Increase in primitive stem cell numbers in equine peripheral blood following stress

Abstract

Stout et al. (Amer Surg. 73:1106‐1110, 2007) reported base‐line levels of primitive stem cells circulating in adult porcine peripheral blood, which increased dramatically after just 90 minutes of trauma. Ongoing studies have shown similar stem cells in adult equine blood and that base‐line levels varied according to breed of the horse. The current study was undertaken to determine whether these stem cells would increase in number in the peripheral blood following stress in the same horse. Stress was defined as moderate exercise, i.e., 10 minutes of cantering. Blood withdrawal followed the guidelines of FVSU‐IACUC. Adult horses had 8 ml of blood withdrawn by venipuncture immediately prior to and immediately after exercising. After gravity separation, the plasma was withdrawn and 15 microliters of plasma from each sample was mixed with 15 microliters of 0.4% Trypan blue. The resultant solution was mixed, placed onto a hemocytometer and photographed: blastomere‐like stem cells (BLSCs) were Trypan blue positive and < 2.0 microns in size; transitional‐BLSCs (Tr‐BLSCs) were both Trypan blue positive & negative and 2‐5 microns in size; and epiblast‐like stem cells (ELSCs) were Trypan blue negative and 6‐8 microns in size (Young and Black, Minerva Biotech 17:55‐63, 2005). This study demonstrates that moderate exercise will increase the level of these primitive pluripotent stem cells in the blood of adult equines.