Define the surfaceome landscape of hematopoietic stem cells and pediatric leukemia specimens to improve the development of novel therapies for hematological diseases.
(2019) Cole Foundation research day — Location: Montreal, Canada
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- Authors
Aubert, Léo 
- Abstract
- Background Information: Despite great advances in understanding the pathogenesis of various types of adult and childhood leukemias, there has been little progress in the development of new therapies and the 5-year survival rate remains low due to high incidence of relapse. Over the past decades, hematopoietic stem cell transplantation (HSCT) isolated from umbilical cord blood (CB) has evolved as a potent curative treatment intervention for patients with different type of blood disorders. Unfortunately, many patients are deprived of access to such therapies due to the low stem cell dose in CB units. The group of Dr. Guy Sauvageau and their collaborators have recently discovered a small-molecule, UM171, which promotes the ex vivo expansion of CB HSCs. However, the lack of reliable surface markers that can prospectively identify HSCs is still a major hurdle for the optimization of CB grafts. Purpose of the study: The aim of this collaborative research project is to identify novel and reliable HSC surface markers using a state-of-the-art surfaceomics approach. These results will help better purify and characterize HSCs in vitro, with the ultimate goal of developing novel strategies to achieve better ex vivo expansion of HSCs and generate optimized CB grafts. Methods: We have optimized and adapted a surface proteomic approach to simultaneously identify and quantify surface proteins in UM171-expanded CB cells. As a proof of concept experiment, we first used the hematopoietic cell line, OCI-AML5, which is responsive to UM171-induced cell expansion. To optimize this method for the analysis of CB cells, we performed a OCI-AML5 cell titration and determined the minimal number of hematopoietic cells required. Results: Using the recently discovered HSC marker, EPCR, we have performed a surfaceomics analysis of UM171-expanded CB HSCs and revealed the enrichment in more than 100 surface proteins in the CD34+EPCR+ population. In addition to well-known HSC markers (CD34, EPCR, CD133 and GPR56), we identified several surface proteins that may further subdivide the EPCR-positive population. To determine if these surface molecules are specific to HSC or other hematopoietic populations, their surface expression are being assessed by flow cytometry when antibodies are available. One such candidate could be GPA33, which appears to further subdivide the HSC population from CB cells. We are currently performing transplantation experiments in NSG mice to determine if GPA33 expression correlates with better engraftments. We are also producing unavailable antibodies against the other surface proteins to make possible their expression analysis via flow cytometry. Conclusion: Altogether, our published and preliminary data demonstrate the great potential of our surfaceomics method to identify novel and reliable HSC markers. The availability of the surfaceome landscape of HSCs will undeniably open new avenues for the optimization of HSCT. In addition, our potent surfaceomics approach will offer new opportunities for the development of antibody-based immunotherapies by uncovering targetable surface proteins from primary leukemia specimens.
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Citations
Aubert, L., Tomellini, E., Ansari, U., Chagraoui, J., Girard, S., Bordeleau, M.-E., Sauvageau, G., & Roux, P. P. (2019). Define the surfaceome landscape of hematopoietic stem cells and pediatric leukemia specimens to improve the development of novel therapies for hematological diseases. Cole Foundation research day, Montreal, Canada. https://hdl.handle.net/2078.5/26949