The Microenvironment of DFU
Mamdouh Radwan El-Nahas
Professor of Internal Medicine
Diabetic foot team
Diabetes and Endocrinology Unit
Mansoura University
What happens when wound
occur in the skin
wound healing
start immediately
and can be
categorized into 4
stages.
1. Coagulation
2. Inflammation
3. Cellular proliferation
4. Remodelling
Haemostasis
Stop
Bleeding
Platelet Degranulation
Growth factors
Serotonin
Provide Matrix for
Cell Migration
Inflammation
PNL
Phagocytose
Microorgan.
Monocytes
Tissue
Macrophage
phagocytosis
Proteol. Enz
GFs
Cellular
Proliferation
Fibroblast
Endothelial cells
EC matrix
Deposition
Neovascularization
Keratinocytes
Epithelialization
Remodelling
Provisional wound
matrix
Mature scar
MMPs
consists predominately
of fibrin and fibronectin
collagen molecules
(type III, type I)
cross-linked
by enzymatic action
Matrix metalloproteinases (MMPs)
Plasmin
(-)
Inactive form
Active form
Matrix degradation
tissue inhibitors of
metalloproteinases
The chronic wound is not the acute
wound
Lessons learned from acute wound healing
cannot be applied to chronic wound.
Cellular and molecular abnormalities
of Chronic wound
1. Overproduction of the inflammatory cytokines e.g.
TNF-α
2. Cellular
abnormalities:
Defective
PNL
&
Macrophages and senescent Fibroblasts
3. Excessive amounts of MMPs.
4. Reduced concentration of growth factors e.g. PDGF,
VEGF and TGF β.
So, for healing to occur, we need to
change the environment of chronic
wound toward that of acute wound.
Cellular and molecular abnormalities
of Chronic wound
1. Overproduction of the inflammatory cytokines e.g.
TNF-α
2. Cellular
abnormalities:
Defective
PNL
&
Macrophages and senescent Fibroblasts
3. Excessive amounts of MMPs.
4. Reduced concentration of growth factors e.g. PDGF,
VEGF and TGF β.
The microenvironment of Chronic
wound
1. Overproduction of the inflammatory cytokines e.g.
TNF-α
2. Cellular abnormalities: Defective PNL & Macrophages
and senescent fibroblasts
3. Excessive amounts of MMPs.
4. Reduced concentration of growth factors e.g. PDGF,
VEGF and TGF β.
Exudates from chronic wounds contain very high
levels of inflammatory cytokines and proteases.
Removal of the excess exudates can be accomplished
by:
1. A foam or an alginate dressing
2. VAC (vacuum assisted closure) device.
The ancient Egyptian discovery
7000 years ago
The ancient Egyptians used a
combination of:
 honey
 lint
 animal grease
 Others
Sekhmet Netjert
(Goddess) of Healing
The microenvironment of Chronic
wound
1. Overproduction of the inflammatory cytokines e.g. TNFα
2. Cellular
abnormalities:
Defective
PNL
&
Macrophages and senescent Fibroblasts
3. Excessive amounts of MMPs.
4. Reduced concentration of growth factors e.g. PDGF,
VEGF and TGF β.
Debridement
In microenvironmental
terms we can think of
Debridement
as
removal of
old cells
giving space to new
cells to start wound
healing.
Cell therapy with bioengineered skin
• Using living fibroblasts and keratinocytes from
neonatal foreskin.
• The mechanisms of action of bioengineered skin
might involve increased availability of growth
factors, and perhaps recruitment of stem and
progenitor cells to the wound site.
Stem cell therapy
• There is great interest in delivery of stem or
progenitor cells, either applied topically or recruited
from the circulation.
• Some preliminary work suggests that topically
applied autologous bone-marrow cultured cells can
heal human chronic wounds.
Using electricity to revert cells into
their normal behavior
• High-voltage, pulsegalvanic
electric
stimulation
enhances
wound
healing (Peters et al
2001).
low-level Laser therapy
low-energy laser has a stimulating effect on cell
mitosis, keratinocyte migration, proliferation and
cytokine production and it may lead to increased
dermal angiogenesis
Topical Phenytoin
• The gingival hyperplasia appear during phenytoin
therapy, raise interest in its use to prompt wound
healing.
• Habibipour et al (2003) showed that phenytoin
treated wounds had significant increase in collagen
deposition and neovascularization.
• Shaw et al (2007) reviewed the effectiveness of
topical phenytoin on wound healing and concluded
that it had positive effect on wound healing in a
variety of wounds including DFU
The microenvironment of Chronic
wound
1. Overproduction of the inflammatory cytokines e.g. THFα
2. Cellular abnormalities: Defective PNL and Macrophages
senescent fibroblsts
3. Excessive amounts of MMPs.
4. Reduced concentration of growth factors e.g. PDGF,
VEGF and TGF β.
Inhibitors of MMPs
• Tetracycline derivatives
activity of MMPs
can
reduce
the
• Supporting this concept, an initial report of a
randomized controlled trial showed improved
healing of chronic diabetic foot ulcers
treated with a topical Doxycycline gel (Chin
et al 2003) .
• Metallic ions and citric acid e.g Poly Hydrated
Ionogen positively restore MMP ratios within chronic
wounds.
• Dressing consisting of metal ions and citric acid
(Dermax) decrease MMP-2 production in vitro (van
den Berg 2003)
• Pirayesh et al (2007) reported efficacy of PHI in the
treatment of DFU.
Silver
Silver-containing dressings are effective in
sequestering matrix metalloproteinase-2 and
-9 (walker et al 2007).
Walker et al: In vitro studies to show sequestration of matrix
metalloproteinases by silver-containing wound care products.
Ostomy Wound Manage. 2007 Sep;53(9):18-25.
The microenvironment of Chronic
wound
1. Overproduction of the inflammatory cytokines e.g. TNFα
2. Cellular abnormalities: Defective PNL & Macrophages
and senescent Fibroblasts
3. Excessive amounts of MMPs.
4. Reduced concentration of growth factors e.g. PDGF,
VEGF and TGF β.
Growth factors
PDGF gel (Regranex) improved healing
quality, enhanced angiogenesis, cell
proliferation and epithelialization (Li et
al 2007).
But the effectiveness of PDGF is far
below our expectations
• Senescent cells, which may be unresponsive to
growth factors.
• excessive amount of proteases that have been
shown to be capable of destroying PDGF.
• There is a need to improve these results with growth
factors. Greater efficiency of delivery of growth
factors, by gene therapy or by cell therapy, is now
possible and being tested.
Epidermal growth factor (EGF)
Recombinant human epidermal growth
factor (REGEN-D™ 150) has been found
to result in healthy granulation and
stimulate epithelization (Mohan 2007).
VEFG
Successful in experimental animals
(Galeano et al 2003) but clinical trials
using VEGF therapy did not succeed in
ameliorating healing as expected (YlaHerttuala 2006)
Conclusions
• Optimum healing of a wound requires a well-orchestrated
integration of complex cellular and molecular factors.
• It is a complex process that need appropriate and precise cellular
response to: inflammatory mediators, to growth factors and
cytokines.
The chronic wound is not the acute wound
• In chronic wounds the progression of the healing process is
impaired and the wound usually stuck in the inflammatory
stage.
• Enhanced understanding and correction of pathogenic factors,
combined with stricter adherence to standards of care is giving
new hope to the problem of impaired healing.
Successful Treatment of DFU depends
on how we understand the complex
and dynamic interaction of multiple
factors that contribute to chronicity of
the wound.
Only then, when we put together what we
‘take off the wound’ (pressure)
with
what we ‘put on’ the wound (advanced dressings)
will we see any real improvement in wound healing
David Armstrong
Thank you