Identification of a Factor That Rescues Dysregulated Endocytosis in Cultured Human Hematopoietic Stem Cells (UCLA Case No. 2023-051)

UCLA researchers in the Departments of Molecular, Cell & Developmental Biology have developed a novel method to enhance the function of hematopoietic stem cells (HSCs) to improve the transplantability of ex vivo expanded human HSCs in clinical settings.

BACKGROUND: Hematopoietic stem cells (HSCs), present in blood and bone marrow, can form mature blood cells, including red blood cells, platelets, and white blood cells. These cells are used in bone marrow transplants (BMT) to replace or rebuild a patient's hematopoietic system. According to the FDA, there are over 75 diseases afflicting millions of lives that can be treated by BMT. However, during ex vivo culture, HSC self-renewal and engraftment ability are severely compromised, hindering the ability to manipulate and expand functional HSCs for therapeutic use. The biological processes governing HSC self-renewal and engraftment ability are still not fully elucidated and can’t be perfectly recapitulated ex vivo. Despite recent advances, the ability to expand functional human HSCs in culture for therapeutic use remains limited.

INNOVATION: UCLA researchers have recently developed a new method to enhance the function of HSCs to improve the transplantability of ex vivo expanded human HSCs in clinical settings. To achieve this, UCLA researchers have elucidated various mechanisms underlying culture-associated HSC dysfunction in which MYCT1 (Myc target 1), an endosomal protein, governs HSC stemness through interacting with vesicle trafficking and signaling components. Experiments showed that MYCT1 knockdown led to hyperactivation of endocytosis, increased ROS (reactive oxygen species) and dysregulation of cell division and self-renewal genes while MYCT1 overexpression had the opposite effect. Furthermore, the enhanced function of HSCs is achieved through the introduction of a recombinant lentiviral vector to express MYCT1 in HSCs. Restoring proper MYCT1 levels in cultured HSC improves the ability to expand transplantable human HSCs in culture without negative effects on differentiation. The use of this technology allows for control of endocytosis needed for therapeutic gene modifications of HSCs. The development of this method is an important step forward in the field of hematopoietic stem cell gene therapy and has the potential to significantly improve patient outcomes in the future.

POTENTIAL APPLICATIONS:

• Restoring defective MYCT1 expression of HSCs for transplantation
• Restore compromised function of ex vivo expanded human HSCs.
• Increase the ability to maintain the stemness of HSCs in ex vivo culture.

ADVANTAGES:

• This invention allows ex vivo expanded human HSCs to be transplantable in BMT, a successful therapy for blood disorders
• Maintenance of HSCs in culture allows for enables safer and more efficient use of CRISPR technology to correct disease-causing mutations

DEVELOPMENT-TO-DATE: The effectiveness of this invention has been demonstrated with ex vivo cultured HSCs using relevant lab models. Application of the engineered ex vivo HSCs in BMTs for human subjects is pending.

Related Papers (from the inventors only): 

• Aguade-Gorgorio, J., Kardouh, M., Jami-alahmadi, Y., Fares, I., Calvanese, V., Magnusson, M., ... & Mikkola, H. (2021). 2009–THE ENDOSOMAL ADAPTOR PROTEIN MYCT1 CONTROLS HUMAN HEMATOPOIETIC STEM CELL FUNCTION. Experimental Hematology, 100, S31-S32.
• Calvanese, V., Nguyen, A. T., Bolan, T. J., Vavilina, A., Su, T., Lee, L. K., ... & Mikkola, H. K. (2019). MLLT3 governs human haematopoietic stem-cell self-renewal and engraftment. Nature, 576(7786), 281-286.

Keywords: hematopoietic stem cells, HSCs, bone marrow transplants, BMT, transplantability, engraftment, MYCT1, endocytosis, environmental sensing, MLLT3, CRISPR, leukemia, sickle cell anemia, beta-thalassemia, blood disorders