Engineered neurogenesis in naïve adult rat cortex by Ngn2-mediated neuronal reprogramming of resident oligodendrocyte progenitor cells.

Adult tissue stem cells contribute to tissue homeostasis and repair but the long-lived neurons in the human adult cerebral cortex are not replaced, despite evidence for a limited regenerative response. However, the adult cortex contains a population of proliferating oligodendrocyte progenitor cells (OPCs). We examined the capacity of rat cortical OPCs to be re-specified to a neuronal lineage both in vitro and in vivo. Expressing the developmental transcription factor Neurogenin2 (Ngn2) in OPCs isolated from adult rat cortex resulted in their expression of early neuronal lineage markers and genes while downregulating expression of OPC markers and genes. Ngn2 induced progression through a neuronal lineage to express mature neuronal markers and functional activity as glutamatergic neurons. In vivo retroviral gene delivery of Ngn2 to naive adult rat cortex ensured restricted targeting to proliferating OPCs. Ngn2 expression in OPCs resulted in their lineage re-specification and transition through an immature neuronal morphology into mature pyramidal cortical neurons with spiny dendrites, axons, synaptic contacts, and subtype specification matching local cytoarchitecture. Lineage re-specification of rat cortical OPCs occurred without prior injury, demonstrating these glial progenitor cells need not be put into a reactive state to achieve lineage reprogramming. These results show it may be feasible to precisely engineer additional neurons directly in adult cerebral cortex for experimental study or potentially for therapeutic use to modify dysfunctional or damaged circuitry.

Intravascular Large B-Cell Lymphoma Presenting as Acute Axonal Polyneuropathy: A Case Report and Literature Review.

Intravascular large B-cell lymphoma (ILBL) is a rare and difficult to diagnose subtype of large B-cell lymphoma. The most common locations of presentation are in the central nervous system and the skin, but there are reports of other organ involvement. Due to the indolence, nonspecific symptoms, and rarity of the disease, this form of lymphoma is most often diagnosed postmortem. In this article, we describe a case of ILBL that presented as a rapidly progressive acute axonal polyneuropathy. Acute axonal polyneuropathy is a common disease process with a wide differential diagnosis, but there is limited literature on its prevalence as the presenting symptom of ILBL. This patient was treated with R-EPOCH and intrathecal methotrexate with significant improvement in his polyneuropathy after 1 cycle, and complete remission after 6 cycles. Data on chemotherapy regimens and their success rates for this disease are lacking.