Quantifying the effect of pore size and surface treatment on epidermal incorporation into percutaneously implanted sphere-templated porous biomaterials in mice.

The sinus between skin and a percutaneous medical device is often a portal for infection. Epidermal integration into an optimized porous biomaterial could seal this sinus. In this study, we measured epithelial ingrowth into rods of sphere-templated porous poly(2-hydroxyethyl methacrylate) implanted percutaneously in mice. The rods contained spherical 20-, 40-, or 60-μm pores with and without surface modification. Epithelial migration was measured 3, 7, and 14 days post-implantation utilizing immunohistochemistry for pankeratins and image analysis. Our global results showed average keratinocyte migration distances of 81 ± 16.85 μm (SD). Migration was shorter through 20-μm pores (69.32 ± 21.73) compared with 40 and 60 μm (87.04 ± 13.38 μm and 86.63 ± 8.31 μm, respectively). Migration was unaffected by 1,1' carbonyldiimidazole surface modification without considering factors of pore size and healing duration. Epithelial integration occurred quickly showing an average migration distance of 74.13 ± 12.54 μm after 3 days without significant progression over time. These data show that the epidermis closes the sinus within 3 days, migrates into the biomaterial (an average of 11% of total rod diameter), and stops. This process forms an integrated epithelial collar without evidence of marsupialization or permigration.