A lyophilized form of xenogeneic total RNA stimulates hematopoiesis in post-radiation myelosuppression

Abstract

Introduction. Allogeneic total RNA isolated from cells of lymphoid organs stimulates regeneration of hematopoietic tissue after acute and chronic disturbance of hematopoietic function. Aim. 1) To prove the absence of xenogeneic limitation for the lymphocytic regulation of regenerative processes using an example of the hemo-stimulating effect of total RNA from bovine spleen lymphocytes on hematopoiesis in rats exposed to sublethal gamma-irradiation; 2) To perform a comparative analysis of the effectiveness of the native and lyophilized forms of the total RNA. Methods. Experiments were performed on white outbred male rats weighing 200-220 g. Total RNA was isolated from bovine spleen lymphoid cells by phenol-chloroform extraction. To create the initial myelosuppression, 30 rats were exposed to a single general ⁶⁰Co gamma radiation (6 Gy at 0.1 Gy/s). The rats were then divided into 3 equal groups. Two hrs after irradiation, the rats of the control group were injected intraperitoneally with 0.5 ml of 0.9% NaCl; rats of the second group received native total RNA, 30 μg/100 g body weight, and rats of the third group received lyophilized total RNA at a similar dose. On days 3, 7, and 12, the number of peripheral blood reticulocytes, leukocytes, and platelets was measured. The rats were then sacrificed, and bone marrow hematopoiesis was studied. After 12 days, the number of bone marrow erythroid, lymphoid, megakaryocytic, and myeloid cells was measured. Erythroblastic islets (EIs) were isolated from the bone marrow and differentiated into proliferating (class 1 and 2 EIs and reconstructing EIs) and mature (class 3 EIs and involving EIs) morpho-functional cell associations. Results. Under the influence of xenogeneic total RNA, the number of peripheral blood leukocytes increased by 2-3 times, and the number of reticulocytes increased by 1.6-1.75 times. In the bone marrow, the number of proliferating myeloid and lymphoid cells increased, as did the total number of erythroid cells. Xenogeneic total RNA stimulated formation of EIs, based both on the contact of free bone marrow macrophages with young erythroid cells (class 1 and 2 EIs) and on reconstruction (reconstructing EIs). Comparative analysis of the effects of native and lyophilized total RNA did not reveal differences between hematopoietic parameters in rats that received these agents. Conclusion. Total RNA isolated from bovine spleen lymphoid cells activates hematopoiesis in rats with post-radiation myelosuppression. This indicates the absence of mammalian xenogenic limitation of lymphocytic control of recovery processes. Lyophilized total RNA activates bone marrow hematopoiesis at the same rate and to the same extent as the native form.