不同配比纳米羟基磷灰石/聚己内酯复合材料细胞相容性的研究

目的：观察不同配比nPCL/HA电纺纤维取向薄膜材料的细胞相容性。方法：将人骨髓间充质干细胞（hBMSCs）体外诱导培养为成骨细胞;并经传代培养第5代的人骨髓间充质干细胞,以2×105cm2的密度与不同配比nPCL/HA电纺纤维取向薄膜支架在培养板内共培养,同时以nPCL电纺纤维非取向薄膜材料作为对照,初步观察hBMSCs在不同配比nPCL/HA支架材料上复合培养,对其细胞相容性进行评价。结果：hBMSCs与3种电纺薄膜支架材料均有细胞相容性,细胞能在不同材料表面黏附生长、分化增殖。但是PCL/HA的配比为20：1电纺纤维取向薄膜材料黏附率（35.3±2.6）%,为3中材料中黏附率最高的一种,材料表面细胞生长良好,体积变大,有伪足生长。结论：PCL/HA的配比为20：1电纺纤维取向薄膜材料,较适合作为支架材料应用于hBMSCs为种子细胞的组织工程构建。     

Biodegradable Pseudolatexes: The Chemical Stability of Poly(D,L-Lactide) and Poly (ε-Caprolactone) Nanoparticles in Aqueous Media

Pseudolatexes of the biodegradable polyesters poly(D,L-lactide) (PLA) and poly(-caprolactone) (PCL) have been developed as potential aqueous coatings for sustained release. Since PLA and PCL are known to hydrolyze, the influence of the surfactant system, temperature, pH, and particle size on the chemical stability of the polymers as aqueous colloidal dispersions was investigated. Pseudolatexes of PLA and PCL formulated with a nonionic surfactant system were the most stable. When these dispersions were stored in unbuffered media for 350 days at 5°C, only small changes in the weight-average molecular weights (M _w) of the polymers were observed. At 37°C there was rapid degradation of both polymers in the dispersions. Arrhenius plots for the degradation of PLA and PCL resulted in a linear relationship for PCL. The nonlinear relationship for PLA was attributed to the polymer being in two different physical states within the 5 to 37°C range which was used for the Arrhenius plots. PCL was in the rubbery state at all temperatures studied. Storage of the pseudolatexes in pH 1.65 buffer at 37°C catalyzed the rates of degradation of both PLA and PCL. However, refrigeration of the pseudolatexes stabilized the polymers even at pH 1.65 for up to 4 months. Particle size had an insignificant effect on PLA and PCL stability in pseudolatexes prepared with either a nonionic or an anionic surfactant system.     

羧基官能化己内酯的合成

以2 乙酸乙酯环己酮为起始原料,首先将原料水解为2 乙酸环己酮,然后分别用对位带吸电子基团硝基、推电子基团甲基和无取代基的苄基保护羧基,通过拜耳 维立格氧化反应的选择性同时得到2号位或6号位带羧基保护基的己内酯同分异构体化合物,最后使用急骤层析法分离同分异构体得到高纯度的6号位羧基官能化己内酯。保护基上取代基电子效应的不同导致生成不同比率的2号位和6号位产物,带有推电子基团时生成6号位单体的比率最大。取代基的极性差异也会影响同分异构体分离的难易程度,同分异构体的极性差距越大越容易分离。     

Increased Adipogenic and Decreased Chondrogenic Differentiation of Adipose Derived Stem Cells on Nanowire Surfaces

Despite many advances in tissue engineering, there are still significant challenges associated with restructuring, repairing, or replacing damaged tissue in the body. Currently, a major obstacle has been trying to develop a scaffold for cartilage tissue engineering that provides the correct mechanical properties to endure the loads associated with articular joints as well as promote cell-scaffold interactions to aid in extracellular matrix deposition. In addition, adipogenic tissue engineering is widely growing due to an increased need for more innovative reconstructive therapies following adipose tissue traumas and cosmetic surgeries. Recently, lipoaspirate tissue has been identified as a viable alternative source for mesenchymal stem cells because it contains a supportive stroma that can easily be isolated. Adipose derived stem cells (ADSCs) can differentiate into a variety of mesodermal lineages including the adipogenic and chondrogenic phenotypes. Biodegradable polymeric scaffolds have been shown to be a promising alternative and stem cells have been widely used to evaluate the compatibility, viability, and bioactivity of these materials. Polycaprolactone is a bioresorbable polymer, which has been widely used for biomedical and tissue engineering applications. The fundamental concept behind successful synthetic tissue-engineered scaffolds is to promote progenitor cell migration, adhesion, proliferation, and induce differentiation, extracellular matrix synthesis, and finally integration with host tissue. In this study, we investigated the adhesion, proliferation, and chondrogenic and adipogenic differentiation of ADSCs on nanowire surfaces. A solvent-free gravimetric template technique was used to fabricate polycaprolactone nanowires surfaces. The results indicated that during the growth period i.e., initial 7 days of culture, the nanowire surfaces (NW) supported adhesion and proliferation of the cells that had elongated morphologies. However, cell on surfaces without nanowires had non-elongated morphologies. Further, immunofluorescence imaging of marker proteins showed that the nanowires surfaces did not appear to support chondrogenic differentiation whereas supported adipogenic differentiation of ADSCs.     

Proof of concept,design, and manufacture via 3‐D printing of a mesh with bactericidal capacity: Behaviour in vitro and in vivo

Currently, hernia treatment involves implantation of a mesh prosthesis, usually made of polypropylene, and the primary complication is infection of the device, which leads to an exponential increase in morbidity. Three‐dimensional printing offers a method of dealing with complications of this magnitude. Therefore, in this study, the bactericidal properties and effectiveness of three‐dimensional‐printed meshes with polycaprolactone (PCL) and gentamicin were evaluated in vitro in Escherichia coli cultures, and their histological behaviour was examined in vivo. Different PCL meshes were implanted into four groups of rats, with 10 rats in each group: PCL meshes, PCL meshes with alginate and calcium chloride, PCL meshes with gentamicin, and PCL meshes with alginate and gentamicin. Thirty‐six microporous meshes were manufactured, and their bactericidal properties were assessed. When the meshes did not include an antibiotic, an inhibition halo was not observed; when the gentamicin was free, an asymmetric inhibition area of 5.65 ± 0.46 cm² was present; when the gentamicin was encapsulated, a rectangular area of 5.40 ± 0.38 cm² was observed. In the rats, macroporous and microporous mesh implants produced mild inflammation and substantial fibrosis with collagen and neovascular foci. A significant difference was observed in fibroblastic activity between the PCL with alginate group and the PCL with alginate and gentamicin group microporous meshes (p = .013) and in collagen deposits between the macroporous and microporous meshes in the PCL mesh group (p = .033). The feasibility of manufacturing drug‐doped printed PCL meshes containing alginate and gentamicin was verified, and the meshes exhibited bactericidal effects and good histopathological behaviour.     

Advances in Regenerative Orthopedics

Orthopedic injuries are common and a source of much misery and economic stress. Several relevant tissues, such as cartilage, meniscus, and intra-articular ligaments, do not heal. And even bone, which normally regenerates spontaneously, can fail to mend. The regeneration of orthopedic tissues requires 4 key components: cells, morphogenetic signals, scaffolds, and an appropriate mechanical environment. Although differentiated cells from the tissue in question can be used, most cellular research focuses on the use of mesenchymal stem cells. These can be retrieved from many different tissues, and one unresolved question is the degree to which the origin of the cells matters. Embryonic and induced pluripotent stem cells are also under investigation. Morphogenetic signals are most frequently supplied by individual recombinant growth factors or native mixtures provided by, for example, platelet-rich plasma; mesenchymal stem cells are also a rich source of trophic factors. Obstacles to the sustained delivery of individual growth factors can be addressed by gene transfer or smart scaffolds, but we still lack detailed, necessary information on which delivery profiles are needed. Scaffolds may be based on natural products, synthetic materials, or devitalized extracellular matrix. Strategies to combine these components to regenerate tissue can follow traditional tissue engineering practices, but these are costly, cumbersome, and not well suited to treating large numbers of individuals. More expeditious approaches make full use of intrinsic biological processes in vivo to avoid the need for ex vivo expansion of autologous cells and multiple procedures. Clinical translation remains a bottleneck.