Fullerol nanoparticles suppress inflammatory response and adipogenesis of vertebral bone marrow stromal cells--a potential novel treatment for intervertebral disc degeneration

Abstract

Background context: Intervertebral disc degeneration, leading to chronic back pain, is a major health problem in western societies. Vertebral bone marrow has been considered to play an important role in nutrition supply and metabolic exchange for discs. Vertebral bone marrow lesions, including fatty marrow replacement and inflammatory edema, noted on magnetic resonance imaging were first described in 1988.

Purpose: To investigate the potential of a free radical scavenger, fullerol nanoparticles, to prevent vertebral bone marrow lesion and prevent disc degeneration by inhibiting inflammation and adipogenic differentiation of vertebral bone marrow stromal cells (vBMSCs).

Study design/setting: Fullerol nanoparticle solutions were prepared to test their in vitro suppression effects on mouse vBMSC inflammation and adipogenic differentiation compared with non-fullerol-treated groups.

Methods: With or without fullerol treatment, vBMSCs from Swiss Webster mice were incubated with 10 ng/mL interleukin-1 β (IL-1 β). The intracellular reactive oxygen species (ROS) were measured with fluorescence staining and flow cytometry. In addition, vBMSCs were cultured with adipogenic medium (AM) with or without fullerol. Gene and protein expressions were evaluated by real-time polymerase chain reaction and histologic methods.

Results: Fluorescence staining and flow cytometry results showed that IL-1 β markedly increased intracellular ROS level, which could be prevented by fullerol administration. Fullerol also decreased the basal ROS level to 77%. Cellular production of matrix metalloproteinase (MMP)-1, 3, and 13 and tumor necrosis factor alpha (TNF-α) induced by IL-1 β was suppressed by fullerol treatment. Furthermore, adipogenic differentiation of the vBMSCs was retarded markedly by fullerol as revealed by less lipid droplets in the fullerol treatment group compared with the adipogenic group. The expression of adipogenic genes PPARγ and aP2 was highly elevated with AM but decreased on fullerol administration.

Conclusions: These results suggest that fullerol prevents the catabolic activity of vBMSCs under inflammatory stimulus by decreasing the level of ROS, MMPs, and TNF-α. Also, fat formation in vBMSCs is prevented by fullerol nanoparticles, and, therefore, fullerol may warrant further in vivo investigation as an effective biological therapy for disc degeneration.

Keywords: Adipogenesis; Fullerol; Inflammation; Reactive oxygen species; Vertebral bone marrow.