Siebold E; Division of Sport and Exercise Medicine, Basel, Switzerland.
Infanti L; Gruber HJ; Stehle GT;

European Journal of Applied Physiology. 126(7):4113-4126, 2026 Jul.

PURPOSE: Hematopoietic stem cell transplantation (HSCT) depends on
effective HSC mobilization with granulocyte colony-stimulating factor
(G-CSF), though some allogeneic donors experience severe side effects.
This study compares G-CSF and acute maximal exercise for HSC collection
and cellular composition in 10 healthy family donors, examining links to
donor fitness and recipient outcomes.

METHODS: Ten donors (3 females; 40.8 (18.3) years) and their recipients
(n = 8; 3 females; 47.5 (18.5) years) were enrolled. Donors completed
cardiopulmonary exercise testing with blood samples taken pre- and
post-exercise and on apheresis day for flow cytometric analysis.
Recipients were followed up on day ~ 30 post-transplant.

RESULTS: Exercise significantly increased circulating total CD34+ cells
(1.76-fold (0.51), p = 0.002) and select progenitor subsets (CD34+CD45dim,
1.74-fold (0.56), p = 0.006; and CD34+CD38+CD133+, 1.60-fold (0.46), p =
0.013), while other subsets showed no significant change (p > 0.05).
Compared with post-exercise, apheresis resulted in markedly higher
concentrations of total CD34+ cells (20.7-fold (9.7), p < 0.001) and all
measured subsets. The largest enrichments were observed in CD34+
CD38-CD133+ (52.7-fold (69.3) p = 0.005) and CD34+CD38+CD133+ (38.2-fold
(17.0), p < 0.001) populations. HSC collection at apheresis contained a
186.1-fold (72.3) elevation of immature granulocytes (p < 0.001) compared
to the acute exercise (1.5-fold (0.3)). The proportions of apoptotic CD34+
cells and their subpopulations were similar post-exercise to apheresis (p
> 0.05). Donor CD34+CD38- cell number was significantly negatively
associated with recipient engrafting CD34+CD45dimCD90+ cells/microl
(r=-0.70, p = 0.05, n = 8).

CONCLUSION: Exercise might complement pharmacological mobilization by
enhancing key HSC subgroups, improving collection quality, and supporting
transplantation success; future research should evaluate combined
approaches and the role of CRF in donor suitability and recipient
outcomes.