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Wagner DR, Karnik S, Gunderson ZJ, Nielsen JJ, Fennimore A, Promer HJ, Lowery JW, Loghmani MT, Low PS, McKinley TO, Kacena MA, Clauss M, Li J. Dysfunctional stem and progenitor cells impair fracture healing with age. World J Stem Cells 2019; 11:281-296. [PMID: 31293713 PMCID: PMC6600851 DOI: 10.4252/wjsc.v11.i6.281] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/26/2019] [Accepted: 06/13/2019] [Indexed: 02/06/2023] Open
Abstract
Successful fracture healing requires the simultaneous regeneration of both the bone and vasculature; mesenchymal stem cells (MSCs) are directed to replace the bone tissue, while endothelial progenitor cells (EPCs) form the new vasculature that supplies blood to the fracture site. In the elderly, the healing process is slowed, partly due to decreased regenerative function of these stem and progenitor cells. MSCs from older individuals are impaired with regard to cell number, proliferative capacity, ability to migrate, and osteochondrogenic differentiation potential. The proliferation, migration and function of EPCs are also compromised with advanced age. Although the reasons for cellular dysfunction with age are complex and multidimensional, reduced expression of growth factors, accumulation of oxidative damage from reactive oxygen species, and altered signaling of the Sirtuin-1 pathway are contributing factors to aging at the cellular level of both MSCs and EPCs. Because of these geriatric-specific issues, effective treatment for fracture repair may require new therapeutic techniques to restore cellular function. Some suggested directions for potential treatments include cellular therapies, pharmacological agents, treatments targeting age-related molecular mechanisms, and physical therapeutics. Advanced age is the primary risk factor for a fracture, due to the low bone mass and inferior bone quality associated with aging; a better understanding of the dysfunctional behavior of the aging cell will provide a foundation for new treatments to decrease healing time and reduce the development of complications during the extended recovery from fracture healing in the elderly.
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Affiliation(s)
- Diane R Wagner
- Department of Mechanical and Energy Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, United States
| | - Sonali Karnik
- Department of Mechanical and Energy Engineering, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, United States
| | - Zachary J Gunderson
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Jeffery J Nielsen
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, United States
| | - Alanna Fennimore
- Department of Physical Therapy, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, United States
| | - Hunter J Promer
- Division of Biomedical Science, Marian University College of Osteopathic Medicine, Indianapolis, IN 46222, United States
| | - Jonathan W Lowery
- Division of Biomedical Science, Marian University College of Osteopathic Medicine, Indianapolis, IN 46222, United States
| | - M Terry Loghmani
- Department of Physical Therapy, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, United States
| | - Philip S Low
- Department of Chemistry, Purdue University, West Lafayette, IN 47907 United States
| | - Todd O McKinley
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Melissa A Kacena
- Department of Orthopaedic Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, United States
- Richard L. Roudebush VA Medical Center, Indianapolis, IN 46202, United States
| | - Matthias Clauss
- Department of Medicine, Indiana University School of Medicine, Indianapolis, IN 46202, United States
| | - Jiliang Li
- Department of Biology, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202, United States
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