Advances in Wound Healing

1
Advances in Wound Healing

• Adrian Barbul, MD, FACS
• Sinai Hospital and Johns Hopkins Medical
  Institutions, Baltimore, MD

2
(No Transcript)
3
(No Transcript)
4
(No Transcript)
5
SCHEMATIC REPRESENTATION OF WOUND HEALING
INJURY
COAGULATIONPLATELETS
COMPLEMENTKININS
MIGRATION/PROLIFERATION
INFLAMMATION
FIBROBLASTS
GRANULOCYTES MACROPHAGES LYMPHOCYTES
RESISTANCETO INFECTION
CONTRACTION
KERATINOCYTES
ENDOTHELIAL CELLS(ANGIOGENESIS)
DEBRIDEMENT
PROTEOGLYCANSYNTHESIS
COLLAGENLYSIS
COLLAGENSYNTHESIS
REMODELING
HEALED WOUND
Adapted with permission from Zabel DD and Hunt
TK. Perspect Colon Rectal Surg.
19936192.Thieme Medical Publishers, New York.
6
COMPONENTS OF WOUND HEALINGSequence
Coagulation
Inflammation
Migration/Proliferation Angiogenesis Epithelizatio
n Contraction Fibroplasia
Remodeling
Witte MB, Barbul A. Surg Clin North Am.
199777509-528.
7
COMPONENTS OF WOUND HEALING
Cell Types Involved
CoagulationProcess
Platelets
Platelets Macrophages Neutrophils
InflammatoryProcess
Macrophages Lymphocytes Fibroblasts Epithelial
cells Endothelial cells
Migratory/ProliferativeProcess
RemodelingProcess
Fibroblasts
Injury
Hours
Days
Weeks
Kane DP, Krasner D. In Chronic Wound Care.
2nd ed. Health Management Publications Inc
19971-4.
8
Wounding Time 0 hour
Fibrin
Platelets
ADP TXA2
Disrupted collagen
Red blood cells
Disrupted blood vessel
9
Wound Healing 0-1 hour
Fibrin clot
Serum
Platelets
Fibrinogen Fibronectin
TGF-? PDGF PF4
10
Wound Healing 1-6 hours
Clot
Neutrophils ()
Free radicals
Lymphocytes ()
Lymphokines
11
Wound Healing Day 2
Scab
Epithelization begins
Fibronectin
Macrophages
TGF-? TGF-? PDGF TNF-? FGF PAF KGF
12
Acute Wound - Day 3
13
CELL RECRUITMENT IN THE WOUND
Coagulation
Inflammation
Migration/Proliferation
Remodeling
Neutrophils
Platelets
Macrophages
Fibroblasts
Relative Number of Cells
Lymphocytes
0
2
4
6
8
10
12
14
16
Days Postwounding
Adapted with permission from Witte MB and Barbul
A. Surg Clin North Am. 199777512.
14
ROLE OF MACROPHAGES IN WOUND HEALING
Phagocytosis, antimicrobial function
Macrophage
Matrix synthesisregulation
Wound debridement
Angiogenesis
Cell recruitmentand activation
Oxygen radicals H2O2 , O2, OH Nitric oxide
Growth factorsTGF-b, EGF, PDGF CytokinesTNF-?,
IL-1, IFN-? Enzymescollagenase,
arginase ProstaglandinsPGE2
Growth factorsbFGF, VEGF CytokinesTNF-?
Phagocytosis Enzymescollagenase, elastase
Growth factorsPDGF, TGF-? , EGF,
IGF CytokinesTNF-? , IL-1, IL-6 Fibronectin
Adapted with permission from Witte MB and Barbul
A. Surg Clin North Am. 199777513.
15
Wound Healing Day 3-5
Scab
Fibroblasts
Macrophages
Collagen
Endothelial buds
16
Acute Wound - Day 5
17
Wound Healing Day 7-10
Epithelization is completed
Collagen remodeling
7 days-1 year
Fibroblasts
Macrophages
Blood vessel
18
ROLE OF FIBROBLASTS IN WOUND HEALING
Proteaserelease
Migration/Proliferation
Fibroblast
ECMproduction
Angiogenesis

• ECM remodeling
• Dissolves
• Nonviable tissue
• Fibrin barrier

• From surrounding tissues influenced by growth
  factors/cytokines
• PDGF
• EGF
• FGF-7
• CTGF
• Activin

Growth factor/cytokine production

• Linkage between actin bundles and ECM
• Serves as scaffold
• Tensile strength

• Growth Factors/cytokines
• FGF-7
• EGF
• Activin

• PDGF
• EGF
• FGF-7
• CTGF
• Activin

ECM extracellular matrix.
19
REGENERATION vs SCAR FORMATION
Amoeba
Newt
Human
20
COLLAGEN

• unique AA - OH-proline, OH-lysine (hydroxylation
  requires vit C)
• every 3rd AA - glycine
• scar - type I and III collagen

21
(No Transcript)
22
(No Transcript)
23
REMODELING

• Changes in physical properties of extracellular
  matrix

l
WoundBreakingStrength
l
n
TotalCollagen Content
n
n
l
n
n
l
n
l
n
7
14
21
28
35
42
Days Postwounding
Adapted with permission from Madden JW and
Peacock EE Jr. Ann Surg. 1971174517.
24
REMODELLING PHASE

• collagen equilibrium (synthesisdegradation)
• wound collagen maximal _at_2-3 weeks
• tensile strength? steadily
• restoration of nl adult collagen
  phenotype (typeItype III - 41)
• ? alignment of fibrils
• ? proteoglycan

25
SCHEMATIC REPRESENTATION OF WOUND HEALING
INJURY
COAGULATIONPLATELETS
COMPLEMENTKININS
MIGRATION/PROLIFERATION
INFLAMMATION
FIBROBLASTS
GRANULOCYTES MACROPHAGES LYMPHOCYTES
RESISTANCETO INFECTION
CONTRACTION
KERATINOCYTES
ENDOTHELIAL CELLS(ANGIOGENESIS)
DEBRIDEMENT
PROTEOGLYCANSYNTHESIS
COLLAGENLYSIS
COLLAGENSYNTHESIS
REMODELING
HEALED WOUND
Adapted with permission from Zabel DD and Hunt
TK. Perspect Colon Rectal Surg.
19936192.Thieme Medical Publishers, New York.
26
Epidermis
Dermis
Hair follicle
Sweat gland
Blood vessels
27
Epidermal islands
Epidermis
Dermis
Hair follicle
Sweat gland
Blood vessels
28
Epidermis
Regenerating epidermis
Dermis
Hair follicle
Sweat gland
Blood vessels
29
Epidermis
Dermis
Hair follicle
Sweat gland
Blood vessels
30
SCAR WARS

• FAILURE dehiscence, herniation
• EXCESS -keloids, hypertrophy

31
HEALING PROCESS ACUTE WOUNDS

• Sequence completed in continuous and expected
  time frame
• Usually achieved with few or no complications
• Overreaction in acute wound healing
• Keloids
• Hypertrophic Scarring

32
Continuum between Normal and Impaired Healing
Normal Healing
Delayed Healing

Impaired Healing/Chronic Wound
TIME
33
Healing Deficits

• Delayed Healing
• Nutritional Deficiencies
• Trauma
• Sepsis

• Impaired Healing
• Diabetes
• Steroids
• Radiation

34
CHRONIC WOUNDS

• Failure or delay of healing component(s)
• Unresponsiveness to normal regulatory signals
• Repeated trauma, poor perfusion/oxygenation,
  and/or excessive inflammation
• Systemic disease
• Genetic factors

35
CHRONIC WOUNDSHealing vs Non-healing
Is the biology different? Deficiency of
Signaling? Interconversion Chronic wounds heal
when converted to acute!? Are the patient/doctor
expectations realistic?
36
CHRONIC WOUNDSTrue Non-healers
Cancer Nutritional deficiencies - scurvy,
etc Lack of blood supply Infected/foreign body
37
The Conspiracy of Chronic Wounds

SYSTEMIC FACTORS
Steroids
Chemotherapy
N
U
M
T
E
R
T
CHRONIC
DM
PCM
I
A
T
B
WOUND
Renal failure
Vitamin Def.
I
O
O
L
N
I
Pressure
A
C
Infection
L
Venous Pres
O

2
Denervation
LOCAL FACTORS
38
SYSTEMIC FACTORS IN WOUND HEALING

• Age
• Nutrition
• Trauma
• Metabolic diseases
• Immunosuppression
• Connective tissue disorders
• Smoking

39
Aging and Wound Healing

• ? inflammatory response
• ? epithelialization
• no clear ? in collagen synthesis

40
Effect of Age on Wound Healing

• Greater Incidence of Wound Dehiscence in Elderly
  Patients
• ? Effect of Concomitant Diseases
• Are there physiological alterations in wound
  healing related to age?

41
Human Studies

• tensile strength
• rate of epithelialization of blisters
• Histologically
• No differences in epidermis
• Less matrix in dermis
• More compacted elastic and collagen fibers in
  dermis
• "Unraveling of collagen bundles"

42
Human Studies (2)

43
(No Transcript)
44
(No Transcript)
45
(No Transcript)
46
(No Transcript)
47
MICROSCOPIC THICKNESS OF EXCISED SKIN (cm)

• Total Epidermis
  Dermis
• Young .031.003 .005.001 .026.002
• Old .029.003 .005.001
  .024.003
• p NS NS
  NS

48
Rate of Epithelialization (days)
p0.037
12
8
4
10.60.4
12.50.6

young
old
young
old
49
ANALYSIS OF PTFE TUBING
OHP (nmol/cm)

40

DNA (mg/cm)
-AN (mg/cm)
a
30
plt0.001
20
10
Young
Old
50
SYSTEMIC FACTORS IN WOUND HEALING

• Age
• Nutrition
• Trauma
• Metabolic diseases
• Immunosuppression
• Connective tissue disorders
• Smoking

51
Nutrition and Wound Healing

• Historical perspectives
• Biblical times - feed the wound
• J. Hunter - injury has a tendency to produce
  both the disposition and the means of cure
• FD Moore - biological priority of the
  wound wisdom of the wound
• SM Levenson - the demanding wound
• TK Hunt - wound nutrition is whole-body nutrition

52
MALNUTRITION

• usually mixed type (PCM) -
• if uncomplicated it delays healing
• PCM in conjunction with other risk factors
  impairs wound healing
• increases susceptibility to wound infections
• nutritional intervention leads to rapid
  resolution - route does not matter

53
Nutrition and Wound Healing
Recent Food Intake OHP Content of Human
Experimental Wounds




Adequate
Inadequate


Weight loss () 91 111




Windsor JA BJS 75135, 1988
54
Effect of TPN on Collagen Accumulation in
Experimental Human Wounds
OHP (mg/cm)
Malnourished Post-TPN
Well Nourished
Malnourished Pre-TPN






Haydock - BJS 74320, 1987
55
Effect of PCM (50 of food intake) on Body
Weight (g)
350
Control
300
Wounding
PCM
250
Schaeffer MR - JACS 18437, 1997
56
Effect of PCM (50 of food intake) on Wound
Collagen Accumulation
2000
OHP (mg/100 mg sponge)
plt0.001
plt0.001
1000


Control
PCM
Schaeffer MR - JACS 18437, 1997
57
Effect of PCM (50 of food intake) on Wound
Fluid NO Metabolites
300
80
150


60


200
100
mM
40


100
50
20
Ornithine
N O2/NO3
Citrulline
Schaeffer MR - JACS 18437, 1997
58
Effect of Nutritional Status (albumin, TLC) on
Healing of Lower Extremity Amputations
50
Delayed Healing
30
Failed Healing
Systemic Complications
10
Normal
Malnourished
Kay et al Clin Orth 217253, 1987
59
Effect of Nutritional Status on Wound
Complications following Vascular Operations
40
30
1
Healing
0
1
0
Healing
20
Complications
Complications
88
10
60
plt0.001
plt0.001
Casey - Surgery 93822, 1983
gt3g
lt3g
60
SINGLE NUTRIENT DEFICIENCY

• vitamin C, thiamin, riboflavin, zinc, manganese
• biochemical deficiency more common than overt
  clinical deficiency
• major trauma increases losses of various
  nutrients
• no evidence that more is better
• often easier to treat than to diagnose

61
Nutritional Therapy

• Correct deficiencies - calories, protein, trace
  minerals, vitamins
• No proven role for supra-normal supplementation
• Specific amino acids for collagen synthesis -
  arginine

62
ARGININE
constituent of proteins
nucleoproteins, collagen, etc,

precursor for other AA

glutamic acid, proline

regulator of enzyme function

regulator of hormone release
precursor for phosphoguanidine
source of polyamines
63
Effect of arginine on wound healing
Chow
Chow
Arg 3d
Arg 10d
4000
4000
5000
5000
0.005
0.005
3000
3000
0.001
0.001
3000
3000
2000
2000
0.005
0.005
1000
1000
1000
1000
0.01
0.001
0.01
0.001
OHP
FxBS
OHP
FBS
FxBS
FBS
FxBS
OHP
FBS
FBS
FxBS
OHP
64
EFFECT OF ARGININE ON WOUND HEALING
Collagen Deposition (mg)
Breaking Strength (g)
300
2500


2000
200
1500


1000
100
500
DM
Control
DM
Control
DM Arg.
Control Arg.
DM Arg.
Control Arg.
Saline
Arginine
Plt0.05 vs saline
65
Arginine
Placebo
0.015
0.001
OHP

a-amino N DNA
(nMol/cm)

(nMol/cm)
(nMol/cm)
(?Mol/cm)
66
SYSTEMIC FACTORS IN WOUND HEALING

• Age
• Nutrition
• Trauma
• Metabolic diseases
• Immunosuppression
• Connective tissue disorders
• Smoking

67
EFFECT OF TRAUMA ON HUMAN EXPERIMENTAL WOUNDS
8
8
6
6
4-HYP (nmol/mg sponge)
Healthy
Healthy
4
4
T
rauma
T
rauma
2
2
Diegelmann - JSR 40229, 1986
68
LOCAL FACTORS AFFECTING WOUND HEALING

• Mechanical injury
• Infection
• Edema
• Ischemia/necrotic tissue
• Topical agents
• Ionizing radiation
• Low oxygen tension
• Foreign bodies

69
New Approaches

• Understanding the pathophysiology
• Dressings
• Growth factors
• Skin Substitutes - Tissue Engineering
• Drugs
• Nutritional Therapy

70
Desired Features of Engineered Skin

• Rapid reestablishment of functional skin
  (epidermis/dermis)
• Receptive to bodys own cells (eg, rapid take
  and integration)
• Graftable by a single, simple procedure
• Graftable on chronic or acute wounds
• Engraftment without use of immunosuppression

71
Desired Features of Engineered Skin

• Alleviate wound pain
• Sterilizable/free of infection
• Costbenefit ratio
• Effective shelf life

72
Tissue Engineered Skin Replacement

• Cultured autologous keratinocyte grafts
• Cultured allogeneic keratinocyte grafts
• Acellular collagen matrices
• Cellular matrices
• Human Dermal Equivalents

73
What is Apligraf?
Supplied as a living, bi-layered skin
substitute Indications Venous Leg
Ulcers Diabetic Foot Ulcers
74
Apligraf and Venous Ulcers
All Patients Achieving 100 Closure1
60
By 24 weeks P.022
50
Control (n110)
APLIGRAF (n130)
40
Percent of Protiens With Ulcers 100 Closed
30
20
10
0
4 Weeks
8 Weeks
12 Weeks
24 Weeks
APLIGRAF vs Compression Therapy
In patients with ulcers gt 1 years duration
(n120), Apligraf plus compression therapy was
more than twice as effective in achieving
complete wound closure by week 24 (47 vs 19,
P.002). These data compare with 66 vs 73
(Apligraf vs control), for patients with lt 1
years duration (n120)
75
Apligraf and Diabetic Foot Ulcers
76
Apligraf and Closure of Diabetic Ulcers
Median Time to 100 Wound Closure
P.0026
APLIGRAF (n112)
65 days
Conventional Therapy (n96)
90 days
0
20
40
60
80
100
Days to Closure
77
Long Term Results

• Donor cells replaced by host cells
• Effect may be related to 1) delivery of growth
  factors to wounds 2) synthesis of matrix
  components

78
Cytokines and Wound Healing

• EGF FamilyEGFTGF-aHeparin-binding EGF
• FGF Familybasic FGFacidic FGFKGF

• TGF-b FamilyTGF-b 1,2,3,
• OtherPDGFVEGFTNF-aIL1IGF-1CSF-1

79
Platelet-Derived Growth Factor (PDGF)
80
Binding of PDGF Isoforms to Receptors
?
?
PDGF-AA
?
?
PDGF-AB
?
?
?
?
?
PDGF-BB
PDGF-BB
?
?
?
81
Activation of Receptor Sites by PDGF-BB
?
Chemotaxis
?
?
Mitosis
PDGF-BB
?
?
Synthesis
?
82
Summary of REGRANEX (becaplermin) Gel 0.01
Clinical Trials
100 80 60 40 20

• .

Placebo gel Good wound care Becaplermin
0.003 Becaplermin 0.01
Ulcers Healed ()
Study 1
Study 2
Study 3
Study 4
83
Characteristics of Ideal Dressings

• Promote Wound Healing (maintain moist
  environment)
• Conformability
• Pain Control
• Odor Control
• Nonallergenic and nonirritating

84
Characteristics of Ideal Dressings

• Permeability to gas
• Safety
• Non-traumatic Removal
• Cost Effectiveness
• Convenience

85
Benefits of Moist Wound Healing

• Faster re-epithelialization
• Fewer infections
• Less pain
• Less re-injury upon dressing removal
• More efficient autolytic debridement

86
Effects of Occlusive Dressings on Wounds
Occlusive Dressing
PO
Fibrinolysis
2
Macrophages
Growth Factors
Fibroblast
Keratinocytes
Endothelium
87
Hydrogels

• three dimensional networks of hydrophilic
  polymers derived from gelatin, polysaccharides,
  polyelectrolyte complexes and methacryl ester
  polymers.
• swell with uptake of liquid
• contain great deal of water, which can be donated
  to a dry wound bed thus promoting autolytic
  debridement

88
Hydrocolloids

• combination of hydrophylic polymers in an
  adhesive (e.g., gelatin/pectin/
  carboxymethycellulose) with polyurethane backing
• absorb up to 12 times their weight in wound
  fluid, conform to wound contour
• pain-free application and removal

89
Hydrocolloids

• Indicated for light to moderately exudating
  wounds (pressure ulcers, minor burns, leg ulcers,
  traumatic injuries)
• Initially virtually impermeable to water vapor
  which may facilitate wound rehydration and
  autolytic debridement
• Interactive

90
ADVANTAGES

• Hydrogels
• permeable to water vapor
• keeps wound moist
• fluid absorbent
• no adherence

• Hydrocolloids
• fluid absorbent
• no adherence to wound
• debrides
• adheres to wound edges

91
DISADVANTAGES

• Hydrogels
• unused portion desiccates
• requires anchoring
• expensive

• Hydrocolloids
• impermeable to oxygen
• may macerate tissues
• may mask infection
• leaves residue on wound

92
ALGINATES

• Derived from brown algae
• Long chain polysaccharides containing mannuronic
  and guluronic acid ratio of these sugars varies
  with the species of seaweed and the season of
  harvest
• Each manufacturers product different in
  calciumsodium ratio and mannuronic/guluronic
  acid content

93
ALGINATES

• Processed as the calcium form, alginates turn
  into soluble sodium forms through ion exchange in
  the presence of wound exudates.
• The polymers gel, swell and absorb a great deal
  of fluid.
• Interactive
• Hemostatic
• Used in exuding wounds such as leg ulcers, acute
  cavitated surgical wounds, pressure sores

94
Alginates
95
Alginates
96
Choosing the Right Dressing

• Exudate Absorption - AlginatesgtHydrocolloidgtHydrog
  els
• Debridement -Hydrogel/Hydrocolloid
• Microbial barrier - Hydrogels/Hydrocolloid
• Antimicrobial function - ??