Porous shape memory scaffold of dextran and hydroxyapatite for minimum invasive implantation for bone tissue engineering applications.

Minimally invasive implantation of a porous scaffold of large volume into bone defect site remains a challenge. Scaffolds based on shape memory polymer (SMP) show potential to be delivered in the compact form via minimally invasive surgery. The present study chooses poly (ε-caprolactone)-diols (PCL-diols) as the SMP to cross-link carboxyl dextran via ester bonds together with particle leaching method to yield a porous SMP scaffold. The inner surfaces of porous SMP scaffold are then mineralized via in situ precipitation to yield mineralized porous SMP-hydroxyapatite (SMP-HA) scaffold. The porous SMP-HA scaffold possesses pore size of 400-500 µm, with HA particles uniformly distributed and orientationally aligned on the inner surfaces of scaffold. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) are carried out to identify the HA deposition. The phase transition temperature of the scaffold is adjusted to 38°C via changing the dosage of PCL (molecule weight: 2800) to endow the scaffold with shape deformation and fixed properties, as well as well-performed shape recovery property under body temperature. Bone marrow mesenchymal stem cells (BMSCs) adhere on the inner surfaces of SMP-HA scaffold, exhibiting larger spreading area when compared to cells adhered on SMP scaffold without HA, promoting its osteogenesis. In vivo degradation showed that the scaffold degrades completely after 6 months post-implantation. At the same time, significant tissue and capillary invasion indicated that the present porous SMP-HA scaffold hold great promise towards bone tissue engineering applications.

Inhibition of Src by microRNA-23b increases the cisplatin sensitivity of chondrosarcoma cells.

Chondrosarcomas are malignant cartilage-forming tumors from low-grade to high-grade aggressive tumors characterized by metastasis. Cisplatin is an effective DNA-damaging anti-tumor agent for the treatment against a wide variety of solid tumors. However, chondrosarcomas are notorious for their resistance to conventional chemo- and radio- therapies. In this study, we report miR-23b acts as a tumor suppressor in chondrosarcoma. The expressions of miR-23b are down-regulated in chondrosarcoma patient samples and cell lines compared with adjacent normal tissues and human primary chondrocytes. In addition, overexpression of miR-23b suppresses chondrosarcoma cell proliferation. By comparison of the cisplatin resistant chondrosarcoma cells and parental cells, we observed miR-23b was significantly down regulated in cisplatin resistant cells. Moreover, we demonstrate here Src kinase is a direct target of miR-23b in chondrosarcoma cells. Overexpression of miR-23b suppresses Src-Akt pathway, leading to the sensitization of cisplatin resistant chondrosarcoma cells to cisplatin. This chemo-sensitivity effect by the miR-23b-mediated inhibition of Src-Akt pathway is verified with the restoration of Src kinase in miR-23b-overespressing chondrosarcoma cells, resulting in the acquirement of resistance to cisplatin. In summary, our study reveals a novel role of miR-23b in cisplatin resistance in chondrosarcoma and will contribute to the development of the microRNA-targeted anti-cancer therapeutics.

[Surgical treatment and prognosis of aneurysmal bone cyst in mobile spine].

OBJECTIVE: To investigate the effects of surgical treatment and prognosis of aneurysmal bone cyst (ABC) in mobile spine. METHODS: A total of 12 patients with ABC were operated on from 1996 to 2006, and the clinical data were retrospectively reviewed. The patients included 7 male and 5 female, aged from 16 to 52 years (mean, 29 years). Surgical interventions were selected according to WBB criteria. Seven patients underwent total spondylectomy, four underwent resection of posterior arch, one patient received sagittal resection only. Anti-poster or post-lateral approach reconstruction with bone-graft or bone cement and transpedicular screws fixation were performed in the cases. Eight cases received radiotherapy after the operation. RESULTS: The mean operation blood lose was 3210 ml. The patients were followed-up for 10 to 116 months (mean, 41.8 months). Seven patients got complete recover of spinal cord function, 4 patients experienced local recurrence in 1-2 years post operation. One patient died of multiple metastasis of chondrosarcoma after radiotherapy. CONCLUSIONS: ABC in spine is an aggressive disease with high local recurrence rate. Enbloc if possible provides the best result, with excellent prognosis. Radiotherapy should be selected carefully.