Some alterations in the RBCs induced by the D-gal model are also characteristic
for natural aging. This model causes a significant decrease in RBC deformability, which
affects their rheological properties and their ability to squeeze through microvessels. When
compared with the control, deterioration of RBC morphology in the D-gal model follows
the trend observed in natural aging of C57BL/6J mice, namely, a decrease in MCV and an
increase in MCHC. It is worth highlighting that comparison of the dry smears of fresh RBCs
isolated from the studied groups of animals did not provide any statistically significant
changes in their RBC shape (majority with a bio-concave shape). This stays in agreement
with our previous results, where we have evaluated the morphological alterations and
ultrastructural features among the control and natural aging groups in C57BL/6J RBCs
using not only the classical dry smear analysis, but also nano-scale AFM to finely analyze
the RBC ultrastructural features [3]. Those results clearly proved that only detailed AFM
analysis provided insight into an age-dependent decrease in RBC height and no signs of
ultrastructural deteriorations in RBC morphology were found.
The biochemical composition of RBC membranes observed in the D-gal model and
natural aging includes a decrease in the phospholipid amount, lipid unsaturation level,
and an increase in acyl chain shortening. Even though some alterations are not statistically
significant in the D-gal model, their direction remains the same as in natural aging. Here
we may list the changes to the secondary structure of the proteins of intact RBCs, revealed
by a decrease in the ratio of turns to α-helices, a decrease in MCH and LDL, and lack of
changes in RDW and blood plasma parameters, such as HDL, cholesterol, triglycerides,
and LDH. Altogether, these suggest that the D-gal model mimics both the mechanical and
functional properties of the RBCs of naturally aging mice.
It was previously reported that alterations in the secondary structures of proteins
in intact RBCs may be regarded as biomarkers of aging or specific diseases. Progressive