The L1CAM gene encoding the neural cell adhesion molecule L1 is an adhesion molecule immunoglobulin G superfamily, is expressed in nerve cells, a neuron adhesion and some other important neurons interact with neurons. Jouet , found in the study of HSP-1 the L1CAM gene mutations associated with HSP-1 incidence, mutant forms can be expressed as missense mutations, nonsense mutations and deletion mutations.Addition, L1CAM gene mutations can also cause X-linked MASA syndrome (Mental Retardation, Aphasia Shuffling gait Adducted Thumb Syndrome), X-chain hydrocephalus and X-linked corpus callosum hypoplasia. Therefore, we call these four kinds of disease allele disease. Four kinds of disease the clinical characteristics show considerable overlap in the corpus callosum hypoplasia , mental retardation thumb closing, hereditary spastic paraplegia and hydrocephalus is characterized recently summarized together, these diseases named CRASH syndrome.
Expression of surface molecules in GSCs may be the ideal treatment of glioblastoma. The goal of these molecules are: CD133 (prominin-1), CD15, L1CAM, A2B5. Although CD133 has been widely used as a marker of GSCs but is normal neural stem cells also express CD133, limit its application. These molecules, in order to nerve cells best adhesion molecule L1CAM application prospects, it is expressed in the GSCs, play a key role on the the GSCs retention, survival and function. The L1CAM mediated extracellular and intracellular signal transduction, regulation of cell adhesion, migration, survival, growth, and tumor cells cellular invasion. Compared to glioblastoma tumor cells and normal neural progenitor cells the Cellular, L1CAM in GSCs high expression. Specific shRNA knockdown the L1CAM stem cells can interfere with in vitro form a ball of cells, and GSCs growth, for glioma stem cells L1CAM treatment can significantly inhibit intracranial Dutch GBM transplanted mice, tumor growth and prolong the life of tumor-bearing mice.
L1 cell adhesion molecule (L1 cell adhesion molecular, L1CAM) belong to the neural cell adhesion molecule, type I transmembrane glycoprotein belonging to the immunoglobulin superfamily. L1 is mainly expressed in the nervous system involved in nervous system development, learning and memory process role. L1 intracellular region may be involved in signal transduction, very important for the function of L1, L1 intracellular region as bait To investigate the mechanism of L1 intracellular the area signal transduction molecules in the human brain cDNA library screening using yeast two-hybrid technology its binding protein and the selection of positive clones, DNA sequence analysis and homology search, positive clones encoding several different proteins, one of the candidate protein PAX6 transcription factor.To further validate the interaction of L1 intracellular region and PAX6, cloning its gene into the expression plasmid of transfected COS-7 cells, co-immunoprecipitation confirmed the interaction of L1 intracellular region and PAX6, Step L1 intracellular region may be involved in transcriptionalregulation, provide important clues for an in-depth study of its function.
Each experimental group of early postoperative serum IL-2, IL-10, IL-2 increased gradually in the early A group, B group and C group increased significantly (P <0.05) postoperative 3d 1w already started to decline, at the same time point serum IL-2 levels between the two groups was no significant difference; each experimental group of early postoperative IL-10 levels were slightly elevated, but not significant, 2w gradually returned to normal after the group There was no significant difference; RT-PCR check of IL-2, IL-10mRNA expression in group A, group B and group C raised in the early postoperative period (1w), D group is not obvious. Group A and B in the same period of IL-2 and IL-10 mRNA expression differences; organization observed: A group, B group and C group early have a small amount of inflammatory cells and lymphocytes and mononuclear cell infiltration. Immunohistochemistry showed that in group A and group B, a small amount of CD4 <’+, CD8 <’ +> cells between the two groups was no significant difference. A group and B group is visible in the early postoperative weak IgG complex deposition, no C, <3> the deposition of the holder gap. Group C and Group D no IgG and C3 deposition; A postoperative 8w visible new bone cells was labeled in Brdu. Conclusion: The early mild inflammatory response after the transplantation of allogeneic tissue engineered bone failed to monitor rejection, the survival of transplanted allogeneic cells into bone. Display: low immunogenicity of MSCs as seed cells allogeneic tissue engineered bone.
Embryonic ossification process with the fracture callus formation and ectopic bone formation process is similar to, and are subject to the regulation of certain hormones and local growth factor body. Generally believed, parathyroid hormone (PTH), growth hormone, thyroxine, calcitonin, estrogen hormones affect bone tissue formation; mainly of BMPs local growth factors affect bone tissue formation, transfer factor (TGF) platelet-derived growth factor (PDGF), insulin-like growth factors (IGFs), interleukin (ILs). In the process of bone tissue formation, between hormones and growth factors regulating both relative independence, and mutual contact. Two regulatory nervous system together form a nerve – endocrine – immune – local growth factor regulatory networks involved in the formation of bone tissue throughout the adjustment process. Is generally believed that the local growth factor plays a dominant role in the regulation of bone formation process. Especially BMPs is the only one able to alone induced differentiation of mesenchymal cells to the direction of the bone tissue growth factor, is the most critical regulatory factor in the process of bone tissue formation. The experiments show that the low concentrations of BMPs able to induce mesenchymal cells into bone tissue formation region transitional; the medium concentration BMPs can promote mesenchymal cells to differentiate into chondrocytes and osteoblasts direction; while high concentrations of BMPs into mesenchymal cells can promote proliferation. The study, BMP-2, the main role of the recruitment and differentiation of undifferentiated mesenchymal cells and bone lineage cells play. In early bone formation, BMP-2 can undifferentiated mesenchymal cells to bone form the center raised and differentiate into bone lineage cells, but also enable the fibroblasts, myoblasts and bone marrow reversal of basal cell differentiation to bone lineage cells . The main process is to: increase or inhibit the secretion of certain specific proteins within these cells, fibroblasts differentiate into osteoblasts, myoblasts quick to differentiate into cartilage cells hypertrophy, and promote matrix calcification. For osteoblasts, BMP-2 can maintain their unique cell phenotype, and the induction increased markers of bone cells and promoting the calcification of the extracellular matrix. In the late stage of bone formation, BMP-2 as an osteoclast cell differentiation factor, and other support osteoclast differentiation factor, either directly or indirectly, to stimulate osteoclast differentiation involved in bone reconstruction. BMP-2 whether to promote cell mitosis and replication role, are still controversial. But to be sure, in promoting cell mitosis and replication process, BMP-2 and other local factors have a synergistic effect. Therefore, the formation of bone tissue is co-regulated by a variety of local factors.
Percoll and Ficoll two media and adherent separation and purification of small pig bone marrow MSCs results show that Percoll media combination of MSCs adherent method has good vigor, purity, and osteogenic activity. Identified MSCs attributes. Conclusion: Percoll medium and adherent is a suitable method for the separation and purification of small pig bone marrow MSCs.
Miniature pig MSCs can not stimulate allogeneic lymphocyte activation, proliferation; MSCs by osteogenic induction different times can not stimulate allogeneic lymphocyte proliferation; were lower immunogenicity prompted miniature pig MSCs by osteogenic differentiation. MSCs and porous β-TCP composite construct tissue engineering bone; high concentrations of MSCs by precipitation method to obtain high shelves rate; no significant effect on the cell viability and immunogenicity of β-TCP MSCs
This study was to carry out a large animal experiments, selection of experimental animals pig with human organs and immune system. Small pigs in Guizhou and Guangxi Bama pigs two inbred miniature pigs for experimental donor, acceptor, the establishment of small the porcine tibial shaft middle 2cm segmental bone defect model. Discussed separation and purification and identification of small pig bone marrow MSCs, allogeneic tissue engineered bone constructed in vitro. According to the characteristics of allogeneic tissue engineered bone graft, using the streaming technology, ELISA, RT-PCR, immunohistochemistry and other methods for monitoring after transplantation rejection, and X-ray examination, organization special staining, biomechanical testing and observation The osteoblasts effect.
Allogeneic bone tissue engineering reported fewer research involving immunogenicity. De Kok applications such as allogeneic MSCs construct tissue engineered bone repair dog alveolar bone defects by circulating antibody test confirmed no immune row reaction; Hiroyuki constructed allogeneic tissue engineered bone to repair bone defects in the rat experiment found that use of immunosuppressive agent in the experimental group bone defect can better be repaired without the use of the composition of bone is more difficult, not to repair bone defects; allogeneic tissue engineered bone osteogenic ability is closely related to its immunogenicity. Allogeneic tissue engineered bone study was limited to mice and other small animals, transplant rejection study only compared obtained the the peripheral humoral immune detection as well as application inhibitor conclusion is also uncertain.
Large bone defects caused by trauma, tumors,and other causes has been a problem that plagued orthopedic surgeons.Autogenous bone graft,allograft or xenograft bone transplantation, biological materials such as filling in treatment. White bone graft is the most effective methods and the gold standard for treatment of bone defects, autologous bone often can not meet the large bone defect grafting amount, at the same time cause for new bone area trauma; allogeneic or xenogeneic bone transplantation biological material, but are difficult to obtain satisfactory results.
In recent years the study of bone tissue engineering for bone defect repair has brought new hope. Bone tissue engineering principles to apply engineering and life science and technology to build artificial bone with a biological function, mainly including the construction of three aspects: seed cells, scaffolds, and tissue engineering bone. The mesenchymal stem cells (MSCs) are ideal seed cells for tissue engineering bone, according to the source of the gene can be classified as autologous tissue engineered bone and allogeneic tissue engineered bone. Main research from body tissue engineering bone, animal experiments show a better osteogenic potential and successful repair of bone defects; clinical trials be successful and achieved good results. But from the bone tissue engineering can not be pre-built, often 3 ~ 4w waiting period and lack limit its clinical application and industrialization. Allogeneic tissue engineered bone to overcome these deficiencies, and to meet with the check with « clinical application purpose.
Bone defects, nonunion is one of the intractable problems of orthopedics. The gold standard for bone morphogenetic protein bone graft is better than the treatment of bone graft – autogenous bone graft, or both, the difference was not significant. In recent years, some researchers at home and abroad has begun to bone morphogenetic protein in bone defects, nonunion patients on clinical research. Bone morphogenetic protein and autogenous bone, allograft bone, the treatment of intractable nonunion excellent healing. Also uses bone morphogenetic protein composite injection of autologous bone marrow promote fracture healing. As the principal investigator of the bone morphogenetic protein and bone xenograft series of studies topics has won the National Science and Technology Progress Award, the State Food and Drug Administration Batch, and put into the market for the clinical treatment of bone defects, nonunion patients. FDA has approved bone morphogenetic protein-7 in the United States multi-center, large-scale clinical trials for the treatment of tibial nonunion of bone morphogenetic protein listed as soon as possible to provide experimental basis.