{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T05:02:07Z","timestamp":1790226127785,"version":"4.1.0"},"reference-count":25,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T00:00:00Z","timestamp":1790208000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Med."],"abstract":"<jats:p>This case report describes a 22-year-old female patient who developed refractory grade IV BK virus-associated late-onset hemorrhagic cystitis (HC) on day 69 following haploidentical hematopoietic stem cell transplantation. After conventional stepwise interventions\u2014including bladder irrigation, repeated transcatheter arterial embolization, and endoscopic electrocoagulation\u2014failed to achieve disease control, a combination regimen comprising umbilical cord-derived mesenchymal stem cells (MSCs) and intravenous cidofovir was administered on day 84 post-transplant. Following this combined therapy, the patient's bladder hemorrhage was progressively controlled, dysuria was relieved, and transfusion requirements decreased. Macroscopic hematuria began to decrease on day 98 post-transplant and resolved completely by day 124, accompanied by a marked decline in BK viral load during follow-up. This case suggests that the combination of MSCs and cidofovir may serve as a potential salvage strategy for severe, refractory virus-associated HC and may also offer ancillary benefit in promoting hematopoietic recovery.<\/jats:p>","DOI":"10.3389\/fmed.2026.1865978","type":"journal-article","created":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T04:36:46Z","timestamp":1790224606000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Combination of mesenchymal stem cells and cidofovir for the treatment of BK virus-associated late-onset hemorrhagic cystitis after allogeneic hematopoietic stem cell transplantation: a case report"],"prefix":"10.3389","volume":"13","author":[{"given":"Feifei","family":"Liu","sequence":"first","affiliation":[{"name":"Department of Hematology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University","place":["Hangzhou, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cheng","family":"Zhang","sequence":"additional","affiliation":[{"name":"Department of Hematology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University","place":["Hangzhou, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Huaping","family":"Du","sequence":"additional","affiliation":[{"name":"Department of Hematology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University","place":["Hangzhou, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,9,24]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"929","DOI":"10.1038\/sj.bmt.1705139","article-title":"Polyoma BK virus and haemorrhagic cystitis in haematopoietic stem cell transplantation: a changing paradigm","volume":"36","author":"Leung","year":"2005","journal-title":"Bone Marrow 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