"A lactose-modified chitosan accelerates chondrogenic differentiation in mesenchymal stem cells spheroids".

Spheroids derived from human mesenchymal stem cells (hMSCs) are of limited use for cartilage regeneration, as the viability of the cells progressively decreases during the period required for chondrogenic differentiation (21 days). In this work, spheroids based on hMSCs and a lactose-modified chitosan (CTL) were formed by seeding cells onto an air-dried coating of CTL. The polymer coating can inhibit cell adhesion and it is simultaneously incorporated into spheroid structure. CTL-spheroids were characterized from a morphological and biological perspective, and their properties were compared with those of spheroids obtained by seeding the cells onto a non-adherent surface (agar gel). Compared to the latter, smaller and more viable spheroids form in the presence of CTL as early as 4 days of culture. At this time point, analysis of stem cells differentiation in spheroids showed a remarkable increase in collagen type-2 (COL2A1) gene expression (~700-fold compared to day 0), whereas only a 2-fold increase was observed in the control spheroids at day 21. These results were confirmed by histological and transmission electron microscopy (TEM) analyses, which showed that in CTL-spheroids an early deposition of collagen with a banding structure already occurred at day 7. Overall, these results support the use of CTL-spheroids as a novel system for cartilage regeneration, characterized by increased cell viability and differentiation capacity within a short time-frame. This will pave the way for approaches aimed at increasing the success rate of procedures and reducing the time required for tissue regeneration.

A hydrogel system based on a lactose-modified chitosan for viscosupplementation in osteoarthritis.

Osteoarthritis (OA) is a chronic disease affecting joint functionality and often managed with hyaluronic acid (HA) administration. In this study, a hydrogel based on a lactose-modified chitosan (CTL) reticulated with boric acid has been developed as a viscosupplement for OA treatment. The rheological characterization allowed to identify a composition whose properties were in line with those of commercial products (in the order of tens of Pascal). The selected CTL-hydrogel showed biocompatibility and antioxidant activity in vitro, and it did not influence cytokines release by macrophages. Degradation studies carried out over 24 h pointed out its higher resistance to chemical degradation with respect to HA samples. Overall, this study underlines the advantages of the CTL-hydrogel to address the treatment of OA and shed light on an innovative application of CTL polymer, which is one of the main component of the proposed hydrogel system and not used in mixture with other molecules.

Effects of supercritical carbon dioxide sterilization on polysaccharidic membranes for surgical applications.

Sterilization methods such as ɣ-irradiation, steam sterilization and ethylene oxide gas treatment can have negative effects on molecular structure and properties of polysaccharide-based biomaterials. In this perspective, the use of supercritical carbon dioxide (scCO2) has been proposed as an alternative method for biomaterial sterilization. In this work, chemical, mechanical and biological properties of polysaccharidic membranes for surgical applications were investigated after sterilization by scCO2. Four sets of sterilizing conditions were considered and SEC analyses were performed in order to identify the one with lower impact on the polysaccharidic matrix of membranes (alginate). Mechanical tests showed that the resistance of membranes was slightly affected after sterilization. Biological analyses proved the biocompatibility of the sterilized membranes both in vitro and in a preliminary in vivo test. Overall, this study points out that this sterilization technique can be successfully employed to achieve an effective and safe sterilization of polysaccharidic membranes for surgical use.

Enhanced bioadhesivity of dopamine-functionalized polysaccharidic membranes for general surgery applications.

UNLABELLED: An emerging strategy to improve adhesiveness of biomaterials in wet conditions takes inspiration from the adhesive features of marine mussel, which reside in the chemical reactivity of catechols. In this work, a catechol-bearing molecule (dopamine) was chemically grafted onto alginate to develop a polysaccharide-based membrane with improved adhesive properties. The dopamine-modified alginates were characterized by NMR, UV spectroscopy and in vitro biocompatibility. Mechanical tests and in vitro adhesion studies pointed out the effects of the grafted dopamine within the membranes. The release of HA from these resorbable membranes was shown to stimulate fibroblasts activities (in vitro). Finally, a preliminary in vivo test was performed to evaluate the adhesiveness of the membrane on porcine intestine (serosa). Overall, this functionalized membrane was shown to be biocompatible and to possess considerable adhesive properties owing to the presence of dopamine residues grafted on the alginate backbone. STATEMENT OF SIGNIFICANCE: This article describes the development of a mussels-inspired strategy for the development of an adhesive polysaccharide-based membrane for wound healing applications. Bioadhesion was achieved by grafting dopamine moieties on the structural component on the membrane (alginate): this novel biomaterial showed improved adhesiveness to the intestinal tissue, which was demonstrated by both in vitro and in vivo studies. Overall, this study points out how this nature-inspired strategy may be successfully exploited for the development of novel engineered biomaterials with enhanced bioadhesion, thus opening for novel applications in the field of general surgery.

Silver-polysaccharide antimicrobial nanocomposite coating for methacrylic surfaces reduces Streptococcus mutans biofilm formation in vitro.

OBJECTIVES: The aim of this study was to determine the in vitro microbiological performances of a lactose-modified chitosan (Chitlac) coating inside which silver nanoparticles were embedded (Chitlac-nAg) for BisGMA/TEGDMA methacrylic specimens. METHODS: Different concentrations of nAg inside Chitlac coating were tested (1 mM, 2 mM, 5 mM). Specimen surface was analyzed by means of field-emission scanning electron microscopy (FEISEM) and energy-dispersive X-ray spectroscopy (EDS). A 48 h monospecific Streptococcus mutans biofilm was developed over the specimen surfaces using a modified drip-flow bioreactor; adherent viable biomass was assessed by MTT test and biofilm was imaged by confocal laser-scanning microscopy (CLSM). RESULTS: The presence of finely dispersed nanoparticles inside the Chitlac coating was confirmed by FEISEM and EDS analysis. All nanoparticles were embedded in the Chitlac coating layer. Chitlac-nAg coatings were able to significantly decrease biofilm formation depending on the nAg concentration, reaching a -80% viable biomass decrease when the 5 mM nAg-Chitlac group was confronted to non-coated control specimens. CLSM analysis did not provide evidence of a contact-killing activity, however the antibacterial Chitlac-nAg coating was able to alter biofilm morphology preventing the development of mature biofilm structures. CONCLUSIONS: The microbiological model applied in this study helped in assessing the antibacterial properties of a coating designed for methacrylate surfaces. CLINICAL SIGNIFICANCE: A microbiological model based on a bioreactor-grown biofilm is useful for preliminary in vitro tests of dental materials. In translational terms, an antibacterial nanocomposite coating based on Chitlac-nAg and designed to be applied to methacrylic surfaces may be a promising way to obtain dental materials able to actively prevent secondary caries.

Biological responses of silver-coated thermosets: an in vitro and in vivo study.

Bisphenol A glycidylmethacrylate (BisGMA)/triethyleneglycol dimethacrylate (TEGDMA) thermosets are biomaterials commonly employed for orthopedic and dental applications; for both these fields, bacterial adhesion to the surface of the implant represents a major issue for the outcome of the surgical procedures. In this study, the antimicrobial properties of a nanocomposite coating formed by polysaccharide 1-deoxylactit-1-yl chitosan (Chitlac) and silver nanoparticles (nAg) on methacrylate thermosets were studied. The Chitlac-nAg system showed good anti-bacterial and anti-biofilm activity although its biocidal properties can be moderately, albeit significantly, inhibited by serum proteins. In vitro studies on the silver release kinetic in physiological conditions showed a steady metal release associated with a gradual loss of antimicrobial activity. However, after 3weeks there was still effective protection against bacterial colonization which could be accounted for by the residual silver. This time-span could be considered adequate to confer short-term protection from early peri-implant infections. Preliminary in vivo tests in a mini-pig animal model showed good biological compatibility of Chitlac-nAg-coated materials when implanted in bony tissue. The comparison was made with implants of titanium Ti6Al4V alloy and with a Chitlac-coated thermoset. Bone healing patterns and biocompatibility parameters observed for nAg-treated material were comparable with those observed for control implants.

Mechanical properties of C-5 epimerized alginates.

There is an increased need for alginate materials with both enhanced and controllable mechanical properties in the fields of food, pharmaceutical and specialty applications. In the present work, well-characterized algal polymers and mannuronan were enzymatically modified using C-5 epimerases converting mannuronic acid residues to guluronic acid in the polymer chain. Composition and sequential structure of controls and epimerized alginates were analyzed by (1)H NMR spectroscopy. Mechanical properties of Ca-alginate gels were further examined giving Young's modulus, syneresis, rupture strength, and elasticity of the gels. Both mechanical strength and elasticity of hydrogels could be improved and manipulated by epimerization. In particular, alternating sequences were found to play an important role for the final mechanical properties of alginate gels, and interestingly, a pure polyalternating sample resulted in gels with extremely high syneresis and rupture strength. In conclusion, enzymatic modification was shown to be a valuable tool in modifying the mechanical properties of alginates in a highly specific manner.

Molecular engineering as an approach to design new functional properties of alginate.

Through enzymatic modification, we are now able to manipulate the composition and sequential nanostructures of alginate, one of the most versatile gelling polymers found in nature. Here we report the application of a set of processive polymer-modifying epimerases for the preparation of novel alginates with highly improved functional properties essential for numerous applications as gel matrices. Gels of enzymatically engineered alginate were found to be more elastic and compact, less permeable, and extremely stable under physiological conditions, offering significant advantages over native alginates. As a result, this study shows that, by controlling alginate nanostructure, its macroscopic properties can be highly controlled. The ability to tailor alginate has a great impact on the wide use of this biomaterial in industry and medicine. More importantly, this adds more knowledge to the link between polymer nanostructure and macroscopic properties and may serve as a model system for other polymer-based materials.

The aggregation of pig articular chondrocyte and synthesis of extracellular matrix by a lactose-modified chitosan.

A reductive amination reaction (N-alkylation) obtained exploiting the aldheyde group of lactose and the amino group of the glucosamine residues of chitosan (d.a. 89%) afforded a highly soluble engineered polysaccharide (chitlac) for a potential application in the repair of the articular cartilage. Chitosan derivatives with 9% and 64% of side chain groups introduced have been prepared and characterized by means of potentiometric titration, (1)H-NMR and intrinsic viscosity. Both polymers, with respect to the unmodified chitosan, induce cell aggregation when in contact with a primary culture of pig chondrocytes, leading to the formation of nodules of considerable dimensions (up to 0.5-1 mm in diameter). The nodules obtained from chondrocytes treated with chitlac with the higher degree of substitution have been studied by means of optical and electron microscopy (SEM, TEM) and the production of glycosaminoglycans (GAGs) and collagen has been measured by means of colorimetric assays. The chondro-specificity of GAG and collagen was determined by RT-PCR. The results show that the lactose-modified chitosan is non-toxic and stimulates the production of aggrecan and type II collagen.

Long-term infusion in cancer chemotherapy with the Groshong catheter via the inferior vena cava.

AIMS AND BACKGROUND: Vascular access through a vein draining into the superior vena cava is commonly used for long-term infusion of drugs inr cancer chemotherapy; prolonged cannulation of the inferior vena cava is generally considered as having an excessively high complication rate. METHODS: Prolonged cisplatin infusion via the inferior vena cava by means of a Groshong catheter was evaluated in 20 consecutive patients with thoracic malignancies showing evidence of superior vena cava infiltration or obstruction. RESULTS: We achieved 1,291 catheter days for our survey with a mean duration of vascular access of 64.5 days per patient and a mean duration of infusion time of 40 days. There were 2 complications, a catheter obstruction after a 7-day rest period and an ileo-femoral thrombosis 6 days after catheter placement. CONCLUSIONS: Our experience compared favourably with the results obtained by long-term central venous access via the supraumbilical route, and demonstrated the reliability and safety of this approach in cases where the superior vena cava cannulation is technically difficult or impossible.

Effect of home care on the place of death of advanced cancer patients.

This study presents a prospective evaluation of the home care programme for patients with advanced cancer at the National Cancer Institute of Milan. Demographic, psychosocial and physical variables were evaluated. The Therapy Impact Questionnaire was used for symptom and quality of life assessment. The association of clinical and demographic variables with the place of death was investigated, considering that the aim of the home care programme is to follow up patients until death in their houses. Eighty-six per cent (86%) of patients died at home and 14% in hospitals. Multivariate analysis showed that only a higher degree of family support was associated with home death. Several changes in symptoms and quality of life items scores were seen, pain improved while physical debility and cognitive functions worsened throughout the home care duration to death. High intensity pain and dyspnoea were still present in, respectively, 23.8 and 15.3% of patients in the last week of life. Psychological distress was high at the end of life and did not seem to be affected by treatment. Home care is a feasible alternative for implementing palliative care in a selected population of patients with advanced cancer. Palliation of physical symptoms is more easily achieved than the control of psychological suffering. Family and economical issues implied by home care models should be part of the discussion in implementing palliative care for advanced cancer patients.