Effects of Low-Intensity Pulsed Ultrasound and Functional Electrical Stimulation on Skeletal System

• Main Authors: Chien-Hung Lai, 賴建宏
• Other Authors: Walter Hong-Shong Chang
• Format: Others
• Language: en_US
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/56660205290143164016

博士 === 中原大學 === 生物醫學工程研究所 === 98 === Abstract Osteoporosis is a well-recognized complication among disabled individuals. Secondary to the characteristic bone loss of osteoporosis, fractures caused by minimal trauma often occur among these individuals. Therefore, prevention of osteoporosis and subsequent reduction in fractures due to bone loss in disabled subjects is an important issue. Additionally, healing of fractures is an extremely complex process; delayed union or non-union are frequently observed in clinical practice and present potential morbidities. The mechanical strain received by cells may result in biochemical events that, in the skeleton, have been shown to promote bone formation. Non-invasive low intensity pulsed ultrasound (LIPUS) and functional electrical stimulation cycling exercises (FESCE) can mimic the effects of mechanical loading on bone. This dissertation addresses these treatment modalities and consists of two parts: the investigation of LIPUS in in vitro models and the investigation of FESCE in clinical circumstances involving bone regeneration. In the first part of this study, the effects of LIPUS on the differentiation of human mesenchymal stem cells (hMSCs) were investigated. The hMSCs were subjected to LIPUS either with or without dexamethasone/transforming growth factor-β1 (TD) or bone morphogenetic protein-2 (BMP-2), and the effects of these treatments were assessed in two groups, a LIPUS-only group and a LIPUS-with-TD treatment group. The TD-treated hMSCs exhibited characteristic chondrogenic morphology and increased mRNA expression of chondrogenic markers, and LIPUS enhanced the chondrogenic differentiation of hMSCs treated with TD. No alterations were seen in the expression of Runx2, an osteogenic transcription factor, in either the LIPUS-only group or the LIPUS-with-TD treatment group; however, a significant increase was detected in the LIPUS-only group. The osteogenic appearance was seen three days after LIPUS and/or BMP-2 treatment. Increases in the mRNA expression levels of osteogenic markers, Runx2 and ALP were also detected. No additive or altered effects were noted with combined LIPUS and BMP-2 treatment. LIPUS alone can increase osteogenic differentiation of hMSCs and LIPUS enhances TD-mediated chondrogenic differentiation of hMSCs. Clinically, LIPUS may differentially influence bone versus cartilage repair. The second part of this study was designed to determine whether loss of bone mineral density (BMD) after spinal cord injury (SCI) can be attenuated by early intervention with FESCE and to ascertain whether the effect persists after FESCE is discontinued. Twenty-four patients with SCI, 26-52 days after injury, were divided into a FESCE group and a control group. In the treatment group, FESCE was applied in the initial three months and then suspended in the subsequent three months. BMDs of the femoral neck and distal femur (DF) were obtained by dual energy X-ray absorptiometry (DXA) before training, immediately after the initial three months of training, and at the end of the subsequent three months. During the initial three months, the reduction rate for BMD in the DF of the FESCE group was significantly less than that of the control group. However, no significant differences were noted in the subsequent three months when treatment was suspended. In summary, FESCE in the early stages of SCI can partly attenuate BMD loss in the DF. However, BMD loss in the DF cannot be ameliorated completely by FESCE. In addition, the effect on the attenuation of bone loss in the DF faded once FESCE was discontinued. These findings suggest that LIPUS and FESCE mimicking mechanical strain may have a positive skeletal impact. LIPUS enhances chondrogenic differentiation of hMSCs that have received TD induction and promotes osteogenic differentiation of hMSC. FESCE applied in the early stages of SCI can partly attenuate BMD loss in the DF.