Controlled formation of polylysinized inner pores in injectable microspheres of low molecular weight poly(lactide-co-glycolide) designed for efficient loading of therapeutic cells.

This study aimed to develop porous microspheres with a suitable porous structure and mechanical property for cell delivery using a comparatively low molecular weight (MW) poly(lactide-co-glycolide) (PLGA) having a weak mechanical strength and fast degradation rate, which could be potentially used for treatment of corneal endothelial diseases. Porous microspheres of 30 kDa PLGA with different pore sizes were prepared by varying preparation conditions, and the microspheres with mean pore diameters approximately 0.5, 1, 2 and 3 times that of a single green fluorescent protein-expressing human embryonic kidney 293 cell, used as a model cell, were chosen for cell loading study. The microspheres with an average pore diameter two times greater than that of the single cell were found to be the most appropriate for efficient cell loading in the inner pore spaces, along with demonstrating a good mechanical property, injectability and biodegradability. To maximize the cell loading amount in the microspheres, the cell adhesive property of the microspheres and cell loading conditions were optimized, leading to approximately 4.2 times increase in the cell loading amount. The porous microspheres designed using the low MW PLGA hold promise as a delivery system of corneal endothelial cells for regeneration of the corneal endothelium.

Biocompatibility of nanocomposites used for artificial conjunctiva: in vivo experiments.

PURPOSE: To evaluate the biocompatibility of nanocomposites used for artificial conjunctiva. METHODS: Fifty New Zealand white rabbits were used for the experiments. Nanocomposites of poly -caprolactone (PCL) and of PCL coated with polyvinyl alcohol (PCL+PVA), polyvinyl pyrrolidone (PCL+PVP), or chitosan (PCL+C), and amniotic membrane (AM) as a control, were cut into small disks with a diameter of 3.5 mm. The disks were inserted underneath the conjunctiva to measure their inflammation-inducing properties. To investigate epithelial adhesion and goblet cell differentiation, the disks were transplanted after round conjunctival excision. Cultivated conjunctival epithelial cells on nanocomposite were then transplanted onto the abdomen of Balb/c athymic mice. The number of inflammatory cells and the density of goblet cells were measured using hematoxylin and eosin, periodic-acid-Schiff, and immunohistochemistry after 2 weeks. RESULTS: The number of inflammatory cells found inside of the inserts was as follows: 21 +/- 4.9 for controls, 21 +/- 15.1 for PCL, 49.6 +/- 26.0 for PCL+PVP, 40.2 +/- 17.1 for PCL+C, and 13.8 +/- 3.9 for PCL+PVA. In PCL+PVA, the accumulation of inflammatory cells was significantly lower than in the controls (p < 0.01, Mann-Whitney U). The reepithelialization of conjunctival cells was accomplished in more than 75% of all disks except for the PCL+C. In addition, we found the differentiation of goblet cells in the following order from greatest to least: amniotic membrane, PCL, and PCL+PVP. CONCLUSIONS: Nanocomposites of PCL were biocompatible in rabbit conjunctiva, suggesting that PCL may be considered as a candidate for use in the development of artificial conjunctiva.