Response of engineered cartilage tissue to biochemical agents as studied by proton magnetic resonance microscopy

Abstract

Objective. To test the hypothesis that magnetic resonance imaging (MRI) results correlate with the biochemical composition of cartilage matrix and can therefore be used to evaluate natural tissue development and the effects of biologic interventions. Methods. Chondrocytes harvested from day-16 chick embryo sterna were inoculated into an MRI-compatible hollow-fiber bioreactor. The tissue that formed over a period of 2-4 weeks was studied biochemically , histologically, and with MRI. Besides natural development, the response of the tissue to administration of retinoic acid, interleukin-1 (IL-1), and daily dosing with ascorbic acid was studied. Results. Tissue wet and dry weight, glycosamino-glycan (GAG) content, and collagen content all increased with development time, while tissue hydration decreased. The administration of retinoic acid resulted in a significant reduction in tissue wet weight, proteo-glycan content, and cell number and an increase in hydration as compared with controls. Daily dosing with ascorbic acid increased tissue collagen content significantly compared with controls, while the administration of IL-1 resulted in increased proteoglycan content. The water proton longitudinal and transverse relaxation rates correlated well with GAG and collagen concentrations of the matrix as well as with tissue hydration. In contrast, the magnetization transfer value for the tissue correlated only with total collagen. Finally, the self-diffusion coefficient of water correlated with tissue hydration. Conclusion. Parameters derived from MR images obtained noninvasively can be used to quantitatively assess the composition of cartilage tissue generated in a bioreactor. We conclude that MRI is a promising modality for the assessment of certain biochemical properties of cartilage in a wide variety of settings.

Characterization of skin abnormalities in a mouse model of osteogenesis imperfecta using high resolution magnetic resonance imaging and Fourier transform infrared imaging spectroscopy

“…In a study of k m as a function of collagen concentration in gels, values in the range of 1 to 2 s -1 were obtained for collagen concentrations above 5% w/v (38). Similar results were obtained in engineered cartilage (48). These values are similar to those obtained in our study, consistent with the interpretation that collagen and/or elastin concentration is the dominant determinant of the MT phenomenon.…”

“…Relationships between tissue hydration and T2 relaxation rates have been well established in cartilage and isolated collagen fibrils (48,54,55), with the greater water mobility associated with increased hydration being reflected in longer T2 values. T2 is also sensitive to collagen content (48,56) and is therefore often used to evaluate cartilage degeneration. Similarly, T2 measurements have been interpreted as reflecting bound and free water content in skin layers (31).…”

Hyaline cartilage engineered by chondrocytes in pellet culture: histological, immunohistochemical and ultrastructural analysis in comparison with cartilage explants

“…The lack of self-healing capacity in cartilage and the considerable morbidity caused by cartilage injuries and diseases have encouraged the search for a biomedical solution for repairing or restoration of damaged articular cartilage. The recent progress in tissue engineering of cartilage includes the introduction of new biomaterials for the scaffold, development of a bioreactor culture system, and the investigation of various cell resources and use of growth factors (Cao et al 1998;Vunjak-Novakovic et al 1999;Potter et al 2000;Temenoff & Mikos, 2000;Solchaga et al 2001;Cancedda et al 2003). However, at the present time engineered cartilage still does not satisfy the need for functional cartilage repair ( Anderer & Libera, 2002).…”

Cartilage Calcification Studied by Proton Nuclear Magnetic Resonance Microscopy

“…For this study a three-dimensional (3D) mineralizing cell culture system based on an NMR-compatible hollow fiber bioreactor (HFBR) has been developed. (12)(13)(14) The system models the process of endochondral ossification of a long bone in which cartilage matrix, elaborated around the hollow fibers, mineralizes. Over a 6-week period, the growth and eventual mineralization of the cartilage in this system have been studied spatially and temporally with proton NMR microscopy, and various NMR parameters have been measured and correlated with the regions of mineral formation imaged by this technique.…”