Functional dressing membrane and therapeutic powder for the treatment of diabetic foot ulcer = 당뇨병성 족부궤양 치료를 위한 기능성 드레싱 막 및 치료용 분말

다국어 초록 (Multilingual Abstract)

Diabetic foot ulcers (DFUs), a major complication of diabetes, present a critical clinical challenge due to delayed wound healing and impaired vascular regeneration. Their chronic nature often results in prolonged open wounds and increased susceptibility to infection, eventually leading to limb amputation in severe cases. Despite extensive research into therapeutic strategies, a definitive and effective treatment remains elusive. This thesis investigates advanced wound healing approaches that integrate functional materials and regenerative biomolecules to address the unmet clinical demands in DFU management.
Chapters one and two provide a general introduction and scientific background regarding diabetic wound pathology, functional skin dressings, and stem cell-derived therapeutics. Particular attention was paid to the therapeutic role of adipose-derived stem cell (ADSC) secretome, as well as how drying techniques impact its bioactivity. In addition, the potential of secretome-based biomaterials to modulate inflammation and promote tissue regeneration was discussed.
In chapter three, a redox-active wound patch was developed using a zinc/silver chloride (Zn/AgCl) membrane that generates a mild electric field. Polyvinyl alcohol (PVA) nanofibers were electrospun onto this redox membrane to form a patch with both antibacterial activity and immunomodulatory potential. When applied to diabetic wounds, the patch facilitated accelerated healing, which may be attributed to the synergistic effects of electrical stimulation and macrophage polarization.
Chapter four introduces a complementary strategy utilizing supercritical carbon dioxide-dried ADSC secretome powder. Unlike conventional lyophilization, this method effectively preserved the bioactivity of therapeutic factors. In vivo, experiments demonstrated that the powder enhanced angiogenesis alleviated inflammation, and promoted wound closure in diabetic mouse models.
Chapter five offers critical insights into current technological limitations and proposes future directions for integrating bioactive scaffolds with advanced delivery platforms. Overall, the functional redox patch and supercritical CO₂-dried secretome powder developed in this thesis may provide a synergistic therapeutic strategy for DFU treatment. By combining physical stimulation and regenerative biomolecules, these systems simultaneously address the biological and structural challenges of chronic wound healing. In this sense, the integrated platform proposed herein offers a promising foundation for next-generation wound care systems tailored to diabetic foot ulcers.

국문 초록 (Abstract)

당뇨병성 족부궤양(Diabetic Foot Ulcers, DFUs)은 당뇨병의 주요
합병증 중 하나로, 상처 치유 지연과 혈관 재생 저하로 인해 심각한
임상적 문제로 간주된다. 이러한 만성 상처는 장기간 개방된 채로
유지되며 감염 위험이 높아지고, 심한 경우 절단 수술로 이어지게 된다.
다양한 치료 전략이 연구되어 왔음에도 불구하고, 아직까지 결정적이고
효과적인 치료법은 확립되지 않았다. 본 논문은 기능성 소재와 재생
유도 생체분자를 기반으로 한 고도화된 상처 치유 접근법을
제시함으로써 DFU 치료에 있어 미충족된 임상적 요구를 해결하고자 하였다.
제1장과 제2장에서는 당뇨병성 상처의 병태생리, 기능성 드레싱 기술,
줄기세포 유래 치료제에 대한 과학적 배경을 다루었다. 특히 지방유래
줄기세포(adipose-derived stem cell, ADSC) 시크리톰의 치료적
역할과, 건조 방식이 생리활성에 미치는 영향에 중점을 두었다. 아울러
시크리톰 기반 바이오소재가 염증을 조절하고 조직 재생을 유도하는
가능성에 대해서도 논의하였다.
제3장에서는 아연/염화은(Zn/AgCl) 기반의 산화환원막을 활용하여 미세
전기장을 생성할 수 있는 기능성 패치를 개발하였다. 이 산화환원막
위에 폴리비닐알코올(PVA) 나노섬유를 정전기 방사하여 항균성과
면역조절 효과를 갖는 패치를 제조하였다. 이 패치를 당뇨 상처에
적용한 결과, 전기 자극과 대식세포 극화의 시너지 효과로 인해 상처
치유가 촉진되는 것을 확인하였다.
제4장에서는 보완적 치료 전략으로 초임계 이산화탄소(supercritical
CO₂) 건조법을 활용하여 제조한 ADSC 시크리톰 분말을 제시하였다.
이 방법은 기존 동결건조에 비해 생리활성을 효과적으로 유지할 수
있었다. 동물실험을 통해 해당 시크리톰 분말이 혈관 신생을 촉진하고
염증을 완화하며, 상처 폐쇄를 유도하는 효과가 있음을 확인하였다.
제5장에서는 현재 기술의 한계를 비판적으로 분석하고, 생체활성
지지체와 고급 약물전달 시스템의 통합 방향을 제안하였다. 본 논문에서
제시한 기능성 산화환원 패치와 초임계 이산화탄소 기반 시크리톰
분말은 DFU 치료를 위한 시너지적 치료 플랫폼으로 작용할 수 있다.
물리적 자극과 재생 생체분자를 결합함으로써, 이 시스템은 만성 상처
치유에 있어 생물학적·구조적 문제를 동시에 해결할 수 있다. 이러한
통합적 플랫폼은 향후 당뇨병성 족부궤양 치료에 특화된 차세대 상처
관리 시스템 개발의 기반이 될 수 있을 것으로 기대된다.

목차 (Table of Contents)

• Abstract i
• Table of content iv
• List of Figures viii
• Chapter 1. Introduction 1
• 1.1 Objective and overview of the thesis 1
• 1.2 Organization of the thesis 2
• Chapter 2. The scientific background 3
• 2.1. Diabetic wound healing 3
• 2.1.1. Wound healing 3
• 2.1.2. Diabetic wound healing 3
• 2.2. Functional skin wound dressing 5
• 2.2.1. Passive wound dressing 5
• 2.2.2. Advanced functional wound dressings 7
• 2.3. Stem cell secretome 9
• 2.3.1. Stem cell therapy and limitation 9
• 2.3.2. Stem cell secretome 11
• 2.4. Drying process 12
• 2.4.1. Lyophilization 12
• 2.4.2. Precipitation with compressed anti-solvent (PCA) 13
• Chapter 3. Electrical stimulating redox membrane incorporated with PVA/Gelatin nanofiber for diabetic wound healing 25
• 3.1. Introduction 25
• 3.2. Materials and methods 31
• 3.2.1. Materials 31
• 3.2.2. Preparation of the Redox Membrane 31
• 3.2.3. Simulative Modeling of the Electrical Current of the Redox Membrane 32
• 3.2.4. Electrospinning of PVA/Gelatin Solution onto PU Film 32
• 3.2.5. Microstructure of the Electrospun Nanofibers 33
• 3.2.6. In Vitro Ion Release Profile of the Redox Membrane 33
• 3.2.7. Measurement of the M-Sheet’s Voltage Profile 34
• 3.2.8. In Vitro Antibacterial Property of the Patterned Membrane 34
• 3.2.9. Cell Attachment and Biocompatibility of M-Sheet 35
• 3.2.10. In Vitro Wound Healing Test by Scratch Assay 35
• 3.2.11. In Vitro Polarization of Macrophages 36
• 3.2.12. Animal Experiments and Inducing Diabetes in Mice 36
• 3.2.13. In Vivo Wound Healing Assessments of M-Sheet on Normal Wounds and Diabetic Wounds 37
• 3.2.14. Histological Analysis 37
• 3.2.15. Panniculus Gap and Granulation Tissue Thickness 38
• 3.2.16. Measurement of ECM Fiber Alignment 38
• 3.2.17. Immunofluorescence Staining for Analyzing the Regenerated Skin Tissues 38
• 3.2.18. Statistical Analysis 39
• 3.3. Results and discussion 40
• 3.3.1. Fabrication and Characterization of Redox Membranes 40
• 3.3.2. Antibacterial Effect of the Redox Membrane 43
• 3.3.3. Preparation and Characterization of the M-Sheet 47
• 3.3.4. The Effect of Electrical Field on the In Vitro Cellular Behaviors 54
• 3.3.5. In Vitro Macrophage Polarization Effect of M-Sheet 58
• 3.3.6. In Vivo Wound Healing Effect of the M-Sheet in Diabetic Mice 60
• 3.3.7. Immunofluorescence Analysis of the Regenerated Tissues 67
• 3.3.8. Discussion 71
• 3.3. Summary 78
• Chapter 4. Stem cell secretome powder with supercritical CO2-drying process for advanced diabetic wound treatment 79
• 4.1. Introduction 79
• 4.2. Materials and methods 85
• 4.2.1. Aerosol Solvent Extraction System (ASES) process 85
• 4.2.2. ADSC isolation and Conditioned medium collection 85
• 4.2.3. Proteomics 86
• 4.2.4. Cell proliferation assays 89
• 4.2.5. Scratch wound healing 90
• 4.2.6. Enzyme-Linked Immunosorbent Assay 90
• 4.2.7. In vivo wound model in diabetic mice 90
• 4.2.8. Wound closure assessment 91
• 4.2.9. Histological analysis 92
• 4.2.10. Immunohistochemistry 92
• 4.2.11. Quantitative Polymerase Chain Reaction 93
• 4.2.12. Bulk RNA sequencing and data analysis 93
• 4.2.13. Statistical analysis 95
• 4.3. Results and discussions 96
• 4.3.1. Procedure of the PCA Process and Characterization of PCA-dried conditioned media powder (P_PCA) 96
• 4.3.2. Proteomic Analysis of the CM and P_PCA 101
• 4.3.3. Cellular treatment with the P_PCA in Vitro 106
• 4.3.4. Evaluation of wound healing promotion in the diabetic mouse model 110
• 4.3.5. Angiogenesis and ECM remodeling in secretome-treated wounds 114
• 4.3.6. Bulk-RNA sequencing in D-HDF treated with P_PCA 120
• 4.4. Summary 126
• Chapter 5. Concluding remarks 128
• 5.1. Summary and future perspectives 128
• Reference 130
• Bibliography 144
• Abstract in Korean (국문 초록) 149