Fibroblast dysfunction is a key factor in the non-healing of chronic venous leg ulcers

From the rarest to the most common: insights from progeroid syndromes into skin cancer and aging

Despite their rarity, diseases of premature aging, or "progeroid" syndromes, have provided important insights into basic mechanisms that may underlie cancer and normal aging. In this review, we highlight these recent developments in Hutchinson-Gilford progeria syndrome (HGPS), Werner syndrome, Bloom syndrome, Cockayne syndrome, trichothiodystrophy, ataxia-telangiectasia, Rothmund-Thomson syndrome, and xeroderma pigmentosum. Though they are caused by different mutations in various genes and often result in quite disparate phenotypes, deciphering the molecular bases of these conditions has served to highlight their underlying basic similarities. Studies of progeroid syndromes, particularly HGPS, the most dramatic form of premature aging, have contributed to our knowledge of fundamental processes of importance to skin biology, including DNA transcription, replication, and repair, genome instability, cellular senescence, and stem-cell differentiation.

Evaluation of a near-senescent human dermal fibroblast cell line and effect of amelogenin

BACKGROUND

Fibroblast senescence may delay healing of chronic wounds.

OBJECTIVES

To characterize a chronic human dermal fibroblast cell line (CRL-7815) with near-senescent properties, cell proliferation and production of wound-healing modulating cytokines, and biosynthesis and remodelling of collagen were compared with normal human dermal fibroblasts. Also, the response of CRL-7815 fibroblasts to the extracellular matrix protein amelogenin that is beneficial in the treatment of stalled chronic wounds was studied.

METHODS

Fibroblast proliferation was monitored by time-resolved growth curves and factors secreted into the culture medium containing 10% fetal bovine serum were measured by enzyme-linked immunosorbent assays. Fibroblast-mediated reorganization was examined in three-dimensional type I collagen matrices.

RESULTS

Cell proliferation over 9 days was significantly (P < 0.01) slower for CRL-7815 than for normal fibroblasts. Amelogenin at 1 mg mL(-1) increased (P < 0.01) CRL-7815 proliferation to the level of the normal fibroblasts. The neutrophil chemoattractant interleukin (IL)-8 was low while the constitutive production of monocyte chemoattractant protein (MCP)-1 was highly elevated in medium from cultured CRL-7815 fibroblasts. Amelogenin augmented IL-8 but attenuated MCP-1 secretion in CRL-7815 fibroblasts. The elevated vascular endothelial growth factor production in CRL-7815 fibroblasts was further increased with amelogenin while increased type I collagen synthesis by CRL-7815 was reduced with 0.1 mg mL(-1) amelogenin. The dramatically impaired collagen matrix remodelling with CRL-7815 fibroblasts (P < 0.001) was slightly improved with amelogenin (P = 0.0011).

CONCLUSIONS

The near-senescent cell line CRL-7815 shares functional anomalies with fibroblasts isolated from nonhealing chronic cutaneous wounds. Amelogenin has the capacity to switch chronic fibroblasts into an acute-like phenotype.

Oxidative stress and "senescent" fibroblasts in non-healing wounds as potential therapeutic targets

In chronic wounds, fibroblast dysfunctions, such as increased apoptosis, premature senescence, senescence-like phenotype, or poor growth response in the absence of senescence markers, have been reported. Some of these differential dysfunctions may be secondary to differences in patient age or sex, ulcer size or duration, edge versus base sampling, or culture technique. Nevertheless, the entire spectrum of fibroblast dysfunction may exist and be secondary to, or a response to, different amounts of oxidative stress.