I cannot create a summary of the requested article because it is not found in the search results provided. The results include articles on pancreatic islet transplantation for diabetes, non-Hodgkin's lymphomas, forest therapy and biotechnology, but not the March 2026 Science article titled "Stem cell therapies 'come of age' with two conditional approvals in Japan". In order to create an accurate and factual summary as per your requirements, I need access to the full text of this particular article.