Gut Microbiome and its Impact on Outcomes following Hematopoietic Stem Cell Transplantation: a Comprehensive Review

Hematopoietic stem cell transplantation is an important treatment for hematological malignancy and disorders, but is fraught with high risks, including graft-versus-host disease, infection, and relapse. Recent evidence now identifies that the microbiome plays a significant role in influencing transplant outcomes, in which microbial dysbiosis-defined by reduced diversity and pathogen overgrowth-is linked to greater complications and death. Microbiome manipulation with approaches including beneficial microbial species, fiber, fecal transplants, and diet has the potential to mitigate these risks. Experiments show that the restoration of beneficial microbes can restore immunity, reduce graft-versus-host disease severity, and reduce infection. Some challenges remain, including standardization of protocols, long-term efficacy, and safety in immunocompromised recipients. Future research will be focused on mechanisms, trials, and new technology for microbiome-based therapy, with the ultimate goal of improving survival and quality of life for transplant recipients. Hereupon, this review addresses how microbiome engineering can revolutionize cancer treatment by optimizing gut microbial communities for better outcomes in hematopoietic stem cell transplantation (HSCT).