In vivo and in vitro effects of cord blood hematopoietic stem and progenitor cell (HSPC) expansion using valproic acid and/or nicotinamide.

BACKGROUND: High self-renewal capacity and most permissive nature of umbilical cord blood (CB) results with successful transplant outcomes but low hematopoietic stem and progenitor cell (HSPC) counts limits wider use. In order to overcome this problem ex vivo expansion with small molecules such as Valproic acid (VPA) or Nicotinamide (NAM) have been shown to be effective. To the best of our knowledge, the combinatory effects of VPA and NAM on HSPC expansion has not been studied earlier. The aim of this study was to analyze ex vivo and in vivo efficacy of VPA and NAM either alone or in combination in terms of expansion and engraftment. METHODS: A total of 44 CB units were included in this study. To determine the ex vivo and in vivo efficacy, human CB CD34+ cells were expanded with VPA and/or NAM and colony forming unit (CFU) assay was performed on expanded HSPC. Xenotransplantation was performed simultaneously by intravenous injection of expanded HSPC to NOD-SCID gamma (NSG) mice (n = 22). Significance of the difference between the expansion groups or xenotransplantation models was analyzed using t-test, Mann-Whitney, ANOVA or Kruskal-Wallis tests as appropriate considering the normality of distributions and the number of groups analyzed. RESULTS: In vitro CD34+ HSPC expansion fold relative to cytokines-only was significantly higher with VPA compared to NAM [2.23 (1.07-5.59) vs 1.48 (1.00-4.40); p < 0.05]. Synergistic effect of VPA+NAM has achieved a maximum relative expansion fold at 21 days (D21) of incubation [2.95 (1.00-11.94)]. There was no significant difference between VPA and VPA+NAM D21 (p = 0.44). Fold number of colony-forming unit granulocyte-macrophage (CFU-GM) colonies relative to the cytokine-only group was in favor of NAM compared to VPA [1.87 (1.00-3.59) vs 1.00 (1.00-1.81); p < 0.01]. VPA+NAM D21 [1.62 (1.00-2.77)] was also superior against VPA (p < 0.05). There was no significant difference between NAM and VPA+NAM D21. Following human CB34+ CB transplantation (CBT) in the mouse model, fastest in vivo leukocyte recovery was observed with VPA+NAM expanded cells (6 ± 2 days) and the highest levels of human CD45 chimerism was detectable with VPA-expanded CBT (VPA: 5.42 % at day 28; NAM: 2.45 % at day 31; VPA+NAM 1.8 % at day 31). CONCLUSION: Our study results suggest using VPA alone, rather than in combination with NAM or NAM alone, to achieve better and faster expansion and engraftment of CB HSPC.

Germline genetic variants in Turkish familial multiple myeloma/monoclonal gammopathy of undetermined significance cases.

Multiple myeloma (MM) is a haematological malignancy primarily affecting the elderly, with a striking male predilection and ethnic disparities in incidence. Familial predisposition to MM has long been recognized, but the genetic underpinnings remain elusive. This study aimed to investigate germline variants in Turkish families with recurrent MM cases. A total of 37 MM-affected families, comprising 77 individuals, were included. Targeted next-generation sequencing analysis yielded no previously reported rare variants. Whole exome sequencing analysis in 11 families identified rare disease-causing variants in various genes, some previously linked to familial MM and others not previously associated. Notably, genes involved in ubiquitination, V(D)J recombination and the PI3K/AKT/mTOR pathway were among those identified. Furthermore, a specific variant in BNIP1 (rs28199) was found in 13 patients across nine families, indicating its potential significance in MM pathogenesis. While this study sheds light on genetic variations in familial MM in Turkey, its limitations include sample size and the absence of in vivo investigations. In conclusion, familial MM likely involves a polygenic inheritance pattern with rare, disease-causing variants in various genes, emphasizing the need for international collaborative efforts to unravel the intricate genetic basis of MM and develop targeted therapies.

A Novel Hypothesis: Certain KIR/Cognate Ligand Containing Genotypes Differ in Frequency Among Patients With Myeloma and Have an Effect on Age of Disease Onset.

BACKGROUND: Natural killer (NK) cells are known to have cytotoxic effects mediated through killer immunoglobulin-like receptors (KIRs) and their cognate ligands. Role of KIRs in myeloma is yet unresolved. PATIENTS AND METHODS: KIR genotypes and ligands of 204 newly diagnosed MM patients are compared with 424 healthy subjects. Statistical analysis included t-test, chi-square and binary logistic regression. RESULTS: KIR ligands were significantly more (C2C2: 27.5% vs 15.1%; OR 2.128; 95% CI, 1.417-3.196; P < .001) or less (C1C2: 40.2% vs 51.9%; OR 0.623; 95% CI, 0.444-0.874; P = .006) frequent among MM. Co-occurrence of genotype AA with C2C2 was also higher in frequency among MM (OR 2.509; 95% CI, 1.171-5.378; P = .015) likewise cAB1 with C1C2 was less frequent (OR 0.553; 95% CI, 0.333-0.919; P = .021). Genotypes AA with C1C1, cAB1 with C1C2 or C1C2 alone were associated with a delay (median age: 61 [48-73]; P = .044; 62 [31-81]; P = .030 or 59 [31-85]; P = .028), but AA with C2C2 with an earlier age of onset (48 [29-77]; P = .042). In multivariate analysis including R-ISS, light chain, KIR genotype/ligands; ligand C1C2 (P = .02) and genotype AA-C1C1 (P = .037) were independently associated with age of onset ≥60. CONCLUSION: C1C2 and C2C2 alone or in combination with KIR genotype (cAB1 and AA, respectively), is observed in less or higher frequency among MM cases and associated with delayed/earlier age of onset, respectively. Genotype AA-C1C1 although in similar frequency between patients and healthy subjects, is also associated with delay. To our knowledge, this is the first study demonstrating an association between KIR and MM onset age, independent from R-ISS or light chain type.