Papers by Keyword: Poly(L-lactide-co-ε-carprolactone)

Abstract: The bulk ring-opening copolymerisation of L-lactide (LL) and ε-caprolactone (CL) with an initial comonomer feed ratio of LL:CL = 75:25 mol % was carried out using stannous acetate as the initiator at 120 oC for 48 hrs. The copolymer was characterised by GPC, DSC and TGA. Due to its ability to biodegrade in the human body, this type of copolymer has potential for use as an absorbable surgical suture. The copolymer obtained was melt spun at 153 oC using a small-scale melt-spinning apparatus and extruded into ice-cooled water to produce an as-spun monofilament fibre which was largely if not completely amorphous. Alternate off-line hot-drawing and annealing (3 cycles) was carried out in order to develop the fibre’s oriented semi-crystalline morphology. To complete the processing operation, thermal treatment was necessary to stabilize the fibre morphology. It was found that fixed annealing at 60 oC followed by free annealing at 60 oC stabilized the fibre morphology as a result of molecular relaxation. In vitro hydrolytic degradation studied in a phosphate buffer saline (PBS) solution of pH 7.4 at 37.0 ± 0.1 oC indicated that, after 6 weeks immersion in the buffer, the fibre’s tensile strength decreased by approximately 50% whereas a commercial ‘PDS’ suture of similar size lost its strength completely after only 4 weeks.

Abstract: In cartilage tissue engineering, as a cell source, adult stem cells are very attractive for clinical applications. Recent studies suggest that human adipose tissue-derived stromal cells (ASCs) have multilineage potential similar to bone marrow-derived stromal cells (BMSCs). ASCs are obtained from adipose tissue easily isolated by suction-assisted lipectomy in various body parts. Also, as one of major factors of cartilage tissue engineering, scaffolds have an important role in cartilage formation. Poly(L-lactide-co-ε-carprolactone) scaffolds have physiological activity, biodegradability, high cell affinity, and mechano-activity. The object of this study is cartilaginous tissue formation using highly elastic PLCL scaffolds and ASCs in vitro and in vivo. Poly(L-lactide-co-ε-carprolactone) copolymers were synthesized from lactide and ε-carprolactone in the presence of stannous octoate as catalyst. The scaffolds with 85% porosity and 300-500μm pore size were fabricated by gel-pressing method. ASCs were seeded on scaffolds and cultured for 21days in vitro. Cell/polymer constructs were characterized by reverse transcriptase-polymerase chain reaction for confirming differentiation to chondrocytes onto PLCL scaffolds. Also, for examining cartilaginous tissue formation in vivo, ASCs seeded scaffolds which were induced chondrogenesis for 2 weeks were implanted in nude mice subcutaneously for up to 8weeks. Histological studies showed that implants partially developed cartilaginous tissue within lacunae. And there was an accumulation of sulfated glycoaminoglycans. Immunohistochemical analysis revealed that implants were positively stained for specific extracellular matrix. These results indicate that ASCs and PLCL scaffols could be used to cartilage tissue engineering.

Abstract: A tubular and fibrous scaffold was fabricated from an elastic polymer, poly (L-lactideco- ε-caprolactone) (PLCL; Mn 193,813, Mw 538,623) 50:50 by using a novel gel spinning apparatus. To characterize the gel-spun scaffold, we investigated morphology, tensile property, tissue in-growth rate and degradation rate. From SEM images, fibrous structure in the scaffold wasn’t fabricated well in the condition of 4% gel concentration. In general, the thickness level of microfibers increased as the gel concentration increased. In addition, the gel-spun scaffolds showed stronger tensile properties in the circumferential direction than the longitudinal direction. 5%, 7.5%, 10% and 12.5% scaffolds were analyzed in both directions: circumferential direction and longitudinal direction. On the other hand, the gel-spun scaffolds have been implanted in mouse to examine the degradation rate in vivo and tissue in-growth aspects, compared to extruded scaffolds. Both shows very similar degradation rates, but the aspect in tissue in-growth was different. In conclusion, gel-spun PLCL scaffolds have good characteristics as a plausible scaffold for cardiovascular tissue engineering.

Abstract: To engineer cartilaginous constructs with a mechano-active scaffold and dynamic compression was performed for effective cartilage tissue engineering. Mechano-active scaffolds were fabricated from very elastic poly(L-lactide-co-ε-carprolactone)(5:5). The scaffolds with 85 % porosity and 300~500 μm pore size were prepared by a gel-pressing method. The scaffolds were seeded with chondrocytes and the continuous compressive deformation of 5% strain was applied to cell-polymer constructs with 0.1Hz to evaluate for the effect of dynamic compression for regeneration of cartilage. Also, the chondrocytes-seeded constructs stimulated by the continuous compressive deformation of 5% strain with 0.1Hz for 10 days and 24 days respectively were implanted in nude mice subcutaneously to investigate their biocompatibility and cartilage formation. From biochemical analyses, chondrogenic differentiation was sustained and enhanced significantly and chondrial extracellular matrix was increased through mechanical stimulation. Histological analysis showed that implants stimulated mechanically formed mature and well-developed cartilaginous tissue, as evidenced by chondrocytes within lacunae. Masson’s trichrome and Safranin O staining indicated an abundant accumulation of collagens and GAGs. Also, ECM in constructs was strongly immuno-stained with anti-rabbit collagen type II antibody. Consequently, the periodic application of dynamic compression can improve the quality of cartilaginous tissue formed in vitro and in vivo.