Abstract
Purpose: :
A novel formulation of poly(N-isopropylacrylamide) crosslinked to collagen has tremendous potential for the delivery of drugs and cells to the posterior segment of the eye. The chemistry of this polymer accords the properties of a liquid at room temperature, and a thermosensitive phase shift to a gel once within the body at physiologic temperature. This allows cell and drug scaffolds, to be injected through a syringe, instead of requiring surgical implantation. The biological feasibility of using this material for ocular applications will be thoroughly examined with a variety of in vitro and in vivo experiments.
Methods: :
Immunological implications were tested using a variety of techniques, including the MTT cell viability assay, cytokine release profiling from human macrophage cell lines, and histological sectioning of subcutaneous and intravitreal injection sites in murine models.
Results: :
When cultured with human retinal pigment epithelial cells, MTT viability assay showed the cells to be very tolerant to this material. No significant cell death occurred when the polymer was seeded on the culture plate. This validates its use as a cell scaffold. Human macrophages were furthermore cultured with this biomaterial, and levels of several excreted cytokines were quantified using western blotting. Cytokine release indicates acceptable immune response. This is further confirmed using histology.Hematoxylin and eosin staining do not show any adverse reaction to implanted material in either the eye, hypodermus or peritoneum.
Conclusions: :
poly(NIPAAM) - co- collagen is a thermosensitive polymer with the ability to gel in situ, creating a potentially intriguing cell and drug delivery system for inaccessible locations, such as the posterior section of the eye. The biological characterization of this material demonstrates its potential feasibility in this capacity.
Keywords: cytokines/chemokines • cell survival • immunohistochemistry