Effect Of Macromolecular Crosslinked Hyaluronic Acid On The Histology Of Expanded Back Capsule In The Early Stage In Rabbits

Objective:To investigate the effect of macromolecular crosslinked hyaluronic acid on the histology of expanded back capsule and its possible mechanism in the early stage in rabbits.Methods:thirty six new zealand rabbits with no statistical difference in size,weight and growth status were selected as the subjects,and the experiment was divided into two groups.The left side of the rabbit was randomly selected for the experiment.The experiment was divided into two groups,there are 18 rabbits in each group.The experimental group was injected with 1ml macromolecular crosslinked hyaluronic acid around the separation space.At the same time,the control group was injected with 1 ml physiological saline.The specific methods are as follows:1.Skin preparation,new zealand rabbits were anesthetized with20%uratan at a dose of 1g/kg.Then,mark the surgical site and design1cm incision,the depth up to the superficial fascia.2.In the experimental group,1ml Haiwei macromolecular crosslinked hyaluronic acid was injected evenly around the free cavity wall on the left side of rabbit back.30ml dilator was placed in a flat way,keeping the expansion direction perpendicular to the tension direction of incision.Place the drain strips;3.In the control group,1ml 0.9%normal saline was injected into the free cavity wall evenly at the symmetrical position on the same side of the rabbit back,30ml dilator was placed.Place drainage strip and Suture the incision in layers.4.Five days after the operation,30ml of 0.9%saline was injected into each dilator.At the same time,thumb press the expanded flap lightly,then the thumb was relaxed immediately.The test standard was to detect the change of flaps from white to ruddy in 2s.And The experimental group was injected with the same amount of saline as the control group.This test standard is the same as above.Repeat the above operation with the same method every 3-4 days,requiring the same time and amount of water injected each time;5.The fibrous capsule of central regional were regularly stained with HE staining,MASSON tricolor staining andα-SMA immunohistochemical staining at 1w,2w and 4w respectively.The thickness of fibrous capsule,content of collagen fibers,morphology and distribution of myoblasts were measured and analyzed statistically.Results:1.The thickness of the fibrous capsule in hematoxylin-eosin stained sections was measured under 200 times light microscope.Experimental group had lower envelope thickness(X_1w=189.03±26.23μm,X_2w=271.86±34.61μm,X_4w=421.36±57.34μm)than control group(X?_1w=265.54±51.23μm,X?_2w=360.12±68.62μm,X?_4w=588.16±114.92μm)at 1w,2w and 4w.T test was used to compare the capsule thickness of the two groups at 1w,2w and 4w,P<0.05,the difference was statistically significant;2.The content of collagen and myofibroblasts in the macromolecular crosslinked hyaluronic acid group(Collagen fiber surface density:X_1w=19.51±2.25%,X_2w=25.48±3.45%,X_4w=46.54±5.51%;α-SMA average optical density:X?_1w=0.0299±0.0028 OD,X?_2w=0.0462±0.0058 OD,X?_4w=0.0563±0.0069 OD)were lower than those in the control group(Collagen fiber surface density:X_1w=28.12±5.10%,X_2w=36.32±6.40%,X_4w=65.82±12.60%;α-SMA average optical density:X?_1w=0.0361±0.0064OD,X?_2w=0.0557±0.0112 OD,X?_4w=0.0678±0.0120 OD)at 1w,2w and 4w.Collagen fiber surface density andα-SMA average optical density were compared between the two groups,P<0.05,there were statistical differences between the two groups at 1w,2w and 4w.At 1w and 2w,the experimental group was mainly immature fibroblasts,while the control group mainly consisted of myofibroblast.Two groups of collagen fibers were sparse.During the time frong 2w to 4w,the content of collagen fibers in the two groups increased obviously,and the control group was more than the experimental group;3.Analysis of the correlation between capsule thickness andcollagen fiber content in,The correlation coefficient r=0.7258;（The correlation between 0.6 and 0.8 indicates highly linear correlation between the two sets of data）;4.Analysis of correlation between envelope thickness and average optical density,The correlation coefficient r=0.5127;（The correlation between 0.3 and 0.6 indicates a moderate correlation between the two sets of data）.Conclusion:1.Macromolecular crosslinked hyaluronic acid can inhibit the formation of myofibroblast and Collagen in rabbit back,which is a safe and effective method to control the proliferation of expanded capsule;2.During the formation of rabbit dorsal capsule in the early stage,there is a highly positive linear correlation between envelope thickness and collagen content.