1. Physiology 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
2. Phases of wound healing
process (WHP)
Haemostasis
Inflammation
Proliferation
Maturation
Where does a chronic
wound get stuck?
3. Platelet Activity
WOUND
Exposed collagen
Intrinsic pathway
XII
Tissue factor
Intrinsic pathway
intermediates
IX, VII
Extrinsic pathway
VII
Coagulation pathway
intermediates
V, X
Messengers for
Aggregation &
coagulation
Growth factors
(PDGF)
Other enzymes
(proteases)
Platelet
Fibrinogen
FIBRIN
Prothrombin & thrombin
Xlila
Cross-linked fibrin clot
(structural support for wound healing)
11. Tissue engineering – combining cells and
biomaterials into functional tissues
Cells are seeded onto a biomaterial
scaffold to be integrated into a specific
tissue
12. Tissue 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
13. Tissue engineering implants
Synthetic polymeric biomaterials
• Nonbiodegradable
Is required to provide and maintain optimal
cellular function -> e.g. alginate, liposome,…
• Biodegradable
To restore the histological structure and
replace the cellular function of recipients -> e.g.
poly L-lactic acid, poly glycolic acid, …
14. Wound 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
15. Methods 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)
16. Methods of tissue
bioengineering
• Active dressings (f.i.: with maggot’s
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)
17.
18. Allogeneic 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
20. Methods of tissue
bioengineering
• Autologous platelet rich plasma product
(platelet gel)
• Allogeneic platelet gel
The effect is attributed to the growth
factors
21. Fracture Delayed union
Pseudoarthrosis - nonunion
(bone defect)
Infection ?
Method of
treatment?
Impaired
healing
Impaired
healing
22. • Large bone defect
Lack of osteogenic progenitor cells
• Diabetes, glucocorticoid treatment,
chemotherapy, ...
23. Accepted 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)
24. Properties of bone grafts
• Osteogenesis (bone marrow, cancellous
bone)
• Osteoinduction
– Demineralized bone matrix
– Growth factors (platelet rich plasma, bone
morphogenic proteins – BMPs)
• Osteoconduction
– Ceramics
– Collagen
25. Alternatives
Bone substitute (biomaterials for scaffold):
– Demineralized bone matrix
– Biocompatible ceramics
– Synthetic Calcium phosphate
– Mineral bone
– Collagen
– Composite grafts
– Osteoinductive collagen
27. Collagen based matrices in
tissue engineering
• Skin equivalent
• Cartilage repair
• Bone repair
Matrices are also prepared from
synthetic polymers
28. Fracture healing promoting
molecules
Growth and different factors
– The transforming growth factor-β (TGF-β)
superfamily
• Bone morphogenetic proteins
(osteoprogenitors, mesenchymal cells, osteoblasts and
chondrocytes within the extracellular matrix produce BMPs.)
BMP-2, BMP-4
BMP-5, BMP-6, BMP-7
GDF-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
PPDDGGFF
TTGGFF--ββ
MONOCITE
FIBROBLAST
MACROPHAGE
NEUTROPHILS
SMOOTH MUSCLE
ENDOTHELIUM OSTEOBLASTS
PDGF
TGF-β
30. • Mesenchymal stem cell: the promise for
treating skeletal disorders
• Adult stem cell are being isolated from
various tissues
31. Adult 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
35. Our method of tissue
engineering
Combined graft
Autologous cancellous bone with
stem 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
37.
38.
39. Our graft
Autologous cancellous bone with stem
cells and allogeneic platelet gel
40.
41. Conclusions
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
43. FUTURE
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
