Dose- and time-dependent effects of cobalt protoporphyrin IX on granulocyte mobilization and metabolic markers in mice

Abstract

Recombinant granulocyte colony-stimulating factor (G-CSF) is the most commonly used agent for treating neutropenia and mobilizing hematopoietic stem cells (HSCs) for transplantation. However, some patients do not respond effectively to existing mobilization protocols. To address this, the development of new therapeutic approaches is necessary. One potential strategy is the pharmacological induction of endogenous mobilizing factors, which can be achieved through the administration of cobalt protoporphyrin IX (CoPP). CoPP induces mobilization of HSCs and granulocytes by increasing endogenous G-CSF production, though the optimal dosing and potential side effects remain unclear. The aim of our study was to optimize the dose and timing of CoPP administration and evaluate its safety in mobilizing cells from the bone marrow to the blood. Our results show that CoPP exerts a dose-dependent mobilizing effect, with the highest G-CSF levels and number of mobilized leukocytes observed in mice treated with 10 mg/kg of CoPP. While there were no severe adverse effects, there were mild fluctuations in markers of liver and kidney function, including a slight reduction in urea nitrogen (BUN) and glucose levels during the five days of administration. Additionally, although most parameters normalized within 30 days after treatment, the decrease in BUN persisted. Mice experienced short-term weight loss following CoPP administration, but they regained their initial weight within two weeks. By day 30, leukocyte counts, hematopoietic stem and progenitor cells (HSPCs) in bone marrow, and G-CSF concentration in the blood had returned to baseline. This study demonstrates that CoPP mobilizes cells from the bone marrow to the blood in a dose-dependent manner, with mild side effects, including temporary changes in biochemical markers and a sustained reduction in BUN levels.