Reprogramming of bone marrow derived mesenchymal stromal cells to human induced pluripotent stem cells from pediatric patients with hematological diseases using a commercial mRNA kit.

The potential use of patient-specific induced pluripotent stem cells (hiPSCs) in the study and treatment of hematological diseases requires the setup of efficient and safe protocols for hiPSC generation. We aimed to adopt a reprogramming method for large-scale production of integration-free patient-specific hiPSC-lines in our stem cell processing laboratory, which supports a pediatric hematopoietic stem cell transplant unit located at a tertiary care children's hospital. We describe our 5-year experience in generation of hiPSC-lines from human bone marrow-derived mesenchymal stromal cells (BM-MSCs) using synthetic mRNAs encoding reprogramming factors. We generated hiPSC-lines from pediatric patients with ß-Thalassemia, Sickle Cell Anemia, Blackfan-Diamond Anemia, Severe Aplastic Anemia, DOCK8 Immunodeficiency and 1 healthy control. After optimization of the reprogramming procedure, average reprogramming efficiency of BM-MSCs was 0.29% (range 0.25-0.4). The complete reprogramming process lasted 14-16 days. Three to five hiPSC-colonies per sample were selected, expanded to 5 culture passages and then frozen. The whole procedure took an average time of 1.8 months (range 1.6-2.2). The hiPSC-lines expressed embryonic stem cell markers and exhibited pluripotency. This mRNA reprogramming method can be applicable in a hematopoietic stem cell culture lab setting and would be useful for the clinical translation of patient-specific hiPSCs.

Richter's transformation as leptomeningeal infiltration in a chronic lymphocytic leukemia patient receiving venetoclax. Could blood-brain barrier be a disease "sanctuary" during venetoclax treatment?

Our unique case of Richter's Transformation presenting as leptomeningial infiltration in a CLL patient receiving venetoclax raises questions on whether the drug penetrates the blood-brain barrier and at what extend, especially in reduced doses given for drug-drug interactions.