I. Expression of IGF-II and IGFBPs in developing fetal rhesus monkey (Macaca mulatta) tissues. II. Characterization of fetal rhesus monkey hematopoietic and mesenchymal stem cells.

摘要

The insulin-like growth factor (IGF) is the major modulator of somatic fetal growth and differentiation, and understanding spatial and temporal patterns of expression may provide important insights into the utilization of the IGF system for gene therapy approaches. Studies focused on the expression of IGF-II, IGF-binding protein-1 (IGFBP-1), and IGFBP-3 genes in fetal liver, kidney, brain, and lung in the second and third trimesters. These studies have provided information which suggests that fetal monkey tissues express IGF-II and IGFBP mRNAs in a similar manner when compared to human fetuses. In order to further explore cellular ontogeny issues, the characteristic features of fetal hematopoietic stem cells (HSC), bone marrow-derived mesenchymal stem cells (MSC) or stromal cells, and the effects of simian immunodeficiency virus (SIV) infection on these stem cell populations in vivo was also investigated. To study the characteristic features of fetal HSC, immunoselected CD34 + and mononuclear cells derived from blood and bone marrow from fetal, newborn, infant, adult, and aged monkeys were evaluated for their frequency, cell cycle status, and differentiation potential. The growth and transduction kinetics of rhesus MSC (rhMSC) using an HIV-1-derived lentiviral vector, and the effects of transduction on the cell cycle were also explored. Finally, we investigated the potential for SIV infection of early CD34+CD38 − HSC, more mature CD34−CD38+ hematopoietic progenitors, and marrow stromal cells to better characterize bone marrow abnormalities in SIV-infected fetuses in vivo, using a well-characterized fetal rhesus monkey model. Results indicate that: (1) IGF-II, IGFBP-1, and IGFBP-3 are expressed in developing fetal monkeys in a cell type- and age-specific manner, suggesting that the utilization of the IGF-II promoter may be beneficial for fetal gene therapy applications; (2) fetal HSC contain higher self-renewal and differentiation potential compared to older animals, and are resistant to SIV infection; and (3) HIV-1-derived lentiviral vectors can efficiently transduce rhMSC in vitro. Overall, the results of these studies provide unique insights into fetal primate stem cell populations and IGF gene expression, information which is highly relevant in the design of novel in utero therapies for the treatment of human congenital diseases.