A human neuron injury model for molecular studies of axonal regeneration.

The enhancement of regeneration of damaged axons in both the peripheral and central nervous systems is a widely pursued goal in clinical medicine. Although some of the molecular mechanisms involved in the intrinsic neurite regeneration program have been elucidated, much additional study is required for development of new therapeutics. The majority of studies in the field of axonal regeneration have utilized animal models due to obvious limitations of the accessibility of human neural tissues. Here we describe the use of human embryonic stem cell (hESC)-derived neurons as a novel model for studying neuronal responses to axonal injury. Neurons were generated using PA6 induction and neurites injured in vitro using trituration or laser microdissection. Lesioned neurons re-extended neurites with distinct growth cones. Expression of proteins associated with regeneration were observed in this human in vitro system, including appearance of importin beta1 in processes after neuritomy. Laser-transected hESC-derived neuronal cultures were analyzed for their transcriptional response to injury using Affymetrix expression microarrays. Profound changes in gene expression were observed over a time course of 2 to 24 hours after lesion. The expression of several genes reported to be involved in axonal injury responses in animal models changed following injury of hESC-derived neurons. Thus, hESC-derived neurons may be a useful in vitro model system for mechanistic studies on human axonal injury and regeneration.

Human T-leukemia and T-lymphoma express glutamate receptor AMPA GluR3, and the neurotransmitter glutamate elevates the cancer-related matrix-metalloproteinases inducer CD147/EMMPRIN, MMP-9 secretion and engraftment of T-leukemia in vivo.

Glutamate is the major excitatory neurotransmitter of the nervous system. We previously found that glutamate activates normal human T-cells, inducing their adhesion and chemotaxis, via its glutamate receptors of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) subtype 3 (GluR3) expressed in these cells. Here, we discovered that human T-leukemia (Jurkat) and cutaneous sezary T-lymphoma (HuT-78) cells also express high levels of GluR3. Furthermore, glutamate (10 nM) elevates CD147/EMMPRIN, a cancer-associated matrix metalloproteinases (MMPs) inducer, promoting spread of many tumors. Glutamate-induced CD147 elevation in both cancerous and normal human T-cells was mimicked by AMPA (glutamate/AMPA-receptor agonist) and blocked by CNQX (glutamate/AMPA-receptor antagonist). Importantly, glutamate also increased gelatinase MMP-9 secretion by T-lymphoma. Finally, ex vivo pre-treatment of T-leukemia with glutamate enhanced their subsequent in vivo engraftment into chick embryo liver and chorioallantoic membrane. Together, these findings reveal that glutamate elevates cancer associated proteins and activity in T-cell cancers and by doing so may facilitate their growth and spread, especially to and within the nervous system. If so, glutamate receptors in T-cell malignancies should be blocked.

Engraftment of human blood malignancies to the turkey embryo: a robust new in vivo model.

Xenografting of human blood malignancies to immunodeficient SCID mice is a powerful research tool. We evaluate here whether the immunodeficient turkey embryo can also serve as a xenograft host for human blood malignancies. Human leukemia, lymphoma and myeloma lines engrafted robustly into medullary and extramedullary tissues of turkey embryos as detected by PCR, FACS and histology in 8-10 days. Four of eleven patient AML samples also engrafted the bone marrow. Grafts of two lines responded to chemotherapy with doxorubicin. The turkey embryo therefore has the potential to be a complementary xenograft model for the study of human blood malignancies.