AAV-DJ Enables Targeted Gene Modulation in Human Ovarian Cells

Study question: Can adeno-associated viruses (AAVs) efficiently and safely transduce human primary granulosa cells and human ovarian stromal fibroblasts to modulate the expression of genes involved in follicle recruitment and ovarian microenvironment regulation? Summary answer: AAVs can efficiently transduce human primary granulosa cells and human ovarian stromal cells with low toxicity, with the serotype DJ (AAV-DJ) demonstrating superior performance. AAVs enable targeted modulation of ovarian genes such as AMHR2 in human primary granulosa cells and TGF{beta}1 in human ovarian stromal cells, supporting the feasibility of gene-based approaches to improve ovarian function. What is known already: Infertility affects approximately 15% of couples, with diminished oocyte quality and quantity being major contributors, particularly with advanced reproductive age. Assisted reproductive technologies rely primarily on hormonal stimulation and do not directly target molecular pathways governing folliculogenesis or the ovarian microenvironment. Animal studies suggest that gene therapy using AAVs offers a promising strategy for tissue-specific and durable gene modulation, yet its application in human ovarian cells remains largely unexplored. Study design, size, duration: This was an experimental laboratory study using primary human granulosa cells from patients undergoing in vitro fertilization (IVF) and ovarian stromal cells obtained from post-pubertal patients who donated surplus ovarian tissue from ovarian tissue cryopreservation procedures for research. Sixteen AAV serotypes were evaluated for transduction efficiency, toxicity, and expression dynamics, followed by functional gene knockdown studies using AAV-DJ-based shRNA vectors. Participants/materials, setting, methods: Primary human granulosa cells and ovarian stromal cells were isolated from follicular aspirates and ovarian tissue, respectively. Cells were transduced with GFP-expressing AAV serotypes at varying multiplicities of infection (MOIs), incubation times, and culture days to assess transduction efficiency and cytotoxicity. Lead serotypes were further evaluated in dose-response studies. Functional gene modulation was assessed using AAV-DJ-mediated shRNA knockdown of AMHR2 in granulosa cells and TGF{beta}1 in stromal cells, quantified by RT-qPCR, immunofluorescence, and western blotting. Main results and the role of chance: Six of sixteen AAV serotypes (AAV2, AAV3, AAV6, AAV9, AAV-DJ, and AAV-X1.1) achieved greater than 10% transduction efficiency in human primary granulosa cells. Among these, AAV-DJ demonstrated the highest efficiency across all MOIs tested, reaching up to 48% transduction at 100,000 MOI, significantly outperforming AAV2 and AAV9. Toxicity increased with viral dose for all serotypes but remained comparable across vectors, with AAV-DJ exhibiting higher efficiency with comparable toxicity. The AAV-DJ-shRNA-AMHR2 construct produced a significant reduction in expression of AMHR2 mRNA by ~81% (p<0.05) in human primary granulosa cells as well as at the protein level in HEK293T-AMHR2-ZsGreen engineered cells (~85% knockdown, p<0.01). In human ovarian stromal cells, AAV-DJ preferentially transduced EMILIN1 and ACTA2-positive fibroblast and myofibroblast-like cells and enabled robust knockdown of TGF{beta}1 at both transcript (~89% knockdown, p<0.05) and protein levels (~67% knockdown, p<0.0001) using AAV-DJ-shRNA-TGF{beta}1 construct. Limitations, reasons for caution: These experiments were performed in vitro using primary human ovarian cells, which may not fully recapitulate the in vivo ovarian environment. Functional reproductive outcomes were not assessed, and future studies will be required to evaluate the effects of gene modulation on folliculogenesis and fertility. Wider implications of the findings: These findings establish AAV-DJ as a promising vector for targeted gene modulation in human ovarian cells. This approach introduces a novel framework for addressing infertility and ovarian function by directly targeting molecular pathways involved in follicle recruitment and ovarian stromal signaling, potentially enhancing current assisted reproductive technologies.