Elevated Oxidative Stress Impairs Hematopoietic Progenitor Function in C57BL/6 Substrains.

Area of Science:

• Hematology
• Immunology
• Mitochondrial Biology

Background:

• C57BL/6N and C57BL/6J mice have genetic differences, notably a non-functional Nicotinamide nucleotide transhydrogenase (Nnt) gene in J mice.
• Nicotinamide nucleotide transhydrogenase (NNT) is crucial for regulating mitochondrial oxidative stress.
• The functional impact of NNT deficiency on hematopoietic stem and progenitor cell (HSPC) activity remains unclear.

Purpose of the Study:

• To investigate the functional equivalence of C57BL/6N (N) and C57BL/6J (J) HSPCs.
• To determine the role of NNT in HSPC function and oxidative stress regulation.

Main Methods:

• Comparative analysis of N-HSPCs and J-HSPCs post-transplant.
• Assessment of hematopoietic repopulating activity, including lymphoid reconstitution.
• Measurement of reactive oxygen species (ROS) levels in HSPCs under basal and stressed conditions.
• Nnt gene knockdown in N-HSPCs to assess functional impact.

Main Results:

• J-HSPCs demonstrated reduced short-term hematopoietic repopulating activity compared to N-HSPCs.
• A delay in lymphoid reconstitution and impaired multi-potent progenitor function was observed in J-HSPCs post-transplant.
• J-HSPCs exhibited elevated ROS levels and a heightened ROS response to hematopoietic stress.
• Nnt knockdown in N-HSPCs mimicked the repopulating defect seen in J-HSPCs.

Conclusions:

• C57BL/6N and C57BL/6J HSPCs are functionally distinct, with J-HSPCs showing compromised repopulating capacity.
• NNT deficiency contributes to impaired HSPC function and increased oxidative stress.
• Substrain selection is critical for HSPC research, as genetic differences impact cell function.