An Experimental Study On Repairing The Digital Flexor Tendons In Chickens Using Silk As The Scaffolds Of Tissue-engineered Tendons

Objective It is always a great problem to repair the defect of tendon in hand surgery.Previously, tendon transplantation, tendon transfer, allograft tendontransplantation are used to resolve this problem. Although they can bringsome therapeutic effects, but the additional trauma and the limitation of thetendons which could be incised are the dilemmas to these methods in clinic.In the middle of 80s, people begin to use the technique of tissue engineer torepair the defect of tendon. With the development of the knowledge to thetenocytes, people begin to utilize the characteristics of proliferation andgeneration to culture the tenocytes with the scaffold in vitro and latertransplant them to the defect. After the degradation and absorption, thescaffold gradually disappeared, tissue engineered tendon is formed, thusthe therapeutic effect is satisfactory. Chickens are used in the research, wemake the models of tendon defects artificially, use the embryonic tendoncells as the seed-cells, and culture them with silk scaffolds in vitro, thentransplant them to the defects of tendons. We use the methods ofmorphology, pathology and vitodynamics to observe and measure thetissue engineered tendons in different times, in order to research thefeasibility of the tissue engineered tendons which use the embryonictendon cells as the seed-cells and the silk as the scaffolds.Methods We extract the embryonic tendon cells from the 19-day eggs, after a periodof cultivation, we combine them with the silk scaffolds, then transplantthem to the defects of tendons. As the comparison we use the silk scaffoldsrepair the defects simply. So we have two groups, the one is "withtenocytes group", the other is "without tenocytes group". We take out ourtissue engineered tendons at 2-week, 4-week, 6-week, 8-weekpost-operation, each time we obtain 4 samples per-group, then use themethods of morphology, pathology to observe the tissue engineered tendons, and measure the values of vitodynamics and elongation, then usethe software SPSS 13.0 to make the analysis.Results We observe the tenocytes in each generation through the inverted phasecontrast microscope and find that the tenocytes in P₂ proliferate best withgreat activity and the evidence of apolexis is absent. So we use this kind oftenocytes as the seed-cells. We take out our tissue engineered tendons at2-week, 4-week, 6-week, 8-week post-operation, we observe them throughthe somatotype microscope and find that the silk scaffolds of "withtenocytes group" are covered with light yellow collagen completely, thecollagen becomes thicker and thicker with the development of time. In"without tenocytes group", collagen with lighter color exists, but thinner andless than that in "with tenocytes group", and the silk scaffolds are exposedpartly. The collagen also becomes thicker and thicker with the developmentof time, the silk scaffolds are gradually covered completely but the amountis also less than the other group finally. We can find the evidence of collagenproduction at 2-week post-operation in "with tenocytes group" by theexamination of pathology. The inflammatory reaction is obvious and thevascularize is also observed. The amount of collagen becomes more andmore with the development of time. In "without tenocytes group", theinflammatory reaction is major at 2-week and 4-week post-operation, at6-week post-operation, we can find the evidence of collagen production.These are the verification of the results of the somatotype microscope. In thesame time, the vitodynamics results of "with tenocytes group" are betterthan those of "without tenocytes group" obviously (p＜0.05). In "withtenocytes group", the vitodynamics results become better and better with thedevelopment of time (p＜0.05) except for the results of 8-weekpost-operation (p＞0.05). But in "without tenocytes group", the differencesbetween the results of 8-week post-operation and other results are of statistical significance (p＜0.05). The difference between every two results ofthe elongation is not of statistical significance (p＞0.05).Conclusion The results of this experiment demonstrate that silk can stick tenocyteswell, with the characteristics of slow-degradation and great resistance todraw, after the adhesion of tenocytes, they will form the tissue engineeredtendon gradually in chickens. After some advanced experiments orresearches, silk would release its great potency in the field of treating thedefect of tendon.