HER2 and P-gp are expressed in most of the human osteosarcoma tissue. The multidrug resistance of osteosarcoma is mediated by P-gp. The insusceptibility of human osteosarcoma to chemotherapy and the poor prognosis is correlated with the expression of P-gp. The expression of the carcinogene HER2 is a prognostic risk factor of the malignancy and metastasis of osteosarcoma. The review will narrate the expression of the HER2 and P-gp in osteosarcoma and its prognostic significance.

OBJECTIVE: To expound the research status of the seed cells in tissue-engineered articular cartilage, and explore the resource, in vitro amplification and gene modification, so as to propose the application prospect in future.DATA SOURCES: A computer-based online search of PubMed was undertaken to identify the articles about the seed cells in tissue-engineered articular cartilage published in English between January 1994 and April 2006 with the key words of "cartilage, joint, tissue engineering, stem cell, cell culture, gene modification". Other articles were searched from Tsinghua Tongfang and Vip database according to the journal and article titles.STUDY SELECTION: The data were selected firstly to choose those about the seed cells in tissue-engineered articular cartilage and eliminate those not accorded with the requirements. The full-texts of left articles were searched manually.DATA EXTRACTION: Totally 89 articles were collected, of which 34 were included and 55 were excluded.DATA SYNTHESIS: Cells for the construction of artificial cartilage tissues include autologous or homologous chondrocytes, periost and perichondrium cells, mesenchymal stem cells and embryonic stem cells, all of which could be cultured and amplified by specific culturing system in vitro, they also could be genic modified under certain condition with different strategies and methods to repair articular cartilage defects.CONCLUSION: Seed cells with their particular characteristics play an important role in the repair of articular cartilage defects with tissue engineering technique.

Neoadjuvant chemotherapy evaluation methods are becoming the focus of osteosarcoma chemotherapy research in recent years.This paper updates the evaluation methods of osteosarcoma neoadjuvant chemotherapy in such aspects as pathological histology,imaging studies,and the examination of molecular levels.

Tissue engineering technology is a new method to repair articular cartilage defects,and received extensive attention.One of its characters which makes this technology different from a single cell transplantation is the application of scalfold materials.The materials used for scalfold must accord with certain requirements.The previous researches have achieved some break through,but constant improvements still are needed for the alteration from laboratory to clinics.

The occurrence and development of solid tumor is a multi-factor,multi-step and multi-gene interactive process.The generation of micro vasculature of solid tumor,as well as the interaction between tumor and micro-environment,decides the tumor's biological characteristics of growth,recurrence,invasion and metastasis.Reasonable application of anti-angiogenesis therapy enables the normalization of tumor vascular system to enhance the efficiency of chemotherapy and radiation treatment and prolong survival time in patients.

Objective To evaluate the expression of Integrin α2β1 in serum of osteosarcoma patients and to investigate the effect of Integrin α2β1 on metastasis of osteosarcoma. Methods Sandwich enzymelinked immunosorbent assay was applied to test Integrin α2β1 in serum of 26 healthy controls (male 16, female 10; age 18-32, average age 23.54±3.82) and 43 osteosarcoma patients (male 28, female 15;age 8-47,average age 18.42±9.10)before and after the surgery and the chemotherapy. The patients included osteoprogenitor cells type in 24 cases, fibroblast type in 9 cases, chondroblast type in 7 cases, and other types in 3cases; with Enneking stage ⅡA in 13 cases, stage ⅡB in 26 cases, stage Ⅲ in 4 cases. Among them, 22 patients receive the neo-adjuvant chemotherapy. After that, we compared the data of different groups. At the same time, in accordance with tumor size, position, clinical stage, histology grade and metastasis situation to categorize groups compared among the groups of serum Integrin α2β1 differences in order to explore its relationship with patients' prognosis and metastasis. Results The Integrin α2β1 of osteosarcoma patients in blood before the surgery was expressed highly. It was significantly higher than the control group. The expression before surgery had significant correlation with osteosarcoma Enneking clinical stages, tumor size and metastasis. And it was independent of tumor position and Dahlin histology grade. The expression of Integrin α2β1 in blood of the osteosarcoma patients after limb salvage surgery decreased significantly. And the expression of Integrin α2β1 in blood of patients receiving new adjuvant chemotherapy was significant differences before and after the chemotherapy. Conclusion The expression of Integrin α2β1 has positive correlation with the occurrence, development and metastasis of the osteosarcoma. It is probably a new biological indicator for diagnosis and estimating prognosis of osteosarcoma. Simultaneously surgery and new adjuvant chemotherapy are still effective methods to treat osteosarcoma.

The early diagnosis , the prediction of recurrence and metastasis of osteosarcoma and avoiding chemotherapy resist -ance play a key role in the therapeutic areas of osteosarcoma .DNA methylation is the main reason of activation of oncogene and inacti-vation of tumor suppressor gene .It has been proven that the methylation of multiple genes is closely related to clinical indicators and targeted therapy of osteosarcoma .It is expected that DNA methylation can be used for the clinical diagnosis and treatment of osteosarco -ma.In this paper, the relationship between DNA methylation and osteosarcoma is reviewed .

Osteosarcoma is the most common aggressive malignancy of bone.Recent studies have discovered that exosomes can mediate intercellular transfer of biologically active molecules such as RNAs, dsDNA, and miRNAs.The specific membrane struc-ture and contents of exosomes are widely engaged into the exchange of material and information among tumor cells, which play an im-portant role in regulating the tumor microenvironment of osteosarcoma, mediating the expression of Wnt/β-catenin, TGF-βsignaling and inducing tumor cell immune escape.Exosomes derived from osteosarcoma cells with antigen-presenting cells cause significant anti-tumor effect by activating the immune response.Research on exosomes has therefore opened up a new avenue for treatment of osteosar-coma.In this article we review the role of exosomes in pathogenesis of osteosarcoma and its potential application on diagnosis and treat-ment of osteosarcoma.

s:Bone allografts have been successfully used in repairing bone defect caused by tumor, infection or trauma. The mechanism of bone-healing of allografts has been widely studied. The article reviews the factors affecting the bone-healing of allografts.

Objective: Changes in the ?2 integrin of adhesion molecules between cells are closely associated with the invasion and migration of tumor cells.This study aimed at the effect of anti-?2 integrin on the invasion and migration of osteosarcoma MG63 cells. Methods: The osteosarcoma MG63 cell line was cultured in the DMEM medium.The effect of the anti-?2 integrin monoclonal antibody on the migration and invasion of tumor cells were measured by scratch assay and Transwell assay.The migration and invasion cells were stained by Crystal violet staining and counted under the hundredfold microscope.Results: Compared with the control group,the migration and invasion abilities of the MG63 cells were significantly decreased in the anti-?2 treatment groups.Conclusion: Anti-?2 integrin may inhibit the migration and invasion of osteosarcoma cells.