Distinct Hemostasis and Blood Composition in Spiny Mouse Acomys cahirinus

Abstract

The spiny mouse (Acomys species) is capable of scarless wound regeneration through largely yet unknown mechanisms. To investigate whether this capacity is related to peculiarities of the hemostatic system, we studied the blood of Acomys cahirinus in comparison to Mus musculus (Balb/c) to reveal differences in blood composition and clotting in both males and females. In response to surgical manipulations, blood clots formed in wounds of Acomys comprised a stronger hemostatic seal with reduced surgical bleeding in comparison with Balb/c. Acomys demonstrated notably shorter tail bleeding times and elevated clottable fibrinogen levels. Histological analysis revealed that clots from Acomys blood had densely packed fibrin-rich clots with pronounced fibrin segregation from erythrocytes. Acomys exhibited superior plasma clot stiffness as revealed with thromboelastography. The latter two characteristics are likely due to hyperfibrinogenemia. Light transmission platelet aggregometry demonstrated that ADP-induced platelet aggregates in Acomys males are stable, unlike the aggregates formed in the plasma of Balb/c undergoing progressive disaggregation over time. There were no apparent distinctions in platelet contractility and baseline expression of phosphatidylserine. Hematological profiling revealed a reduced erythrocytes count but increased mean corpuscular volume and hemoglobin content in Acomys. These results demonstrate the distinctive hemostatic potential of Acomys cahirinus, which may contribute to their remarkable regenerative capacity.

Keywords: Acomys cahirinus; fibrinogen concentration; haemostasis; hematological profile.

Figure 1

Results of the tail bleeding assay (A) and levels of clottable fibrinogen in blood plasma (B) of male and female Acomys cahirinus mice versus Balb/c. The results are presented as mean ± SD (n = 5 for each species and gender group). * p < 0.05; ** p < 0.01.

Figure 2

Representative histological images of blood clots from Acomys cahirinus (A,C) and Balb/c (B,D) (n = 3 for each). Arrows indicate red fibrin in the clot. Erythrocytes are yellow. (E) Characteristic dense red fibrin accumulations within the Acomys cahirinus blood clot. Multiple giant densely packed clusters and fibrous structures of fibrin are visualized (within dashed ovals), mostly separated from yellow erythrocytes. (F) Typical loose distribution of fibrin within the Balb/c blood clot. A significant predominance of loosely arranged fibrin (red), colocalized with erythrocytes (stained pink, not yellow as in the Acomys clot). Single islets of fibrin aggregates (marked by dashed ovals) were observed. Picro–Mallory stain. Magnification 25× (A–D) and 200× (E,F).

Figure 3

TEG parameters of whole blood (A–C) and PFP (D–F) in male and female Acomys cahirinus and Balb/c: R (reaction time), α-angle (fibrin polymerization rate), and G (shear elastic modulus). n = 6 for paired whole blood samples and n = 9 for PFP samples from males; n = 5 for paired blood and PFP samples in females. The results are presented as mean ± SD. * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001. ns—not significant.

Figure 4

Parameters of clot contraction in whole blood (A,B) and in PRP (C,D) from Acomys cahirinus and Balb/c males and females. n = 6 for paired whole blood samples and n = 5 for PRP samples from males; n = 5 for paired blood and PRP samples from females. The results are presented as mean ± SD. * p < 0.05, ** p < 0.01, *** p < 0.001. ns—not significant.

Figure 5

Averaged light transmission aggregograms recorded after ADP-induced platelet aggregation in PRP from male (A) and female (B) Acomys cahirinus and Balb/c (n = 5 for each species and gender group). Two-way ANOVA test in (A): p < 0.05 at 12 min, p < 0.01 at 15 min, p < 0.001 at 20–30 min.

Figure 6

A characteristic thromboelastogram and the key parameters of clot formation: R—reaction time, α—alpha angle, MA—maximum amplitude.