In Vivo Characterization of 3D Bone Repair Scaffolds with Controlled Architectures Fabricated Via Rapid Prototyping Techniques

T. Dutta Roy¹, J.L. Simon^2,3, H.A. Beam⁴, E.D. Rekow⁵, J.L. Ricci⁵, V.P. Thompson⁵, J.R. Parsons^2,3

¹Biomaterials Group, Polymers Division, MSEL, NIST

²Dept. of Orthopaedics, UMDNJ-New Jersey Medical School, Newark, NJ

³Dept. of Biomedical Engineering, Rutgers University, Piscataway, NJ

⁴Xylos Corporation, Langhorne, PA

⁵New York University College of Dentistry, New York, NY

            This proof-of-concept study analyzed the in vivo performance of 3D bone repair scaffolds fabricated using the TheriForm^TM (Therics, Inc., Princeton, NJ) rapid prototyping process.  These scaffolds were implanted bilaterally into rabbit calvarial defects and analyzed at 4, 8, and 16-week timepoints.  The bone repair scaffolds contained architectures with engineered macroscopic channels and a controlled range of pore sizes for promotion of new bone ingrowth.  Scaffolds were fabricated from different biocompatible materials: a composite of 80 % mass fraction of poly(lactide-co-glycolide) [PLG] polymer and 20% mass fraction of b-tricalcium phosphate (b-TCP) ceramic, and sintered hydroxyapatite (HA) ceramic. 

            Bone repair scaffolds with engineered macroscopic channels had a higher percentage of new bone area compared to scaffolds without channels and to unfilled controls.  An interesting finding was that the scaffolds with engineered macroscopic channels had similar percentages of new bone area compared to autograft-filled control defects, suggesting that their performance was comparable to the “gold standard” material for bone grafting.  An unexpected finding was the consistently unusually large amounts of new bone within the small pores of the HA scaffolds.  It is generally accepted that the minimum scaffold pore size for new bone ingrowth is 100 μm, while the HA scaffolds contained pores less than 20 μm in size.  This demonstrated that the TheriForm^TM scaffold fabrication process, along with the right choice of biocompatible material, can create a favorable scaffold environment, both physically and biologically, for osteoblasts to proliferate and differentiate into mature bone. 

            Work here at NIST in the Biomaterials Group involves the in vitro analysis of various polymer scaffolds made by rapid prototyping, which are being considered as reference scaffolds for tissue engineering.  Specifically, the differences in the mechanisms of osteoblast adhesion on these scaffolds compared to 2D polymeric surfaces are currently being studied.  Differences in migration, proliferation, and differentiation on these scaffolds compared to 2D surfaces will also be studied. 

Post-Doc: Tithi Dutta Roy

Mentor: Francis Wang

Division: Polymers

Laboratory: Materials Science and Engineering Laboratory (MSEL)

Address: Room A107, Building 224

Mail Stop: 8543

Telephone: 6747

Fax: 4977

Email: tithi.duttaroy@nist.gov

Sigma Xi member: No

Category: Biotechnology and Biology, Materials