Irvine, Calif., Oct. 26, 2023 — A study from the University of California, Irvine has revealed that in 2022, 38 North American businesses used direct-to-consumer advertising to promote unproven stem cell interventions and exosome products as purported treatments and preventatives for COVID-19. Collectively, these organizations operated or facilitated access to 60 clinics – with 24 in the U.