Two linked advances address translational bottlenecks in AAV gene therapy: researchers reported engineered AAV variants that improve transduction of human vascular endothelial cells, and a separate study mapped how matrix effects distort AAV neutralization assays and proposed mitigation strategies. Improved capsids expand targetable cell types and may lower required doses; assay fixes reduce false positives and enhance comparability across neutralizing‑antibody screens. Together the findings tackle both vector design and the immunological assays that gate patient eligibility and trial enrollment. The work underscores upstream R&D gains and diagnostic standardization as complementary steps toward safer, more effective systemic gene therapies.