posters 5th Asia-Pacific NMR Symposium 2013

MRI T1 investigation of porous alginate gel scaffolds for soft tissue engineering (#212)

Monique Tourell , Konstantin Momot 1 , Florian Despang 2 , Michael Gelinsky 2
  1. Queensland Universtiy of Technology, Brisbane, QLD, Australia
  2. Dresden University of Technology, Dresden, Germany

Porous alginate hydrogels or scaffolds have applications in cartilage regeneration and the treatment of cartilage lesions or diseases, like osteoarthritis1,2. Cartilage producing cells, seeded in alginate scaffolds, have successfully shown cartilage extracellular matrix formation ex vivo and in vivo (in mice)2 . Magnetic Resonance Imaging (MRI) techniques provide a non-invasive method for monitoring this regenerated cartilage, both in vivo3  and ex vivo4 . Therefore, MR investigations of the hydrogels, prior to seeding, which relate quantitative MR characteristics of the gel (e.g. chemical shifts, relaxation rates) to the physical characteristics to be monitored (e.g. composition, structure, pore size) may be crucial for clinical evaluations4 and refined development of the scaffolds.

In this study, we use μ-MRI (with a 7 T static magnetic field) to investigate the longitudinal relaxation rates in alginate scaffolds with the potential for use in treating osteo-chondral defects. The cylindrical scaffolds (diameter ~ 8 mm, height ~ 4 mm) investigated were produced through ionotropic gelation with Ca2+ ions. Two types of scaffolds were investigated: the first is a homogenous alginate gel; the second contains channels, or pores (diameter ~ 150 μm), which run parallel to the cylindrical axis of the sample. Six scaffolds were imaged in total, three of each type. The samples were first imaged in an uncompressed state, in 3 mM CaCl2 solution, and then compressed by the application of Teflon plugs. We discuss the results in the context of water loss and gel deformation, with a focus on how the pores change during compression. Pore size is a crucial factor in the successful cultivation of cells in scaffolds5 and, given that any scaffold implanted in a joint would undergo compressive stresses, the extent to which pore sizes change may be the difference between an unsuccessful or successful scaffold. 

  1. Sun J and Tan H (2013) Alginate-Based Biomaterials for Regenerative Medicine Applications. Materials, 6 1285–309
  2. Wang C-C, Yang K-C, Lin K-H, Liu Y-L, Liu H-C and Lin F-H (2012) Cartilage regeneration in SCID mice using a highly organized three-dimensional alginate scaffold. Biomaterials, 33 120–7
  3. Joshi N, Reverte-Vinaixa M, Díaz-Ferreiro E W and Domínguez-Oronoz R (2012) Synthetic resorbable scaffolds for the treatment of isolated patellofemoral cartilage defects in young patients: magnetic resonance imaging and clinical evaluation. The American journal of sports medicine, 40 1289–95
  4. Kotecha M, Klatt D and Magin R L (2013) Monitoring Cartilage Tissue Engineering Using Magnetic Resonance Spectroscopy, Imaging, and Elastography. Tissue engineering Part B: Reviews, doi:10.1089/ten.teb.2012.0755
  5. Loh Q L and Choong C (2013) Three-dimensional Scaffolds for Tissue Engineering: Role of Porosity and Pore Size. Tissue engineering Part B: Reviews, doi:10.1089/ten.teb.2012.0437