组织工程技术仿生构建颅颌骨组织的研究

目的:探索构建组织工程化仿生骨种植体的方法流程,并制备成骨细胞-可吸收载体种植体样品,同时尝试建立组织工程化非承载骨种植体的评价方法。方法:实验于2001-05/2005-12分别在天津市口腔医院组织工程实验室和天津大学材料学院高分子材料研究所完成。①通过相分离技术制备壳聚糖/明胶三维网络多孔支架,在支架材料表面原位沉积纳米级的羟基磷灰石晶体,构筑纳米羟基磷灰石/壳聚糖/明胶仿生骨组织工程支架材料,并进行表征和性能检测。②用酶消化法和条件培养法分离、诱导培养中国小型猪成骨细胞作为组织工程种子细胞。③用静态复合共培养法体外构建2种骨组织工程种植体样品:成骨细胞-纳米羟基磷灰石/壳聚糖/明胶仿生骨种植体,成骨细胞-纳米羟基磷灰石/胶原种植体。④采用扫描电镜、透射电镜、FDA荧光、LDH、MTT等定期观测仿生骨样品中细胞形态、细胞增殖速率、碱性磷酸酶活性、矿化结节形成等指标,以比较样品的细胞增殖活性和成骨活性。结果:①成功构筑了具有良好的生物相容性和力学相容性的纳米羟基磷灰石/壳聚糖/明胶,这种材料具有适于细胞黏附与生长的(90±1)%的孔隙率,孔径为100￣300μm的微孔结构,且原位沉积的纳米羟基磷灰石晶体的粒径为50nm左右,接近与天然骨的组成。②自中国小型猪腿骨成功分离培养了成骨细胞,并在诱导培养条件下,表现出很强的增殖活力和成骨活性,适合作为实验用骨组织工程的种子细胞。③成功构建了两种成骨细胞-可吸收载体种植体样品:经检验仿生构建的小型猪成骨细胞-纳米羟基磷灰石/壳聚糖/明胶种植体具有细胞亲和性和体外成骨活性。结论:①在体外成功仿生构建了结构与活性接近天然骨的骨组织工程种植体--纳米羟基磷灰石/壳聚糖/明胶种植体。②初步建立了仿生组织工程化非承载骨种植体的评价方法,为其进一步用于体内修复颅颌骨组织损伤的深化研究提供了实验数据和科学依据。     

Enhanced expression of transforming growth factor beta during megakaryoblastic differentiation of K562 leukemia cells

Platelet alpha granules contain several growth factors such as the transforming growth factor beta (TGF-beta) that are released during blood clotting and are thought to participate in the repair of tissue injury; however, the site of synthesis of platelet TGF-beta has not been demonstrated. We studied TGF-beta expression during megakaryoblastic differentiation of the chronic myeloid leukemia cell line K562 in vitro. These cells have mainly erythroid characteristics but acquire several megakaryoblastic properties when treated with the phorbol diester 12-0-tetradecanoyl-13-phorbolacetate (TPA). During four subsequent days of megakaryoblastic differentiation the amount of the 2.5-kilobase (kb) TGF-beta mRNA increased about eightfold, and a novel 2.3-kb mRNA species was induced in the K562 cells. This occurred concomitantly with distinct induction patterns of platelet-derived growth factor A (PDGF-A) and c-sis (PDGF-B chain) RNAs and several platelet antigens. The expression of erythroid markers such as glycophorin A decreased. Culture media of TPA-differentiated K562 cells also contained TGF-beta polypeptides as shown by a sensitive radioreceptor assay and by immunoprecipitation after metabolic labeling of the cells. These polypeptides were not seen in culture media from dimethyl sulfoxide- or sodium butyrate-treated cells. Unlike in several other cells, exogenously added TGF-beta 1 or 2 affected neither TGF- beta nor PDGF RNA expression in K562 cells.     

Syngeneic bone marrow transplantation reduces the hearing loss associated with murine mucopolysaccharidosis type VII

MPS VII mice are deficient in beta-glucuronidase and share many clinical, biochemical, and pathologic characteristics with human mucopolysaccharidosis type VII (MPS VII). We have shown that syngeneic bone marrow transplantation (BMT) prolongs survival and reduces lysosomal storage in many organs of the MPS VII mouse. In this report, we quantify the hearing loss and determine the impact of syngeneic BMT on the development of deafness and the associated pathology in the MPS VII mouse. Eleven weeks after syngeneic BMT performed at birth, treated MPS VII mice had normal auditory-evoked brainstem responses (ABR), whereas untreated MPS VII mice had ABR thresholds 43 dB higher than normal. Treated MPS VII mice had beta-glucuronidase-positive cells in the temporal bone and in the subepithelial connective tissue of the external auditory canal. There was less thickening of the tympanic membrane and middle ear mucosa and decreased distortion of the ossicles and the cochlear bone. Although transplanted MPS VII mice had increased ABR thresholds by 33 weeks of age, four of the six had thresholds 12 to 32 dB lower than untreated mutants. These data indicate that syngeneic BMT in newborn MPS VII mice prevents early hearing loss and, in some animals, results in long-term improved auditory function.     

Immunohistochemical study on gastroenteric nervous system in trisomy 16 mice:an animal model of Down syndrome

AIM:To study the development of gastroenteric nervous system in trisomy 16 mouse embryos.The gastroenteric nervous system in trisomy 16 mice and their normal littermates, serving as controls from embryonic days 13 to 18 (ED13-18) was identified by using primary antibody against protein gene product (PGP) 9.5.METHODS:Trisomy 16 mouse breeding and trisomy 16 mouse embryos were identified from their normal littermates by chromosome examination; PGP 9.5 immunohistochemical stainning.RESULTS:In normal littermates embryos, the precursor cells from the neural crest migrated into stomach and intestine at ED 13 and ED 14 respectively.Numerous nervous processes connected to each other and formed early nervous networks at ED 14 stomach and ED 15 intestine. Original ganglia in the muscular nervous plexus of the stomach appeared at ED15 with very simple arrangement. At ED 16 the early developed myenteric nervous plexuses were regularly found in the stomach and intestine respectively. In both stomach and intestine, the development of submucosal nervous plexuses were finished at ED17. However, the myenteric nervous plexus and the internal and external submucosal nervous plexuses were differentiated only in the stomach at ED 18.In comparison with the normal littermates, stomach and intestine nervous system developed much slower in trisomy 16 mice. Their immature neurons did not appear in the stomach and intestine until ED 14 and ED 15. Between ED 14 and ED 16, the gastroenteric nervous system was composed of only some scattered neurons with different distribution density and size. The development and differentiation of the gastroenteric nervous system were delayed and the myenteric nervous plexus did not appear until ED 18. There was no submucosal nervous plexus in all stomach and intestine specimens. A semiquantitative analysis and rank sum test of the data showed that the trisomy 16 mouse embryos were markedly retarded in the gastroenteric nervous development compared with their normal littermates.CONCLUSION:Trisomy 16 mice, as an animal model for Down syndrome, has abnormality not only in several systems and organs but also in gastroenteric innervation. This report describes for the first time that the development of the gastroenteric nervous system was not only delayed but also pathological.     

Two case reports of perineal hernia after laparoscopic abdominoperineal resection with a proposed modification to the operative technique

Perineal hernia is a rare complication following laparoscopic abdominoperineal resection (APR) for rectal cancer. We present two case reports of perineal hernia following laparoscopic APR and discuss their management. We suggest that they developed because the pelvic peritoneum was left open during laparoscopic APR and propose that closure of the pelvic peritoneum should be routine in this operation.     

看见美丽饮品好气色要内外兼修与朱丹一同探寻胶原蛋白是怎么来的

七月盛夏，宝岛台湾却惬意非常!浙江卫视女主播朱丹带领许多媒体朋友一同到南台湾做了一个很特别的美丽之旅，这一次，胶原蛋白不仅可以喝，还能被“看”出来。     

Plasmacytoid myoepithelioma of minor salivary glands: report of case with emphasis in the immunohistochemical findings

Extracorporeal formation of mineralized bone-like tissue is still an unsolved challenge in tissue engineering. Embryonic stem cells may open up new therapeutic options for the future and should be an interesting model for the analysis of fetal organogenesis. Here we describe a technique for culturing embryonic stem cells (ESCs) in the absence of artificial scaffolds which generated mineralized miromasses. Embryonic stem cells were harvested and osteogenic differentiation was stimulated by the addition of dexamethasone, ascorbic acid, and ß-glycerolphosphate (DAG). After three days of cultivation microspheres were formed. These spherical three-dimensional cell units showed a peripheral zone consisting of densely packed cell layers surrounded by minerals that were embedded in the extracellular matrix. Alizarine red staining confirmed evidence of mineralization after 10 days of DAG stimulation in the stimulated but not in the control group. Transmission electron microscopy demonstrated scorching crystallites and collagenous fibrils as early indication of bone formation. These extracellular structures resembled hydroxyl apatite-like crystals as demonstrated by distinct diffraction patterns using electron diffraction analysis. The micromass culture technique is an appropriate model to form three-dimensional bone-like micro-units without the need for an underlying scaffold. Further studies will have to show whether the technique is applicable also to pluripotent stem cells of different origin.