Hyaluronic acid based materials for intestine tissue engineering: a morphological and biochemical study of cell-material interaction

Development of hyaluronan-based membranes for the healing of intestinal surgical wounds: a preliminary study

Implantable membranes based on alginate and hyaluronic acid (HA) were manufactured to obtain a rapidly resorbing pliable mesh for the in situ administration of HA to intestinal tissue. Morphological analyses of this interpenetrated matrix pointed out a homogeneous polymeric texture while degradation studies demonstrated that the material is able to dissolve in physiological solutions within few days. Biological studies in vitro showed that the membrane is biocompatible towards human dermal fibroblasts and that liquid extracts from the HA-containing membrane can stimulate wound healing. A preliminary in vivo biocompatibility study on rats showed that the membranes in direct contact with the intestine did not elicit any acute adverse reaction or immune response, while only a mild inflammatory reaction was noticed at the mesenteric or serosal region. Overall, these results appear to support the application of these polysaccharide-based materials for intestinal wound healing.

Designing the new generation of intelligent biocompatible carriers for protein and peptide delivery

Therapeutic proteins and peptides have revolutionized treatment for a number of diseases, and the expected increase in macromolecule-based therapies brings a new set of challenges for the pharmaceutics field. Due to their poor stability, large molecular weight, and poor transport properties, therapeutic proteins and peptides are predominantly limited to parenteral administration. The short serum half-lives typically require frequent injections to maintain an effective dose, and patient compliance is a growing issue as therapeutic protein treatments become more widely available. A number of studies have underscored the relationship of subcutaneous injections with patient non-adherence, estimating that over half of insulin-dependent adults intentionally skip injections. The development of oral formulations has the potential to address some issues associated with non-adherence including the interference with daily activities, embarrassment, and injection pain. Oral delivery can also help to eliminate the adverse effects and scar tissue buildup associated with repeated injections. However, there are several major challenges associated with oral delivery of proteins and peptides, such as the instability in the gastrointestinal (GI) tract, low permeability, and a narrow absorption window in the intestine. This review provides a detailed overview of the oral delivery route and associated challenges. Recent advances in formulation and drug delivery technologies to enhance bioavailability are discussed, including the co-administration of compounds to alter conditions in the GI tract, the modification of the macromolecule physicochemical properties, and the use of improved targeted and controlled release carriers.

Are synthetic scaffolds suitable for the development of clinical tissue-engineered tubular organs?

Transplantation of tissues and organs is currently the only available treatment for patients with end-stage diseases. However, its feasibility is limited by the chronic shortage of suitable donors, the need for life-long immunosuppression, and by socioeconomical and religious concerns. Recently, tissue engineering has garnered interest as a means to generate cell-seeded three-dimensional scaffolds that could replace diseased organs without requiring immunosuppression. Using a regenerative approach, scaffolds made by synthetic, nonimmunogenic, and biocompatible materials have been developed and successfully clinically implanted. This strategy, based on a viable and ready-to-use bioengineered scaffold, able to promote novel tissue formation, favoring cell adhesion and proliferation, could become a reliable alternative to allotransplatation in the next future. In this article, tissue-engineered synthetic substitutes for tubular organs (such as trachea, esophagus, bile ducts, and bowel) are reviewed, including a discussion on their morphological and functional properties.

Process optimization and biocompatibility of cell carriers suitable for automated magnetic manipulation

There is increasing demand for automated cell reprogramming in the fields of cell biology, biotechnology and the biomedical sciences. Microfluidic-based platforms that provide unattended manipulation of adherent cells promise to be an appropriate basis for cell manipulation. In this study we developed a magnetically driven cell carrier to serve as a vehicle within an in vitro environment. To elucidate the impact of the carrier on cells, biocompatibility was estimated using the human adenocarcinoma cell line Caco-2. Besides evaluation of the quality of the magnetic carriers by field emission scanning electron microscopy, the rate of adherence, proliferation and differentiation of Caco-2 cells grown on the carriers was quantified. Moreover, the morphology of the cells was monitored by immunofluorescent staining. Early generations of the cell carrier suffered from release of cytotoxic nickel from the magnetic cushion. Biocompatibility was achieved by complete encapsulation of the nickel bulk within galvanic gold. The insulation process had to be developed stepwise and was controlled by parallel monitoring of the cell viability. The final carrier generation proved to be a proper support for cell manipulation, allowing proliferation of Caco-2 cells equal to that on glass or polystyrene as a reference for up to 10 days. Functional differentiation was enhanced by more than 30% compared with the reference. A flat, ferromagnetic and fully biocompatible carrier for cell manipulation was developed for application in microfluidic systems. Beyond that, this study offers advice for the development of magnetic cell carriers and the estimation of their biocompatibility.

Comparison of murine fibroblast cell response to fluor-hydroxyapatite composite, fluorapatite and hydroxyapatite by eluate assay

Fluorapatite (FA) is one of the inorganic constituents of bone or teeth used for hard tissue repairs and replacements. Fluor-hydroxyapatite (FHA) is a new synthetic composite that contains the same molecular concentration of OH(-) groups and F(-) ions. The aim of this experiment was to evaluate the cellular responses of murine fibroblast NIH-3T3 cells in vitro to solid solutions of FHA and FA and to compare them with the effect of hydroxyapatite (HA). We studied 24, 48 and 72 h effects of biomaterials on cell morphology, proliferation and cell cycle of NIH-3T3 cells by eluate assay. Furthermore, we examined the ability of FHA, FA and HA to induce cell death and DNA damage. Our cytotoxic/antiproliferative studies indicated that any of tested biomaterials did not cause the total inhibition of cell division. Biomaterials induced different antiproliferative effects increasing in the order HA < FHA < FA which were time- and concentration-dependent. None of the tested biomaterials induced necrotic/apoptotic death of NIH-3T3 cells. On the other hand, after 72 h we found that FHA and FA induced G0/G1 arrest of NIH-3T3 cells, while HA did not affect any cell cycle phases. Comet assay showed that while HA demonstrated weaker genotoxicity, DNA damage induced by FHA and FA caused G0/G1 arrest of NIH-3T3 cells. Fluoridation of hydroxyapatite and different FHA and FA structure caused different cell response of NIH-3T3 cells to biomaterials.