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Articles by Samantha C.W. Chan in JoVE

Other articles by Samantha C.W. Chan on PubMed

Outcome Assessment of Bracing in Adolescent Idiopathic Scoliosis by the Use of the SRS-22 Questionnaire

The SRS-22 questionnaire is specifically designed for the assessment of quality of life in spinal deformity patients. This study is the first to use it to assess the quality of life of adolescent idiopathic scoliosis patients under brace treatment and compares the results with an observational group matched by age and curve magnitude. Forty-six patients were enrolled into each group. Overall, it was found that patients under observation had a significantly better quality of life than braced patients. Specifically, the domains for function/activity and self-image were most affected. This effect was most apparent in those with a curve magnitude of under 20 degrees . The scores did not improve significantly with the duration of brace wear, suggesting little adaptation. This study has implications for treatment, and more attention will need to be given to those with mild but progressive curves to help improve patients' understanding of their treatment and hence their compliance and satisfaction.

Cryopreserved Intervertebral Disc with Injected Bone Marrow-derived Stromal Cells: a Feasibility Study Using Organ Culture

A recent clinical study demonstrated that cryopreserved allogeneic intervertebral disc transplantation relieved pain and preserved motion, thus opening up a new treatment option for degenerative disc disease. However, these transplanted discs continued to degenerate, possibly due to a lack of viable cells. Bone marrow-derived stromal cell (BMSC) implantation has been shown to delay disc degeneration.

Minimizing Cryopreservation-induced Loss of Disc Cell Activity for Storage of Whole Intervertebral Discs

Severe intervertebral disc (IVD) degeneration often requires disc excision and spinal fusion, which leads to loss of spinal segment mobility. Implantation of an allograft disc or tissue engineered disc construct emerges as an alternative to artificial disc replacement for preserving the motion of the degenerated level. Establishment of a bank of cadaveric or engineered cryopreserved discs enables size matching, and facilitates clinical management. However, there is a lack of understanding of the behaviour of disc cells during cryopreservation, as well as how to maximize their survival, such that disc graft properties can be preserved. Here, we report on the effect of alterations in cooling rates, cryoprotective agents (CPAs), and duration of pre-cryopreservation incubation in CPA on cellular activity in whole porcine lumbar discs. Our results indicated that cooling rates of -0.3 degrees C/min and -0.5 degrees C/min resulted in the least loss of metabolic activity in nucleus pulposus (NP) and annulus fibrosus (AF) respectively, while metabolic activity is best maintained by using a combination of 10% dimethylsulphoxide (DMSO) and 10% propylene-glycol (PG) as CPA. By the use of such parameters, metabolic activity of the NP and the AF cells could be maintained at 70% and 45%, respectively, of that of the fresh tissue. Mechanical testing and histological evaluation showed no significant differences in mechanical properties or alterations in disc structure compared to fresh discs. Despite the limitations of the animal model, our findings provide a framework for establishing an applicable cryopreservation protocol for human disc allografts or tissue-engineered disc constructs.

Biological Response of the Intervertebral Disc to Repetitive Short-term Cyclic Torsion

In vitro study of the biological response of the intervertebral disc (IVD) to cyclic torsion by using bovine caudal IVDs.

The Effects of Dynamic Loading on the Intervertebral Disc

Loading is important to maintain the balance of matrix turnover in the intervertebral disc (IVD). Daily cyclic diurnal assists in the transport of large soluble factors across the IVD and its surrounding circulation and applies direct and indirect stimulus to disc cells. Acute mechanical injury and accumulated overloading, however, could induce disc degeneration. Recently, there is more information available on how cyclic loading, especially axial compression and hydrostatic pressure, affects IVD cell biology. This review summarises recent studies on the response of the IVD and stem cells to applied cyclic compression and hydrostatic pressure. These studies investigate the possible role of loading in the initiation and progression of disc degeneration as well as quantifying a physiological loading condition for the study of disc degeneration biological therapy. Subsequently, a possible physiological/beneficial loading range is proposed. This physiological/beneficial loading could provide insight into how to design loading regimes in specific system for the testing of various biological therapies such as cell therapy, chemical therapy or tissue engineering constructs to achieve a better final outcome. In addition, the parameter space of 'physiological' loading may also be an important factor for the differentiation of stem cells towards most ideally 'discogenic' cells for tissue engineering purpose.

The Evolutionary Importance of Cell Ratio Between Notochordal and Nucleus Pulposus Cells: an Experimental 3-D Co-culture Study

INTRODUCTION: Notochordal cells and nucleus pulposus cells are co-existing in the intervertebral disc at various ratios among different mammalians. This fact rises the question about the interactions and the evolutionary relevance of this phenomenon. It has been described that these relatively large notochordal cells are mainly dominant in early lifetime of all vertebrates and then differences occur with ageing. Human, cattle, sheep, and goat lose the cells with age, whereas rodents and lagomorphs maintain these throughout their lifetime. MATERIALS AND METHODS: Here, we addressed the importance of cell ratio using alginate bead 3-D co-culture of bovine nucleus pulposus cells (bNPC) and porcine notochordal cells (pNCs) for 14 days using culture inserts. RESULT: We found a significant stimulation of bNPC in the presence of pNC in terms of cell activity and glycosaminoglycan production, but not for proliferation (DNA content). Relative gene expression was significantly stimulated for collagen type 2 and aggrecan. CONCLUSION: The stimulating effect of NC was confirmed and the ideal ratio of NPC: NC was found to be ~50:50. This has direct implications for tissue-engineering approaches, which aim to repopulate discs with NP-like precursor cells.

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