Abstract
Purpose:
In this study, our objective was to analyze age-related architectural changes in the endogenous limbal lymphatic vasculature of two frequently used mouse strains BALB/cN and C57BL/6N.
Methods:
Naïve corneas from young BALB/c (n=19) or C57BL/6 (n=9) mice (8-10weeks) and old BALB/c (n=5) or C57BL/6 (n=5) mice (66-68weeks) were excised and whole mounts were stained with the lymphatic vessel marker LYVE-1. Mice were obtained from the animal facility at the Centre of Molecular Medicine, Cologne (CMMC). The vessel area was calculated semi-automatically by an algorithm using cellF software, the vessel length, number of branching points (BPs) and endpoints (EPs) was analyzed manually using cellF and related to the analyzed area. ANOVA was used for statistical analysis.
Results:
a) In BALB/c mice the vessel area and vessel length did not change significantly between young and aged mice. In C57BL/6 the vessel area (1.77% in young C57BL/6 versus 2.34% in aged C57BL/6, p<0.05) and vessel length (0.85mm/mm2 versus 1.35mm/mm2, p<0.001) significantly increased with age. The number of BPs and EPs did not change significantly in both strains during aging.<br /> <br /> b) Comparing the parameters between both strains showed that the vessel area in young C57BL/6 was increased compared to young BALB/c (1.77% versus 1.08%, p<0.001). This difference was also found when aged C57BL/6 were compared to aged BALB/c mice (2.34% versus 0.69% p<0.001). Similar, vessel length was significantly increased in young C57BL/6 versus young BALB/c and aged C57BL/6 versus aged BALB/c. The relative number of EPs and BPs was significantly higher in young and aged C57BL/6 compared to young and aged BALB/c.
Conclusions:
Age-related changes in the limbal lymphatic vasculature may be strain-specific, since vessel area and vessel length were increased in aged C57BL/6 but not in BALB/c mice. The relative number of BPs and EPs was not significantly altered in aged mice, indicating that the complexity of the network remains similar in both strains. The strain-specific differences in the vasculature between young C57BL/6 versus young BALB/c mice persisted also in aged C57BL/6 versus BALB/c mice.