An approach is presented for the graft copolymerization of acrylamide (AAm) onto the surface of polyethylene films treated with an oxidative plasma or inert gas plasmas, followed by exposure to air. In both cases, peroxides formed by the plasma treatment are likely to be the species responsible for initiating the graft copolymerization. It is shown that the amount of peroxides (~1CT10 mol-cm"2) and grafted PAAm (-10 Mg-cm"2) can be determined with good accuracy by the l,l-diphenyl-2-picrylhydrazyl and the ninhydrin method, respectively. A striking finding is that the amounts of peroxides and the grafted PAAm do not monotonously increase with the plasma exposure time but decrease after passing a maximum. A mechanism is proposed to explain this peculiar dependence of the grafted amount on the exposure time. Optical microscopy on the cross-section of the grafted film reveals the graft copolymerization to be limited to a very thin surface region. Both the merely plasma-treated film and the subsequently grafted film are hydrophilic, but only the grafted film has an invariably low contact angle and a slippery surface when hydrated.

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The adsorption of proteins on poly(2-hydroxyethyl methacrylate) (PHEMA) brushes was systematically studied by quartz crystal microbalance (QCM) and fluorescence microscopy as a function of graft density and protein size. The graft density σ (chains/nm2) ranged from 0.007 (dilute or semidilute brush regime) to 0.7 (concentrated brush regime), and the protein size ranged from 2 to 13 nm in an effective diameter. The lowest-density brush (σ = 0.007) adsorbed all the tested four proteins, while the highest-density brush (σ = 0.7) adsorbed none of them. The middle-density brush (σ = 0.06) showed an intermediate behavior, adsorbing the smallest two proteins but effectively repelling the largest two. PHEMA cast films adsorbed a probe protein with the adsorbed amount increasing approximately proportionally to the film thickness, indicating that the adsorption mainly occurred in the bulk of the film. The noted results for the brushes support the idea of size-exclusion effect, an effect characteristic of concentrated polymer brushes, in which the graft chains are highly extended and highly oriented so that large molecules, sufficiently large compared with the distance between the nearest-neighbor graft points, are physically excluded from the entire brush layer. In this regard, the behavior of the lowest-density brush should be essentially similar to that of the cast film, as was in fact observed.

A novel method of hydroxyapatite (HAp) formation on/in a three-dimensional hydrogel matrix was developed. This method is based on the widely-known wet synthesis of HAp and is alternate soaking process in CaCl2/Tris-HCl (pH 7.4) and Na2HPO4 aqueous solutions. Using a poly(vinyl alcohol) (PVA) gel as model matrix, PVA-HAp composites could be prepared and characterized.

Cell-based or pharmacological approaches for promoting tendon repair are currently not available because the molecular mechanisms of tendon development and healing are not well understood. Although analysis of knockout mice provides many critical insights, small animals such as mice have some limitations. In particular, precise physiological examination for mechanical load and the ability to obtain a sufficient number of primary tendon cells for molecular biology studies are challenging using mice. Here, we generated Mohawk (Mkx) −/− rats by using CRISPR/Cas9, which showed not only systemic hypoplasia of tendons similar to Mkx −/− mice, but also earlier heterotopic ossification of the Achilles tendon compared with Mkx −/− mice. Analysis of tendon-derived cells (TDCs) revealed that Mkx deficiency accelerated chondrogenic and osteogenic differentiation, whereas Mkx overexpression suppressed chondrogenic, osteogenic, and adipogenic differentiation. Furthermore, mechanical stretch stimulation of Mkx −/− TDCs led to chondrogenic differentiation, whereas the same stimulation in Mkx +/+ TDCs led to formation of tenocytes. ChIP-seq of Mkx overexpressing TDCs revealed significant peaks in tenogenic-related genes, such as collagen type (Col)1a1 and Col3a1, and chondrogenic differentiation-related genes, such as SRY-box (Sox)5, Sox6, and Sox9. Our results demonstrate that Mkx has a dual role, including accelerating tendon differentiation and preventing chondrogenic/ osteogenic differentiation. This molecular network of Mkx provides a basis for tendon physiology and tissue engineering.Achilles tendon ossification T endons play a critical role in the musculoskeletal system by connecting muscle to bone to transmit mechanical loads and enable movement. Tendon injuries and damage are repaired slowly and incompletely because of poor intrinsic healing capacity, which in part results from tissue hypocellularity and hypovascularity (1). Even after surgical tendon repair, a standard treatment for tendon rupture, clinical outcomes are not satisfactory because of recurrent rupture or adhesions (2). To develop cell-based or pharmacological approaches for promoting tendon repair, the molecular mechanism of tendon development and regeneration must be determined; however, the key genome network for tendon differentiation and homeostasis has not been well characterized.We, along with other researchers, recently reported the tendon-specific expression and functions of the transcription factor Mohawk (Mkx), which regulates tendon-related gene expression (3, 4). Mkx knockout mice showed general tendon hypoplasia (5, 6), suggesting that Mkx plays an important role during tendon development. Moreover, overexpression of Mkx in mesenchymal stem cells (MSC) elevates tendon-related markers, and transplantation of these cells increases the diameter of collagen fibers in tendons (7,8), suggesting the potential application of Mkx in cell therapy for tendon injury.Although the results from analysis of Mkx knockout mice have provided critical informatio...

A well-defined, high-density poly(2-hydroxyethyl methacrylate) (PHEMA) brush was fabricated on the surface of a poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) film by surfaceinitiated living radical polymerization (LRP). First, a sufficient amount of peroxides as initiating moieties were successfully introduced on the film surface without causing etching by the O 2-plasma treatment. Subsequently, the polymerization mediated by reversible addition-fragmentation chain transfer (RAFT) was carried out at a mild temperature in a nonsolvent for FEP to minimize the swelling of the FEP film surface and avoid the growth of chains from deep inside of the film. The contact angle and ESCA measurements indicated that the boundary intermixing layer between FEP and PHEMA layers was reasonably thin (e10 nm), meaning that the PHEMA brush was grown nearly regioselectively from the surface of the FEP film. The graft density was estimated to be about 0.3 chains/nm 2 , which is almost the same as the one achievable by the RAFT technique on inorganic substrates with a hard surface. This graft density is much higher than the ones obtainable by conventional techniques.

Infertility caused by ovarian or tubal problems can be treated using In Vitro Fertilization and Embryo Transfer (IVF-ET); however, this is not possible for women with uterine loss and malformations that require uterine reconstruction for the treatment of their infertility. In this study, we are the first to report the usefulness of decellularized matrices as a scaffold for uterine reconstruction. Uterine tissues were extracted from Sprague Dawley (SD) rats and decellularized using either sodium dodecyl sulfate (SDS) or high hydrostatic pressure (HHP) at optimized conditions. Histological staining and quantitative analysis showed that both SDS and HHP methods effectively removed cells from the tissues with, specifically, a significant reduction of DNA contents for HHP constructs. HHP constructs highly retained the collagen content, the main component of extracellular matrices in uterine tissue, compared to SDS constructs and had similar content levels of collagen to the native tissue. The mechanical strength of the HHP constructs was similar to that of the native tissue, while that of the SDS constructs was significantly elevated. Transmission electron microscopy (TEM) revealed no apparent denaturation of collagen fibers in the HHP constructs compared to the SDS constructs. Transplantation of the decellularized tissues into rat uteri revealed the successful regeneration of the uterine tissues with a 3-layer structure 30 days after the transplantation. Moreover, a lot of epithelial gland tissue and Ki67 positive cells were detected. Immunohistochemical analyses showed that the regenerated tissues have a normal response to ovarian hormone for pregnancy. The subsequent pregnancy test after 30 days transplantation revealed successful pregnancy for both the SDS and HHP groups. These findings indicate that the decellularized matrix from the uterine tissue can be a potential scaffold for uterine regeneration.