Frequency of lumbar intervertebral disc calcification and angiogenesis, and their correlation with clinical, surgical, and magnetic resonance imaging findings

[Spontaneous resorption of thoracic calcified disc herniation: Report of two cases and review of the literature]

We report on two cases of spontaneous resorption of a calcified thoracic hernia. This phenomenom is widely recognised in lumbar and cervical hernia, but is exceptional at the thoracic level. The potential mechanisms underlying this resorption are discussed trough a review of the literature. We think this could be another argument for a "wait and watch" period before a surgical decision in the patients who have few symptoms.

Effects of hypoxias and scaffold architecture on rabbit mesenchymal stem cell differentiation towards a nucleus pulposus-like phenotype

Nucleus pulposus grafts are needed for patients requiring replacement of their degenerated intervertebral discs. Bone marrow-derived mesenchymal stem cells (MSCs) are a potential autologous stem cell source for the nucleus pulposus regeneration. One of the key issues of constructing functional nucleus pulposus using MSCs, however, is to differentiate MSCs into nucleus pulposus phenotype in vitro and to maintain their phenotypic stability in vivo. In this study, three-dimensional (3D) nanofibrous poly(l-lactide) (PLLA) scaffolds were seeded with multi-potent rabbit MSCs and the constructs were induced along nucleus pulposus development routes in a hypoxia chamber (2% O(2)) in the presence of TGF-β1. It was found that nanofibrous scaffold could support the differentiation of rabbit MSCs towards a nucleus pulposus-like phenotype in vitro, as evidenced by upregulated expression of a few important nucleus pulposus-associated genes (aggrecan, type II collagen and Sox-9), abundant deposition of extracellular matrix (glycosaminoglycan (GAG) and type II collagen), and the continuous expression of the nucleus pulposus-specific marker, hypoxia-inducible factor (HIF)-1α. The subcutaneous implantation results confirmed that hypoxic induction before implantation could help the constructs to retain their phenotype and resist calcification in vivo. Therefore, the above data showed the promise of using 3D nanofibrous scaffolds in combination with TGF-β1 and hypoxic induction to regenerate functional nucleus pulposus grafts for intervertebral disc replacement.