significantly differed from that of the control group.Statistical analysis showed a significant difference in the clinical grades of the outcomes among the control,PDLLA and amnion groups.The incidence of complications in the control and PDLLA groups was found to be significantly higher than that in the amniotic membrane group;no significant difference was observed between the control and PDLLA groups.Conclusion: In this study,lyophilized amnion transplantation was applied to promote healing of the flexor tendon in zone II and prevent adhesion.This technique presents a new method to solve the issue of tendon adhesion after repair.Part Two Preparation and Characterization of Amnion/PCL Nanofiber Composite Membrane by ElectrospinningObjective: The application of a physical barrier to block exogenous healing is currently the main method used to prevent tendon adhesion.Given the different physical and chemical properties of materials,their mechanism of action and clinical effects vary.In clinical application,the amnion lacks mechanical strength,and dissolves very quickly,which causes slippage.To overcome the above limitations of amniotic materials,other materials should be introduced for maximizing the potential of amniotic materials.Methods: Fresh amnion was treated by freezing and vacuum drying.By utilizing electrospinning technology,PCL nanofibers were received on the two surfaces of the lyophilized amnion to form an amnion/PCL Nanofiber Composite Membrane,and a growth factor-sustained release system was constructed to meet the tendon healing cycle.The characterization of the composite membrane was measured.Results: The fresh amnion was treated by freezing and vacuum drying.By utilizing electrospinning technology,PCL nanofibers were received on the two surfaces of the lyophilized amnion to form an amnion/PCL Nanofiber Composite Membrane,and a growth factor-sustained release system was constructed to meet the tendon healing cycle.The hydrophilic angles of lyophilized amnion and composite membrane were 51.18 ± 2.72° and 59.44 ± 4.15°,respectively.Pressure-strain tests showed that composite membrane had higher tensile strength than lyophilized amnion.EDS analysis showed that C,N,O,S and P elements were evenly distributed in the amnion.FT-IR analysis showed that all kinds of process had no adverse effects on the active proteins contained in the amnion.Conclusion: The tensile strength of the amnion was significantly improved by electrospinning.At the same time,the hydrophobicity was increased appropriately,which was more conducive to the operation.Part Three Biological Detection of Amnion/PCL Nanofiber Composite MembraneObjective: Tenocytes are important activated cells during tendon healing and adhesion after tendon injury.Many growth factors are involved in regulating cellular response during tendon injury repair.We would study the effect of the amnion/PCL Nanofiber Composite Membranes on the biological activity of tenocytes and fibroblasts,and explore the mechanism of amniotic materials to promote tendon healing,so as to provide a theoretical basis for the clinical application.Methods: Tenocytes and fibroblasts were extracted from the flexor tendon and peritendon tissues of New Zealand white rabbits.The cells were cultured on lyophilized amnion and composite membrane with a control group.CCK-8 method was used to detect the cell activity on the 1st,3rd,5th,7th,10 th and 15 th day.The expression of TGF-?1,b FGF,VEGF,PDGF,COL1,SMAD2/3,p-SMAD2/3,ERK1/2 and P-ERK1/2 were analyzed by Western blot.Results: The cells in the lyophilized amnion group and nanofiber membrane group grew rapidly,and their activities increased on the 5th,7th,10 the,and 15 th days(P < 0.05).The cell growth curve showed that the growth trend of cells in each group slowed down after 7 days.In the first 7 days,the growth trend of cells in the lyophilized amnion group was high,and the growth trend of nanofiber membrane increased thereafter.The expression levels of TGF-?1,b FGF,VEGF,PDGF,COL1,p-SMAD2/3,and P-ERK1/2 in the lyophilized amnion group and composite membrane group were higher than those in the control group.No significant difference was observed in the expression levels of SMAD2/3 and ERK1/2.Conclusion: In vitro,acellular amnion resulted in the fast proliferation trend for tenocytes with relatively static properties by releasing TGF-? and b FGF,thereby providing a new direction for the prevention and treatment of tendon adhesion.Part Four In Vivo Study on Prevention of Tendon Adhesion by Amnion/PCL Nanofiber Composite MembraneObjective: The tendon sheath wrapped around the tendon is an important structure for maintaining tendon slip and nutrition.The purpose of this chapter was to apply the composite membrane which imitates tendon sheath to the animal model,so as to evaluate its effect on promoting tendon healing and preventing adhesion.Methods: A total of 81 adult New Zealand rabbits were randomly divided into the control,lyophilized amnion,and composite membrane groups.Three weeks after operation,the third toe was obtained to observe tendon healing and adhesion to surrounding tissues.Results: Serious adhesion was found between the tendons and surrounding tissues in most of the samples of the control group.In the amnion group,the tendon healed well,but loose fibrous tissue bundles were found with the surrounding tissue.In the composite membrane group,almost no adhesion tissue was found.The healing of the composite membrane and amnion groups was significantly better than that of the control group(P < 0.016).At each time point after the operation,significant statistical differences were found in the tendon sliding distance and total flexion angle in the composite membrane and amnion groups compared with the control group(P < 0.05).The maximum tensile breaking strength of tendons in the composite membrane group and amnion group was lower than that in the control group,but the difference was not significant.Conclusion: In the rabbit model experiment,the composite composite membrane effectively isolated exogenous adhesion tissue and promoted the endogenous healing of tendons.This study provides a new treatment strategy to solve the clinical problem of tendon adhesion and has broad application prospects. |
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