Trackable spheres of similar size to those typically used for sustained protein delivery are prepared by incorporating superparamagnetic iron oxide (SPIO) nanoparticles into the core of poly(lactide‐co‐glycolide) microspheres. The visibility of injections in static and temporally in dynamic tissue systems is demonstrated. This method improves upon other, less sensitive imaging modalities in their ability to track injectable delivery systems. The results obtained confirm the localization of microspheres to the injected target area and highlight the novelty of tracking delivery vehicles for other applications.
In situ vascular tissue engineering has been proposed as a promising approach to fulfill the need for small‐diameter blood vessel substitutes. The approach comprises the use of a cell‐free instructive scaffold to guide and control cell recruitment, differentiation, and tissue formation at the locus of implantation. Here we review the design parameters for such scaffolds, with special emphasis on differentiation of recruited ECFCs into the different lineages that constitute the vessel wall. Next to defining the target properties of the vessel, we concentrate on the target cell source, the ECFCs, and on the environmental control of the fate of these cells within the scaffold. The prospects of the approach are discussed in the light of current technical and biological hurdles.
For tissue engineering purpose biopolymer chondroitin sulfate (CS), one of the major components of cartilage and bone extracellular matrix, was immobilized onto the surface of amino‐functionalized polyurethane (PU) films derived from naturally occurring oleic and 10‐undecenoic acids. The amino‐functionalized PUs were prepared by aminolysis with 1,6‐hexamethylenediamine of synthesized PUs containing methyl ester groups. FTIR‐ATR, XPS, SEM, and water contact angle measurements were used to confirm the surface changes at each step of treatment, both in morphologies and chemical composition. Cytotoxicity and cell morphology analysis using osteoblast cell line MG63 showed that PU‐CS films are suitable materials for cell growth, spreading, and differentiation.
Current approaches to skin equivalents often only include the epidermis and dermis. Here, a full‐thickness skin equivalent is described including epidermis, dermis, and hypodermis, that could serve as an in vitro model for studying skin biology or as a platform for consumer product testing. The construct is easy to handle and is maintained for >14 d while expressing physiological morphologies of the epidermis and dermis, seen by keratin 10, collagens I and IV expression. The skin equivalent produces glycerol and leptin, markers of adipose metabolism. This work serves as a foundation for understanding a few necessary factors needed to develop a stable, functional model of full‐thickness skin.
Therapies for corneal disease and injury often rely on artificial implants, but integrating cells into synthetic corneal materials remains a significant challenge. The electrochemically formed collagen-based matrix presented here is non-toxic to cells and controls the proliferation in the corneal fibroblasts seeded onto it. Histology and biomolecular studies show a behavior similar to corneal stromal cells in a native corneal environment. Not only is this result an important first step toward developing a more realistic, multi-component artificial cornea, but it also opens possibilities for using this matrix to control and contain the growth of cells in engineered tissues. 相似文献
Polylaminin (polyLM) is a polymerized form of the extracellular matrix protein laminin obtained upon pH acidification. Here microscopy and spectroscopic tools are used to study the cell compatibility and the structural stability of polyLM, aiming at establishing its robustness as a biopolymer for therapeutic use. PolyLM is cell compatible as judged by the efficiency of attachment and neuritogenesis. It is resistant to low temperature. Addition of urea or an increase in hydrostatic pressure leads to polymer disassembly. PolyLM biofilms remain stable for 48 h in contact with cell culture medium. The sedimented polymer recovered after centrifugation and adsorbed on a glass coverslip preserved its original structure and its biological properties.
The promising perspectives of PLLA‐based nanostructured biomaterials and their relevance in tissue engineering are reported. Nanocomposites based on PLLA and MWCNTs are developed with an MWCNT content ranging from 0 to 3 wt%. The electrical properties show a percolation threshold within a range of 0.21–0.33 wt% MWCNTs, and the conductivity increases by six orders of magnitude. The surface structure shows changes with the carbon nanotube concentration. The functional role of MWCNTs incorporation in terms of interactions with adult stem cells suggests that PLLA/MWCNT nanocomposites are suitable substrates for primary stem cell culture.
Therapeutic apheresis is established as supportive therapy for various diseases, such as hypercholesterolemia, autoimmune diseases, liver failure, and sepsis. In combined membrane-adsorption systems, the patient's plasma is continuously separated from whole blood by means of a hollow fiber filter, and pathogenic factors are removed from the plasma by selective or specific adsorbents. While adsorbent particles with a size range of 300–800 µm are used in conventional systems, we are currently developing a system based on adsorbent microparticles (1–5 µm), the Microspheres-Based Detoxification System (MDS). The characteristics of the matrix used for immobilization of specific ligands influence the performance of the resulting adsorbents. Desirable matrix characteristics are an open porous structure with an inner surface accessible for target molecules, mechanical stability, narrow particle size distribution, and ease of derivatization. In addition, biocompatibility is a critical issue, since the particles are in direct contact with the patient's plasma. Cellulose represents an ideal support matrix, as it combines all the above-mentioned features, and cellulosic polymers are widely applied in medicine and generally regarded as biocompatible. Cellulose microparticles can be activated using e.g. sodium periodate and functionalized with Polymyxin B or anti-tumor necrosis factor (TNF) antibodies to generate specific adsorbents for endotoxins or TNF. In summary, cellulose microparticles represent an excellent matrix as basis for adsorbent development in blood purification. 相似文献
