Distribution of AAV-TK following Intracranial Convection-Enhanced Delivery into Rats

Abstract

Adeno-associated virus (AAV)-based vectors are being tested in animal models as viable treatments for glioma and neurodegenerative disease and could potentially be employed to target a variety of central nervous system disorders. The relationship between dose of injected vector and its resulting distribution in brain tissue has not been previously reported nor has the most efficient method of delivery been determined. Here we report that convection-enhanced delivery (CED) of 2.5 x 10(8), 2.5 x 10(9), or 2.5 x 10(10) particles of AAV-thymidine kinase (AAV-TK) into rat brain revealed a clear dose response. In the high-dose group, a volume of 300 mm3 of brain tissue was partially transduced. Results showed that infusion pump and subcutaneous osmotic pumps were both capable of delivering vector via CED and that total particle number was the most important determining factor in obtaining efficient expression. Results further showed differences in histopathology between the delivery groups. While administration of vector using infusion pump had relatively benign effects, the use of osmotic pumps resulted in notable toxicity to the surrounding brain tissue. To determine tissue distribution of vector following intracranial delivery, PCR analysis was performed on tissues from rats that received high doses of AAV-TK. Three weeks following CED, vector could be detected in both hemispheres of the brain, spinal cord, spleen, and kidney.

Early Oligodendrocyte/Myelin Pathology in Alzheimer's Disease Mice Constitutes a Novel Therapeutic Target

“…Mice were sacrificed and brains were analyzed 4 months post-transduction (6 months of age). 26,27 Immunohistochemistry for c-myc was performed, and the results revealed comparable rAAV-scFvphe KDEL IB and rAAV-scFvA␤ KDEL IB IB staining in the transduced CA1 hippocampal field ( Figure 4E-L). Co-immunohistochemistry for IB and the neuronal marker NeuN demonstrated that IB expression was restricted to pyramidal neurons of the vector-infused CA1 subregion (Figure 4, M-X).…”

A novel glioblastoma cancer gene therapy using AAV-mediated long-term expression of human TERT C-terminal polypeptide

“…Fourth, when coupled to a strong promoter like the hybrid CMV enhancer/chicken b-actin (CAG) promoter used in this study, it is capable of delivering high levels of transgene expression in a wide variety of cell types. For these reasons, AAV carrying therapeutic genes like angiostatin, 31,32 herpes simplex virus thymidine kinase (HSV-tK), 33,34 and interleukin-2 (IL-2) 35 have been employed in the treatment of malignant gliomas with varying degree of success. In the present study, we demonstrated that intratumoral delivery of rAAVhTERTC27, but not rAAV-EGFP, potently inhibits the growth of the glioblastoma cells by more than 80% at 5 weeks post-treatment and significantly prolongs the median survival time of the treated mice by approximately twofold.…”

Chemotherapeutic dose intensification for treatment of malignant brain tumors: Recent developments and future directions

“…Groothuis et al [27••] demonstrated that convection may enhance diffusion of water-soluble molecule delivery to the brain in a rat model. Several other recent studies detailed use of this approach in rat animal models [28][29][30][31]. Paclitaxel and topotecan were recently tested with interesting results in both preclinical [28] and clinical models [32].…”