Effects Of Botulinum Toxin Type A On Tissue Response And Degradation Of PPDO Thread

BackgroundThread lifting as a newly-emerged minimally invasive plastic surgery in recent years,by embedding threads at different levels,lifting sagging tissues,stimulating collagen regeneration,and repairing loose ligaments to achieve facial rejuvenation,However,due to scar hyperplasia,uneven tension distribution or excessive tension after thread lifting alone,complications such as obvious thread marks,asymmetric facial expressions,and unnatural expressions are often caused.Botulinum toxin type A can relax and paralyze the target muscles,reduce tension,and also has the advantages of anti-inflammatory,pain relief,and scar hyperplasia.Therefore,thread lifting combined with injection of botulinum toxin type A can enhance the lifting effect and reduce complications.However,a retrospective study found that the effectiveness and persistence of facial lifting are still unclear.The facial lifting effect and maintenance time are mainly affected by the tissue reaction caused by the embedded thread and the degradation time of the thread.PPDO thread is the latest generation of absorbable thread because of its good histocompatibility and biodegradability,it is widely used for thread lifting.After the thread is embedded in the body,it causes tissue reactions,stimulates collagen fiber proliferation,forms a fiber capsule,and is degraded by macrophages,but botulinum toxin type A can inhibit collagen proliferation and regulate immune response of macrophages.At present,there is no histological research related to the combined use of the two.This experiment intends to study the effect of botulinum toxin type A on the tissue reaction and degradation of PPDO thread,providing some references for clinical application.ObjectiveTo study the effect of botulinum toxin type A on tissue response and degradation of PPDO thread.Methods1.Grouping:30 Wistar rats were embedded with PPDO threads subcutaneously on both sides of their backs,and were divided into two groups according to self control.Six injection points were selected on both sides of the embedded thread on the left side,and each point was 1.0cm away from the thread.The interval between the points was 2.0cm,and each point was injected with 1.0U/0.05ml of botulinum toxin type A(BA group),and the same dose of saline was injected on the right side as the control group(NS group).2.Drawing materials:At 1d,7d,30d,60 d,90d after surgery,6 rats were randomly selected from each group,after abdominal anesthesia with 10%chloral hydrate(0.3ml/100g),the back was shaved,sterilized with 75%alcohol,cut the back skin along the middle of the spine,peel to both sides,and expose the thread embedding sites.One of the rats was taken to draw materials,with PPDO thread as the axis,cut the tissue with the thread as the center(including the thread)2.0cm×2.0cm×0.5cm,,and the removed tissue is quickly fixed in 10%formaldehyde fixing solution.The slice is perpendicular to the axis of the PPDO thread.The remaining 5 rats in each group were exposed to the threads in the same way,and the tissue around the thread was bluntly separated,carefully stripped,and the threads were removed.The rats were sacrificed by excessive anesthesia in the abdominal cavity.3.Observing:(1)general observation of the local skin of two groups for redness,swelling,induration,and external thread exposure;(2)HE staining of pathological slices was used to observe the inflammation and foreign body reactions in each group,and score using Duranti grading standard.(3)MASSON staining of pathological sections,measuring the fiber capsule thickness of each group under 40×10magnification,and calculating the volume fraction of collagen with ImageJ software;(4)Immunohistochemical method to detect the expression of CD68,using ImageJ software to measure;(5)Observe the morphology of PPDO threads in each group under optical microscope,and measure the trunk diameter of PPDO threads;(6)breaking strength measurement:use"universal material testing machine"to measure the breaking strength.4.The measurement data are expressed as mean±standard deviation,and the count data are expressed as incidence or composition ratio.SPSS20.0 statistical software was used for statistical analysis of data.One-way analysis of variance was used for the measurement data.The non-parametric rank sum test was used for the grade data.The x~2 test or exact probability method was used for the comparison of the incidence rate or composition ratio.P<0.05 is considered statistically significant.Results1.General observation:the back of all rats(100%)was slightly red and swollen on both sides immediately after operation,and subsided after 1 day;5(16.67%)rats had thread marks on the left side of the back,and 7(23.33%)rats had thread marks on the right;2(6.67%)rats were exposed on the right side of the back with external thread;1(3.33%)rats had sclerosis on the left side of the back;no scars were observed in all rats.The incidence of complications such as redness,thread marks,exposed thread,and induration was the same in two groups(P>0.05).2.Inflammatory response:Inflammatory response scores show a downward trend with time.Comparison between groups suggests that there is no difference between groups in grading score of inflammation reaction(P>0.05).Time points comparison:The BA group had the most intense inflammatory response on day1,which was significantly higher than that on Day 7,30,60,and 90(P<0.05).The inflammatory response grade changes significantly with time,by day 60,the inflammatory response score was similar to day 90(P>0.05).In the NS group,the inflammatory reaction was severe on day 1 and 7,which were significantly higher than those on day 90(P<0.05),the inflammatory response scores were similar on days 7,30,and 60(P>0.05).3.Foreign body reaction:There was no significant difference in foreign body reaction classification between groups(P>0.05).Time point comparison:There was no significant change in foreign body reaction at each time point(P>0.05).4.Collagen volume fraction:Collagen volume fraction showed an upward trend with time.Comparison between groups:on the 30th and 90th days,the BA group collagen volume fraction was less than that of the NS group(P<0.05),and the collagen volume fraction was the same at other time points(P>0.05).Comparison of time points:The collagen volume fraction on day 1 of NS group was lower than that on days 7,30,60,and 90(P<0.05).Collagen volume fraction increased significantly with time,by day 30 the collagen volume fraction was similar to that at day 60 and day 90(P>0.05).The change trend of collagen volume fraction in BA group was the same as that in NS group.5.Thickness of fiber capsule:The capsule was not formed on day1 after the operation,and the capsule was gradually formed on day 7.The fibrous capsule was intact on day 30 after the operation and had the largest thickness,the capsule thickness gradually decreased at day 60 and 90 after surgery.Comparison between groups:The thickness of the fibrous capsule in the BA group was significantly lower than that in the NS group at day30 after surgery(P<0.05),and the thickness of the fiber capsule in the BA group was the same as that of the NS group at other time points(P>0.05).Comparison of time points:The thickness of the fiber capsule on day7 of the BA group was less than the day30,60,and 90(P<0.05).The thickness of the fiber capsule increased significantly with time,and the thickness of the fiber capsule on the day 60 was the same as the day90(P>0.05).The trend of the thickness of the fiber capsule in the NA group was the same as that in the BA group.6.CD68:The expression of CD68 in both groups gradually increased with time,and began to decrease by the day90.Comparison between groups:There was no difference in the expression of CD68 between the BA group and the NS group(P>0.05).Comparison of time points:The expression of CD68 in both groups gradually increased with time.The expression of CD68 on days 1 and 7 of BA group was significantly lower than that on day 60(P<0.05),and the expression of CD68 on days30,60 and 90 was the same(P>0.05).The expression of CD68 on day 1 and day 7 of NS group was significantly lower than that on days 60 and 90(P<0.05);the expression of CD68 on days 30,60 and 90 was the same(P>0.05).7.PPDO thread morphology observation:The PPDO thread was purple before operation,the thread body was smooth,the serrations were evenly distributed,and the serrations were sharp.The purple became lighter on the day 1 and day 7 after operation,the thread remained smooth,and the serrations became slightly dull.The thread body was white,and the surface was rough under the microscope,and the serrations became short and dull on day 30.The thread body was white,and the surface was rough,the jagged was broken,and some fragments were visible on day 60.The threads can not be completely removed from the rat on day 90.The general observations of two groups were same.8.PPDO thread trunk diameter:The PPDO thread diameter gradually decreases with time.Comparison between groups:On day1,the diameters of the PPDO thread in the two groups were the same(P>0.05);on the day7,30h,and 60,the diameter of BA group was significantly larger than NS group(P<0.05).Comparison of time points:The diameter of the PPDO thread gradually decreased with time,and the diameter of the PPDO thread in the BA group was the same on day 0(preoperative),day 1,and day 7(P>0.05).On the day7,30 and 60,the PPDO diameter decreased significantly with time(P<0.05).In the NS group,the diameter of the PPDO thread on day 0(preoperative)and day 1,day 1 and day 7 are the same(P>0.05),day 0(preoperative)is greater than day 7.The diameter of PPDO thread decreased significantly with time on day7,30 and 60(P<0.05).9.Breaking strength:The breaking strength of PPDO thread decreases continuously with time.Comparison between groups:On the day 30,the breaking strength of the BA group was significantly greater than that of the NS group(P<0.05).Comparison of time points:The breaking strength of the BA group on day 0(preoperative)and day 1 were the same(P>0.05),and the breaking strength on days 7,30,and 60 decreased significantly(P<0.05).The trend of breaking strength of NS group with time is the same as that of BA group.Conclusions1.Botulinum toxin type A has inhibitory effect on the proliferation of collagen fibers and the thickness of the fiber capsule caused by the PPDO thread.2.Botulinum toxin type A has inhibitory effect on the degradation of PPDO thread.