Dysfunctional Stem Cells Contribute to Impaired Fracture Repair in Old Age

Stem cells perform the vital function of supporting surrounding tissue by providing new daughter somatic cells to make up losses and take their place to maintain tissue function. This stem cell activity declines with age, however, due to a combination of intrinsic damage to these cell populations, and increasing inactivity. The latter is an evolved reaction to rising levels of damage, one that serves to reduce cancer risk in earlier old age, but at the cost of a lengthy decline into incapacity. Pick near any dysfunction of aging and it is likely that loss of stem cell activity is to some degree contributing to the outcome. 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, a...
Source: Fight Aging! - Category: Research Authors: Tags: Daily News Source Type: blogs