The generation of anchoring fibrils by epidermal keratinocytes: a quantitative long-term study.

Anchoring fibrils (AFs) are derived from basal keratinocytes, but the kinetics of their formation is unknown. In this study, de novo generation of AFs by cultured human keratinocyte autografts was assessed from 1 week to 6 years postgrafting. Within 2 weeks, AF population densities were equal to those of normal controls and remained normal thereafter. However, AF diameters were narrow compared to controls (P < 0.05) until 3 years postgrafting. The depth of extension of AF-anchoring plaque lattices into the subjacent stroma was normal by 3 weeks but, after 1 month, was typically 1.5-to 2-fold greater than normal. The findings indicate that: (1) basal keratinocytes immediately re-establish a full complement of AFs; (2) once reformed, AF populations remain normal in density over time; (3) nascent AFs are thin and require several years to reach full maturity; and (4) abnormally thick AF lattices may form over time in healed wounds.