Oral Administration of PBI-1402 Significantly Reduces Erythropenia and Accelerates Peripheral Blood Recovery in Myeloablated Mice Post Transplantation.

The goal of this study was to determine the potential of PBI-1402, a compound that was shown to provide radio- and chemoprotection, to ameliorate the myeloablative therapy induced cytopenia and/or accelerate blood cell recovery of myeloablated hosts following autologous bone marrow transplantation in mouse model. Mice were exposed to irradiation and transplanted the following day with 5×10⁵ bone marrow cells from syngeneic donors. Following transplantation, mice were divided into two groups that received two different doses of PBI-1402 orally and a control group that received PBS for 14 days post transplantation. The results showed that PBI-1402 treatment significantly diminished post-transplant erythropenia in a dose dependent manner. Similarly, determination of haemoglobin (Hb) demonstrated a significant attenuation of Hb loss and additionally, significantly accelerated post-transplantation recovery with the highest dose of PBI-1402. A significantly higher number of platelets was observed with the highest dose of PBI-1402. In addition, similar results were obtained with analysis of white blood cell (WBC) recovery. To determine if the observed effect of PBI-1402 treatment on red blood cell cytopenia and Hb recovery is the consequence of increased erythrocyte progenitor response to Epo, we performed an Epo dose response experiment on CFU-E bone marrow samples obtained from treated and control mice at different time points post transplantation. The results indicated that erythroid progenitors from treated and control mice responded similarly to Epo. However, PBI-1402 treated mice contained significantly higher number of CFU-E. Interestingly, analysis of more primitive Sca1+ progenitors revealed a significant increase in the number of Sca1+ cells from the bone marrow of mice treated with PBI-1402 (p < 0.05). These results demonstrate that PBI-1402 treatment significantly reduced irradiation induced erythropenia with concomitant acceleration in erythroid and Hb recovery. Additionally, treatment with PBI-1402 accelerated WBC recovery and platelet recovery and increased more primitive Sca1+ progenitors. PBI-1402 may offer protection from myeloabaltive therapy or accelerate recovery from remaining resident or transplanted stem cells.