Fatma Visal Okur

Preimplantation genetic diagnosis (PGD) with human leukocyte antigen (HLA) typing represents a significant advancement in treating inherited hematological disorders, particularly thalassemia major. This technology enables the birth of healthy children who can serve as compatible stem cell donors for their affected siblings. Turkey is a world leader in both PGD+HLA typing technology and hematopoietic stem cell transplantation from savior siblings born through PGD+HLA typing. This study investigated the experiences of Turkish parents who underwent successful savior sibling procedures using preimplantation genetic diagnosis (PGD) with human leukocyte antigen (HLA) typing and then successful hematopoietic stem cell transplantation, from this savior sibling, for the treatment of their thalassemia major child. The research aimed to understand the medical, psychological, and socio-cultural dimensions of this complex process within the Turkish healthcare context. A qualitative study using descriptive phenomenological approach was conducted. In-depth interviews were performed with 16 parents, who successfully completed PGD+HLA matching and subsequent successful stem cell transplantation process from this savior sibling to their thalassemia child. Data were analyzed using Colaizzi's seven-step method and MAXQDA 20.0 software. Analysis revealed six main themes: Disease Stage, Treatment, Recovery Process, Social Family, Support Systems, and Recommendations. Parents reported significant emotional challenges but demonstrated unexpected resilience. Religious and cultural factors played nuanced roles, with most parents viewing the process as compatible with their beliefs. Economic burden, prolonged hospitalizations, and geographical access to treatment centers emerged as key challenges. Extended family support and healthcare professional guidance were identified as crucial support mechanisms. The study highlights the complex interplay between advanced medical technologies and traditional values in Turkish society. Findings emphasize the need for comprehensive, culturally sensitive support systems and long-term follow-up for families. Results suggest implementing multidisciplinary care teams and developing specialized support programs for families undergoing savior sibling procedures.

Fanconi anemia is the most common inherited bone marrow failure syndrome. HSCT remains the only curative treatment for hematological manifestations of FA. Despite restoration of long-term hematopoiesis, patients continue to remain at risk of late effects. In our study, we aimed to reveal the problems that occur in the long-term follow-up of FA patients, and point out an ongoing need for the improvement of long-term follow-up guidelines for childhood transplant survivors with FA. In this single centered, cross-sectional study, we analyzed the long-term outcome of 36 patients with FA according to current recommendations with a median age of 18.1 years (range: 6.1-36 years, male/female, 24/12) who underwent a HSCT at Pediatric Bone Marrow Transplantation (BMT) Unit between 1995 and 2019 and survived at least one year post-transplant. The median long-term follow-up time was 8 years (range, 1-25 years). Gonadal dysfunction was detected in about 35% of our patients. 31% of the patients had hypergonadotropic hypogonadism, 4 % had hypogonadotropic hypogonadism. When the patients were evaluated for growth impairment, 7 of 12 patients who reached their final adult height and 12 of 21 patients who didn't complete their growth, had height standard deviation score below -2 SD. Three patients (9%) developed subclinical hypothyroidism, two (6%) had overt hypothyroidism and one (3%) had central hypothyroidism. Although, none of our patients fully met the criteria for metabolic syndrome, 23% of the patients had insulin resistance and 39% had dyslipidemia. Evaluation of organ dysfunctions revealed that almost 50% of the patients had obstructive and 21 % had restrictive changes in their pulmonary function tests. Hepatosteatosis was detected in 15% of the patients and mild valve dysfunction was detected in 50 % of evaluable patients. Three patients developed secondary malignancies. Squamous cell cancer developed in 2 patients and basal cell cancer in one patient. A risk-defined multidisciplinary approach for long-term follow up of children with FA undergoing HSCT is essential for early detection and management of late effects.

Osteopetrosis is a rare inherited disease characterized by impaired osteoclast activity causing defective bone resorption and bone marrow aplasia. It is fatal in early childhood unless hematopoietic stem cell transplantation is performed. But, the transplant course is complicated with engraftment failure. Recently, osteoclasts have been described as the potential regulators of hematopoietic stem cell (HSC) niche. Here we investigated the alterations in the HSC and mesenchymal stromal cell (MSC) components of osteopetrotic niche and their interactions to mimic the stem cell dynamics/trafficking in the BM niche after HSC transplantation. Induced pluripotent stem cells were generated from peripheral blood mononuclear cells of patients with osteopetrosis carrying TCIRG1 mutation. iPSC lines were differentiated into hematopoietic and myeloid progenitors, then into osteoclasts using a step-wise protocol. We first demonstrated a shift toward monocyte-macrophages lineage regarding hematopoietic differentiation potential of osteopetrotic iPSC-derived hematopoietic progenitors (HPCs) and phenotypically normal and functionally defective osteoclast formation. The expression of the genes involved in HSC homing and maintenance (Sdf-1, Jagged-1, Kit-L, and Opn) in osteopetrotic MSCs recovered significantly after coculture with healthy HPCs. Similarly, the restoration of phenotype, impaired differentiation, and migratory potential of osteopetrotic iHPCs were observed upon interaction with healthy MSCs. Our results establish significant alterations in both MSC and HPC compartments of the osteopetrotic niche, and support the impact of functionally impaired osteoclasts in defective niche formation.

We report the national data on the outcomes of hematopoietic stem cell transplantation (HSCT) for thalassemia major (TM) patients in Turkey on behalf of the Turkish Pediatric Stem Cell Transplantation Group. We retrospectively enrolled 1469 patients with TM who underwent their first HSCT between 1988 and 2020 in 25 pediatric centers in Turkey. The median follow-up duration and transplant ages were 62 months and 7 years, respectively; 113 patients had chronic graft versus host disease (cGVHD) and the cGVHD rate was 8.3% in surviving patients. Upon the last visit, 30 patients still had cGvHD (2.2%). The 5-year overall survival (OS), thalassemia-free survival (TFS) and thalassemia-GVHD-free survival (TGFS) rates were 92.3%, 82.1%, and 80.8%, respectively. cGVHD incidence was significantly lower in the mixed chimerism (MC) group compared to the complete chimerism (CC) group (p < 0.001). In survival analysis, OS, TFS, and TGFS rates were significantly higher for transplants after 2010. TFS and TGFS rates were better for patients under 7 years and at centers that had performed over 100 thalassemia transplants. Transplants from matched unrelated donors had significantly higher TFS rates. We recommend HSCT before 7 years old in thalassemia patients who have a matched donor for improved outcomes.

Objective: Angiogenic factors (AFs) released under endothelial stress are reflective of tissue healing, while some may also contribute to tissue damage/inflammation. We investigated whether alterations in the pre-transplant levels of AFs were associated with the risk of acute graft-versus-host disease (aGvHD). Materials and Methods: The pre-conditioning plasma levels of angiopoietin-2 (Ang2), endoglin, and follistatin were measured for 37 patients together with inflammatory markers. The index values defined were evaluated to better identify the alterations. Results: The patients had higher pre-conditioning levels of Ang2, endoglin, and follistatin compared to controls. The patients with aGvHD had higher Ang2 index and lower albumin index scores in comparison to those without aGvHD. Multivariate analysis revealed that the pre-transplant Ang2 index was an independent risk factor for aGvHD development. Conclusion: Pre-transplant evaluation of plasma Ang2 levels along with inflammatory status even before conditioning is associated with endothelial vulnerability. The pre-transplant Ang2 index could be a promising candidate to estimate the risk of aGvHD.

Objective: Uric acid (UA), a known danger signal released from injured cells, is a valuable sign of inflammation. We aimed to evaluate the association of serum UA levels before the start of conditioning regimens with the risk of hepatic sinusoidal obstruction syndrome (SOS) development after hematopoietic stem cell transplantation (HSCT). Materials and Methods: Two hundred and twenty-two children who underwent allogeneic HSCT at the Pediatric BMT Unit of Hacettepe University between 2000 and 2014 were included in this retrospective study. Serum UA levels were measured before conditioning as an indicator of the pre-transplant inflammatory status of the patients. Patients with and without a diagnosis of SOS were compared regarding primary diagnosis, previously described risk factors for SOS, and preconditioning serum UA. Results: SOS was diagnosed in 42 patients who had higher pre-conditioning serum UA levels compared to those who did not. Pre-transplant serum creatinine, gamma-glutamyl transferase, bilirubin, ferritin, and C-reactive protein levels did not differ significantly among patients with and without SOS; however, serum albumin was lower in the patients who developed SOS. Receiver operating characteristic analysis revealed that a pre-conditioning UA level higher than 3.32 mg/dL was predictive of SOS. When applied to a multivariate model, only pre-conditioning UA and albumin levels remained significant risk factors for SOS (UA: odds ratio [OR], 2.54; 95% confidence interval [CI], 1.26-5.12, p=0.009; albumin: OR, 0.45, 95% CI, 0.22-0.95, p=0.037). Conclusion: Our results suggest that pre-conditioning serum UA is an independent risk factor for SOS, and it might be used as an early predictor of hepatic SOS together with previously described clinical and laboratory parameters.

Background Patients with osteopetrosis present with defective bone resorption caused by the lack of osteoclast activity and hematopoietic alterations, but their bone marrow hematopoietic stem/progenitor cell and osteoclast contents might be different. Osteoclasts recently have been described as the main regulators of HSCs niche, however, their exact role remains controversial due to the use of different models and conditions. Investigation of their role in hematopoietic stem cell niche formation and maintenance in osteopetrosis patients would provide critical information about the mechanisms of altered hematopoiesis. We used patient-derived induced pluripotent stem cells (iPSCs) to model osteoclast defect and hematopoietic niche compartments in vitro. Methods iPSCs were generated from peripheral blood mononuclear cells of patients carrying TCIRG1 mutation. iPSC lines were differentiated first into hematopoietic stem cells-(HSCs), and then into myeloid progenitors and osteoclasts using a step-wise protocol. Then, we established different co-culture conditions with bone marrow-derived hMSCs and iHSCs of osteopetrosis patients as an in vitro hematopoietic niche model to evaluate the interactions between osteopetrotic-HSCs and bone marrow-derived MSCs as osteogenic progenitor cells. Results We first demonstrated myeloid-skewed hematopoietic differentiation potential of osteopetrotic iPSC-derived hematopoietic progenitors and phenotypically normal and functionally defective osteoclast formation. Upon co-culture with healthy iHSCs, the expression of the genes involved in HSC homing and maintenance (Ang-1, Sdf-1, Jagged-1, N-Cadherine, Kit-L, Opn) in osteopetrotic MSCs which revealed impaired osteogeneic differentiation, as well as their attraction ability over HSCs recovered significantly. Similar change in the phenotype of osteopetrotic iHSCs occured when they interacted with healthy MSCs. Conclusion Our results establish significant alterations in both MSC and HSC compartments of the hematopoietic niche in osteopetrosis patients, which are restored with normal MSC activity supporting the role of defective osteoclasts in all these processes.