Gene expression analysis of lentivirally-transduced rhesus macaque CD34+ cells long-term following transplant. Macaca mulatta

The occurrence of clonal perturbations and leukemia in patients transplanted with retrovirally-transduced autologous hematopoietic stem and progenitor cells (HSPCs) has stimulated extensive investigation, demonstrating that proviral insertions perturb adjacent proto-oncogene expression. Although enhancer-deleted lentiviruses are less likely to result in insertional oncogenesis, there is evidence that they may perturb transcript splicing, and one patient with a benign clonal expansion of lentivirally-transduced HPSC has been reported. The rhesus macaque model provides an opportunity for informative long-term analysis to ask whether transduction impacts on long-term HSPC properties. We utilized two techniques to examine whether lentivirally-transduced HSPCs from eight rhesus macaques transplanted 1-13.5 years previously are perturbed at a population level, comparing telomere length as a measure of replicative history and gene expression profile of vector positive versus vector negative cells. There were no differences in telomere lengths between sorted GFP+ and GFP- blood cells, suggesting that lentiviral transduction did not globally disrupt replicative patterns. Bone marrow GFP+ and GFP- CD34+ cells showed no differences in gene expression using unsupervised and principal component analysis. These studies did not uncover any global long-term perturbation of proliferation, differentiation, or other important functional parameters of transduced HSPCs in the rhesus macaque model. Overall design: CD34+ hematopoietic stem and progenitor cells were purified from bone marrow aspirates obtained from 4 rhesus macaques 3-9 years following transplantation with lentivirally-transduced autologous hematopoietic stem and progenitor cells. All lentiviral vectors contained the GFP marker gene. The CD34+ cells from each animal were sorted via flow cytometry into GFP+ and GFP- fractions, and RNA from these cells was used for Affymetrix gene expression analysis as detailed below. There were two samples, GFP+ and GFP-, from each of 4 animals.