Stem Cell Institute

ABSTRACTN,N‐dimethylacetamide (DMA) is an organic solvent, used in busulphan, iv‐formulation, (Busulfex). DMA is metabolized primarily to N‐methylacetamide (MMA) via CYP2E1. In the present study, we investigated the pharmacokinetics and toxicity of DMA and MMA in patients, mice and cell lines. In pediatric patients (6 months to 18 years) undergoing hematopoietic stem cell transplantation, the pharmacokinetics of DMA and MMA were followed during the 4‐days Busulfex conditioning (3.2–4 mg/kg, b.i.d). No accumulation of DMA was found; however, a significant increase in clearance and a significant decrease (p < 0.005) in half‐lives by the end of treatment were observed which might indicate CYP2E1 autoinduction. Furthermore, continuous increases in plasma concentration of MMA were observed during treatment and a terminal half‐life of 15.2 ± 1.7 h was detected. Moreover, ALT was significantly (p = 0.04) increased in > 61% of the patients after conditioning. Additionally, mice were treated with either dimethyl sulfoxide (DMSO), DMA, busulphan in DMSO, Busulfex or saline for 4 days. DMA‐treated mice showed elevated ALT and AST values. Interestingly, Busulfex administration did not alter mice liver enzymes. Busulphan in DMA showed higher cytotoxicity compared to busulphan in DMSO in HepG‐2, Huh‐7 and HL‐60 cells. The combination Bu‐DMA‐MMA exhibited increased cytotoxicity in a concentration‐dependent manner. In conclusion, Busulfex administration to pediatric patients resulted in an accumulation of MMA during the 4‐days treatment. Busulfex is less toxic compared to Bu dissolved in DMA. MMA addition to Bu in DMA showed higher cytotoxicity. Therefore, MMA with a relatively long half‐life may induce hepatotoxicity and/or interaction with subsequently administered drugs; thus further investigations are urgently warranted.

( Obstet Gynecol . 2024;143(6):785-793. doi: 10.1097/AOG.0000000000005571) Hypertensive disorders of pregnancy (HDP) are associated with an increased risk of complications beyond the peripartum period. About a decade ago, it was hypothesized that severe episodes of hypertension in pregnancy were associated with increased reports of cognitive impairment (CI). Subsequent studies suggested HDP was associated with longer-term decreased cognitive processing speed, working memory, verbal learning, and brain volume on MRI. Improved understanding of the relationship between HDP and CI is essential to design interventions to improve outcomes in these patients. Because of the multifactorial nature of CI, it is critical for the research to include large diverse populations. This study focused on the risk of neurocognitive decline associated with the Hispanic/Latino population following pregnancies affected by hypertensive disorders.

<title>Abstract</title> Acute Myeloid Leukemia (AML) remains challenging to treat, especially in cases with mutations in the BCL-6 co-repressor (BCOR), which are associated with poor prognosis and chemo-resistance. In this study, we reveal a synthetic lethal interaction between <italic>BCOR</italic> and dihydroorotate dehydrogenase (DHODH). We demonstrate that <italic>BCOR</italic> -deficient cells have a heightened sensitivity to DHODH inhibitors such as brequinar and leflunomide, that are already in clinical use. We confirm that DHODH inhibition selectively induces cell death in BCOR-mutant cells in multiple cellular models, in malignant and non-malignant cells, through chemical and genetic manipulation. Interestingly, we find that the dependency on DHODH does not stem from its role in <italic>de novo</italic> pyrimidine biosynthesis disruption. Rather, DHODH’s role in the electron transport chain, essential for mitigating reactive oxygen species, may be the physiological vulnerability that pushes BCOR-mutant cells toward cell death when DHODH is inhibited. DHODH inhibitors could be repurposed as targeted therapies for BCOR-mutant tumors, offering a promising strategy for precision medicine in AML and other cancers.

Naïve pluripotency represents the ground state of mammalian development. A comprehensive understanding of the molecular mechanisms governing its establishment is crucial for elucidating the unique properties of embryonic cells and the regulatory mechanisms controlling cell fate determination. However, the key molecule to robustly achieve naïve pluripotency with minimal manipulation remains unclear. We found that the acetylation status of lysine 49 (K49) of Catenin beta-1 (Ctnnb1) plays a critical role in naïve pluripotency of murine stem cells. Deacetylated Ctnnb1 at K49 binds to transcription factor Nanog, impeding its repressor function and thereby promoting differentiation. Remarkably, treatment with IQ1, an inhibitor of interaction between acetyltransferase Ep300 and Ctnnb1, enhances acetylation at K49 of Ctnnb1, enabling the establishment and long-term maintenance of embryonic stem cells independently of the leukemia inhibitory factor, and also driving complete conversion of epiblast stem cells to the naïve state. This study reveals the critical role of Ctnnb1 in naïve pluripotency and introduces an effective strategy for its induction and maintenance.

Female‐biased incidence in primary mediastinal large B‐cell lymphoma (PMBCL) is enigmatic and points to a potential contribution of the X chromosome in this disease. To elucidate the postulated involvement of X‐linked factor(s), we profiled the X chromosome in 48 diagnostic PMBCLs of male (21) and female (27) origin. Molecular cytogenetic analysis detected copy number gain of X/Xq in all male patients and 59.3% (16/27) of female patients. The remaining female cases revealed either a cytogenetically cryptic copy‐neutral loss of heterozygosity (CNLOH) of X/Xq (14.8%) or germline XX (25.9%). Remarkably, RNAseq data of 28 cases indicated a nonrandom involvement of transcriptionally active X homolog in gain/CNLOH, validated by hXIST RNA‐fluorescence in situ hybridization (FISH) in two PMBCL‐derived cell lines. Further transcriptomic analysis revealed IL13RA1 (Xq24) as the target of the Xq aberrations. In agreement with this, the vast majority (32/38, 84.2%) of PMBCL cases were IL13RA1‐positive by immunohistochemistry. The intriguing finding of IL13RA1 protein expression in female PMBCLs with germline XX suggests epigenetic reactivation and expression of IL13RA1 on the inactive X. Functional in vitro studies performed on Ba/F3 cells showed that overexpressed IL13RA1 is potent to transform murine pro‐B cells and constitutively activate the oncogenic JAK‐STAT signaling pathway. The novel pathogenic Xq24/IL13RA1 defects appeared as disease‐defining aberrations driving PMBCL and contributing to the related sex disparity. Our findings indicate that female predominance in PMBCL is due to the higher risk of women of acquiring pathogenic Xq24/IL13RA1 defects by female‐exclusive genetic/epigenetic mechanisms (CN‐LOHX and reactivation of IL13RA1 on Xi) not operating in males.

Abstract Acute lymphoblastic leukemia (ALL) is the most prevalent childhood cancer. Bone marrow (BM) fibrosis in ALL has been associated with adverse outcomes, however, little is known about the mechanisms that cause fibrosis in ALL. Therefore, we established a novel and advanced analysis method by combining multi-color immunofluorescence staining with in-situ RNA expression analysis (RNAscope ® ) investigate the spatial expression of putative fibrotic drivers in ALL bone marrows. We analyzed standard BM biopsies from pediatric ALL patients. Sequential 5-color immunofluorescence (IF) staining with CD45, CD271, CD31, CD34 and DAPI was used to identify different BM cell types. Combined RNAscope ® and IF staining was established for spatial mRNA expression analysis of transforming growth factor beta 1 ( TGFB1 ) and platelet-derived growth factor alpha 1 ( PDGFA1 ), which are known to play major roles in primary myelofibrosis (PMF). PMF and normal BM samples served as controls. As expected, ALL bone marrows showed high cellularities and prominent populations of blast cells. CD271 + MSC density was increased in ALL and was associated with fibrosis in a similar manner as observed for PMF. TGFB1 and PDGFA1 expression was considerably increased in ALL megakaryocytes (MKs) compared to PMF patients and normal controls. Furthermore, MK TGFB1 and PDGFA1 expression intensities in fibrotic ALL correlated with fibrosis grade. TGFB1 and PDGFA1 were also expressed in leukemic blasts, however at lower intensities compared to ALL MKs. Taken together, advanced in-situ RNA and IF staining not only revealed increased expression of TGFB1 and PDGFA1 in fibrotic pediatric ALL, but also identified ALL blasts and MKs as their cellular origin at the single cell level. These novel data strongly suggest a role of these cytokines as potential fibrosis drivers in ALL. More broadly, our findings demonstrate that combined RNA and surface marker analysis is a powerful tool to provide new and valuable insights into bone marrow pathophysiology.

IntroductionWe describe a novel colopathy associated with pentosan polysulfate (PPS) use and assess the strength of the drug-disease association in a two-part investigation.Methods1. Cohort Study: We studied individuals with a history of long-term PPS use. Case histories concerning gastrointestinal disease were obtained with review of endoscopy records and histopathology specimens. Findings were summarized with descriptive statistics. 2. Cross-Sectional Study: We evaluated patients with interstitial cystitis at a single clinical center. We obtained data on drug exposure and medical histories and measured the strength of association between PPS use and diagnosis of inflammatory bowel disease (IBD) using multivariate logistic regression.Results1. Cohort Study: Among 13 participants, the median PPS exposure was 2.04 kg (range 0.99–2.54 kg). Eleven participants (84.6%) developed IBD symptomatology after initiating PPS therapy, and 9 (69.2%) were diagnosed with IBD. Two others (18%) were diagnosed with irritable bowel syndrome. Of the 10 participants with endoscopic and histopathologic data, six had abnormal colonic mucosa on endoscopy, and all 10 had histologic abnormalities. Clinical and histologic improvement was noted after PPS cessation, though two (18%) required colectomy for colitis-associated dysplasia. 2. Cross-Sectional Study: Among 219 subjects with interstitial cystitis, PPS use was a statistically significant predictor of an IBD diagnosis, with an adjusted odds ratio of 3.3 (95% confidence interval, 1.2–8.8, p = 0.02).DiscussionOur study identifies a strong association between PPS use and clinical diagnosis of IBD. Histopathologic findings suggest a novel drug-associated colopathy, with some subjects necessitating colectomy for dysplasia. Further investigation into the causality of this association is warranted.