Rete Ridge Topography as a Determinant of Epidermal Stem Cell Identity: Implications for Skin Aging

Rete Ridge Topography as a Determinant of Epidermal Stem Cell Identity: Implications for Skin Aging | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Rete Ridge Topography as a Determinant of Epidermal Stem Cell Identity: Implications for Skin Aging Christine Lian, Rui Fang, Ryoko Hamanguchi, Shuyun Xu, Wonhye Lee, and 9 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9359924/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Stem cell niches are dynamic microenvironments that regulate tissue homeostasis. Epidermal stem cells (EpiSC) preferentially localize to concave regions of epidermal rete ridges, which serve as primary niches for stem cell maintenance. EpiSC number and functional integrity decline during chronological aging. A defining feature of aged skin is epidermal atrophy, in which the prominent rete ridges present in young skin become flattened. Whether such topographical alterations influence EpiSC homeostasis and differentiation remains unclear. To address this, we generated anatomically accurate rete ridge structures using 3D bioprinting of collagen matrices as an ex vivo model and compared EpiSC cultured within concave topography to those maintained on a flat matrix resembling aged skin. Transcriptomic analysis revealed that concave niches promoted keratinocyte differentiation, marked by increased type I and II keratin gene expression and downregulation of cell cycle–associated genes. ATAC-seq identified topography-dependent chromatin accessibility changes enriched for transcription factors regulating epidermal differentiation, including upregulation of KLF4 and GRHL3 and downregulation of SOX9, HOXA1, and ETS1. Consistently, aged human skin showed reduced KLF4 and GRHL3 and increased SOX9 compared with young skin. Our findings demonstrate that concave niche topography imposes a spatially defined EpiSC microenvironment that promotes differentiation, alters cell cycle, and when perturbed, potentially contributes to the aging process. We conclude that spatial localization within rete ridge regions significantly affects epidermal progenitor stemness properties as fundamental differences in the physical microenvironment appear to influence cell fate decisions, thus, form shapes function of EpiSC. Biological sciences/Developmental biology/Ageing Biological sciences/Stem cells/Skin stem cells Epidermal stem cells keratinocytes rete ridge stem cell niche ATAC-seq skin aging stem cell microenvironment topology CK15 GRHL3 KLF4 Full Text Additional Declarations There is NO Competing Interest. Supplementary Files SupplementarymaterialsFINAL.pdf Rete Ridge Topography as a Determinant of Epidermal Stem Cell Identity: Implications for Skin Aging Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9359924","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":620909898,"identity":"fa3894a9-35f0-4b67-8e48-6a8a09e1df9c","order_by":0,"name":"Christine 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microenvironment, topology, CK15, GRHL3, KLF4","lastPublishedDoi":"10.21203/rs.3.rs-9359924/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9359924/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Stem cell niches are dynamic microenvironments that regulate tissue homeostasis. Epidermal stem \r\ncells (EpiSC) preferentially localize to concave regions of epidermal rete ridges, which serve as \r\nprimary niches for stem cell maintenance. EpiSC number and functional integrity decline during \r\nchronological aging. A defining feature of aged skin is epidermal atrophy, in which the prominent \r\nrete ridges present in young skin become flattened. Whether such topographical alterations \r\ninfluence EpiSC homeostasis and differentiation remains unclear. To address this, we generated \r\nanatomically accurate rete ridge structures using 3D bioprinting of collagen matrices as an ex vivo\r\nmodel and compared EpiSC cultured within concave topography to those maintained on a flat \r\nmatrix resembling aged skin. Transcriptomic analysis revealed that concave niches promoted \r\nkeratinocyte differentiation, marked by increased type I and II keratin gene expression and \r\ndownregulation of cell cycle–associated genes. ATAC-seq identified topography-dependent \r\nchromatin accessibility changes enriched for transcription factors regulating epidermal \r\ndifferentiation, including upregulation of KLF4 and GRHL3 and downregulation of SOX9, \r\nHOXA1, and ETS1. Consistently, aged human skin showed reduced KLF4 and GRHL3 and \r\nincreased SOX9 compared with young skin. Our findings demonstrate that concave niche \r\ntopography imposes a spatially defined EpiSC microenvironment that promotes differentiation, \r\nalters cell cycle, and when perturbed, potentially contributes to the aging process. We conclude \r\nthat spatial localization within rete ridge regions significantly affects epidermal progenitor \r\nstemness properties as fundamental differences in the physical microenvironment appear to \r\ninfluence cell fate decisions, thus, form shapes function of EpiSC.","manuscriptTitle":"Rete Ridge Topography as a Determinant of Epidermal Stem Cell Identity: Implications for Skin Aging","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-14 03:55:46","doi":"10.21203/rs.3.rs-9359924/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"aed428eb-8f3b-496b-b984-9b43291a909b","owner":[],"postedDate":"April 14th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Reject after peer review","date":"2026-05-11T08:03:18+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"This content is not available.","date":"2026-05-08T10:59:04+00:00","index":1,"fulltext":"This content is not available."},{"type":"editorInvitedReview","content":"This content is not available.","date":"2026-05-04T23:05:41+00:00","index":3,"fulltext":"This content is not available."},{"type":"editorInvitedReview","content":"This content is not available.","date":"2026-05-01T17:04:57+00:00","index":2,"fulltext":"This content is not available."}],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":66079694,"name":"Biological sciences/Developmental biology/Ageing"},{"id":66079695,"name":"Biological sciences/Stem cells/Skin stem cells"}],"tags":[],"updatedAt":"2026-05-11T08:06:10+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-14 03:55:46","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9359924","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9359924","identity":"rs-9359924","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}