Intravenous application of allogenic peripheral blood-derived mesenchymal stem cells: a safety assessment in 291 equine recipients.

This study evaluates the safety of injecting mesenchymal stem cells (MSCs), derived from peripheral blood, directly into the veins of horses. The study tracked 291 horses for a year following the treatment and found no adverse side effects.

Methodology and Procedure

The researchers carried out this large-scale study on horses to understand the safety implications of transplanting mesenchal stem cells (MSCs) intravenously. For the experiment:

• Mesenchymal stem cells were derived from the peripheral blood of two donor horses, one aged 4 years old and another aged 6 years old.
• Both donor horses were tested extensively for a variety of transmittable diseases before deriving the MSCs.
• The MSCs were then characterized and resuspended in a solution known as Dulbecco’s Modified Eagle Medium (DMEM) that also contained 10% Dimethyl Sulfoxide (DMSO).
• These cells were then injected into the jugular vein of 291 horses that ranged from 3 months to 33 years old.

Injection Dosages and Follow-up

Different dosage levels were administered to the recipients:

• A vast majority of the horses, about 281, received a single physiological dose of 0.2 x 10^6 MSCs.
• Five of the horses were re-injected after 6 weeks with the same dosage and same donor cells for the experiment.
• A super-physiological dosage of 10^6 MSCs were administered to 5 horses.
• For the former two categories, the cells were derived from the two donor horses — 176 recipients received cells from the 4-year-old donor, and 115 recipients received cells from the 6-year-old donor.

All horses (291 in total) were monitored for a year after the injection.

Results and Conclusion

Overall, the researchers did not observe any acute clinical adverse effects in the horses following the injection. Out of the 291 horses, only one died of colic 7 months after the treatment; however, there’s no clear indication that the death was directly linked to the injections.

The conclusion drawn from the study is that not a single horse showed adverse effects from an intravenous injection of allogenic PB-derived MSCs. However, the researchers acknowledge the need for further research to better understand the immunogenic properties of these cells when they are transplanted into different physiological conditions.