Safety and Feasibility of FMT for Immune Recovery After HSCT

Patients who undergo allogeneic hematopoietic stem cell transplantation (allo-HSCT) often experience slow and incomplete recovery of their immune system, particularly the part responsible for producing antibodies (humoral immunity). This can lead to increased risk of infections and other complications. Previous studies suggest that the gut microbiome and its metabolites, such as short-chain fatty acids (propionate and butyrate), play a critical role in immune recovery.

This study has two phases. In the first phase, we will observe changes in immune function, lymphocyte subsets, and gut metabolites (propionate and butyrate) before and at 1, 3, and 6 months after transplantation in 50-80 patients. We will compare patients with severe immune deficiency to those with normal recovery to identify differences in gut bacteria and metabolites.

In the second phase, we will perform selective fecal microbiota transplantation (FMT) in 6 patients who still have severe humoral immunodeficiency at 6 months post-transplant. The FMT capsules will be specially selected from donors whose gut bacteria are rich in both propionate-producing and butyrate-producing strains. Patients will receive 20 capsules daily for 3 consecutive days (60 capsules total). We will evaluate the safety and feasibility of this approach, and observe whether fecal secretory immunoglobulin A (sIgA) shows signs of recovery at 3 months after FMT.

The study is expected to take approximately 2 years to complete. Findings may provide a new precision microbiome-based strategy to promote immune recovery after transplantation.