Enhancing esophageal repair with bioactive bilayer mesh containing FGF.

We aimed to prepare a bioactive and biodegradable bilayer mesh formed by fibroblast growth factor (FGF) loaded gelatin film layer, and poly ε-caprolactone (PCL) film layer, and to investigate its treatment efficacy on esophageal anastomosis. It is envisaged that the bioactive mesh in in vivo model would improve tissue healing in rats. The full thickness semicircular defects of 0.5 × 0.5 cm2 were created in anterior walls of abdominal esophagus. The control group had abdominal esophagus isolated with distal esophageal blunt dissection, and sham group had primary anastomosis. In the test groups, the defects were covered with bilayer polymeric meshes containing FGF (5 µg/2 cm2), or not. All rats were sacrificed for histopathology investigation after 7 or 28 days of operation. The groups are coded as FGF(-)-7th day, FGF(+)-7th day, and FGF(+)-28th day, based on their content and operation day. Highest burst pressures were obtained for FGF(+)-7th day, and FGF(+)-28th day groups (p < 0.005) and decreased inflammation grades were observed. Submucosal and muscular collagen deposition scores were markedly increased in these groups compared to sham and FGF(-)-7th day groups having no FGF (p = 0.002, p = 0.001, respectively). It was proved that FGF loaded bioactive bilayer mesh provided effective repair, reinforcement and tissue healing of esophageal defects.

Preparation and characterization of poly(ε-caprolactone) scaffolds modified with cell-loaded fibrin gel.

Poly(ε-caprolactone) (PCL) is one of the most commonly used polymers in the production of tissue engineered scaffolds for hard tissue treatments. Incorporation of cells into these scaffolds significantly enhances the healing rate of the tissue. In this study, PCL scaffolds were prepared by wet spinning technique and modified by addition of fibrinogen in order to form a fibrin network between the PCL fibers. By this way, scaffolds would have micro- and nanofibers in their structures. Drying of the wet spun constructs was achieved by application of ethanol dehydration or freeze drying techniques. Fibrinogen solutions (as low: 2 mg/mL; or high: 10 mg/mL concentrations) were added onto the scaffolds and fibrin formation was achieved via fibrinogen crosslinking. Results showed that ethanol dehydration led to film-like coating on the fibers while freeze-drying led to nanofiber bridges between PCL fibers establishing an interconnected web in the structure. Mechanical properties of the scaffolds were improved in the presence of the fibrin net. After the seeding of Saos-2 cells, higher attachment and homogeneous distribution of the cells was achieved on the samples modified with high concentration of fibrinogen. These scaffolds can be good candidates for the treatment of problematic bone defects.

PCL and PCL-based materials in biomedical applications.

Biodegradable polymers have met with an increasing demand in medical usage over the last decades. One of such polymers is poly(ε-caprolactone) (PCL), which is a polyester that has been widely used in tissue engineering field for its availability, relatively inexpensive price and suitability for modification. Its chemical and biological properties, physicochemical state, degradability and mechanical strength can be adjusted, and therefore, it can be used under harsh mechanical, physical and chemical conditions without significant loss of its properties. Degradation time of PCL is quite long, thus it is used mainly in the replacement of hard tissues in the body where healing also takes an extended period of time. It is also used at load-bearing tissues of the body by enhancing its stiffness. However, due to its tailorability, use of PCL is not restricted to one type of tissue and it can be extended to engineering of soft tissues by decreasing its molecular weight and degradation time. This review outlines the basic properties of PCL, its composites, blends and copolymers. We report on various techniques for the production of different forms, and provide examples of medical applications such as tissue engineering and drug delivery systems covering the studies performed in the last decades.

PCL-TCP wet spun scaffolds carrying antibiotic-loaded microspheres for bone tissue engineering.

Scaffolds produced for tissue engineering applications are proven to be promising alternatives to be used in healing and regeneration of injured tissues and organs. In this study, porous and fibrous poly(ε-caprolactone) (PCL) scaffolds were prepared by wet spinning technique and modified by addition of tricalcium phosphate (TCP) and by immobilizing gelatin onto fibers. Meanwhile, gelatin microspheres carrying Ceftriaxone sodium (CS), a model antibiotic, were added onto the scaffolds and antimicrobial activity of CS was investigated against Escherichia coli (E. coli), a model gram-negative bacterium. TCP and gelatin were added to enhance mechanical properties while directing the scaffold towards osteogenic infrastructure and to increase hydrophilicity by activating cell attachment via protein molecules, respectively. Modifications with TCP and gelatin enhanced the compression modulus by about 70%, and attachment of Saos-2 cells by 60%, respectively. Release of the antibiotic demonstrated effective antimicrobial activity against E. coli. The bioactive scaffolds were shown to be good candidates for bone tissue engineering applications.