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Materials Measurement Laboratory • Biosystems & Biomaterials Division • Biomaterials Group
National Institute of Standards and TechnologyUnited States Department of Commerce
Tissue Engineering Scaffolds
Dana Schneider, Sligo Middle School
Carl SimonStudents = 31, 28 and 23
10.07.12: 8:19-9:04, 9:57- 10:42,12:17-1:02
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
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
What Does NIST Do?
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
Isolated Cells
Donor Cellsfrom Injured
Knee
Scaffold Grow New Knee Tissue in the Lab
Repair Damaged Knee
Paolo Macchiarini Careggi, Italy
Nanofiber scaffold seeded stem cells
Nanofiber Scaffolds for Human Trachea
Nanofiber trachea
Trachea
0.05 mm
Polymers
A polymer is a chemical compound consisting of repeating structural units
Atomic force micrograph of single polymer chain
Dry polymer powder
Polystyrene Polyethylene
Polymers
Poly(e-Caprolactone) (PCL)
Salt-Leached Scaffold Fabrication
NaCl
Mold
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)
250 mm
25 mm100 mm
2 mm
10
00
0 c
ell
s7 d 14 d
25
00
0 c
ell
s5
00
0 c
ell
s1 d
Mouse Osteoblasts Cultured on PCL Salt-Leached Scaffolds
1 mm
Each green dot is a cell nuclei stained with a
fluorescent dye
Freeform Fabrication
Dana Schneider, Summer 2012Stem Cells Cultured on Freeform Fabricated PCL Scaffolds
5 mm
2 mm
0.2 mm 0.1 mm
Human Bone Marrow Stromal Cells (7d)
Cell nuclei are green
Cell bodies are red (actin)
20 mm 20 mm20 mm
Red = Cells (Actin)
Green = Nanofibers
Stem Cells in PCL Nanofiber Scaffolds
De-Cellularization (Lung)
Native rat lung
De-cellularized rat lung
Re-seeded with cells
Detergent treatment to
extract cells & antigens
Seed w/neonatal rat lung epithelium and rat lung
microvascular endothelium; 1 wk culture
in bioreactor
Implanted in syngeneic rat
Lasts several hours in rat and exchanges gas
The 3D structure of natural ECM directs the cells, “they just know
where to go, and what to do”
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)
50 mm0.25 mm
3 mm
24-Well Plate with Scaffolds
Tissue-Engineered Bladder (De-Cellularization)
Anthony Atala (Wake Forest)
• 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
Tissue Engineered Bladder: 7 implants functioning up to 4 years later
• 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.
What Does NIST Do?
ElectrospinningNanofibers
Nanofiber Diameter = 900 nm
0.05 mm
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