[Role of exogenous supplementation of umbilical cord blood immune cells in reconstructing immune function and restoring hematopoietic function in elderly high-risk myeloid neoplasms patients].

Objective: To investigate the effect of exogenous supplementation of umbilical cord blood (UCB) immune cells on immune function reconstruction and hematopoietic function recovery in elderly high-risk myeloid neoplasms (MN) patients. Methods: The research includes clinical studies and cell experiments. Clinical data of elderly high-risk MN patients aged >60 years admitted to the Department of Hematology at the Second Hospital of Tianjin Medical University from January 2023 to June 2025 were retrospectively included. Based on treatment regimens, the patients were categorized into chemotherapy group ("3+7"regimen), demethylation therapy (HMA) group (decitabine-based therapy), and UCB group (venetoclax combined with azacitidine plus UCB reinfusion). At 28 days post-treatment, differences were compared among the groups regarding disease remission (complete remission rate), hematopoietic function reconstruction (recovery time of white blood cells and platelets), survival outcomes (overall survival rate and event-free survival rate), and cellular immune function reconstruction [levels of various CD4+T cells, CD8+T cells, natural killer (NK)cells, etc.]. To further confirm the role of UCB in the bone marrow microenvironment of MN patients, primary bone marrow cells were collected from 3 elderly high-risk MN patients in the UCB group (ileal bone marrow aspiration was performed on day 15 post-treatment and before UCB infusion, with 10 ml of bone marrow aspirated each time); additionally, UCB cells were obtained from 3 healthy donors (sourced from the Shandong Umbilical Cord Blood Hematopoietic Stem Cell Bank of China, all HLA 2/10 matched male donors). Based on different seeding methods of patient primary bone marrow cells and healthy donor UCB mononuclear cells in Transwell chambers, the cells were divided into a control group (patient bone marrow mononuclear cells cultured separately), an indirect co-culture group (non-contact co-culture of patient bone marrow mononuclear cells and UCB cells), and a direct co-culture group (contact co-culture of patient bone marrow mononuclear cells and UCB cells). After 48 hours of culture, the cells from the lower chamber and the supernatant were collected from each group. The proportional differences among immune cell subsets (various T-cell, B-cell, and NK cell subsets) were compared among the three groups, and the differences in cytokine levels among the three groups of the supernatants [tumor necrosis factor (TNF)-α, interferon (IFN)-γ, and interleukin (IL)-6] were also compared. Results: A total of 109 patients were enrolled, including 54 males and 55 females, with an age range [M (Q1, Q3)] of 68 (60, 87) years. There were 38, 39, and 32 cases in the chemotherapy group, HMA group, and UCB group, respectively. Analysis of disease response revealed that the complete response rates in the UCB group [43.8% (14/32) vs 28.2% (11/39), P<0.001] and the chemotherapy group [44.7% (17/38) vs 28.2% (11/39), P<0.001] were higher than those in the HMA group. In terms of hematopoietic function recovery, the median time to achieve target leukocyte counts in the UCB group was shorter than that in the chemotherapy group [22 (14, 28) vs 28 (24, 37) days, P<0.05] and the HMA group [22 (14, 28) vs 31 (21, 42) days, P<0.05]. Similarly, the median time to achieve target platelet counts in the UCB group was shorter than that in the chemotherapy group [24 (17, 29) vs 28 (23, 33) days, P<0.05] and the HMA group [24 (17, 29) vs 29 (22, 37) days, P<0.05]. The survival analysis demonstrated that the 3-year overall survival rate in the UCB group was higher than that in the HMA group (39.1% vs 19.7%, P<0.05), while no statistically significant difference was observed compared to the chemotherapy group (P>0.05). Similarly, the 3-year event-free survival rate in the UCB group was higher than that in the HMA group (35.8% vs 25.5%, P<0.05), with no statistically significant difference compared to the chemotherapy group (P>0.05). Regarding the reconstruction of cellular immune function, the proportion of CD4+central memory T cells in the UCB group at 28 days post-treatment was lower than that in the chemotherapy group [20% (9%, 29%) vs 32%(23%, 39%), P<0.05], while no statistically significant difference was observed compared to the HMA group (P>0.05). At 28 days post-treatment, the proportions of CD4+naive T cells [45% (30%, 58%) vs 22% (10%, 34%)] and CD8+naive T cells [41% (31%, 52%) vs 22% (8%, 36%)] in the UCB group were significantly higher than those in the HMA group (both P<0.05), while no statistically significant difference was observed compared to the chemotherapy group (both P>0.05). At 28 days post-treatment, the UCB group exhibited higher proportions of CD8+effector T cells [40% (33%, 50%) vs 18% (8%, 28%)], CD19+B cells [20% (13%, 27%) vs 12% (7%, 14%)], and NK cells [20% (15%, 26%) vs 14% (7%, 21%)] compared to the chemotherapy group (all P<0.05). However, the UCB group showed lower proportions of regulatory T cells at 28 days post-treatment than both the chemotherapy group [4% (4%, 6%) vs 7% (7%, 8%), P<0.05] and the HMA group [4% (4%, 6%) vs 8% (6%, 12%), P<0.05]. In terms of cellular experiments, differential analysis of immune cells revealed that the indirect co-culture group exhibited higher levels of CD8+naive T cells, CD4+naive T cells, NK cells, and CD19+B cell subsets compared to the control group; conversely, the levels of regulatory T cells and CD4+central memory T cells were lower than those in the control group (all P<0.05). Cytokine level analysis demonstrated that the direct co-culture group showed higher levels of TNF-α and IFN-γ, as well as lower levels of IL-6 compared to the control group (P<0.001). Conclusion: Immunocytes such as NK cells in UCB may promote immune function reconstruction and hematopoietic recovery in patients, thereby improving their prognosis.