Yixin Sun, MD

1. E DUCATION
Eight-year Medical Doctor Program, Peking Union Medical College/Tsinghua University,
Beijing 2017.8 – now

2. RESEARCH EXPERIENCES
Research area：Keloid; Injection aesthetics .
Advisor：Xiao Long, Doctoral supervisor, Peking Union Medical College Hospital.
Major project and achievement:
· The effect and mechanism of Twist1 on the biological behavior of keloid fibroblasts, 2022
National College Students’ Innovation and Entrepreneurship Training Program.
(Completed)
· LiY, SunY, LanX, et al. Does Linear or Spot Injection Technique Matter in Upper Face
Botulinum Toxin Type A Application? A Split-Face Randomized Trial. Plast Reconstr Surg.
2024 Oct 1;154(4):656e-665e. (Co-first author)
· Sun Y, Zhang M, Zhang Y, et al. Deciphering the Refined Musculature of the Brow Area in
Asians by Micro-Computed Tomography. Aesthet Surg J. 2024 Oct 26: sjae217 (First
author)
· Sun Y, Li Y, Lu X, et al. The Dorsal Nasal Complex in Asians: Anatomical Variations and
Injection Guide for Botulinum Toxin Type A. Aesthet Surg J. 2023 Mar 4:sjad046. doi:
10.1093/asj/sjad046. (First author)
· Sun Y, Li Y, Zhang Y, et al. Unparallel improvement patterns of dynamic wrinkles and skin
quality after botulinum toxin type A treatment on the upper face. Skin Res Technol. 2023
Mar;29(3):e13309. doi: 10.1111/srt.13309. (First author)
· Sun Y, Liu R, Yu N, et al. Tarsus-Orbicularis-Septum Fixation in Double-Eyelid
Blepharoplasty: A Reliable and Flexible Technique. Clin Cosmet Investig Dermatol. 2022
Jun 21;15:1125-1132. doi: 10.2147/CCID.S367202. (First author)
· Li Y, Sun Y, Lan X, et al. Does injection pattern matter in upper face BoNT-A application?
A prospective split-face andomized trial comparing linear and spot technique. Plast
Reconstr Surg. 2023 May 15. doi: 10.1097/PRS.0000000000010652. (Co-first author)
· Liu R, Sun Y, Huang J, et al. Brow Position Change and its Potential Risk Factors Following
Upper Blepharoplasty: A Systematic Review and Meta-Analysis. Aesthetic Plast Surg.
2023 Mar 8. doi: 10.1007/s00266-023-03288-0. (Co-first author)
Research skills: Have received training of random controlled trial design and practice. Familiar
with clinical studies. Skilled in manuscript writing.

3. A W A R D S & HONORS
Award for outstanding student first prize 2020
Award for outstanding study 2020
Award for outstanding work in public welfare 2020
National Scholarship 2021
Award for outstanding scientific research 2021
Award for outstanding student second prize 2022

4. A D D I T I O N A L I N F O R M AT I O N
·Clinical practice: Two-year clerkship experience. Study in Department of General Internal
Medicine, Department of Nephrology, Department of hematology，Department of endocrinology
at PUMCH.
·Social practice & Volunteer work:
Short-term Social practice projects 2018.7/2018.8/2019.1/2019.7/2019.8/2021.8
Volunteering activities for the aged professors 2020.6-2021.6

Abstract submitted for the 5th International Keloid Symposium

Title:Single-cell RNA sequencing revealed key factors of EMT to Promote Fibroblasts Activation and Immune Infiltration in Keloids

AUTHORS: Yixin Sun^1,2, Nanze Yu¹, Xiao Long¹.

AUTHORS’ AFFILIATIONS:

1. Department of Plastic Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
2. Department of Plastic & Reconstructive Surgery, Zhejiang Provincial People’s Hospital (Affiliated People’s Hospital), Hangzhou Medical College, Hangzhou, Zhejiang, China

Presenting author:

Yixin Sun, M.D.

sunyx0000@163.com

Address：Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, No.1, Shuaifuyuan, Dongcheng District, Beijing, China 100005

Corresponding author:

Nanze Yu, M.D.

Department of Plastic and Aesthetic Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, No.1, Shuaifuyuan, Dongcheng District, Beijing, China 100005

Email address: yunanze@pumch.cn

Xiao Long, M.D.

Department of Plastic and Aesthetic Surgery, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, No.1, Shuaifuyuan, Dongcheng District, Beijing, China 100005

Email address: pumclongxiao@126.com

Conflict of interest：

The authors have no financial or other conflicts of interest to disclose.

Background:

Keloid is a fibrotic disorder of soft tissues secondary to abnormal wound healing. Previous studies have predominantly focused on fibroblasts, yet research on epidermal keratinocytes (KCs) remains limited. Existing evidence indicates that KCs in keloid differ from normal KCs in morphology and transcriptional profiles, with keloid KCs exhibiting EMT-like characteristics. However, the molecular drivers of EMT in keloid KCs and how EMT-primed KCs contribute to keloid pathogenesis and progression remain poorly understood.

Methods: 

We collected lesional tissues from 10 keloid patients and 5 normal skin samples for single cell RNA sequencing and downstream bioinformatics analysis. In vitro molecular experiments (quantitative polymerase chain reaction[qPCR], western blotting [WB], enzyme-linked immunosorbent assay [ELISA]) and cellular assays (scratch assay, CCK8 proliferation assay, colony formation assay, immunocytochemistry) were performed. We established a bleomycin-induced skin fibrosis mice model and a keloid xenograft nude mice model. After administering the FOSL1 inhibitor SR11302 for two weeks, fibrosis-related indicators were assessed to evaluate the therapeutic efficacy of the drug.

Results: 

Single-cell sequencing revealed distinct keratinocyte compositions between keloid and normal skin. The proportions of basal-mig and spinous-mig keratinocyte subpopulations were significantly increased in keloid. Pathway enrichment analysis demonstrated that genes in these subpopulations were enriched in wound healing, epithelial-mesenchymal transition (EMT), and related pathways. Notably, basal-mig exhibited a pronounced EMT tendency. SCENIC analysis suggested that the transcription factor FOSL1 plays a critical role in the differentiation of basal-mig and spinous-mig subpopulations. In cell models, FOSL1 overexpression significantly enhanced the proliferation and migration of normal keratinocytes. ChIP-seq further revealed that FOSL1 binds to MED1 to form a super-enhancer complex, regulating downstream gene transcription. In keratinocytes, FOSL1 overexpression markedly increased the transcription and secretion of Matrix Metalloproteinase 3 (MMP3). Co-culture of FOSL1-overexpressing keratinocytes with normal and keloid fibroblasts enhanced fibroblast proliferation, migration, and inflammatory factors secretion, whereas these effects were significantly attenuated by MMP3 antibody treatment. In skin fibrosis mice models, FOSL1 inhibitor SR11302 can significantly alleviate fibrotic pathology.

Conclusion:

Keratinocytes overexpressing FOSL1 can upregulate the secretion of MMP3 and subsequently facilitate the activation of fibroblasts and immune cells infiltration, thereby promoting the initiation and progression of keloid.