Polymers Division • Biomaterials Group

National Institute of Standards and Technology

United States Department of Commerce

Carl G. Simon, Jr., Ph.D.

Measuring Cell Adhesion and Proliferation in Polymer 

Scaffolds by X-Ray Microcomputed Tomography
Need: Method to Quantify Cell Distribution Polymer Scaffolds in 3D

3D Scaffold

Cell

Scaffold use constitutes a central 

dogma in the field of tissue 

engineering 

Tissue engineering 

devices are commonly 

3D scaffolds: Medtronic’s 

Infuse bone graft, $2.6 

billion in 2006, half the 

orthobiologics market

Why is there a need?

• To evaluate scaffold 

performance

• To quantify cell & tissue 

formation in the scaffold in 3D

• To determine optimal scaffold 

composition/properties for 

tissue regeneration

Santos et al., Biomaterials 29 (2008) 4306 Shor et al., Biomaterials 28 (2007) 5291

Scanning Electron Microscopy Confocal Fluorescence Microscopy
Goal: Use X-ray microcomputed tomography (μCT) to 

measure cell distribution in 3D tissue scaffolds

1.0 mm

2 mm

X-ray Microcomputed Tomography

• Uses X-rays for 3D imaging of materials 

that scatter X-rays

• Cells are stained with osmium tetroxide

(OsO4) to make them radiopaque

Disadvantages: hard, lower resolution

Advantages: 3D imaging, quantitative, can 

X-ray Microcomputed Tomography see “thru” scaffolds
0.3 mm 0.3 mm

Fluorescence Microscopy X-ray Microcomputed Tomography

Comparison of Fluorescence Microscopy & μCT

Disadvantages

• μCT is lower resolution than fluorescence microscopy 

and less sensitive than biochemical assays (DNA)

Advantages

• μCT enables imaging through the opaque scaffold

• μCT portrays the 3D nature of cells on scaffolds 

• μCT is quantitative

Cellular Tissue Volume 

(%)

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

0K 5K 10K 25K 100K 400K

1 d

7 d

14 d

4.1 (0.5)

Cell Seeding Density (Cells/Scaffold)

Quantitative!
Collaborative Opportunities

• Please come visit me at my poster if you have interest in:

• Measuring effect of 3D tissue scaffold properties on cell response

• Stem cell fate in 3D scaffolds

• Bone tissue engineering 

• Combinatorial methods for screening scaffolds

• Post-Doctoral Research Opportunities

• NIST-NRC: $63K/yr., 2 yrs., benefits, Feb 1 & Aug 1, US citizens only

• NIST/NIH-NRC: $55K/yr., 2 yrs., benefits, Aug 1, open to foreign nationals

• Undergraduate (SURF): 11-weeks, $4K stipend, travel, housing, Feb 15
Contact Information

Carl G. Simon, Jr., Ph.D.

3D Tissue Scaffolds Project Leader

Polymers Division

National Institute of Standards and Technology

100 Bureau Drive

Gaithersburg, MD 20899-8543

carl.simon@nist.gov

Tel.: 301-975-8574

Fax: 301-975-4977

http://www.nist.gov/msel/polymers/biomaterials/3dtissuescaffolds.cfm

Acknowledgements Support

NIST

NIST/NSF Summer Undergraduate 

Research Fellowship

NIH/NIBIB R21 EB006497-01

Acknowledgements, Support, Reference, Contact Information

Reference

Dorsey SM, Lin-Gibson S, Simon Jr CG 

(2009) Biomaterials 30, 2967 (highlighted 

as a Leading Opinion article)

Shauna Dorsey (SURF)

Currently a UPenn Biomed. 

Eng. Ph.D. Student

Sheng Lin-Gibson

Jirun Sun

Diana Zeiger

Nancy Lin

Yanyin Yang

Matthew Becker

Morgan Alexander (Nottingham)

Terrell Vanderah

Bob Shull