Protein polymer MRI contrast agents: Longitudinal analysis of biomaterials in vivo

Abstract

Despite recent advances in tissue engineering to regenerate biological function by combining cells with material supports, development is hindered by inadequate techniques for characterizing biomaterials in vivo. Magnetic resonance imaging is a tomographic technique with high temporal and spatial resolution and represents an excellent imaging modality for longitudinal noninvasive assessment of biomaterials in vivo. To distinguish biomaterials from surrounding tissues for magnetic resonance imaging, protein polymer contrast agents were developed and incorporated into hydrogels. In vitro and in vivo images of protein polymer hydrogels, with and without covalently incorporated protein polymer contrast agents, were acquired by magnetic resonance imaging. T 1 values of the labeled gels were consistently lower when protein polymer contrast agents were included. As a result, the protein polymer contrast agent hydrogels facilitated fate tracking, quantification of degradation, and detection of immune response in vivo. For the duration of the in vivo study, the protein polymer contrast agent-containing hydrogels could be distinguished from adjacent tissues and from the foreign body response surrounding the gels. The hydrogels containing protein polymer contrast agent have a contrast-to-noise ratio 2-fold greater than hydrogels without protein polymer contrast agent. In the absence of the protein polymer contrast agent, hydrogels cannot be distinguished by the end of the gel lifetime. Magn Reson Med 65:220-228, 2011. V C 2010 Wiley-Liss, Inc.

Controlled intracellular self-assembly of gadolinium nanoparticles as smart molecular MR contrast agents

“…Common strategy for increasing the longitudinal molar relaxivity ( r 1 ) of T 1 CA is to prolong its rotational correlation time ( τ r i.e., the tumbling time of the CA in the water bulk). To achieve this goal, Gd-based agents with higher molecular weights such as Gd functionalized polymer, peptide amphiphiles or viral caspid, dendrimer, liposomes, nanoparticles, micelles, zeolites, fullerenes, carbon nanotubes, clays, and quantum dots were prepared and explored89101112. Nevertheless, these pre-made gadolinium complexes are facing the problem of cell membrane translocation and targeting, besides the difficulty and reproducibility of their fabrications13.…”

Characterization of a novel MR‐detectable nanoantioxidant that mitigates the recall immune response

“…Mice were imaged using a Rapid Acquisition with Refocused Echoes (RARE) protocol to obtain T 1 ‐weighted images with the following parameters: TE = 11.72 ms, TR = 590.94 ms, FOV = 25 mm, matrix size =256 x 256, taking 2 min, 31 s and 280 ms. T 1 ‐measurements were done using a RARE protocol with a Variable Acquisition Time (RAREVTR) as described by with the following parameters: TE = 10 ms, TR = 200–6000 ms, FOV = 20 mm, matrix size =128 x 128, taking 4 min, 3 s and 200 ms. Ex vivo and in vivo scans were carried out using a RARE protocol with the following parameters: TE = 7.51 ms, TR = 1500 ms, average = 4, rare factor = 4, FOV = 36 x 30 mm, matrix size =256 x 256, each taking 4 min and 48 s. All scans were carried out using Paravision 4.0 software (Bruker BioSpin Billerica, MA, USA).…”

Molecular imaging of EGFR/HER2 cancer biomarkers by protein MRI contrast agents

“…Radically different from all other reported methods [46, 50, 56, 117, 118, 121, 122], the design of protein-based MRI contrast agents is based on our careful analysis of more than 500 structures of molecules which bind to Gd 3+ and other lanthanide ions [123]. In solution, Gd 3+ is usually associated with eight or nine oxygen atoms from water molecules [124].…”