Ex Vivo Expansion of Hematopoietic Stem Cells in Conditioned Medium

Immunodeficient children are currently treated with allogenic hematopoietic stem cell (HSC) transplants. Initially, it can be extremely difficult to identify a suitable healthy stem cell donor. Once a donor is found, these transplants introduce severe and potentially life-threatening complications known as ‘Graft-versus-Host disease’, which persist throughout the patient’s lifetime.

The Inspiration Behind the Innovation 

Autotransplantation using a patient’s own gene-edited HSC could circumvent the need for a stem cell donor and mitigate the severe side effects associated with allogenic transplantation. The introduction of CRISPR/Cas9-based gene editing has made precise gene correction possible. However, its clinical introduction is dependent on larger numbers of HSC than what is presently available post-correction, as well as HSC with retained stemness to enable lifelong function after autotransplantation.

The Innovation 

After attempting co-culture with mesenchymal stem cells (MSC) to mimic the interaction of HSC and MSC in bone marrow, the team has demonstrated that heat-activated MSC (HI-MSC) without metabolic activity and evenly conditioned medium from HI-MSC have the ability to support the expansion of HSC with increased retention of hematopoietic stemness as compared to conventional culture conditions. This increase in stemness is key to a successful introduction of CRISPR/Cas9-based gene editing of HSC, and may also facilitate autologous HSC transplantation in patients with inferior mobilisation of stem cells after G-CSF treatment.

This solution uses inactivated mesenchymal stem cells and derivatives for GMP-compliant expansion of hematopoietic stem cells. This will be combined with gene-editing of HSC, resulting in a therapeutic relevant amount of edited cells with retained stemness, which fills an unmet medical need for a group of patients who are dependent on hematopoietic stem cell transplantation.

The Team 

Bjarne Møller: Head Consultant, Assoc. Professor; Department of Clinical Immunology, Aarhus University Hospital; Aarhus University

Anne Louise S. Revenfeld: Clinical Specialist; Department of Clinical Immunology, Aarhus University Hospital; Aarhus University