Understanding Wound Healing and Closure Process

1. 창상치유 ; 학습목표 • 창상의 종류 • 감염위험에 따른 분류 • 폐쇄성창상의 치유과정 • 창상치유에 영향을 주는 전신적 및 국소적요인 • 당뇨병과 창상치유 • Wound dressing의 목적

2. Wound Healing • A complex integrated sequence of cellular, physiologic, and biochemical events initiated by the stimulus of injury to tissue

3. Healing process • The same events, in the same order, occur in every healing process regardless of the tissue type or the inciting injury

4. Healing process • The activation of basic cellular processes of inflammation, cell proliferation, and growth as well as regulation of these processes once repair is complete.

5. Healing process • All repair occurs with an overlapping series of orchestrated events to limit the damage and restore the function and integrity of the structure

6. Types of wound closure • Primary closure • Delayed primary closure • Secondary closure • Closure of partial thickness skin wound

7. Primary closure • First intention closure • Immediately sealed wounds with simple suturing, skin graft placement, or flap closure • Eg. emergency laceration repair, closure of the surgical wound

8. Primary closure

9. Secondary closure • No active intent to seal the wound • The wound is closed by reepithelization and contraction with some deposition of scar tissue

10. Secondary closure

11. Delayed primary closure • Tertiary intention • Surgical intervention, such as suturing, skin graft replacement, or flap design, after repeated debridement and antibiotics therapy

12. Delayed primary closure

13. Partial thickness wound healing

15. TISSUE RESPONSES TO INJURY • Vascular events • Cellular events • Chemical mediators

16. Vascular events • Immediate transient vasoconstriction • active vasodilatation • permeability change

17. TISSUE RESPONSES TO INJURY • Vascular events • Cellular events • Chemical mediators

18. Cellular events • platelets • neutrophils • macrophages • lymphocytes • fibroblasts • endothelial cells

19. platelets • Hemostasis • Release of platelet granules œ- granules dense granules lysosomes

21. Neutrophils • Protection against infection • Intracellular products release free radicals cyclooxygenase products lipooxygenase products protease, antiprotease band2 protein

23. Macrophages • phagocytosis • initiation of fibroplasia • release cellular products neutral protease, complement factors, reactive oxygen metabolites, growth factors, fibronectin, interleukin 1, enzyme inhibitors

26. TISSUE RESPONSES TO INJURY • Vascular events • Cellular events • Chemical mediators

27. Chemical mediators • Vasoactive agents • Chemotactic factors • Cytokines

28. Vasoactive agents • Histamin • Serotonin • Arachidonic acid

29. Cytokines in wound healing • TGF-β • PDGF • FGF • EGF • IGF-1 • Etc. KGF, CTGF, TNF, interleukins

30. TGF-β • platelets, macrophage. fibroblast에서 release되며 healing process의 모든 과정에 영향을 준다. • 작용 ; stimulates the deposition of collagen and other matrix components inhibits collagenase activity blocks plasminogen inhibitor enhance angiogenesis chemotactic for fibroblasts, monocytes, and macrophages

31. PDGF • 주로 platelets의 α-granule에서 release되며 macrophage, endothelial cell, fibroblast에서도 release • 작용; attract the neutrophil, macrophage, and fibroblast to the wound powerful mitogen of the neutrophil, macrophage, and fibroblast stimulate fibroblasts to synthesize new extracellula matrix increase the amount of fibroblast-secretedcollagenase

32. FGF • endothelial cell과 macrophage에서 production • 작용; stimulate endothelial cells to divide and form new capillaries chemoattract endothelial cells and fibroblasts

33. EGF • keratinocytes에서 release • 작용; • stimulates mitosis in epidermal cells and fibroblasts • increase the secretion of collagenase by fibroblasts

35. WOUND HEALING PHASES • Inflammatory phase • Proliferative phase • Maturational phase

36. Inflammatory phase • The body’s defenses are aimed at limiting the amount of damage and preventing further injury

37. At the initial time of tissue disruption, platelets release coagulation factors and cytokines to initiate the healing process

38. Within the first day following tissue injury, neutrophils attatch to surrounding vessel walls and then move through the vessel walls to migrate to the wound site

39. Proliferative phase • angiogenesis • fibroplasia • epithelization

40. Angiogenesis • The process of new blood vessel formation to support a healing wound environment • Stimulants ; tissue hypoxia – major stimulus TNF-α, heparin, VEGF, FGF-1, FGF-2

41. The fibroplasia phase is characterized by movement of wound macrophages into the site of injury, which in turn attract fibroblasts. The fibroblasts then repair the site by producing new connective tissue matrix.

42. Maturational phase ( = remodeling ) • The period of scar contracture with collagen cross-linking, shrinking, and a loss of edema

43. The remodeling phase is characterized by an equilibrium between collagen synthesis and collagen degradation in an effort to reestablish the connective tissue matrix.