Comparison of the human's and camel's erythrocyte deformability by optical tweezers and Raman spectroscopy

The evolution of red blood cells (RBCs) or erythrocytes has led to variation in morphological and mechanical properties of these cells among many species today. Camelids have the most different RBC characteristics among the vertebrates. As a result of adaptation to the desert environment, camelid RBCs can expand twice as much of their total volume in the case of rapid hydration yet are almost undeformable under mechanical stress. In this work, the difference between cell features of the human and the camelid species was explored both mechanically and chemically with optical tweezers and Raman spectroscopy, respectively. We measured the deformability of camel RBCs relative to the human RBCs at the single-cell level using optical tweezers. We found that the deformability index (DI) of the camel and the human RBCs were 0.024{+/-}0.0188 and 0.215{+/-}0.061, respectively. Raman spectral analysis of the whole blood of these two species indicated that some of the Raman peaks observed on the camels blood spectrum were absent on the human bloods spectrum, which further points to the difference in chemical contents of these two species.