We have previously demonstrated that mesenchymal stromal cells (MSCs) in spheroids enter “hibernation”, hence tolerating hypothermal and hypoxic conditions for up to 10 days without loss of their features and functions, and topical application of spheroidal, but not dissociated MSCs, promotes wound healing in mice. These findings indicate a potential advantage of spheroidal versus dissociated MSCs in sustaining their viability and efficacy in the new and unwelcome environment of a recipient following transplantation. However, it doesn’t appear that this advantage applies to intravenous (i.v.) injection due to the obvious concern that MSC spheroids might clog small blood vessels in the host leading to sudden death. We decided to test this concern by injecting human MSC spheroids (at ~400 mm in diameter) or dissociated MSCs (as a control) i.v. into cynomolgus monkeys. Surprisingly, no death happened to the animals until sacrifice on day 21 post the injection nor remarkable physiological differences were found in the animals before and after the i.v. injection in terms of their behaviors, body weight, and laboratory assays. Human cells were found in the lungs of the monkeys at 1 hour and 21 days later after the i.v. injection. This study suggests that it is safe to inject MSCs, probably also other adherent cells, in spheroids of this size to large animals like nonhuman primates, an inspiring message for the clinical application of MSCs in a new format.