Our goal is to develop advanced measurement tools and standards for measuring polymer scaffold properties and their impact on biological response.
Use of 3D tissue scaffolds as a template for regeneration is the basis of tissue engineering. These tools will enable a better understanding cell-scaffold interactions, including identification of the relationships of cell response on 2D surfaces to that in 3D scaffolds, and will facilitate improved design of future scaffold-based medical products. These measurement tools and standards advance the ability of researchers to develop scaffolds that direct stem cell differentiation.
Additional Technical Details:
Reference Material Scaffolds: Reference material scaffolds are being developed that can serve as a calibration point for comparing scaffold measurements between different labs. The first generation reference scaffolds have been deployed and focus on scaffold structure and porosity. A second generation reference scaffold is under development that will focus on measuring cell response (adhesion and proliferation) to 3D scaffolds.
First Generation - Scaffold Structure: A reference scaffold has been developed with input from ASTM (F04.42.WK6507). The scaffolds were made by freeform fabrication since this approach offers the tightest control over scaffold structural morphology. Scaffold structure and porosity have been characterized using microscopy, gravimetrics and μCT imaging. These well-characterized reference scaffolds can serve as standards during development of scaffolds-based products where structure and scaffold porosity are measured.
Left: Three different reference material scaffolds in their packaging: RM8395, RM8396 and RM8397. Middle: Table of RM scaffold properties. Right: 3D X-ray tomograph of RM8397.
Links to Reference Scaffolds:
Second Generation - Cell Response: Second generation reference material scaffolds are being developed that are characterized for cell response. These are freeform fabricated scaffolds that fit into a 96-well plate for cell culture experiments. One unit will proved 24 scaffolds that have been structurally characterized and for which the cell responses of cell adhesion and proliferation have been measured. The reference scaffold plate can be run as a control in cell culture experiments to serve as a calibration point between different labs.
Left: Reference material scaffolds RM8394 are under development. One unit is a 96-well plate with 24 scaffolds. RM8394 will have strut diameter 300 mm, strut spacing 500 mm and porosity 50%. Middle: 3D X-ray tomograph of RM8394. Right: Fluorescence micrograph of MC3T3-E1 osteoblasts culture 1 d on RM8394. Red staining is actin and green staining is the nucleus.
3D Scaffold Libraries: Cells respond differently to different materials. Chemistry, mechanics and structure of the materials have strong impact on whether cells adhere, proliferate, migrate or differentiate. We have pioneered the development of a suite of combinatorial screening methods for 3D scaffolds. Previous combinatorial approaches for screening cell-material interactions have focused on planar (2D) surfaces or films. However, biomaterials are commonly used in 3D scaffolds and cells behave differently when cultured in a 3D environment. Thus, "combi" tests for many types of scaffolds and properties have been developed for a "scaffoldomics" approach.
"Combi" approaches for screening a wide range of 3D scaffolds have been developed to comprise a "scaffoldomics" approach.
Links to Scaffold Library Fabrication YouTube Videos:
Cell-Material Interactions: Combi screens provide exciting "hits" that we can explore with more rigorously. Our goal is to enable design of improved scaffolding materials by determining how 3D scaffold properties influence stem cell differentiation. Much of our current knowledge of biomaterials is phenomenological. In order for tissue engineering to advance, a mechanistic understanding of how material properties direct stem cell function must be developed.
Left: Primary human bone marrow stromal cells (hBMSCs) deposit mineralized matrix when encapsulated in stiff poly(ethylene glycol) tetramethacrylate (PEGTM) hydrogels (21 d). Middle: During culture in PEGTM gels, hBMSCs deposit a matrix containing fibronectin (7 d). Right: RGDS peptides, antibodies that block integrin av , and antibodies that block integrin b3 , inhibit PEGTM-modulus-induced hBMSC mineralization (14 d, 5% PEGTM gels, 11 kPa compressive modulus). These results suggest that interactions between RGD peptides and avb3 integrins (not b1 integrins) are required for osteogenic differentiation of hBMSCs in stiff PEGTM gels.
Start Date:October 1, 2007
Lead Organizational Unit:mml
Joachim Kohn, New Jersey Center for Biomaterials, Rutgers University
Wolgang Losert, Department of Physics, University of Maryland
Antonio Possolo, Statistical Engineering Division, NIST
Pam G. Robey, National Institute of Dental and Craniofacial Research, NIH
Amitabh Varshney, University of Maryland Institute for Advanced Computer Studies (UMIACS), University of Maryland
Hockin Xu, School of Dentistry, University of Maryland - Baltimore
Marian F. Young, National Institute of Dental and Craniofacial Research, NIH
Carl Simon, Jr. - Project Leader
Project Summary (PDF)
Carl Simon, Jr.