Title: Physiology of wound healing
1Physiology of wound healing
- Wound healing is
- Complicated process that involves at least 4
distinct cell types - Commonly referred to as occurring in PHASES
- Affected by several factors
2Phases of wound healing process (WHP)
Maturation
Proliferation
Inflammation
Haemostasis
Where does a chronic wound get stuck?
3Platelet Activity
WOUND
Tissue factor
Exposed collagen
Extrinsic pathwayVII
Intrinsic pathwayXII
Messengers for Aggregation coagulation
Intrinsic pathway intermediates IX, VII
Platelet
Growth factors(PDGF)
Coagulation pathway intermediates V, X
Other enzymes (proteases)
Fibrinogen
Prothrombin thrombin
Xlila
Cross-linked fibrin clot (structural support for
wound healing)
FIBRIN
4Role of keratinocytes in wound healing
Keratinocyte
Migration/ Profileration
Protease release
ECM production
Angiogenesis
- Dissolves
- Nonviable tissue
- Fibrin barrier
Growth factor/ Cytokine production
- Chemoattractants
- VEGF
- KGF (FGF-7)
- Matrix formation
- Basement membrane formation
5Selected growth factors important to wound healing
- EGF (epidermal growth factor). Stimulates wound
re-epithelialization and stimulates blood vessels
and fibroblasts. - FGF (fibroblast growth factor). Stimulates new
blood vessel and collagen formation. - PDGF (platelet derived growth factor).
Attracts/stimulates smooth muscle cells,
fibroblasts, and other cells. Important in ECM
formation. - TGF-ß (transforming growth factor-beta). Slows
buildup of epithelial cells, suppresses
immunoglobulin secretion and is helpful in ECM
formation. - TNF-a (tumor necrosis factor-alpha). Activates
neutrophils, causes fibroblasts to multiply,
causes bone/cartilage resorption. - IL-1 (interleukin-1). Attractant for epithelial
cells, neutrophils, mono and lymphocytes also
stimulates collagen synthesis.
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7Chronic wounds characteristics
- Increased inflammatory cytokines
- Altered fibroblast phenotype
- Abnormalities growth factors
- Increased proteases
- Altered keratinocyte function
- Senescent cells (increased number)
8Wound bed preparation
- Debridement
- Bacterial balance
- Dressing therapies
- (f.i. silver dressings prevent of infections,
help reduce healing time)
9Local wound care
debridement
moisture balance
Foams Calcium alginates Hydrogels Hydrocolloids Ad
hesive films Negative pressure therapy
Surgical Autolytic Enzymatic Biological
10Tissue engineering
- Biology, medicine and technology are today
closely interleaved with each other
11- Tissue engineering combining cells and
biomaterials into functional tissues - Cells are seeded onto a biomaterial scaffold
to be integrated into a specific tissue
12Tissue engineering
- Advances
- Biological wound dressings
- Material scaffolds and cell material interactions
- The use of stem cells for tissue engineering
- Combination of stem cells and material scaffolds
into tissue engineered replacements of tissues
and organs
13Tissue engineering implants
- Synthetic polymeric biomaterials
- Nonbiodegradable
- Is required to provide and maintain optimal
cellular function -gt e.g. alginate, liposome, - Biodegradable
- To restore the histological structure and
replace the cellular function of recipients -gt
e.g. poly L-lactic acid, poly glycolic acid,
14Wound healing promoting anti-adhesive matrix
- The collagen grafting is also applied to
produce a healing / promoting antiadhesive
membrane - Particularly necessary in peritoneal surgery to
prevent postoperative adhesion - To produce skin wound dressing membranes
15Methods of tissue bioengineering
- Skin replacement
- Cultured epidermal graft
- Cultured human autologous and allogeneic
keratinocytes - Semi synthetic materials (composed of human
neonatal dermal fibroblasts cultured onto a
bioabsorbable mesh)
16Methods of tissue bioengineering
- Active dressings (f.i. with maggots excret,
with honey) - Photobiomodulation (modulate cellular activity in
red to near infrared light) - Hyperbaric oxygen therapy as therapeutic benefit
in WT - Growth factors (from blood)
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18Allogeneic cultivated human skin keratinocytes
- Make rapid healing of the ulcers particularly
those that are difficult to heal - No clinical or laboratory evidence of rejection
- No evidence of preexisting cytotoxic antibodies
specific fort the HLA class I antigens expressed
on HSE cells - A fibrin-based skin substitute produced in the
defined keratinocyte medium could be safely used
to threat a number of skin defect
19Preparation of autologous fibrin-based skin
substitutes
20Methods of tissue bioengineering
- Autologous platelet rich plasma product (platelet
gel) - Allogeneic platelet gel
- The effect is attributed to the growth factors
21Impaired healing
Delayed unionPseudoarthrosis - nonunion (bone
defect)
Fracture
Impaired healing
? Method of treatment?
Infection
22- Large bone defect
- Lack of osteogenic progenitor cells
- Diabetes, glucocorticoid treatment, chemotherapy,
...
23Accepted methods of treatment
- Autologous bone transplants
- Cancellous bone graft (contains all necessary
characteristics of bone substitutes) - Corticocancellous graft (possibly vascularized?
limited amount) - Homologous (allogeneic) graft
- Bone banks, treated (no rejection), contains
only osteoconductive properties - Ilizarow intercallary bone transport (traction
method)
24Properties of bone grafts
- Osteogenesis (bone marrow, cancellous bone)
- Osteoinduction
- Demineralized bone matrix
- Growth factors (platelet rich plasma, bone
morphogenic proteins BMPs) - Osteoconduction
- Ceramics
- Collagen
25Alternatives
- Bone substitute (biomaterials for scaffold)
- Demineralized bone matrix
- Biocompatible ceramics
- Synthetic Calcium phosphate
- Mineral bone
- Collagen
- Composite grafts
- Osteoinductive collagen
26Alternatives
- Role of GROWTH FACTORS
- Role of STEM CELLS
27Collagen based matrices in tissue engineering
- Skin equivalent
- Cartilage repair
- Bone repair
- Matrices are also prepared from synthetic
polymers
28Fracture healing promoting molecules
- Growth and different factors
- The transforming growth factor-ß (TGF-ß)
superfamily - Bone morphogenetic proteins(osteoprogenitors,
mesenchymal cells, osteoblasts and chondrocytes
within the extracellular matrix produce
BMPs.)BMP-2, BMP-4BMP-5, BMP-6, BMP-7GDF-5
(BMP-14), GDF-6 (BMP-13), GDF-7 (BMP-12)BMP-3
(Osteogenin), GDF-10 (BMP-3b) - Platelet-derived growth factor (PDGF)
- Fibroblast growth factor (FGFs)
- Insulin-like growth factor (IGFs)
29- Platelet rich plasma (contains high
concentrations of growth factors) especially
TGF-B and PDGF - Autologous
- Allogeneic
PLATELETS
MONOCITE
NEUTROPHILS
PDGF TGF-ß
FIBROBLAST
SMOOTH MUSCLE
MACROPHAGE
ENDOTHELIUM
OSTEOBLASTS
PDGF TGF-ß
30- Mesenchymal stem cell the promise for treating
skeletal disorders - Adult stem cell are being isolated from various
tissues
31Adult stem cells
- Bone marrow contains
- Hematopoietic stem cells (HSCs)
- All types of blood cells
- Bone marrow mesenchymal stem cells (MSCs)
- Generating bone, cartilage, fat, fibrous
connective tissue
32Bone tissue formation
- Osteogenic progenitor cells
- Locations
- Periost
- Peritrabecular soft tissue
- Cancellous bone and bone marrow (in BM aspirate
up to 40x less stem cells then in cancellous bone)
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35Our method of tissue engineering
- Combined graft
-
- Autologous cancellous bone withstem cells
- Allogeneic platelet gel(source of GFs)
36- manually grounded autologous cancellous bone
with stem cells - corresponding amount of allogeneic platelet
concentrate (app. 1,4x109 platelets per 1 ml) - AND
- Added 0,06 ml human thrombin in 40 mM CaCl2
for the activation of platelets - in 1
minute - the resulting gelled graft can be shaped
according to the bone defect and implanted
Mixed
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39Our graft
- Autologous cancellous bone with stem cells and
allogeneic platelet gel
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41Conclusions
- The use of autologous cancellous bone with
stem cells and allogeneic platelet gel is safety
and effective method for the treatment of
nonunion of long bones
42Future
Gene arrays for
gene discovery
43FUTURE
Cell and tissue engineering Detection of
numerous signal pathways activated during
physiological processes Self (re)restoration and
differentiation off mammalian embryonic, fetal
and stem cells of adult tissues
44- Thank you for attention !