Objective: Little is known about telomere dynamics in keloids. keloid. However, telomerase activity is usually repressed in the fully developed keloid. INTRODUCTION Keloids are benign tumors that result from abnormal wound healing. Persons with dark skin, for example, those of recent African or Asian origins, are more prone to keloids than fair-skinned whites of European ancestry.1,2 These fibro-proliferative tumors are more common in adolescents and young adults than in older persons and they occur more frequently in the head, neck and trunk than in the lower extremities. Keloids display a high recurrence rate postresection and there are no effective modalities for their prevention (short of avoiding skin injury) in individuals at risk. Various medical treatments to prevent keloid recurrence after resection have been employed with only limited success.1,2 The histology and composition of keloids have been well-characterized, but their pathogenesis is poorly understood, perhaps because there is no animal model for keloid formation.3 Keloid composition includes fibroblasts, inflammatory cells, an abundance of extracellular matrix, primarily collagen, and supportive vascular network. Previous research suggests the potential role of cytokines, principally interleukin 6 (IL-6),4 transforming growth factor beta (TGF),5,6 and mesenchymal stem cells7 in keloid pathogenesis. Keloid formation or, for that matter, any wound healing depends on cell proliferation. As somatic cells replicate, their telomeres, the TTAGGG tandem repeats at the ends of chromosomes, undergo progressive shortening.8,9 Thus, telomere shortening is an index of the replicative history of somatic cells, unless mechanisms that counteract telomere shortening are activated. One of these is the activation of telomerasea reverse transcriptase that adds telomere repeats to the ends of chromosomes9; the other is referred to as the alternative lengthening of telomeres (ALT).10 Accordingly, understanding telomere dynamics in keloids, which can become quite large, might shed light on potential mechanisms that sustain their growth over and above that of a normal wound healing. We explored this concept in the present work by measuring telomere lengths in keloids. METHODS Subjects We measured telomere length in keloids, in adjacent normal skin, 3599-32-4 manufacture and, when available, in subcutaneous excess fat and blood (leukocyte) samples from 16 individuals. They included 13 African Americans, 2 Hispanics, and 1 Asian; 8 males and 8 females, with age range from 14 to 58 years. Keloid resection 3599-32-4 manufacture and sampling of subcutaneous excess fat and blood Most keloids were resected under local anesthesia. The lesion was removed with minimal injury to adjacent normal skin. In some cases, keloids were removed under general anesthesia. In that setting, the anesthesiologist obtains a blood sample while inserting an intravenous catheter. Subcutaneous fat tissue was obtained only 3599-32-4 manufacture when fat was uncovered in the operative field. Measurements of telomere length and telomerase activity DNA was extracted by phenol/chloroform and telomere length was measured by Southern blot analysis of the terminal restriction fragments (TRFs).11 All DNA samples were subjected to integrity testing; no sample displayed evidence of DNA degradation. Telomerase activity was measured by the TRAP assay (TRAPeze Telomerase Detection kit, Millipore, California). In 9 keloids, we mapped telomere length in 3 distinct regions: the most distant area from the surgical excision, just below the epidermis (keloid 1); area adjacent to the normal skin at the base of the keloid (keloid 2); and the center of the base of the keloid (keloid 3). The remaining 7 keloids were small and the entire keloid was used to measure telomere length. As noted earlier, we obtained keloid and skin samples from the 16 participants but could not always obtain a complete set of samples (including keloid, skin, subcutaneous excess fat, and blood). Statistical analysis We used the mixed procedure in SAS 9.1 to perform repeated-measures ANOVA. Results from all participants were used for analyses, unless otherwise indicated. We assumed unstructured correlations between steps within the same individual to compare telomere lengths in different tissues or keloid regions. The model comparing skin and keloids used the following categories: keloid (in the case that the entire keloid was Rps6kb1 used), keloid 1, keloid 2, or keloid 3 as defined earlier. Least square means and confidence intervals (CIs) from the model are presented. A contrast was used to compare the mean telomere length in skin to keloids; since we had a single keloid sample for some patients but up to 3 samples from.