{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,10,4]],"date-time":"2026-10-04T03:54:05Z","timestamp":1791086045219,"version":"4.1.0"},"posted":{"date-parts":[[2026,9,29]]},"group-title":"Cell Biology","reference-count":25,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T00:00:00Z","timestamp":1790640000000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,9,29]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>\n                  Stem cell factor (SCF) from Leptin Receptor-expressing (LepR\n                  <jats:sup>+<\/jats:sup>\n                  ) mesenchymal stromal cells and endothelial cells is required for hematopoietic stem and progenitor cell maintenance in bone marrow. Consistent with this,\n                  <jats:italic>Scf<\/jats:italic>\n                  is highly expressed by LepR\n                  <jats:sup>+<\/jats:sup>\n                  cells and at lower levels by endothelial cells in bone marrow. However, endothelial cells outside the bone marrow produce circulating SCF, raising the question of whether the SCF that promotes stem and progenitor cell maintenance is produced inside or outside bone marrow. We found that\n                  <jats:italic>Scf<\/jats:italic>\n                  deletion in spleen and liver endothelial cells reduces SCF levels in the blood without affecting stem or progenitor numbers in the bone marrow. Moreover, deletion of\n                  <jats:italic>Scf<\/jats:italic>\n                  from mesenchymal cells in the long bones, but not vertebrae, of\n                  <jats:italic>Prx1<\/jats:italic>\n                  <jats:sup>\n                    <jats:italic>Cre<\/jats:italic>\n                  <\/jats:sup>\n                  ;\n                  <jats:italic>Scf<\/jats:italic>\n                  <jats:sup>\n                    <jats:italic>fl\/fl<\/jats:italic>\n                  <\/jats:sup>\n                  mice depletes stem and progenitor cells in long bones but not vertebrae. SCF thus acts locally within the bones in which it is made to promote stem and progenitor cell maintenance.\n                <\/jats:p>\n                <jats:sec>\n                  <jats:title>Key Points<\/jats:title>\n                  <jats:list list-type=\"bullet\">\n                    <jats:list-item>\n                      <jats:p>\n                        <jats:italic>Scf<\/jats:italic>\n                        deletion in endothelial cells outside of BM reduces SCF levels in blood without affecting stem or progenitor cell frequencies in BM\n                      <\/jats:p>\n                    <\/jats:list-item>\n                    <jats:list-item>\n                      <jats:p>\n                        <jats:italic>Scf<\/jats:italic>\n                        deletion from mesenchymal cells in long bones, but not vertebrae, depletes stem and progenitor cells in long bones but not vertebrae\n                      <\/jats:p>\n                    <\/jats:list-item>\n                  <\/jats:list>\n                <\/jats:sec>","DOI":"10.64898\/2026.09.28.755094","type":"posted-content","created":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T16:45:11Z","timestamp":1790700311000},"source":"Crossref","is-referenced-by-count":0,"title":["Stem cell factor acts locally in the bone marrow to promote stem and progenitor cell maintenance"],"prefix":"10.64898","author":[{"given":"Maria Angelica","family":"Freitas-Cortez","sequence":"first","affiliation":[{"name":"Children\u2019s Research Institute and the Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stefano","family":"Comazzetto","sequence":"additional","affiliation":[{"name":"Children\u2019s Research Institute and the Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA"},{"name":"Centre for Regenerative Medicine, Institute for Regeneration and Repair, University of Edinburgh, Edinburgh, EH16 4UU, United Kingdom"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiang","family":"Gao","sequence":"additional","affiliation":[{"name":"National Institute of Biological Sciences, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100084, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bo","family":"Shen","sequence":"additional","affiliation":[{"name":"National Institute of Biological Sciences, Beijing 102206, China; Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua University, Beijing 100084, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lei","family":"Ding","sequence":"additional","affiliation":[{"name":"Columbia Stem Cell Initiative, Department of Rehabilitation and Regenerative Medicine, Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, NY 10032, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhiyu","family":"Zhao","sequence":"additional","affiliation":[{"name":"Children\u2019s Research Institute and the Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sean J.","family":"Morrison","sequence":"additional","affiliation":[{"name":"Children\u2019s Research Institute and the Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA"},{"name":"Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"54368","reference":[{"key":"2026100320250486000_2026.09.28.755094v1.1","doi-asserted-by":"publisher","DOI":"10.1038\/nature10783"},{"key":"2026100320250486000_2026.09.28.755094v1.2","doi-asserted-by":"publisher","DOI":"10.1016\/S0065-2660(08)60549-0"},{"key":"2026100320250486000_2026.09.28.755094v1.3","doi-asserted-by":"publisher","DOI":"10.1016\/j.stem.2018.11.022"},{"key":"2026100320250486000_2026.09.28.755094v1.4","doi-asserted-by":"publisher","DOI":"10.1038\/s41586-019-1104-8"},{"key":"2026100320250486000_2026.09.28.755094v1.5","doi-asserted-by":"publisher","DOI":"10.1016\/J.CELL.2019.04.040"},{"key":"2026100320250486000_2026.09.28.755094v1.6","doi-asserted-by":"publisher","DOI":"10.1038\/s41556-019-0439-6"},{"key":"2026100320250486000_2026.09.28.755094v1.7","doi-asserted-by":"publisher","DOI":"10.1038\/nature15250"},{"key":"2026100320250486000_2026.09.28.755094v1.8","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.2412317122"},{"key":"2026100320250486000_2026.09.28.755094v1.9","doi-asserted-by":"publisher","DOI":"10.1038\/nature15530"},{"key":"2026100320250486000_2026.09.28.755094v1.10","doi-asserted-by":"publisher","DOI":"10.1038\/nature25739"},{"key":"2026100320250486000_2026.09.28.755094v1.11","doi-asserted-by":"publisher","DOI":"10.1016\/j.yexmp.2021.104678"},{"key":"2026100320250486000_2026.09.28.755094v1.12","doi-asserted-by":"publisher","DOI":"10.1016\/0092-8674(91)90326-T"},{"issue":"2","key":"2026100320250486000_2026.09.28.755094v1.13","first-page":"174","article-title":"Sl\/Sld hematopoietic progenitors are deficient in situ","volume":"22","year":"1994","journal-title":"Exp Hematol"},{"issue":"6","key":"2026100320250486000_2026.09.28.755094v1.14","first-page":"542","article-title":"Early transplantation to a normal microenvironment prevents the development of Steel hematopoietic stem cell defects","volume":"25","year":"1997","journal-title":"Exp Hematol"},{"key":"2026100320250486000_2026.09.28.755094v1.15","doi-asserted-by":"publisher","DOI":"10.1038\/ncb3299"},{"key":"2026100320250486000_2026.09.28.755094v1.16","doi-asserted-by":"publisher","DOI":"10.1182\/blood.2022019018"},{"issue":"4","key":"2026100320250486000_2026.09.28.755094v1.17","first-page":"335","article-title":"Dissecting the hematopoietic microenvironment. 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