Publications by authors named "Christoph A Kahl"

Viral vectors are extensively purified for use in biomedical research, in order to separate biologically active virus particles and to eliminate production related impurities that are assumed to be detrimental to the host. For recombinant adeno-associated virus (rAAV) vectors this is typically accomplished using density gradient-based methods, which are tedious and require specialized ultracentrifugation equipment. In order to streamline the preparation of rAAV vectors for pilot and small animal studies, we recently devised a simple ultrafiltration approach that permits rapid virus concentration and partial removal of production-related impurities.

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Anti-Müllerian hormone (AMH) plays a key role during ovarian follicular development, with local actions associated with a dynamic secretion profile by growing follicles. While results for AMH effects on antral follicle growth and function are consistent among studies in various species, any effects on preantral follicle development remain controversial. Therefore, experiments were conducted to investigate the direct actions and role of AMH during follicle development at the preantral stage.

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There is keen interest to define gene therapies aimed at restoration of auditory and vestibular function in the diseased or damaged mammalian inner ear. A persistent limitation of regenerative medical strategies that seek to correct or modify gene expression in the sensory epithelia of the inner ear involves efficacious delivery of a therapeutic genetic construct. Our approach is to define methodologies that enable fetal gene transfer to the developing mammalian inner ear in an effort to correct defective gene expression during formation of the sensory epithelia or during early postnatal life.

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Adenoviral vectors (vectors) expressing short-hairpin RNAs complementary to macaque nuclear progesterone (P) receptor PGR mRNA (shPGR) or a nontargeting scrambled control (shScram) were used to determine the role PGR plays in ovulation/luteinization in rhesus monkeys. Nonluteinized granulosa cells collected from monkeys (n = 4) undergoing controlled ovarian stimulation protocols were exposed to either shPGR, shScram, or no virus for 24 h; human chorionic gonadotropin (hCG) was then added to half of the wells to induce luteinization (luteinized granulosa cells [LGCs]; n = 4-6 wells/treatment/monkey). Cells/media were collected 48, 72, and 120 h postvector for evaluation of PGR mRNA and P levels.

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The spatiotemporal dynamics of triglyceride (TG) storage in unilocular adipocytes are not well understood. Here we applied ex vivo technology to study trafficking and metabolism of fluorescent fatty acids in adipose tissue explants. Live imaging revealed multiple cytoplasmic nodules surrounding the large central lipid droplet (cLD) of unilocular adipocytes.

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Article Synopsis
  • Researchers have developed a new treatment for monogenic diseases using lentiviral vectors carrying therapeutic genes, specifically aimed at addressing adenosine deaminase (ADA) deficiency.
  • Experiments showed that HIV-1-based vectors, particularly those using vesicular stomatitis virus glycoprotein, were more effective in delivering the gene and achieving higher copy numbers in tissues of ADA-deficient mice and newborn rhesus monkeys.
  • The findings indicate that this gene delivery method has potential for clinical applications, especially for ADA-deficient patients who have limited options for stem cell transplants.
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Immune responses to transgene products may lead to rejection of transduced cells, limiting successful gene therapy for genetic diseases. While moderate dosages of chemotherapeutic agents such as busulfan may increase hematopoietic stem cells (HSC) engraftment, they are not immune suppressive and do not abrogate immune responses to transgene products. Studies focused on nonmyeloablative conditioning with busulfan ± fludarabine in a clinically relevant monkey model to induce immune suppression to allow cells expressing a foreign transgene product to persist.

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Adenovirus vaccine vectors derived from rare human serotypes have been shown to be less potent than serotype 5 (Ad5) at inducing immune responses to encoded antigens. To identify highly immunogenic adenovirus vectors, we assessed pro-inflammatory cytokine expression, binding to the CD46 receptor, and immunogenicity. Species D adenoviruses uniquely suppressed pro-inflammatory cytokines and induced high levels of type I interferon.

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Objective: Non-myeloablative cytoreduction is used in clinical hematopoietic stem cell gene therapy trials to increase engraftment of gene-modified cells. We utilized an infant rhesus monkey model to identify an optimal dosage of busulfan that results in efficient long-term gene marking with minimal toxicities.

Methods: Bone marrow (BM) was harvested, followed by a single 2-hour intravenous infusion of busulfan at escalating dosages of 0 to 160 mg/m(2).

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HIV-1-derived lentiviral vectors have been pseudotyped with various envelope glycoproteins to alter their host range. Previously, we found that envelope glycoproteins derived from the alphavirus Ross River virus (RRV) can pseudotype lentiviral vectors and mediate efficient transduction of a variety of epithelial and fibroblast-derived cell lines. In this study, we have investigated transduction of hematopoietic cells using RRV-pseudotyped vectors encoding the enhanced green fluorescent protein (EGFP).

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Ross River virus (RRV) and Semliki Forest virus (SFV) are two alphaviruses that have a high degree of amino acid homology, as well as a very broad host range. We show here that envelope glycoproteins derived from both viruses can pseudotype human immunodeficiency virus type 1 (HIV-1)-derived lentivirus vectors. Both RRV and SFV glycoproteins considerably expand the host range of the lentivirus vector, and vectors can be efficiently concentrated by ultracentrifugation.

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