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Bhalla P, Du Q, Kumar A, Xing C, Moses A, Dozmorov I, Wysocki CA, Cleaver OB, Pirolli TJ, Markert ML, de la Morena MT, Baldini A, van Oers NS. Mesenchymal cell replacement corrects thymic hypoplasia in murine models of 22q11.2 deletion syndrome. J Clin Invest 2023; 133:e173145. [PMID: 37395280 DOI: 10.1172/jci173145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2023] Open
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Bhalla P, Du Q, Kumar A, Xing C, Moses A, Dozmorov I, Wysocki CA, Cleaver OB, Pirolli TJ, Markert ML, de la Morena MT, Baldini A, van Oers NS. Mesenchymal cell replacement corrects thymus hypoplasia in murine models of 22q11.2 deletion syndrome. J Clin Invest 2022; 132:160101. [PMID: 36136514 DOI: 10.1172/jci160101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Accepted: 09/21/2022] [Indexed: 11/17/2022] Open
Abstract
22q11.2 deletion syndrome (22q11.2DS) is the most common human chromosomal microdeletion, causing developmentally linked congenital malformations; thymus hypoplasia, hypoparathyroidism and/or cardiac defects. Thymus hypoplasia leads to T cell lymphopenia, which most often results in mild SCID. Despite decades of research, the molecular underpinnings leading to thymus hypoplasia in 22q11.2DS remain unknown. Comparing embryonic thymuses from mouse models of 22q11.2DS (Tbx1neo2/neo2) revealed similar proportions of mesenchymal-, epithelial- and hematopoietic- cell types as controls. Yet, the small thymuses were growth restricted in fetal organ cultures. Replacement of Tbx1neo2/neo2 thymus mesenchymal cells with normal ones restored tissue growth. Comparative single cell RNA sequencing of embryonic thymuses uncovered 17 distinct cell subsets, with transcriptome differences predominant in the 5 mesenchymal subsets from the Tbx1neo2/neo2 line. Transcripts impacted include extracellular matrix (ECM) proteins, consistent with increased collagen deposition seen in the small thymuses. Attenuating collagen cross-links with minoxidil restored thymus tissue expansion for hypoplastic lobes. In colony forming assays, the Tbx1neo2/neo2-derived mesenchymal cells had reduced expansion potential, contrasting the normal growth of thymus epithelial cells. These findings suggest that mesenchymal cells are causal to the small embryonic thymuses in 22q11.2DS mouse models, correctable by substituting with normal mesenchyme.
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Affiliation(s)
- Pratibha Bhalla
- Department of Immunology, UT Southwestern Medical Center, Dallas, United States of America
| | - Qiumei Du
- Department of Immunology, UT Southwestern Medical Center, Dallas, United States of America
| | - Ashwani Kumar
- Eugene McDermott Center for Human Growth and Development, UT Southwestern Medical Center, Dallas, United States of America
| | - Chao Xing
- Eugene McDermott Center for Human Growth and Development, UT Southwestern Medical Center, Dallas, United States of America
| | - Angela Moses
- Department of Immunology, UT Southwestern Medical Center, Dallas, United States of America
| | - Igor Dozmorov
- Department of Immunology, UT Southwestern Medical Center, Dallas, United States of America
| | - Christian A Wysocki
- Department of Internal Medicine, University of Texas Southwestern, Dallas, United States of America
| | - Ondine B Cleaver
- Department of Molecular Biology, University of Texas Southwestern, Dallas, United States of America
| | - Timothy J Pirolli
- Department of Pediatrics, UT Southwestern Medical Center, Dallas, United States of America
| | - Mary Louise Markert
- Departments of Pediatrics and Immunology, Duke University Medical Center, Durham, United States of America
| | - M Teresa de la Morena
- Department of Pediatrics, Seattle Children's Hospital, Seattle, United States of America
| | - Antonio Baldini
- Department of Molecular Medicine and Medical Biotechnologies, University Federico II, Naples, Naples, Italy
| | - Nicolai Sc van Oers
- Department of Immunology, UT Southwestern Medical Center, Dallas, United States of America
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