Session Detail

Poly(glycerol sebacate) (PGS) has been shown to be a promising biodegradable elastomer for engineering soft tissues. Fabrication of an anisotropic PGS scaffold, however, remains challenging. In our previous study, we developed a method based on the use of sacrificial fibers to fabricate an anisotropic PGS porous membrane. Briefly, aligned poly(vinyl alcohol) (PVA) membranes were prepared by electrospinning. The membrane was then embedded in PGS prepolymer to form a composite upon drying. After crosslinking of PGS, the embedded PVA fibers were removed by water, leaving numerous cylindrical pores in the PGS membrane. There were two limitations in the previous study, however. First, PVA could react with PGS, leading to incomplete removal of PVA. Second, the PVA electrospun fibers were nano-sized, and hence the resultant pores were in the nanoscale, which not be capable of guiding cell alignment. The purpose of this study was to deal with the two limitations. Polylactide (PLA), which does not react with PGS, was used in replacement of PVA for the preparation of the sacrificial fibers, which was then removed by chloroform upon crosslinking, leaving aligned grooves on the surface of the PGS membrane and cylindrical pores within the membrane. The porous PGS membrane was shown to be mechanically anisotropic. The membrane was not cytotoxic and the grooves on its surface were capable of directing cell alignment via contact guidance. With the same approach, we fabricated a PGS tubular scaffold with uniform wall thickness and examined their mechanical properties. The PGS anisotropic scaffold have potential in the applications of vascular tissue engineering.

 

The current methods of surface modification for anti-corrosion and anti-adhesion on metals include composite plating, electroless plating, and metal plating. Not only do these techniques require meticulous safety measures, but is also prone to cause contaminations to the environment. Extra costs and precautions must be taken when working with poisonous chemicals to prevent hazardous material emission to environment endangering the nature and wellbeing of people. In the field of material surface modification, atmospheric pressure plasma spraying is a common approach. This is a safe and dry process and since air is used as reactant gas no pollutants are produced. A new type of atmospheric pressure plasma spraying equipment is used to measure the process temperature of metal materials, optical emission spectrometer (OES), and water contact angle (WCA), bacteria adhesion test, and salt spray test after surface modification. The test results shown in this research indicates no heat damage is present on the material. OES shows reactive species are present when plasma is ignited. Nitrogen is present at 315.36 nm and 336.44 nm. Singlet oxygen is also present at 777.32 nm and 845.75 nm. After surface modification, WCA showed on metallic surfaces can reach 95 degrees and above forming a super hydrophobic surface. Bacteria adhesion test showed 90% less adhesion after surface modification. A 48-hour salt spray test revealed that after surface modification on metallic surface, the procedure can slow down corrosion and rust prevention performance is better than chrome plating.

 

Type 1 diabetes mellitus is a chronic disease characterized by insulin deficiency and hyperglycemia owing to the loss of pancreatic beta cells. Islet transplantation has been demonstrated as a promising therapy in addition to insulin treatment. The liver, renal capsule or peritoneal cavity are currently chose as the sites for islet transplantation. However, the surgical access of these positions can be very invasive and may cause subsequent complications. In contrast, subcutaneous sites offer advantages of minimally invasive operating procedure and easy access for graft monitoring. Nevertheless, subcutaneous transplantation of islet exhibits only limited therapeutic outcomes, which can be attributable to the inadequate capability of skin tissue to foster revascularization in a short period. In this work, three-dimensional (3D) mesenchymal stem cell aggregates are fabricated using a thermo-responsive methylcellulose hydrogel. We anticipate that the combination of 3D stem cell aggregates with islets may enhance regional neovascularization and increase graft survival by prevent graft apoptosis at subcutaneous site, thus improving the therapeutic efficacy of islet transplantation.

 

The key characteristic of collagen associated with disease is the arrangement of collagen fibers. Osteogenesis imperfecta and asthma to breast and ovarian cancer are good examples of abnormal collagen alignment. Cornea is one of the collagen-rich connective tissue and plays important role in clear vision. While X-ray scattering techniques are able to determine bulk structure of cornea, to distinguish depth-dependent details of the corneal stroma comprised of a layered network of fibrillar collagen are still not sound. Here, we use Fast Fourier Transform second harmonic generation microscopy as a tool to determine the directionality of corneal stroma as a function of depth. Our results also display the position dependent difference of corneal stroma along the temporal –nasal direction

 

This study aimed to evaluate self-healed hydrogels for mesenchymal stem cells (MSCs) culture. Here, self-healing hydrogels were prepared by mixing glycol chitosan with difunctional polyethylene glycol (DF-PEG) at different molecular weight (MW) and concentrations. Hydrogels with lowest MW and highest concentration possessed highest crosslinking degree. Hydrogels with higher crosslinking degree had lower swollen ratio, shorter gelation time, higher strain and stress, and slower degradation rate. Increasing DF-PEG concentration might increase cell viability, however, the hydrogel with highest crosslinking degree had lowest cell viability. Alkaline phosphatase activity and alizarin red S stain proved cell encapsulated hydrogels were able to promote osteogenic differentiation.