00:01
Okay, so that's
too much healing.
00:03
What about too little healing?
Poor healing.
00:05
So clearly, if we don't have
a good blood supply
for whatever reason,
if the tissue is ischemic,
because this is going to be
highly metabolically active,
we're not going to get
very good scar formation.
00:16
Infections because they continue
to recruit inflammatory cells,
because they do their own nastiness
in that area
will also lead to poor
wound healing.
00:26
Clearly, if there's
malnutrition,
you don't have the
fundamental building blocks
to put together scar,
it's not going to be good
wound healing.
00:35
If we give
anti-inflammatory agents,
remember, steroids
affect M2 macrophages
more than they affect
M1 macrophages
so you get less fibrosis,
that's going to be
poor wound healing.
00:47
Mechanical stress.
00:48
If you keep pulling on this,
those thin, delicate capillaries
in angiogenesis,
the granulation tissue will never
have a chance to form properly and
you won't get
good wound healing.
01:01
And if you have a
foreign body in there,
that foreign body continues
to recruit inflammatory cells,
and you will never end
the inflammatory cycle.
01:10
So foreign bodies can
also be a complication
can lead to poor wound healing.
01:17
You can also have just
overenthusiastic healing.
01:20
You can have as
we've already talked about,
in the case of that
intestinal adhesion,
or in the case of the
diffuse alveolar damage,
or in the case of the
fibrinous pericarditis,
organization of exudates
can be deleterious.
01:36
You can also have
exuberant granulation tissue
will show this on the next slide.
01:40
It's kind of interesting to think
about why this happens,
and why it doesn't happen
most of the time.
01:46
And you can have
hypertrophic scar or keloid.
01:49
Okay, in terms of the
exuberant granulation tissue,
it's called proud flesh.
01:54
When you think about it,
if you have a wound in your skin,
how does the granulation tissue know
to stop at the normal level?
Actually, that answer
is not known.
02:06
In most of us,
in the vast majority of the time,
it knows when to stop
and it stops there.
02:11
And then we get
epithelium over the surface
and the wound heals.
02:14
But sometimes
that granulation tissue
extends up
over the surface of the skin.
02:19
It's called proud flesh,
just exuberant tissue,
the only way we get this to heal
is to kind of cauterize that,
burn that off,
and try to get healing to occur.
02:28
So an exuberant granulation tissue
response.
02:32
And the same way you can have
exuberant granulation
tissue responses,
you can have exuberant scars.
02:37
So again, in most of us,
if we cut our skin,
and we heal that
it heels kind of
at the level of the skin,
but sometimes, and there
are certain ethnic groups,
African Americans,
for example,
who have exuberant scarring,
whenever they injure, get injured,
the scar tends to be
much, much more
than just getting back
to the baseline
level of whatever tissue.
03:02
And this is just an example
of a hypertrophic scar.
03:05
We also call this a keloid.
03:08
They are not particularly toxic.
03:11
They're not particularly harmful,
but they may not be
particularly attractive.
03:17
What a hypertrophic scar looks like
is basically just exaggerated
amounts of connective tissue.
03:23
The extracellular matrix,
on the right hand side
in the hypertrophic scar
is much pinker and denser
and there's much more of it
than the normal skin.
03:31
And that's kind of all it is,
and it ends up pushing
the level of overlying skin
up above everything else.
03:38
So you have a very dramatic scar.