Classification Of Unilateral Lesser-form Cleft Lip And Study On The Function Of MMP12 In Muscle Tissue Fibrosis

Purpose:1.1 Classification method of unilateral lesser-form cleft lip is proposed based on pathological muscle relationship.1.2 Establish and evaluate the animal model of muscle tissue fibrosis after injury.1.3 Study on the role and development mechanism of Matrix Metalloproteinase-12(MMP12)in the process of muscle tissue fibrosis.Research content:2.1 Propose a classification method of unilateral cleft lip according to the pathological muscle relationship to better understand the pathogenesis of lesser-form cleft lip and explain the various clinical manifestations of patients with lesser-form cleft lip to provide guidance for choosing the most suitable operation time and treatment plan.2.2 Establish an animal model to study the occurrence and development process of muscle tissue fibrosis,and to study the pathological,physiological and molecular mechanisms in the process of muscle fibrosis and provide a suitable platform for the preclinical research of drugs/materials in preventing/reducing muscle fibrosis.2.3 Study on the role of MMP12 in the process of muscle fibrosis and its occurrence and development mechanism through the rat muscle tissue fibrosis model to provide a potential therapeutic target for the prevention and treatment of muscle tissue fibrosis.Methods:3.1 Patients with lesser-form cleft lip treated by the corresponding author(Ningbei Yin)in the Department of Cleft Lip and Palate,Peking Union Medical College,Plastic Surgery Hospital,from October 2018 to October 2021 were reviewed.Three main lesser-form cleft lip types,including types Ⅰ-Ⅲ(first,second,and third auxiliary tension line types,respectively),and mixed type,including subtypes A-D,were introduced based on the pathological muscle interaction and muscle tension line group concept.3.2 Establish an animal model of fibrosis after muscle injury in rats,and take materials from D1,D3,D7,D14 and D21 respectively for histological,immunohistochemical and genomic research to evaluate the modeling effect.3.3 The function of MMP12,macrophages and fibroblasts in the process of fibrosis healing after muscle tissue injury in rats was evaluated by methods of qRT-PCR to provide reference for follow-up research.Results:4.1 This retrospective review included 135 patients with unilateral lesser-form cleft lip.The patient distribution was as follows:type I,43(31.9%);type Ⅱ,4(3.0%);type Ⅲ,9(6.7%);mixed type A,61(45.2%);mixed type B,1(0.7%);mixed type C,9(6.7%);mixed type D,8(5.8%).4.2 Extensive destruction of muscle ultrastructure and surrounding blood vessels,degeneration and necrosis of damaged myofibroblasts,frequent pro-inflammatory immune response,increased inflammatory cell infiltration and phagocytosis of damaged tissues and fragments after modeling were observed;After that,the damaged muscle fibers were repaired and new extracellular matrix was produced.Connective tissue scar formation and capillary reconstruction were observed at the injury.Finally,the scar tissue was organized.The modeling results had small difference and high repeatability within the group.4.3 Markers COL1α1,COL3α1 and ECM1 in the muscle injury group taken on the 7th day after the use of MMP12 inhibitor and macrophage scavenger decreased significantly;On the 7th day,the expression of MMP12 in fibroblasts isolated from muscle tissue of muscle injury group was significantly higher than that of control group,and the fibrosis markers COL1α1,COL3α1 and ECM1 were also significantly higher.Conclusion:5.1 This novel method of classification of lesser-form cleft lip based on pathological muscle relationships can better describe and explain the various clinical manifestations of lesser-form cleft lip,help determine the treatment strategy and timing according to the mechanism of the deformity,and provide a personalized surgical treatment scheme for patients.At the same time,a new concept of static lesser-form cleft lip is proposed,which provides a new perspective for surgeons when considering cases of lesser-form cleft lip and choosing treatment schemes.5.2 The free posterior cross suture of rat tibialis anterior muscle can be used as a safe and effective modeling method of fiber healing model after muscle tissue injury in rats,which makes up for the defect that there is no report of fibrosis after acute muscle injury.Furthermore,expression of MMP12 continued to be high at each time point after injury,suggesting that MMP12 might be important in the process of fibrosis after muscle injury in rats.5.3 MMP12 may be vital in promoting the process of fibrosis after muscle tissue injury in rats.Macrophages and fibroblasts participate in the process of fibrosis as their secretory cells.MMP12 is expected to become a target gene for predicting fibrosis after muscle tissue injury and an important target for preventing the process of fibrosis.