Tissue Engineering Scaffolds
Dana Schneider, Sligo Middle School
Carl Simon
Students = 31, 28 and 23
10.07.12: 8:19-9:04, 9:57- 10:42,12:17-1:02
National Institute of Standards and Technology
United States Department of Commerce
Materials Measurement Laboratory • Biosystems & Biomaterials Division • Biomaterials Group
NIST
• Mission: to promote U.S. innovation and
industrial competitiveness by advancing
measurement science, standards, and
technology in ways that enhance economic
security and improve our quality of life
• Established by congress in 1901 as the
nation’s measurement lab
• 5000 staff, 3000 PhDs, 4 Nobel Laureates
since 1997, MacArthur Fellowship winner in
2003, National Medal of Science winners in
1998 & 2008, 8 current National Academy
members
What Does NIST Do?
International System of Units (SI)
Base quantity
Name
Symbol
length
meter
m
mass
kilogram
kg
time
second
s
electric current
ampere
A
temperature
kelvin
K
amount of substance
mole
mol
luminous intensity
candela
cd
About 2.6 billion times a day, or
30,000 times a second, NIST’s
Internet Time Service sets computer
clocks and other timekeeping devices
Instructions for a 16th-century
measuring rod: “Take 16 men, short
and tall ones as they leave church and
let each of them put one shoe after the
other and the length thus obtained
shall be a just and common measuring
rod to survey the land with.”
NIST 4 Nobel Prizes in Physics in 15 Years
2012 Nobel Prize in Physics to Dave
Wineland of NIST Time and Frequency
Division
Dave Wineland, Leader of the Ion Storage
Group, shares the 2012 Nobel Prize in
Physics with Serge Haroche of France "for
ground-breaking experimental methods
that enable measuring and manipulation of
individual quantum systems."
Tissue Engineering
Donor Cells
from Injured
Knee
Scaffold
Isolated
Cells
Grow New Knee
Tissue in the Lab
Repair Damaged
Knee
Nanofiber Scaffolds for Human Trachea
Trachea
Paolo Macchiarini
Careggi, Italy
0.05 mm
Nanofiber scaffold
seeded stem cells
Nanofiber trachea
Polymers
A polymer is a chemical compound
consisting of repeating structural units
Atomic force micrograph
of single polymer chain
Dry polymer powder
Polymers
Polystyrene
Polyethylene
Poly(e-Caprolactone) (PCL)
Salt-Leached Scaffold Fabrication
Mold
NaCl
Polymer Solution
Fabrication:
• Fill a mold with NaCl
• Pour polymer solution over NaCl: NaCl is insoluble in solvent
• Air dry to remove solvent
• Leach NaCl porogen in water
• Yields highly porous, scaffold matrix to support cell adhesion & tissue
regeneration
Salt-Leached PCL Scaffolds
(96-Well Plate)
2 mm
100 mm
250 mm
25 mm
Mouse Osteoblasts Cultured on PCL
Salt-Leached Scaffolds
7d
14 d
Each green dot
is a cell nuclei
stained with a
fluorescent dye
25000 cells
10000 cells
5000 cells
1d
1 mm
Freeform
Fabrication
Dana Schneider, Summer 2012
Stem Cells Cultured on Freeform Fabricated PCL Scaffolds
2 mm
5 mm
Human Bone Marrow Stromal Cells (7d)
Cell nuclei
are green
Cell bodies
are red (actin)
0.2 mm
0.1 mm
Stem Cells in PCL Nanofiber Scaffolds
20 mm
20 mm
Red = Cells (Actin)
Green = Nanofibers
De-Cellularization (Lung)
Native rat
lung
De-cellularized
rat lung
Detergent
treatment to
extract cells &
antigens
Re-seeded with
cells
Seed w/neonatal rat lung
epithelium and rat lung
microvascular
endothelium; 1 wk culture
in bioreactor
The 3D structure of natural ECM
directs the cells, “they just know
where to go, and what to do”
Implanted in
syngeneic rat
Lasts several
hours in rat and
exchanges gas
Summary
• Stem cells and scaffolds are the 2 components for tissue
engineering
• Scaffolds can by synthetic polymers or natural
decellularized tissue
• Polymers can be processed into scaffolds with widely
varied structure
• Salt-leached scaffolds
• Freeform fabricated scaffolds
• Nanofiber scaffolds
• Many tissues are being engineered using many strategies
• Trachea (synthetic)
• Lung (natural)
• Bladder (natural + synthetic)
Salt-Leached Scaffold (24-Well Plate)
24-Well Plate with Scaffolds
3 mm
0.25 mm
50 mm
Tissue-Engineered Bladder (De-Cellularization)
Anthony Atala
(Wake Forest)
Tissue Engineered Bladder: 7 implants functioning up to 4 years later
• Scaffold made from decellularized tissue from human cadaver and
degradable polymer fibers to strengthen
• Take bladder biopsy from patient (1-2 cm2) and isolate urothelial cells and
bladder muscle cells
• Seed scaffolds with cells from patients own bladder from biopsy: muscle on
outside, urothelials on inside
What Does NIST Do?
• In the 1920s, purple, orange, green, blue, yellow, and red
traffic lights carried different meanings in different states.
In some states, green meant “go” and in others it meant
“stop.” In 1927, NIST worked with two other agencies to
establish a national code for the color of traffic lights that
we still use today.
• In 1904, a terrible fire raged in Baltimore. Firefighters
arrived on special trains from Washington, D.C., and other
places as far away as New York City. But most of the
crews were helpless to put out the fire since their hoses
would not fit on Baltimore hydrants. More than 1,500
buildings covering more than 70 city blocks burned to the
ground. NIST found there were more than 600 different fire
hose sizes and hydrant connectors in use in the U.S. In
1905, NIST helped pick a national fire hose standard that
was eventually adopted throughout the country.
Electrospinning
Nanofibers
Nanofiber Diameter = 900 nm
0.05 mm