This document provides information about planaria regeneration and stem cells. It discusses that planaria have stem cells called neoblasts that allow them to regenerate tissues and organs. When planaria are cut, the neoblasts migrate to the wound site and divide to form any cell type needed for regeneration. The document outlines an experiment where students can cut planaria and observe their regeneration over time, recording observations about mobility and tissue color changes. Regeneration ability decreases along an evolutionary scale from planaria to salamanders to mammals due to genetic changes affecting stem cell function.

1. Daniela
Sanges,
PhD

2. endoderm
mesoderm
ectoderm
lung
pancreas
heart
red
blood
skin
neuron

4. Regenera9on
poten9al
Evolu9onary
scale
Planaria
Salamander
Mammalian

5. n Planaria
have
an
amazing
ability
to
regenerate
parts
of
themselves
n Planaria
regenera9on
is
a
great
model
for
demonstra9ng
stem
cell
func9on
and
complexity
of
9ssue
regenera9on
n They
can
grow
easily
in
the
lab

6. n Freshwater
flatworms
(phylum:
Platyhelminthes)
n Live
in
freshwater
under
leaves
and
stones
n Avoid
light
(“nega9ve
phototaxis”)
n Free
living
–
not
parasites
n Carnivores
–
eat
decaying
meat,
insects
and
larvae
(egg
yolks
or
liver
in
the
lab)
n 1-­‐20
mm
in
size
n Long
lived
n Use
sexual
or
asexual
reproduc9on

8. n 20-­‐30%
of
all
the
cells
in
a
planaria
are
Neoblasts.
n Neoblasts
divide
by
mitosis
and
can
make
more
of
themselves.
They
are
the
only
dividing
cells
in
planaria.
n When
a
planaria
is
wounded,
neoblasts
migrate
to
the
site
and
begin
dividing
n Neoblasts
can
become
ANY
cell
the
planaria
needs—nerve
cells,
flame
cells,
reproduc9ve
cells…
Ann. Rev. Cell. Dev. Biol. 20:725-757, 2004

9. Three types of planaria
with their neoblasts
labeled with BrdU
BrdU
(bromodeoxyuridine)
is
subs9tuted
for
thymine
during
DNA
replica9on.
Only
dividing
cells—in
this
case
the
neoblasts—will
show
detec9ble
amounts
of
BrdU.
A.
Phagocata
sp.
B.
Girardia
dorotocephala
C.
Schmidtea
mediterranea
Dugesia
sp.

10. To
set
up
an
experiment
of
regenera9on
with
Planaria
in
the
classroom

11. n The
type
of
water
is
very
important!
Fresh
water
from
a
pond,
stream
or
lake
is
best;
spring
water
is
adequate
n Keep
cultures
in
a
cool,
dark
place
n Feed
planaria
at
least
once
a
week
n Change
the
water
twice
a
week,
especially
a_er
feeding
n A_er
cu`ng
them,
the
cultures
should
not
be
fed

12. Each
team
will
receive
3
planaria:
n Experimental
Planaria
#1
Every
team
will
cut
this
into
half,
separa9ng
the
anterior
from
the
posterior
halves.
n Experimental
Planaria
#2
This
will
be
cut
in
a
manner
determined
by
your
team.
n Control
Planaria
This
will
not
be
cut.
Used
with
permission
from
UC
Museum
of
Paleontology

13. How
will
the
Planaria
regenerate?
This
step
is
important
to
learn
to
formulate
an
HIPOTHESIS

14. Report
the
informa9on
and
the
results
DAILY

18. § A_er
you
cut
the
planaria,
how
does
the
mobility
of
the
tail
fragments
compare
with
the
mobility
of
the
head
fragments?
Do
they
move
the
same
or
differently?
If
they
move
differently,
why
do
you
think
that
is?
§ Do
you
think
the
head
fragments
prefer
light
or
shade?
How
could
you
test
this?

19. § Did
all
the
tail
fragments
regenerate
photoreceptors?
If
not,
which
fragments
did
not?
§ Did
all
the
tail
fragments
regenerate
photoreceptors
at
the
same
rate?
If
not,
which
were
slower
and
which
were
faster?
§ Did
you
no9ce
a
change
in
mobility
in
the
tail
fragments
over
9me?
What
about
the
head
fragments?
§ As
the
days
went
by,
what
did
you
no9ce
about
the
color
of
the
regenera9ng
9ssue?

20. Days
Head
Middle
Tail
Did
all
the
tail
fragments
regenerate
photoreceptors
at
the
same
rate?
If
not,
which
were
slower
and
which
were
faster?

21. Regenera9on
poten9al
Evolu9onary
scale
Planaria
Salamander
Mammalian

22. High
Moderate
Low

23.
n LOST
OR
ALTERED
GENETIC
PROGRAM
n SMALLEST
STEM
CELL
PULLS
turning
on
the
right
genes
at
the
right
9me
in
the
cells
that
come
from
the
dividing
stem
cells
(neoblast).

24. What is a stem cell?
a single cell that can…
replicate itself, or…
differentiate into many cell types

29. Differen9a9on
De-­‐differen9a9on
A
B
Trans-­‐differen9a9on

34. Pluripotent
Mul9potent

38. embryonic
stem
cell
soma9c
cell
pluripotent
genes
cell
fusion
reprogramming

39. embryonic
stem
cell
soma9c
cell
pluripotent
genes
cell
fusion
reprogramming
WNT

40. • Re9ni9s
Pigmentosa
• Usher
Syndrome
• Amaurosis
de
Leber
• Glaucoma
• Diabe9s
re9nopathy
• Macular
Degenera9on
• Re9nal
Detachment
RETINAL
DEGENERATIONS

41. Sanges
et
al.,
Cell
reports,
2013

42. d0
d2-­‐4
d30
Damage-­‐dependent
Cell
fusion
Wnt-­‐mediated
reprogramming
Regenera9on
Sanges
et
al.,
Cell
reports,
2013

43. § General
discussion
on
9ssue
regenera9on
§ Planaria
regenera9on
experiment
in
the
classroom
(Wednesday)
Predic9on
exercise
Prac9cal
and
theore9cal
ques9on
on
the
experiment
§ Mammalian
Stem
Cells
and
Reprogramming
(Thursday)
§ Adult
stem
cells.
Summary
of
the
course