Non-human primates are valuable for modelling human disorders and for developing therapeutic strategies; however, little work has been reported in establishing transgenic non-human primate models of human diseases. Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder characterized by motor impairment, cognitive deterioration and psychiatric disturbances followed by death within 10-15 years of the onset of the symptoms 1-4 . HD is caused by the expansion of cytosineadenine-guanine (CAG, translated into glutamine) trinucleotide repeats in the first exon of the human huntingtin (HTT) gene 5 . Mutant HTT with expanded polyglutamine (polyQ) is widely expressed in the brain and peripheral tissues 2,6 , but causes selective neurodegeneration that is most prominent in the striatum and cortex of the brain. Although rodent models of HD have been developed, these models do not satisfactorily parallel the brain changes and behavioural features observed in HD patients. Because of the close physiological 7 , neurological and genetic similarities 8,9 between humans and higher primates, monkeys can serve as very useful models for understanding human physiology and diseases 10,11 . Here we report our progress in developing a transgenic model of HD in a rhesus macaque that expresses polyglutamine-expanded HTT. Hallmark features of HD, including nuclear inclusions and neuropil aggregates, were observed in the brains of the HD transgenic monkeys. Additionally, the transgenic monkeys showed important clinical features Correspondence to: Anthony W. S. Chan.Author Information Reprints and permissions information is available at www.nature.com/reprints. Correspondence and requests for materials should be addressed to A.W.S.C. (achan@genetics.emory.edu).. * These authors contributed equally to this work. Author Contributions S.-H.Y. carried out assisted reproductive technique (ART) in monkeys, viral gene transfer, construct design and molecular analysis; P.-H.C., construct design and evaluation; K.P.-N., ART in monkeys; H.B., animal management; behavioural testing and all animal procedures; K.L., animal care and behavioural testing; E.C.H.C., molecular analysis; J.-J.Y., preparation of high titre lentiviruses; B.S., J.L. and Z.H.F., neuropathological analysis; J.O., surgical procedures and animal care; Y.S., neuropathological analysis; J.B., design of behavioural and cognitive testing; S.M.Z., experimental design and manuscript preparation; S.H.L. and X.J.-L., construct design, analysis and manuscript preparation; A.W.S.C., ART in monkey, viral gene transfer, experimental design, construct design, molecular analysis and manuscript preparation. We injected 130 mature rhesus oocytes with high titre lentiviruses expressing exon 1 of the human HTT gene with 84 CAG repeats (HTT-84Q; Fig. 1c) and lentiviruses expressing the green fluorescent protein (GFP) gene (Fig. 1c), under the control of the human polyubiquitin-C promoter, into the perivitelline space. After fertilization by intracytoplasmic sperm injecti...

Gene therapy for motor neuron diseases requires efficient gene delivery to motor neurons (MNs) throughout the spinal cord and brainstem. The present study compared adeno-associated viral (AAV) vector serotypes 1, 6, 8, and 9 for spinal cord delivery in adult mice, by the intraparenchymal or intrathecal route of administration. Whereas intraparenchymal injections resulted in local transduction of the lumbar segment of the spinal cord, intrathecal injections led to a broader distribution, transducing cells along the sacral, lumbar, and lower thoracic spinal cord. Overall, AAV6 and AAV9 performed better than the other serotypes. Dramatic differences in cell-specific expression patterns could be observed when constructs bearing the chicken β-actin (Cba) versus cytomegalovirus (CMV) promoter were compared. In summary, intrathecal delivery of AAV6 or AAV9 vectors containing the CMV promoter yielded the strongest levels of biodistribution and MN transduction in the spinal cord.

Until now, interest in dental pulp stem/stromal cell (DPSC) research has centered on mineralization and tooth repair. Beginning a new paradigm in DPSC research, we grafted undifferentiated, untreated DPSCs into the hippocampus of immune-suppressed mice. The rhesus DPSC (rDPSC) line used was established from the dental pulp of rhesus macaques and found to be similar to human bone marrow/mesenchymal stem cells, which express Nanog, Rex-1, Oct-4, and various cell surface antigens, and have multi-potent differentiation capability. Implantation of rDPSCs into the hippocampus of mice stimulated proliferation of endogenous neural cells and resulted in the recruitment of pre-existing Nestin+ neural progenitor cells (NPCs) and β-tubulin-III+ mature neurons to the site of the graft. Additionally, many cells born during the first 7 days after implantation proliferated, forming NPCs and neurons, and, to a lesser extent, underwent astrogliosis, forming astrocytes and microglia, by 30 days after implantation. Although the DPSC graft itself was short term, it had long-term effects by promoting growth factor signaling. Implantation of DPSCs enhanced the expression of ciliary neurotrophic factor, vascular endothelial growth factor, and fibroblast growth factor for up to 30 days after implantation. In conclusion, grafting rDPSCs promotes proliferation, cell recruitment, and maturation of endogenous stem/progenitor cells by modulating the local microenvironment. Our results suggest that DPSCs have a valuable, unique therapeutic potential, specifically as a stimulator and modulator of the local repair response in the central nervous system. DPSCs would be a preferable cell source for therapy due to the possibility of a “personalized” stem cell, avoiding the problems associated with host immune rejection.

This article lays out five standards for judging the importance of randomized field trials in estimating the relative effects of new programs and new variations on existing programs. These standards include contemporary evaluation policy, the historical development of trials in diverse sciences, ethics, normative practice, and the credibility of alternative approaches to estimating the effects of programs or variations. Empirical evidence and a line of reasoning bearing on each standard are made plain.