How do scars form? - Sarthak Sinha

Remember the time you fell off your bike,
or bumped your head on a sharp corner?

Childhood injuries are things we'd
often like to forget,

but our bodies often carry the memories
in the form of scars.

So what are these unwanted souveniers,
and why do we keep them for so long

after that unintended vacation
to the emergency room?

The most common place we see scars
are on our skin,

a patch that looks slightly different
from the normal skin around it.

Often, this is considered an
unfortunate disfigurement,

while other times, deliberate
scarification has been used

in both traditional and modern cultures
to mark a right of passage,

or simply for aesthetic decoration.

But the difference isn't only cosmetic.

When we look at healthy skin tissue
under a microscope,

we see the cells that preform
various functions

connected by an extra cellular matrix,
or ECM.

This is composed of structural proteins,
like collagen,

secreted by specialized fibroblast cells.

Well arranged ECM allows for
transportation of nutrients,

cell to cell communication,
and cell adhesion.

But when a deep wound occurs,
this arrangement is disrupted.

During the process of wound healing,
collagen is redeposited at the wound site,

but instead of the basket-weave
formation found in healthy tissue,

the new ECM is aligned
in a single direction,

impeding inter-cell processes,
and reducing durability and elasticity.

To make matters worse,
the healed tissue contains

a higher proportion of ECM than before,
reducing its overall function.

In the skin, the overabundance of collagen
interferes with its original functions,

like producing sweat, controlling body
temperature and even growing hair.

The scar tissue is fragile, sensitive to
changes in temperature and sensation,

and should be kept in moist environments
to maximize healing.

This presence of excessive fibrous
connective tissue in an organ

is known as fibrosis,
and if that term sounds familiar,

its because our skin is not the only organ
vulnerable to scarring.

Cystic fibrosis is a genetic disorder that
causes scarring of the pancreas,

while pulmonary fibrosis is a scarring
of the lungs,

resulting in shortness of breath.

Scarring of the heart and the build up of
ECM following a heart attack

can inhibit its beating, leading to
further heart problems.

What's common to all these conditions

is that although it retains some of the
original functions,

the scar tissue formed after a wound is
inferior to the native tissue it replaces.

However, there is hope.

Medical researchers are now studying
what causes fibroblast cells

to secrete excessive amounts of collagen

and how we can recruit
the body's other cells

in regenerating and repopulating
the damaged tissue.

By learning how to better control wound
healing and the formation of scar tissue,

we can utilize the multi-billion dollar
budgets currently used to address

the aftermath of wounding in a much
more efficient manner,

and help millions of people live better
and healthier lives.

But until then, at least some of our scars

can help us remember to avoid
the sorts of things that cause them.